Department of Medical Imaging Research Day 2009 has been made ...

DEPARTMENT OF MEDICAL IMAGING, UNIVERSITY OF TORONTOANNUAL RESEARCH DAY 2009Date: Thursday, April 16, 2009Location: Ben Sadowski Auditorium, 18th floor, Mount Sinai Hospital, 600 University Avenue9:00 am Patrice Bret IntroductionChest and Cardiac ImagingSession Chair: Narinder Paul9:08 am Susan James Apical hypertrophic cardiomyopathy: When is it benign disease?Correlating MRI findings with clinical outcome9:16 am Robert Kurtz Coronary CT angiography following myocardial perfusion scintigraphy inpatients with low to intermediate risk of coronary artery disease:Determination of predictive variables9:24 am Narinder Paul Optimal phase reconstruction of coronary artery segments: The CORE 64experience9:32 am Ida Chan Reliability of human and computer automated analysis for tracheomalacia:A comparison9:40 am Perry Choi Pulmonary high resolution CT findings and CFTR gene mutations inpatients with chronic sinopulmonary disease9:48 am Monika Dhopeshwarkar Screen detected lung cancer: A retrospective analysis of CT appearance9:56 am Zhi Dong Detection of pleural plaques with low-dose computed tomography(LDCT) in asbestos workers10:04 am Alexander McGregor Analysis of gender differences in emphysema development in smokers10:12 am Ravi Menezes Changes in smoking habits in participants of a lung cancer screeningstudy10:20 am Babak Shamshirsaz Lesions after stereotactic body radiotherapy: Misdiagnoses and pitfalls10:28 am Dennis Boparai Incidental lumbar spine pathology detected on pre-uterine arteryembolization MRIs10:36 am COFFEE BREAKBreast, MSK and PhysicsSession Chair: Marshall Sussman10:48 am Leah Shuparski Merits of five clinical dosimeters in an interventional radiology setting10:56 am Pavel Crystal MRI-guided vacuum-assisted breast biopsy: Initial experience11:04 am Riham Eiada Can DWI be a noninvasive method to predict axillary metastases inpatients with biopsy proven breast carcinoma?11:12 am Arifa Sadaf Potential contribution of computer-aided detection to the sensitivity offull-field digital mammography11:20 am Afsaneh Amirabadi Assessment of early synovium and cartilage changes in hemophilicarthropathy in a rabbit model11:28 am Sam Dabbo An audit of bone mineral density reporting11:36 am Ueli Studler Feasibility study of simultaneous physical and real-time MRI examinationof medial collateral ligament injuries in a 1.5-T wide-bore magnet1 of 71

University of Toronto Department of Medical Imaging Research Day 200911:44 am Andrea Doria MR imaging as a screening tool for early detection of intraarticular bleedin hemophilic children: A systematic review11:52 am April Khademi Automatic contrast enhancement of cerebral white matter lesions inFLAIR MRI12:00 pm Marshall Sussman A post-processing method for generating arbitrary T2-weighted contrast inMRI12:08 pm LUNCHNeuroimagingSession Chair: David Mikulis1:12 pm Daniel Baxter Comparison of Gadofosveset trisodium (Vasovist) steady state enhancedmagnetic resonance angiography (MRA) with first pass and threedimensional time of flight MRA at 1.5 Tesla in the follow-up of coiledcerebral aneurysms1:20 pm Fang Liu Sex differences in the human corpus callosum microstructure: T2 myelinwaterimaging versus diffusion tensor imaging1:28 pm David Mikulis Exhausted cerebral autoregulation is spatially associated with corticalatrophy1:36 pm Vitaly Sygal Comparative detectability of magnetic susceptibility signals seen on EPI-GRE, MPGR and VEN BOLD sequences using 3T MRI: Preliminaryresults1:44 pm Bejoy Thomas Assessment of cerebrovascular reactivity using real time BOLD MRI inchildren with Moyamoya disease: A feasibility study1:52 pm Rebecca Thornhill Dynamic susceptibility contrast MRI in acute ischemic stroke: Surrogatemeasures of BBB permeability for the prediction of hemorrhagictransformation2:00 pm Jean Marie U-King-Im Characterization of carotid plaque hemorrhage: A CT angiography andMR direct thrombus imaging study2:08 pm Jeff Winter DTI and cerebrovascular reactivity MR imaging in the developing swinebrain2:16 pm Johanna Monsalve Imaging features of anterior pyriform aperture stenosis and centralincisor syndrome including labyrinthine dysplasia2:24 pm Aditya Bharatha MR imaging assessment of parapharyngeal extension in nasopharyngealcarcinoma2:32 pm COFFEE BREAKVascular and Interventional ImagingSession Chair: Dheeraj Rajan2:42 pm Rob Beecroft Short-term outcomes after varicocele repair by embolization andmicrosurgical varicocelectomy: Implications for IVF planning2:50 pm Mark Baerlocher Interim results of the Celect IVC filter registry2:58 pm Clare Bent Incidence of type one endoleak in patients with a hostile neck using suprarenal fixation aortic stent grafts: Are the instructions for use (IFU) stillapplicable?2 of 71

University of Toronto Department of Medical Imaging Research Day 20093:06 pm Del Dhanoa Assessment of clinical predictors for endoleaks and complications inpatients undergoing endovascular aneurysm repair (EVAR)3:14 pm Donna D’Souza Combined prophylactic internal iliac artery balloon occlusion and uterineartery embolization in the management of invasive placenta3:22 pm Kiat T. Tan Molecular imaging of atherosclerotic plaque3:30 pm John Kachura Radiofrequency ablation of renal cell carcinoma: Mid-term results3:38 pm Kebby King Bland hepatic artery embolization for symptomatic neuroendocrine tumormetastases: An 11-year experience3:46 pm Dheeraj Rajan Efficacy of stent-graft placement for salvage of dysfunctionalhemodialysis fistulas3:54 pm Ahmed Farooq Retrospective review of non-vascular findings in peripheral CTangiography4:02 pm Joe Barfett Limb perfusion: Characterization of a new techniqueAbdominal, GU, GI ImagingSession Chair: Martin O’Malley4:10 pm Martin O’Malley CT urography: Image quality and accuracy for upper tract urothelialcancer4:18 pm Mostafa Atri Microbubble DCE-US, DCE-CT, and DCE-MRI for the assessment oftumor response to Sunitinib treatment of renal cell carcinoma: Preliminaryresults4:26 pm David Kelton Radiology resident on-call productivity during a night shift schedule: Apilot project4:34 pm Sean McSweeney Biliary anatomy of potential donor for living donor liver transplantation:The utility of CT cholangiography in cases with indeterminate results onMRCP4:42 pm Richa Mittal The impact in abdominal imaging with the introduction of a dedicatedemergency CT4:50 pm Hojun Yu Pseudoenhancement within local ablation zone of hepatic tumors due tononlinear artifact on contrast-enhanced ultrasound4:58 pm Aiden Moktassi Magnetic resonance imaging of liver disease in hereditary hemorrhagictelangiectasia5:06 pm Jaydeep Halankar Interval growth of focal nodular hyperplasia in the liver on MR imaging5:14 pm Paula O’Donoghue No significant difference between nuchal translucency (NT) in weeks 11-13 +6 of singleton pregnancies conceived spontaneously and by IVF/ICSI5:22 pm Patrice Bret Closing RemarksDepartment of Medical Imaging Research Day 2009has been made possible bythe generous support of GE Healthcare.3 of 71

University of Toronto Department of Medical Imaging Research Day 2009Chest and Cardiac Imaging4 of 71

University of Toronto Department of Medical Imaging Research Day 2009Apical hypertrophic cardiomyopathy: When is it benign disease?Susan James, Elsie Nguyen, Visal Pen, Yon Mi Sung, Patrick Sparrow, Naeem MerchantDepartment of Medical Imaging, University of TorontoPurpose: Apical hypertrophic cardiomyopathy (ApHCM) is a rare morphologicalsubtype of HCM thought to have a benign course but recent literature has challenged this.The purpose of our study was to describe the most common imaging findings of ApHCMand to correlate with clinical outcome.Methods and Materials: Retrospective review of MRIs for 30 ApHCM patients (22men, mean age 52 yrs, range 18-81 yrs) by two radiologists blinded to patient clinicaloutcome. Disagreements were resolved by consensus. MR imaging features such asmaximum wall thickness, presence and extent of delayed enhancement, right ventricularinvolvement, left atrial size, apical aneurysms, left ventricular mass and function wererecorded. Clinical outcome measures such as arrhythmia, myocardial infarction, stroke,heart failure and syncope were recorded. Fisher’s exact test was used for categoricalvariables and t-test used for continuous variables to compare MRI findings among thesymptomatic and asymptomatic groups.Results: Atrial fibrillation or flutter (n=3), stroke (n=3) and non-sustained ventriculartachycardia (n=2) were the most common events seen in 27% of patients (8/30) who wereolder than the asymptomatic group (mean 62 yrs vs. 49, p

University of Toronto Department of Medical Imaging Research Day 2009Coronary CT angiography following myocardial perfusion scintigraphyin patients with low to intermediate risk of coronary artery disease:Determination of predictive variablesR Kurtz, V Prabhudesai, D Marcuzzi, P McEwan, J Sloninko, G Tomlinson, M FreemanPurpose: To determine the clinical and scintigraphic variables that predict the presenceof significant coronary artery disease (CAD) by Coronary computed tomographyangiography (CCTA) in those patients with low-to-intermediate risk for CAD followingMyocardial Perfusion Imaging (MPI).Materials and Methods: This study was approved by the local research ethics board.Informed consent was waived. A retrospective analysis was performed on 968consecutive patients who underwent CCTA at our institution in a two-year period (2006-2008). We identified 163 patients with low-to-intermediate risk for CAD (according toage, symptoms, no prior cardiac event, results of stress testing and MPI) who also hadMPI within 12 months of CCTA. CCTA grading of coronary artery stenoses wasperformed and those patients with a stenosis of at least 50% in at least one vessel weredefined as having significant CAD. We performed univariate analyses of age, gender,body mass index (BMI), coronary risk factors (diabetes mellitus, hypertension, smoking,hypercholesterolemia, family history), presenting symptoms (angina, atypical angina,nonanginal chest pain, asymptomatic), exercise induced ST depression and perfusionimaging for the prediction of significant CAD by CCTA. Multiple logistic regression wasused to assess the dependence of significant CAD on patient age, gender, number of riskfactors and MPI results.Results: Increased age (p=0.0002), hypertension (p=0.0373), and hyperlipidemia(p=0.0012) were associated with significant CAD on CCTA. Increased number of riskfactors were present in those with significant CAD on CCTA (p=0.0036). Typical anginawas a more frequent clinical presentation while atypical and non-anginal chest pain was aless frequent clinical presentation in those with significant CAD on CCTA (p=0.03).Those patients with reversible perfusion defects, with and without positive stress testwere most predictive of significant CAD with likelihood ratios of 5.48 and 1.92,respectively. There was a statistically significant association between overall MPI resultand significant CAD on CCTA (p=0.002). Age (OR=2.13; p=0.0003), number of riskfactors (OR=1.58; p=0.015) and MPI results (OR=3.01; p=0.0092) were all found to beassociated with significant CAD in multiple logistic regression.Conclusion: The presence of significant CAD as determined by CCTA is associated withdemographic factors, type of clinical presentation and results of MPI. The presence ofreversible perfusion abnormalities is a strong independent predictor of significant disease.6 of 71

University of Toronto Department of Medical Imaging Research Day 2009Optimal phase reconstruction of coronary artery segments:The CORE 64 experienceNS Paul, A Zadeh, A Vavere, I Gottlieb, J Hoe, J Brinker, M Dewey,J Miller, M Clouse, C Rochitte, E Shapiro, H Niinuma, J AC LimaPurpose: To assess the feasibility of using prospective EKG gating with 64 row MDCTin CT coronary angiography (CTCA), by analysing the optimal phase reconstructionsused in retrospectively gated acquisitions during the CORE 64 trial.Method and Materials: 9 cardiac centres recruited 401 patients to have CTCA andcoronary angiography from Oct 2005-Jan 2007 (CORE 64 Trial). CTCA was performedon 64 row MDCT (Aquilion, Toshiba, Japan), targeting a heart rate (HR) less than orequal to 65 bpm.Raw data were analysed by a central core lab to determine the optimal phase ofreconstruction for motionless coronary artery segments (CAS) using a 15 segment model.Image analysis was performed by 2 blinded, independent readers. Readers could usevolume rendered images, curved MPR's, MIPs, and cross-sectional images. A singlephase of reconstruction (SPR) was recorded when both readers agreed that a singleacquistion window was optimal for all CAS. In all other scenarios, more than one phasewas recorded.Results: To date, 291 patient datasets have been analyzed; 214 men (73%), mean age59y (40-89) totaling 5529 segments. On a per patient basis, overall 70% of patientsrequired a single phase for optimal CTCA reconstruction, on a per segment basis, 5064segments (91.6%) were optimally reconstructed using a single phase (SPR) for the entireexam.SPR as follows: HR (no. of patients, % SPR) per patient analysis; 70 (18, 53%). Per segment analysis: HR(no. of segments, %SPR); 70 (646, 88%).HR determined the optimal phase for SPR as follows: HR (mean phase in ms, 2SD, min,max); 70 (574.6, 159.4,140, 940).Conclusion: 1. At lower heart rates, there is increased likelihood of using a single phasefor optimal reconstruction (SPR) of coronary artery segments using conventional 64 rowMDCT. 2. At heart rates below 55bpm, a SPR is used in 84% of patients. 3. Withincreasing heart rate, the optimal phase of reconstruction shifts from the diastolic towardsthe systolic phase of the cardiac cycle.Clinical Relevance/Application: Prospective EKG gated cardiac CT is a feasibleproposition. To optimize radiation dose reduction, the heart rate needs to be aggressivelycontrolled, ideally to 55bpm or less.7 of 71

University of Toronto Department of Medical Imaging Research Day 2009Reliability of human and computer automated analysisfor tracheomalacia: A comparisonIda H Chan, Department of Medical Imaging, University of TorontoSheldon Mintz, Women’s College Hospital, University of TorontoMartin Shoichet, Faculty of Medicine, University of TorontoEric Stutz, Faculty of Medicine, University of TorontoDavid A Koff, Sunnybrook Health Sciences Centre, University of TorontoPurpose: Comparing the reliability of human and computer automated analysis fortracheomalacia.Materials and Methods: CTs from 18 subjects from a previous tracheomalaciasurveillance study were randomly selected for analysis, 8 meeting standardizeddiagnostic criteria for tracheomalacia as measured by one human observer. Each subjecthad a helical inspiratory MDCT, end inspiratory and expiratory HRCT, and a low dosedynamic expiratory scan. Tracheomalacia was defined as a >50% decrease in trachealcross-sectional area comparing dynamic expiratory to helical scans at the clavicular head(CH) and aortic arch (AA). A human observer then independently re-analyzed theoriginal CTs, and a custom ImageJ plugin (IJ) that automatically segmented andcalculated tracheal cross-sectional area. Ratios comparing expiratory and inspiratoryHRCTs (EI) as well as the forced-expiratory to helical (FH) scans were calculated.Results: The first human observer identified 8/18 participants with tracheomalacia;independent observer 7/18; IJ 7/18. IJ repeat analysis on the same study did not vary.Cohen’s kappa was 0.89 between the two human measurers, and between the computer toaveraged human set. EI ratios did not correlate with FH ratios, and did not predicttracheomalacia as none were less than 50%. The interclass correlation coefficient (ICC)varied from 0.21 to 0.90 between the humans (mean 0.56); and 0.45 to 0.98 between theaveraged human and computer measurers (mean 0.76). For all the EI ratios, there wereno significant differences by paired-t value testing between the groups. FH ratiosdiffered significantly (p

University of Toronto Department of Medical Imaging Research Day 2009Pulmonary high resolution CT findings and CFTR gene mutationsin patients with chronic sinopulmonary diseasePerry Choi, Department of Medical Imaging, University of TorontoWilliam Weiser, Department of Radiology, St. Michael’s HospitalTanja Gonska, Department of Respirology, St. Michael’s HospitalAnnie Dupuis, Department of Respirology, St. Michael’s HospitalElizabeth Tullis Department of Respirology, St. Michael’s HospitalPurpose: To determine the relationship between CFTR gene mutations and severity ofpulmonary CT findings in patients with chronic sinopulmonary disease.Method: Patients with symptoms compatible with chronic sinopulmonary disease wereprospectively recruited. Participating patients underwent medical questionnaire, clinicalassessment, CFTR gene sequencing, pulmonary high resolution CT analysis with theBhalla 1 scoring system, and functional analysis with sweat chloride testing and nasalpotential difference measurements.Results: Eighty-one patients were prospectively recruited. Of those, thirty-sevenpatients had appropriate symptoms to justify completion of all diagnostic tests includingCT thorax scan. Subgroup analysis of the 37 patients with CT scans revealed a mean ageof 38 years. Seven of the 37 patients (19%) had two mutations, 8 (22%) had onemutation, and 22 (59%) did not have any mutations in the CFTR gene. There was a trendtowards a more severe Bhalla CT score in patients with greater number of mutations.Patients with no CFTR mutations had a mean CT score of 5.7 (n=22), those with onemutation had a mean CT score of 7.1 (n=8), and those with two mutations had a mean CTscore of 9.7 2 (n=7). The patients with two CFTR mutations also had sweat chloride andnasal potential difference values compatible with cystic fibrosis. The mean Bhalla CTscore was more severe in patients meeting diagnostic criteria for cystic fibrosis (n=7,19%) compared with those not meeting criteria (Bhalla CT score of 10 vs. 6 respectively,p=0.006).Conclusion: There is an increased frequency of CFTR gene mutations in patients withchronic sinopulmonary disease. CT studies demonstrated a trend towards more severepulmonary findings in patients with increased number of CFTR gene mutations.1Bhalla et al. Radiology. 1991;179:783-788.2A higher value in the CT Bhalla score signifies greater severity of pulmonary findings.9 of 71

University of Toronto Department of Medical Imaging Research Day 2009Screen detected lung cancer: A retrospective analysis of CT appearanceMonika Dhopeshwarkar, Heidi Roberts, Ravi Menezes, Zhi Dong,Igor Sitartchouk, Shaf Keshavjee, Scott BoernerObject or Purpose of Study: To retrospectively evaluate characteristics of cancersdiagnosed in a low dose computed tomography lung cancer screening study.Materials, Methods and Procedures: As part of I-ELCAP, we screened a cohortof 4738 at risk current and former smokers, 2601 (55%) women and 2137 (45%) men.Seventy-seven (77) cancers in 75 individuals were detected and evaluated for time pointof detection, location, morphology, histology, stage at diagnosis, treatment and survival.In 37 cases PET was available for correlation. Follow up imaging for computation ofgrowth rates was available in 57 cases.Results: 77 cancers were found in 75 individuals, 56 women and19 men, raging in agefrom 50-79 years (mean 63). Only 5 (6.5%) cancers were not seen on baseline scan.Histology revealed 56 (73%) adenocarcinoma, 11 (14%) squamous cell cancer (SCC),5 (6%) small cell lung cancer (SCLC), 2 (3%) large cell carcinoma and 3 (4%) carcinoid.Most common location was LUL (34%) & RUL (31%). 44 cancers were solid (57%),14 (18%) non solid & 19 (25%) part solid. 32 (40%) lung cancers had spiculations and54 (70%) irregular margins. Median tumor size was 17x13 mm.53 (69%) cancers were Stage I (IA51%, IB18%). Most of the cancers (n=57, 74%) weretreated surgically. To date 65 patients are alive, with a median observation time of26 months, survival is 87%.Of 37 cancers evaluated by PET scan, 20 (54%) were metabolically active: all of thesquamous, SCLC and large cell cancers but only 12 (48%) of the adenocarcinoma wereactive.Of the 57 cases with follow up CT scans, 34 nodules increased in size. Mean doublingtime (DT) for all cancers was 232 days (median 113). In 26 women, mean DT was239 days (median 131), while in 8 men mean was 110 days (median 87). DT of > 400days was present in 5 cases, all women and all adenocarcinoma. The mean and medianDT for adenocarcinoma was 237 and 123 days respectively, for SCLC 136 and 148 daysrespectively, and for SCC 73 and 63 days, respectively.Significance of the Conclusions: Screening detects lung cancer in early treatable stage.Women have a higher prevalence of lung cancers and have more slow-growingadenocarcinoma. Most cancers can be surgically resected and survival is high after amedium observation time of 26 months.10 of 71

University of Toronto Department of Medical Imaging Research Day 2009Detection of pleural plaques with low-dosecomputed tomography (LDCT) in asbestos workersZhi Dong, Demetris Patsios, Monika Dhopeshwarkar,Andre M Pereira, Ravi J Menezes, Heidi RobertsPurpose: The pleural plaque is a specific sign of asbestos exposure, and can besensitively revealed with low-dose CT. The purpose of this study is to analyze prevalenceof pleural plaques (PP) in asbestos workers with low-dose CT (LDCT) and itsdemographic correlation.Material and Methods: 802 participants (M: F=790:12; mean age 60.6Y) were asbestosworkers from Early Diagnosis of Mesothelioma and Lung Cancer Program. The subjectsmet the enrollment criteria of age above 30 years old being in general good health withno prior cancer history; initiating asbestos exposure over 20 years. The smoking packyear(PKY) and asbestos exposure duration (Years) were recorded.All participants underwent full chest CT scan (GE Lightspeed QXi / Plus). The low-dosetechnique was set up at 120 kV, 50~60 mA, and slice thickness was1.25 mm.The CT demonstration of PP was recorded by its anatomic location of costal,diaphragmatic, mediastinal and fissural pleura. The extent of none, mild, moderate andsevere PP were scored as 0~3 respectively, according to the percentage of pleural surfaceinvolvement (0, 30%).t-tests for average age and exposure duration between PP+ and PP- groups; Pearson'scorrelation for PP extent with age, PKY and exposure Yrs; Chi-square test for PP+/PPandsmoking/nonsmoking factors were analyzed. The p < 0.05 were considered to besignificant.Results: In this (802) investigated population, the positive PP detected with LDCT was497 (62%) and negative 305 (38%).Of 497 CT positive cases, the mild, moderate and severe PP were 341 (69%), 134 (27%)and 22 (4%) respectively.There was 8 year difference of the average age between PP positive (64Y) and negative(56Y) groups (t-test p

University of Toronto Department of Medical Imaging Research Day 2009The PP risk ratio for smoking to non-smoking group was 1.23; while in smokers withPKY >20, the risk ratio was 1.27.In 497 PP cases, the costal pleura was involved in 480 (97%) cases with 28 yrs exposureduration, this prevalence were 1.26 times, 3.2 times and 32 times more frequent thandiaphragmatic (381, 77%, 27.1yrs), mediastinal (150, 30%, 27.5 yrs) and fissural pleura(15, 3%,30.7 yrs) respectively.Conclusion: Aging had a predominant role in the extent of PP development. Smoking(>20PKY) increased the risk of PP in asbestos workers. Costal pleura were morevulnerable to asbestos related pleural plaques than diaphragmatic, mediastinal, andfissural pleura.12 of 71

University of Toronto Department of Medical Imaging Research Day 2009Analysis of gender differences in emphysema development in smokersAlexander McGregor, George Dong, Ravi Menezes, Heidi RobertsPrincess Margaret Hospital, University Health NetworkPurpose: Data on transgender differences in emphysema is still limited. The purpose ofthis study is to verify whether differences exist in the development of emphysematousareas between males and females, and to examine the influence of the relationshipbetween emphysema and clinical features.Methods and Materials: We used multi-detector computed tomography (MDCT) scansobtained by the International Early Lung Cancer Action Project (I-ELCAP) for thisretrospective analysis. The MDCT scans were analyzed using an automated emphysemadetection program (YACTA version 0.9) which provided data on several quantitativeparameters such as Lung volume (ml), MLD (HU), 15th Percentile point (HU),Emphysema clusters by class (%), and Emphysema type (%). For these parameters,multiple linear regression models were applied to asses the gender effect, after allowancefor age, body mass index (BMI), and smoking history.Results: Females when compared to males showed less extensive development inemphysema cluster classes 1 and 2. Centrilobular emphysema development wassignificantly greater in females over males. Males showed more panlobular emphysemadevelopment than females.Conclusion: Males and females develop emphysema differently as a result of lungdamage caused by tobacco exposure. In smokers with relatively similar exposure, genderinfluences the size of the emphysema clusters.13 of 71

University of Toronto Department of Medical Imaging Research Day 2009Changes in smoking habits in participants of a lung cancer screening studyRavi Menezes, Maureen McGregor, Heidi RobertsPurpose: To examine the attitudes towards smoking cessation and health concerns, andto identify predictors of change in smoking behaviour in a group of smokers enrolled in alung cancer screening study.Methods: Data were analyzed from 950 individuals enrolled in a study that examinedthe ability of low dose computed tomography to detect lung cancer at an early stage. Allwere at least 50 years old, current smokers at baseline, and received an annual repeatexamination. Attitudes towards smoking cessation and health concerns were determinedvia a baseline questionnaire. Smoking habits were determined at baseline and annualrepeat screening. The associations between smoking reduction at the annual repeat,baseline LDCT results and questionnaire responses were examined.Results: The most frequent reason provided for participating in the screening study wasconcerns over tobacco use (n=800, 84%), 67% (n=634) of the participants reported beingworried about being diagnosed with cancer, and 79% (n=652) reported a desire to quitsmoking during the next six months. At the annual repeat examination, 13% (n=126)reported having abstained from smoking in the previous month, while another 31%(n=293) reduced the amount of packs smoked per day. Bivariate and multivariateanalyses revealed that being worried about cancer, seriousness about quitting, and time tofirst cigarette were significant predictors of smoking cessation (p

University of Toronto Department of Medical Imaging Research Day 2009Lesions after stereotactic body radiotherapy: Misdiagnoses and pitfallsBabak A Shamshirsaz MD 1 , Andrea Bezjak MD 2 , Ravi Menezes PhD 1 ,Mojgan Taremi MD 2 , Heidi Roberts MD 11 Department of Medical Imaging, University Health Network2 Department of Radiation Oncology, Princess Margaret HospitalPurpose: To demonstrate misdiagnoses and pitfalls in interpretation of the lesions afterstereotactic body radiotherapy (SBRT) for lung cancer treatment.Materials and Methods: We retrospectively evaluated 4 patients (2 male, 2 female)with Stage T1N0M0 (in one case, T2N0M0) non-small cell lung cancer in LUL (in onecases bi-lateral and in other case in LLL), who were treated with SBRT in PrincessMargaret Hospital. Pre and post SBRT treatment CT-scans of the chest have beenperformed in all cases. The CT scans of these patients have been misinterpreted as tumorrecurrence (except one case as SBRT related changes) and eventually found to betreatment related (in one case tumor recurrence). The CT scans were evaluated for thepresence of features differentiating tumor from treatment changes.Results: Follow up CT-scan was done two months after initial treatment which showedgood response in the treatment area in all cases. After 5-34 months a pathological findingwas seen, which was treatment related in 3 cases and recurrent adenocarcinoma in onecase. In two cases, a new nodule appeared adjacent to the treatment area. It wasmisinterpreted as malignancy (5 months post-SBRT) in one case and treatment relatedchanges (11 months post-SBRT) in the other case. In one case, a new hypo-dense intramuscularopacity (17 months post-SBRT) was misinterpreted as tumor invasion to thechest wall. In the last case, a sudden episode of shortness of breath was co-incidental withevidence of worsening of the right hilar/peri-hilar thickening and new partial RULcollapse (34 months post-SBRT) which was misinterpreted as tumor recurrence. Furtherinvestigation in all cases resulted in change in primary diagnosis.Conclusion: Pathological findings after SBRT treatment for lung cancer are various innatures. They could be benign or malignant and they can mimic each other in theirradiological appearance which can cause misdiagnoses of these lesions. Radiologistshould be aware of these imaging pitfalls and try to avoid misinterpretation of CT imagesafter SBRT treatment for lung cancer.15 of 71

University of Toronto Department of Medical Imaging Research Day 2009Due to a special request, this presentation, which moreproperly belongs in the Vascular and InterventionalImaging section, appears here.Incidental lumbar spine pathology detectedon pre-uterine artery embolization MRIsD Boparai, L Wu, R RebelloDepartment of Medical Imaging and Department of Medicine, St. Michael’s Hospital,University of Toronto, CanadaBackground/Aims: This study is a retrospective cohort study comparing the number ofincidental findings of lumbar spine pathology in women undergoing pelvic MRIs forpre-uterine artery embolization evaluation to women of a similar age undergoing pelvicMRIs for all other indications at St. Michael’s Hospital.Methods: The study consisted of looking at every patient undergoing a pre-UFE pelvicMRI over a two year period of time St. Michael’s Hospital who consented to the MRIDatabase. The comparison group consisted of women undergoing pelvic MR, during thesame time period, with the same protocol but for other indications. A similar number ofexams were compared and the groups were age matched.The study utilized two blinded staff radiologists who analyzed sagittal images of theselected pelvic MRIs without knowing the indication of the study. In addition, theradiologist was only provided images of the lumbar spine; the remainder of the organswere covered so that the uterus or fibroids would not bias results. The radiologist wassimply asked to discern whether or not there is lumbar spine pathology and to specify theseverity, graded from 1 to 3. The size and volume of the uterus, a routine measurementon pre-UFE pelvic MRIs, will also be measured separately as ancillary data.Results: Using a chi-squared analysis to compare percentages of presence of lumbarspine pathology between MRI and UFE data sets, 79% of cases in MRI data set had ‘yes’for incidental lumbar spine pathology and 76% in the pre- UFE data set. Differencebetween 79% and 76% was not statistically significant with p=0.6515. Using analysis ofcovariance to compare the means of size between two data sets and adjusting for severityalso showed no significant differences.Conclusions: No significant difference in lumbar spine pathology seen on MRI betweenwomen undergoing pre-uterine artery embolization MRIs compared to those undergoingpelvic MRIs for all other indications.16 of 71

University of Toronto Department of Medical Imaging Research Day 2009Breast, MSK and Physics17 of 71

University of Toronto Department of Medical Imaging Research Day 2009Merits of five clinical dosimeters in an interventional radiology settingLeah Shuparski, Bairbre ConnollyPurpose: As the relative advantages and disadvantages of one dosimeter over anotherare unclear to the clinical interventionalist, our purpose was to evaluate the merits of avariety of dosimeters in a clinical interventional radiology (IR) suite.Method and Materials: Five dosimeters were evaluated: Dose-Area Product (DAP),Patient Exposure Management Network (PEMNET), MOSFETs, TLDs, and Gafchromicfilm. Each dosimeter was tested for linearity, reliability, accuracy and lower limit ofdetection (LLD) using a biplane fluoroscopy system. The merits of each dosimeter werethen assessed by simulating 5 common procedures on a tissue-equivalent,anthropomorphic phantom. The procedures simulated were G/GJ tube insertion, renalangiography, neuroangiography, CVL and chest tube insertions. Field size, table andimage intensifier height and beam orientation, among others, were used to standardize themock exam.Results: The LLD for MOSFETs and TLDs were 0.5 and 1.6 mGy respectively. TheLLD for film was 40 mGy. DAP meter measured doses greater than 10 mGy*cm 2 .PEMNET does not have a LLD, as it calculates exposure using machine parameters suchas kVp, mA and table geometry. Above their respective LLDs, all dosimeters exhibited alinear response with increasing fluoroscopy time (R 2 > 0.9) and agreed within 20% of thetrue dose measured using an ion chamber. PEMNET, DAP and MOSFETs provided adirect readout of entrance skin dose at the end of each examination, and performedreliably across a wide range of doses. TLDs performed well at low to high doses, but, likefilm, required at least 24 hours after exposure to derive a dose result. However, the TLDprocessing time was due to institutional factors, rather than an inherent TLDcharacteristic.Conclusion: For routine use, online dose measurement systems such as PEMNET orDAP are reliable and easy to use. When requiring a detailed knowledge of the entranceexposure, other dosimeters must be utilized. For low-dose applications, MOSFETs areideal due to their ability to provide skin exposure at specific locations, and can be readimmediately. Despite a higher LLD, film was preferred by some interventionalists, whofound it useful to see the dose distribution in addition to the peak dose.18 of 71

University of Toronto Department of Medical Imaging Research Day 2009MRI-guided vacuum-assisted breast biopsy: Initial experiencePavel CrystalPurpose: To evaluate the accuracy of MRI-guided vacuum assisted breast biopsy(MRgVABB).Materials and Methods: We retrospectively reviewed the results of 135 consecutiveMRIg VABB between February 2006 and October 2008. Concordant benign biopsyresults were verified by excisional biopsy or by at least 6-months follow-up breast MRI.Results: Of 135 biopsies, core histology revealed 16 malignant (16/135, 12%), 29 highrisk(29/135, 21%), and 90 benign (90/135, 67%) lesions.Of 6 cases DCIS at MRgVABB, 2 were upgraded to invasive carcinoma (underestimationrate 33%) at lumpectomy. Of 29 high-risk lesions at MRgVABB, 11 were upgraded tomalignancy, all of which were DCIS (underestimation rate 38%) at surgery.Of 90 benign lesions at MRgVABB, repeat biopsy was suggested in 8 cases based onradiology-pathology discordance. Cancer was diagnosed at repeat biopsy in 4 cases.MRI stability without evidence of lesion progression or MRI lesion disappearance weredocumented in 71 cases while 11 patients were lost to follow-up.Overall accuracy of MRgVABB is 96.2%, while false-negative rate is 12.9%.All 8 discordant cases, including 4 false-negative cases, occurred among the first 60 casesor among the first 20 cases done by any one radiologist.Conclusion: MRgVABB is an accurate method for evaluating MRI detected otherwiseoccult lesions. Vigilant radiology-pathology correlation is required in order to avoiddelay in diagnosis of carcinoma. All high-risk lesions need excision in view of highunderestimation rate. There appears to be a learning curve in the performance ofMRgVABB procedures.19 of 71

University of Toronto Department of Medical Imaging Research Day 2009Can DWI be a non invasive method to predict axillary metastasesin patients with biopsy proven breast carcinoma?Riham Eiada, Anabel M Scaranelo, Supriya R Kulkarni, Pavel CrystalJoint Department of Medical Imaging,University Health Network and Mount Sinai HospitalUniversity of TorontoPurpose: To determine the accuracy of diffusion-weighted-MR imaging (DWI) indetecting metastatic axillary lymph nodes in patients with new diagnosis of breast cancerundergoing staging breast MRI.Materials and Methods: From June 2008 to March 2009, 109 axillary lymph nodeswere assessed in 74 patients with biopsy proven breast cancer (BI-RADS category 6)who underwent preoperative staging breast MRI. During the staging MRI, DWI wasacquired with b values of 50, 300, 700 and 1000 s/mm2 using a single shot echo-planarsequence and apparent diffusion coefficient (ADC) map was obtained automatically inreconstructed images. Visual assessment of DWI and ADC maps was performed by 2reviewers and classified using a five point chart. DWI signal intensity and ADC valueswere measured for ipsilateral axillary lymph nodes and a ratio of ADC/DWI usingdifferent b-values was recorded and compared for benign and malignant lymph nodesfrom final surgical pathology.Positive predictive value (PPV) was compared for visual assessment and for DWI (basedon ADC threshold).Results: Pathology results of sentinel node biopsy or axillary lymph node dissectionwere available for 62 DWI cases. The visual assessment showed sensitivity=84 %,specificity= 65%, PPV=86% and NPV= 61%. Our accuracy was 79% (p=0.000333).ADC (mean+/- SD x10-3 mm2/s) values obtained through calculation of different bvalues, were 0.80 and 0.66 respectively for malignant and benign lymph nodes (0.69,0.55, 0.42, 0.36 and 0.36, 0.27, 0.21, 0.17). Our threshold was 0.70 +/- 0.46, todifferentiate between benign and malignant nodes, and showed sensitivity=55 %,specificity= 58%, PPV=78% and NPV= 33%. Our accuracy was 56% (p=0.023).Multiple b values did not show significant precision over single b value.Conclusion: The metastatic axillary lymph node did not exhibit significantly alteredADC values compared to normal lymph nodes, however the visual assessment using afive point chart proved to be a significant tool. Adding DWI to standard dynamiccontrast-enhanced MRI may increase PPV in metastatic axillary lymph nodes in stagingof BIRADS 6 breast cancer.20 of 71

University of Toronto Department of Medical Imaging Research Day 2009Potential contribution of computer-aided detection (CAD)to the sensitivity of full-field digital mammographyArifa Sadaf, Pavel CrystalAim: To assess potential contribution of computer-aided detection applied to full-fielddigital mammography (FFDM).Materials and Methods: Database search revealed 62 patients who have had FFDM atthe time of diagnosis and at least one standard FFDM 4-36 months before the diagnosis.Prior mammograms were reviewed retrospectively in non-blinded fashion in order toassess visibility of cancers. Mammographic characteristics of the malignant lesions wererecorded. CAD system (iCAD) was applied to all current and prior mammograms.Results: 58 out 62 cancers were visible on current mammogram, 4 cancers weremammographically occult (all 4 presented as palpable lesions) and were excluded.Mammographic features of 58 cancers included 25 masses, 22 calcifications, 5 masseswith calcification, and 6 areas of architectural distortion.CAD correctly marked 50 of 58 lesions on current mammogram. 8 lesions not marked byCAD included 3 masses, 2 masses with calcifications and 3 distortions. Sensitivity ofCAD for detection of cancer on current mammogram was 86%.On prior mammogram 41 % (24 of 58) of cancers were visible on non blindedretrospective review. 46 % of these retrospectively visible cancers (11 out of 24) weremarked by CAD; these included 8 masses and 3 calcifications.Conclusion: CAD has marked 46% of retrospectively visible cancers at previousscreening round. CAD standalone sensitivity at the time of diagnosis was only 86%.Interpretation of FFDM using CAD has potential to improve mammographic sensitivity.21 of 71

University of Toronto Department of Medical Imaging Research Day 2009MR imaging as a screening tool for early detection of intraarticular bleedin hemophilic children: A systematic reviewAndrea S. Doria, MD, MSc, PhD, Hospital for Sick Children, University of Toronto;Victor Blanchette, MDBackground: Early treatment of hemophilia (prophylaxis) has been shown to reduce thelong-term joint morbidity related to the development of arthropathy. Imagingexaminations are appealing choices for diagnosis and follow-up of hemophilic jointchanges over time. MRI holds potential as a screening imaging modality for patientselection for secondary prophylaxis, targeting joints that can be treated and saved fromprogressive arthropathy.Objectives: To determine the level of evidence of results of studies related to screeningof early intra-articular soft tissue bleed with MRI in hemophilic children suitable toreceive prophylaxis, and with regard to improvement of functional status of joints overtime as measured by the World Federation of Hemophilia [WFH] Orthopedic joint scaleand Pettersson radiographic scale.Methods: An electronic literature search (January 1966 to March 2009) was conductedto identify studies pertaining to the aforementioned objectives. The reviewersindependently analysed the studies to score the quality of evidence tables using modifiedcriteria for grading the internal validity of individual studies and the QUADAS (qualityassessment of studies of diagnostic accuracy included in systematic reviews) criteria.Results: The electronic literature search retrieved 85 (MEDLINE) and 84 (EMBASE)citations restricted to hemophilia. A total of 12 (752 participants) studies were chosen forthe review. The following bodies of evidence were evaluated:Overarching question: Effect of MRI screening of soft tissue changes in hemophilicjoints on final (functional status of the joint measured by the WFH Orthopedic Score orby the Pettersson radiographic score) outcome measure: MEDLINE AND EMBASE,N=0.Key question #1: Diagnostic performance of MRI as a diagnostic tool for assessmentof soft tissue changes (hemarthrosis or synovial hypertrophy) in a hemophilic joint ascompared with clinical or laboratory data (construct validity), or biopsy data (criterionvalidity): MEDLINE, N=6; EMBASE, N=13 (combined key questions #1 and #4).Key question #2: Effect of intervention (prophylaxis) on intermediate (MRI evidenceof cartilage degeneration) outcome measure: MEDLINE, N=11, EMBASE, N=6.Key question #3: Effect of intervention (prophylaxis) on final (functional status of thejoint) outcome measure: MEDLINE, N=68, EMBASE, N=65.Seven out of 8 studies included in the analysis (1 fair quality, and 6 poor qualityevidence) suggested a beneficial effect of prophylaxis on future orthopedic and/or25 of 71

University of Toronto Department of Medical Imaging Research Day 2009Automatic contrast enhancement of cerebral white matter lesions in FLAIR MRIApril Khademi 1,3 , Anastasios Venetsanopoulos 1,2 , Alan Moody 3,41 Department of Electrical and Computer Engineering, University of Toronto,2 Department of Electrical and Computer Engineering, Ryerson University,3 Medical Imaging Research Department, Sunnybrook Health Sciences Center,4 Department of Medical Imaging, University of Toronto.Introduction: As white matter lesions (WML) are an independent risk factor orintermediate surrogate of stroke [1][2], image processing algorithms are being heavilyresearched to automatically quantify such neurological diseases. Image processors are aset of software algorithms which automatically operate on the images based onmathematical principles and theories. Such techniques are valuable in medical imagingas they can produce robust, reliable and repeatable results for segmentations orclassifications. As FLAIR MRI is the preferred imaging modality for WML detection, itis important to tune the algorithms specifically to FLAIR. Although FLAIR MRIs offerexcellent discrimination between anatomy and pathology, artifacts, such as partialvolume averaging (PVA) and thermal noise corrupt the image and pose challenges toautomated techniques. To combat these image degradations, it is possible to first employan automatic contrast enhancement scheme for better separation (in terms of intensity)between pathology and background. Highlighting pathology and suppressing normalappearing cerebral regions allows image processing schemes, such as segmentationand/or classification, to achieve higher accuracy. Consequently, this work concerns thedevelopment of a novel contrast enhancement algorithm for FLAIR-weighted cerebralMRI with white matter lesions (WML). As such a technique separates WML and brainwith excellent results, a thresholding-based WML segmentation algorithm is alsopresented.Methods: To isolate the cerebral structures, a novel brain extraction algorithm techniqueis first employed on the FLAIR MRI. Based on the brain extracted result, the proposedmethod utilizes both a robust estimate of edge magnitude and intensity values todiscriminate between pathological and non-pathological information. These two featuresare combined through several transformations, such that WML are highlighted, andnormal appearing white/gray matter are suppressed. The technique utilizes informationsolely computed from each image and thus adapts to the input image’s characteristics.For a more detailed outline of the algorithm, please see [3]. For the segmentation aspect,a threshold is automatically set to the value T = μ + σ, where the mean μ and variance σare estimated from the contrast enhanced image’s histogram. All pixels which are greaterthan this threshold are labeled WML.Materials: A retrospective study was performed on images acquired from symptomaticpatients who were referred for cerebral FLAIR imaging. The FLAIR sequence used hasthe following parameters: TR 9000 ms, TE 110 ms, TI 2500 ms, FOV 180x240 mm,matrix 176x256, 4 mm slice thickness, 2 mm gap and two averages. To test the27 of 71

University of Toronto Department of Medical Imaging Research Day 2009enhancement scheme, 5 patients with WML were used, resulting in 18 images (slices) intotal which contain WML.Results: To test the enhancement scheme, the 18 images (slices) were used and theresults for several images are shown in Figure 1. To quantify the performance ofcontrastenhancement schemes either objectively or subjectively is difficult [4]. Someauthors have proposed local contrast measures to compute the Contrast ImprovementRatio (CIR) [4], which compares the contrast of an image before and after contrastenhancement. To measure the local enhancement of the lesions, several small regionsfrom each image were chosen to compute the CIR (typically, regions were approximately25x25 pixels in size). Each region contained normal brain tissue and WML. These valuesare shown in Table 1, and the average value over 18 images is 40%.Conclusions: This work presents a novel contrast enhancement scheme for WML incerebral FLAIR. The results are promising, as the average Contrast Improvement isroughly 40%. Additionally, not only are the results visually appealing, but a simpleautomatic computed threshold is able to segment the lesions. The next stages of thisresearch include WML segmentation validation.References:[1] N. Altaf, L. Daniels, P.S. Morgan, J. Lowe, J. Gladman, S.T. MacSweeney, A.Moody, and D.P. Auer, “Cerebral white matter hyperintense lesions are associatedwith unstable carotid plaques,” EU J. Vascular/Endovascular Surg., 31, pp. 8–13,2006.[2] N. Altaf, A. Beech, S. Goode, J. Gladman, A. Moody, D. Auer, and S. MacSweeney,“Carotid intraplaque hemorrhage detected by magnetic resonance imaging predictsembolization during carotid endarterectomy,” J. Vascular Surgery, 46(1), pp. 31–36,2007.[3] A. Khademi, A. Venetsanopoulos, A. Moody, “Incorporation of Intensity and EdgeInformation for Contrast Enhancement of FLAIR MRI with White Matter Lesions”,IEEE ISBI 2009 (accepted).[4] C.Wyatt, Y.-P.Wang, M. T. Freedman, M. Loew, and Y.Wang, BiomedicalInformation Technology, Chapter 7., pp. 165–169, Elsevier, ‘07.28 of 71

University of Toronto Department of Medical Imaging Research Day 2009Figure 1:Top: brain extracted original images;Middle: contrast enhanced images;Bottom: binary segmentation resultsTable 1: CIR results for 18 images29 of 71

University of Toronto Department of Medical Imaging Research Day 2009A post-processing method for generatingarbitrary T2-weighted contrast in MRIMarshall S. Sussman, Gustav Andreisek, Ali Naraghi, John S. Theodoropoulos,Claire Zhao, Norman Young, Tallal C. Mamisch, Lawrence M. WhitePurpose: To evaluate the feasibility and accuracy of a synthetic-TE magnetic resonance(MR) post-processing technique in the context of meniscal and cartilage abnormalities ofthe knee.Material and Methods: The knees of twenty-four patients were evaluated with standardT2-weighted fast spin-echo (FSE) sequences. In addition, multi-echo fast-gradient-echo(FSGRE) sequences were performed for the generation of synthetic-TE images withvariable T2 (or T2*)-weighted contrast using a new synthetic-TE analysis tool that wasincorporated directly into the picture archiving and communication system (PACS).Sensitivities, specificities and accuracies for detection of meniscal and cartilage lesionswere calculated using surgery as reference standard.Results: The standard T2-weighted MR sequences had overall sensitivities, specificities,and accuracies of 100%, 88%, and 95% for the diagnosis of meniscal tears.Corresponding sensitivities, specificities, and accuracies of synthetic-TE MR imagegeneration were 92%, 88%, and 90%.Conclusions: The synthetic-TE technique was shown to be a technically viablealternative for the evaluation of menisci to standard T2-weighted images. The results ofthis study demonstrated that the synthetic-TE approach allowed for the assessment ofmeniscal abnormalities with high sensitivity and specificity.30 of 71

University of Toronto Department of Medical Imaging Research Day 2009Neuroimaging31 of 71

University of Toronto Department of Medical Imaging Research Day 2009Comparison of Gadofosveset trisodium (Vasovist) steady state enhanced magneticresonance angiography (MRA) with first pass and three dimensional time of flightMRA at 1.5 Tesla in the follow-up of coiled cerebral aneurysmsDaniel Baxter, Walter Montanera, Dipanka Sarma,Sean Symons, Richard Farb, Thomas MarottaPurpose: To compare three different MRA techniques in the follow-up of coiledcerebral aneurysms using Gadofosveset trisodium (Vasovist) steady state enhancedMRA, first pass, and 3D TOF MRA techniques at 1.5 T.Background: Gadofosveset trisodium (Vasovist) is an injectable contrast solution usedin magnetic resonance imaging that binds reversibly to albumin. This albumin bindingcharacteristic extends the vascular life time of the agent and allows for longer vascularimaging time with steady state imaging. This longer vascular imaging time allowscollection of more raw imaging data, increased matrix size, and higher spatial resolutionMR images. Higher spatial resolution MR angiography (MRA) should be useful indetecting residual flow in coiled cerebral aneurysms.Materials and Methods: This is a pilot study. Ten sequential patients followed forcoiled cerebral aneurysms at St. Michael’s Hospital underwent Gadofosveset trisodium(Vasovist) steady state enhanced MRA, first pass, and 3D TOF MRA techniques at 1.5 T.Three blinded independent expert interventional neuroradiologists prospectivelyevaluated the MRA techniques based on three dichotomous questions. 1) Is theresatisfactory vessel conspicuity? 2) What size is the coiled aneurysm remnant? 3) Doyou recommend retreatment or follow up? The first pass contrast enhanced MRA servedas the “gold standard.” A consensus response for the three independent interventionalneuroradiologist readers was derived on the basis of majority opinion.Results: To date fourteen coiled aneurysms were evaluated using 3D time of flightMRA, first pass, and steady state Gadofosveset trosodium enhanced MRA. Satisfactoryconspicuity of the peri-aneurysmal vascular anatomy was present in 12 (86%) TOFMRAs, 14 (100%) first pass MRAs, and 14 (100%) steady state MRAs. Five residualaneurysm remnants greater than 2 mm were described on the first pass MRAs. Of these,four were identified on TOF MRA (sensitivity 80%, specificity 89%), and five weredemonstrated on steady state MRA (sensitivity 100%, specificity 78%). The oneaneurysm remnant not seen on TOF MRA measured 5 mm.Conclusion: Gadofosveset trisodium steady state MRA is a reliable technique for thesurveillance of coiled cerebral aneurysms and is superior to the TOF MRA for thispurpose.32 of 71

University of Toronto Department of Medical Imaging Research Day 2009Sex differences in the human corpus callosum microstructure:T2 myelin-water imaging versus diffusion tensor imagingF. Liu 1 , L. Vidarsson 2 , and A. Kassner 1,31 Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Canada,2 Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada,3 Dept. of Medical Imaging, University of Toronto, Toronto, Canada.Introduction: The corpus callosum (CC) plays an important role in relaying sensory,motor and cognitive function between the cerebral hemispheres. Females seem to employa greater degree of bilateral hemispheric activity than males (1) and also have a largercallosal area in proportion to brain volume (2) which suggests that a larger number offibres are passing through. We have previously shown that fiber density is higher infemales compared to males in subdivisions of the CC using diffusion tensor imaging(DTI) (3). We hypothesize that these sex differences are due to a difference in myelincontent. Short-T2 myelin-water imaging has previously been used to shed light on brainmicrostructure (4-5). In this study we have compared short T2 myelin-water imaging toDTI in the corpus callosum of healthy volunteers.Materials and Methods: Twenty healthy age matched volunteers (10 male, 10 females,age 19-31 years) underwent MR imaging. All subjects were right-handed with no knownneurological disease. A 5 echo myelin-water imaging protocol was adapted to this studyas described previously (4). Imaging parameters used for the 5 echo multi-slice spin echoimages were as follows: TE/TR = 8,23,33,74,110 / 698,713,723,764,800, NSA = 2, FOV= 24 cm, matrix = 128x128, bandwidth = 15.6 kHz and 6 slices (4mm thickness with a1 mm gap). In addition to the T2 myelin-water images, DTI was performed using 15 noncollineardirections of diffusion sensitization with an echo planar readout (b-value=0 and1000s/mm 2 , matrix =128x128, FOV of 240mm; slice thickness 2mm, number of slices54, TE=74ms, 4NEX). Total scan time was 30 mins for both myelin-water images andDTI. DTI datasets were spatially registered using AIR (vs 3.0) and post-processed usingDTI Studio (vs 2.4). Regions of interest (ROIs 18 pixels and 8 pixels, respectively) wereplaced in six subdivisions of the corpus callosum according to the Witelson scheme(6): CC2-Genu, CC3-Rostral body, CC4-Anterior midbody, CC5- Posterior midbody,CC6-Isthmus, CC7-Splenium. For each ROI, the average myelin-water content (4), theaverage fractional anisotropy (FA), and the fiber density index (FDi) (7) were computed.An unpaired Student’s t-test was used to compare all variables between male and femalevolunteers.Results: When compared males to females, a significant myelin-water fraction decreasewas found in CC3 (p

University of Toronto Department of Medical Imaging Research Day 2009Discussion: These findings suggest that in areas where fibers are less densely packed, there ismore myelin content. Significant differences were observed in corpus callosum-rostral body, andsplenium by using myelin-water fraction, which indicates a link between myelin content andgender differences.References:1. Crow et al. Neuropsychologica 1998.2. Mitchell et al. AJNR 2003.3. Kassner et al. ISMRM 2007 #1578.4. Vidarsson et al. MRM 2005.5. Laule et al. Neurotherapeutics 2007.6. Witelson, Brain 1989.7. Roberts et al. AJNR 2005.p

University of Toronto Department of Medical Imaging Research Day 2009Exhausted cerebral autoregulation is spatially associated with cortical atrophyJ. Fierstra, J. Poublanc, H. Wang, J. Han, A. Crawley, J. Fisher, D.J. MikulisThe Toronto Western Hospital, Toronto, ONObjectives: The physiological impact of severely impaired cerebral autoregulatoryvascular reactivity on gray matter integrity is unknown. We hypothesized that corticalgray matter supplied by a defective vascular system with exhausted dilatoryautoregulation reserve will show evidence of cortical atrophy.Methods: 250 BOLD-MRI cerebrovascular reactivity (CVR) studies were reviewed toidentify subjects with severe unilateral impairment in CVR (impaired blood flowresponse to a vasoactive stimulus such as a change in PetCO2.), vasodilatory reserve(negative CVR) but with normal appearing gray matter on FLAIR. Patients with lacunarinfarcts in the white matter were excluded. 17 patients were identified each having a highgrade stenosis or occlusion of the ICA or MCA on one side regardless of etiology,secondary to Moyamoya, atherosclerosis, or unknown. CVR studies were performed byapplying precision control of imposing acute transient vasodilatory stimulus end-tidalpCO2 CO2 between baseline (40mmHg) and to 50mmHg, (Respiract, TRI, Toronto,Canada) during BOLD MRI acquisition on a GE T HDX MRI system. 1 A D T1-weightedvolume (voxel 0.78 x 0.78 x 2.2 mm) was acquired and analyzed for cortical thicknessusing freesurfer (http://surfer.nmr.mgh.harvard.edu/). CVR and cortical thickness mapswere overlapped to determine a ROI encompassing the region of negative impaired CVR.This ROI was mirrored to the normal hemisphere providing a normal versus abnormalhemisphere ROI comparison in each subject. Mean cortical thickness between right andleft hemisphere ROIs for each subject was measured and a paired t-test was applied.Results: The ROI with negative impaired CVR showed thinner cortex(2.23 mm +/- 0.077) than the corresponding contra lateral side (2.42 mm +/- 0.052)(p = 0.0005) in 16 of the 17 cases. Mean cortical thickness was 2.23 mm +/- 0.077 on theabnormal side, and 2.42 mm +/- 0.052 on the normal side (p = 0.0005). Figure 1 showsthe relationship between the spatial extent of abnormal impaired CVR (blue) and thespatial extent of cortical thinning (light blue) in one subject, (decreased extent of lightblue in right hemisphere = thinner cortex and increased extent of blue in right hemisphere= negative CVR).Conclusions: The data indicates that a spatial correspondence exists between exhaustionof autoregulatory capacity, vasodilatory capacity and cortical thinning. The findingsimply that relate the inability to augment flow in response to metabolic stimuli, (as is alsonormally seen with neuronal activation), may be deleterious to the health of thepreservation of gray matter.References:1. Vesely et al. MRM 2001;45:1011-1013.35 of 71

University of Toronto Department of Medical Imaging Research Day 2009Figure 1:36 of 71

University of Toronto Department of Medical Imaging Research Day 2009Comparative detectability of magnetic susceptibility signals seen on EPI-GRE,MPGR and VEN BOLD sequences using 3T MRI: Preliminary resultsVitaly Sygal, Allan J Fox, Peter Howard, Sean P Symons,Richard I Aviv, Robert YeungBackground and Significance: Detecting magnetic susceptibility plays an importantrole in brain imaging, particularly in identifying blood products (deoxyhemoglogbin andhemosiderin) in the setting of disorders like cerebral amyloid angiopathy, hypertensivevasculopathy and traumatic brain injury. Echo-Planar Imaging Gradient Echo (EPI-GRE)and Multi-Planar Gradient Echo (MPGR) have traditionally been the sequences used atour institution for this purpose. A new sequence called Venous Blood OxygenationLevel Dependent MRI (VEN_BOLD) is believed to be more sensitive at detectingmagnetic susceptibility.Materials and Methods: This is a retrospective study that included patients thatunderwent 3T MRI of the head with all three sequences of interest between July toSeptember 2008. Patients with extensive artifact, intraparenchymal hematomas, laminarnecrosis, subarachnoid blood and tumors were excluded. A board-certifiedneuroradiologist analyzed each of the three sequences for each patient in a blindedfashion and identified all areas of magnetic susceptibility. Results were comparedbetween the three sequences.Results: There were a total 80 patients in this study with 103 lesions with magneticsusceptibility detected by at least one sequence. There were 78 true lesions and 25 thatturned out to be either a vessel or developmental venous anomaly on BOLD. EPI-GREdetected 21 (27%), MPGR detected 37 (47%) and BOLD detected 75 (96%) of the truelesions. Of the 25 false lesions detected, 21 were made by EPI and 12 by MPGR.BOLD detected 39 (50%) lesions that were not picked up by either EPI-GRE or MPGR.In contrast, 2 lesions (3%) were detected only by MPGR and none were detected only byEPI-GRE. Nineteen lesions (24%) were detected by all three sequences. Regardingpatients, BOLD detected at least one lesion in 7 patients while EPI-GRE and MPGR didnot detect any lesions in these patients.Conclusion: BOLD was superior to both EPI-GRE and MPGR in detecting lesions andpatients with intracranial magnetic susceptibility. BOLD was also useful indifferentiating true lesions from vessels and developmental venous anomalies. Theresults support the use of VEN-BOLD as the sequence of choice in detecting intracranialmagnetic susceptibility.37 of 71

University of Toronto Department of Medical Imaging Research Day 2009Assessment of cerebrovascular reactivity using real time BOLD MRIin children with Moyamoya disease: A feasibility studyBejoy Thomas; MD; DNB*, William Logan; MD; FRCPC**, Logi Vidarsson; PhD*,Elizabeth Donner; MD; FRCPC**, Manohar Shroff; MD; FRCPC*Departments of Diagnostic Imaging* and Neurology**, The Hospital for Sick Children,University of Toronto, Toronto, Ontario, CanadaIntroduction: Assessment of cerebrovascular reactivity (CVR) is critical in decidingrevascularization procedures in cerebrovascular steno- occlusive diseases like moyamoyadisease. In a clinical context CVR can be estimated using MRI by altering PaCO2through changes in ventilation and measuring the resultant BOLD signal changes. Realtime BOLD MRI (rtfMRI) can analyze functional imaging studies at the time of /immediately after scanning the patient. This is a feasibility study to test the reliability andvalidity of assessment of CVR with rtfMRI (rtCVR) in comparison to standard off- lineprocessing in children with moyamoya disease who are potential candidates for surgicalcerebral revascularization.Methods: Seven patients (ages 4 – 17 years, 4 female, nine sessions of study) withmoyamoya cerebral arteriopathy had undergone of BOLD MRI CVR studies either on a1.5T or on a 3T scanner (Achieva, Philips, Best, Netherlands) for clinical evaluation ofpotential surgical cerebral revascularization. The PaCO2 was manipulated by deliberatebreath holding for 30 seconds followed by 60 seconds of free breathing while the BOLDMRI acquisition in co-operative patients. Three patients who underwent the study undergeneral anaesthesia (GA), the box car times were 120 seconds each. One patient hadundergone CVR study initially without and later with GA. One patient had undergoneCVR study initially without and later with GA. A rise of end tidal PCO2 of 8 to 10 mmHg took between 60 to 100 seconds in the ventilated patients. All cases were analyzedwith standard off-line analysis (Stimulate: Strupp, J. P. “Stimulate: A GUI Based fMRIAnalysis Software Package”, NeuroImage (1996), 3: S607) and also with the vendorsupplied rtfMRI software. Blinded evaluation for interrater reliability of the quality ofrtCVR on a ‘0’ to ‘3’ scale and for validity of real time results compared to off-lineprocessing was performed.Results: There was a high interrater reliability noted among the two independent ratorsfor assessment of quality for clinical utility of real time results (k = 0.77). The rtCVR wascomparable to off-line results with regard to adequacy of the activation, presence orabsence of abnormal reactivity, location, pattern and extent of abnormal activation(absence of response or paradoxical response) when present (sensitivity of 88.8%,specificity 100%). In one of the studies the data could not be processed with rtfMRI dueto technical issues were as off- line analysis could still be possible. In another patientwith excessive movement had to have a repeat study under GA as the results wereinconclusive in both off-line and rtfMRI analysis. Overall the quality and validity ofactivation was better in patients who underwent the study under GA with intubation.38 of 71

University of Toronto Department of Medical Imaging Research Day 2009Conclusion: rtCVR is feasible and the results are comparable to that of standard off- lineanalysis in this series of cases. The results from off-line analysis are available onlyseveral hours or days after the MRI has been completed. This delay precludes immediateassessment of the success of the CVR study or the need to repeat it while the patient isstill in the scanner. rtfMRI analysis can overcome this difficulty. However this methodhas to be standardized in each institution and for the vendor software before routineclinical use.39 of 71

University of Toronto Department of Medical Imaging Research Day 2009Dynamic susceptibility contrast MRI in acute ischemic stroke:Surrogate measures of BBB permeability for theprediction of hemorrhagic transformationRebecca E. Thornhill 1,2 , Shuo Chen 1 , Wael Rammo 1 ,David J. Mikulis 3 , and Andrea Kassner 1,21 Dept. of Medical Imaging, University of Toronto;2 Dept. Physiology & Experimental Medicine, Hospital for Sick Children;3 Dept. of Medical Imaging, Toronto Western Hospital.Objectives: Therapeutic use of recombinant tissue plasminogen activators (rt-PA) inacute ischemic stroke (AIS) is currently limited to patients presenting ≤4.5h post-ictus,due to the increased risk of hemorrhagic transformation (HT) 1 . It has been shown thatpermeability MRI followed by tracer-kinetic modelling can be used to predict HT 2 .However, recent work suggests that information relating to blood-brain barrierpermeability can be more rapidly extracted from the recirculation-phase of routine‘dynamic susceptibility contrast’ (DSC) MRI images 3-5 . Our purpose was to evaluate fourdistinct DSC parameters in discriminating between AIS patients who will proceed to HTand those who will not.Methods: Eighteen AIS patients were examined within 6 hours of symptom onset. Allimaging was performed on a 1.5 T clinical MRI system (GE Signa LX 12.0, Milwaukee,WI). DSC imaging consisted of a single-shot EPI scan with TR 1725 ms, TE 31.5 ms,FOV 240 mm, matrix 96×64, flip angle 90º, slice-thickness 5 mm, 17 slices, and anacquisition time of 86 s. Gadodiamide was injected as a bolus (Omniscan, GE, USA) atthe initiation of DSC. HT was determined by follow-up CT or MRI 24-72 h later. Datawere analyzed offline. Two regions of interests (ROIs) were defined on diffusionweightedMRIs, one within the infarct and another within the homologous location in thecontralateral hemisphere and then copied to the equivalent DSC images. Mean rR, 3 PeakHeight, 4 %Recovery, 4 and Slope of the ΔR 2*v. time curve between 50 and 60 s postinjection5 were recorded (FIG.1) and data grouped based on follow-up HT-status. Foreach parameter, differences between ROIs as well as between HT and non-HT patientswere assessed using Wilcoxon matched pairs and Mann-Whitney U tests, respectively.Results: Eight patients proceeded to HT. While the mean rR for infarcts wassignificantly greater than for contralateral ROIs (0.18±0.02 v. 0.08±0.01, P

University of Toronto Department of Medical Imaging Research Day 2009second perfusion scans, these two measures may provide convenient surrogates for DCE-MRI in the setting of acute ischemic stroke.References:1. Hacke W et al. NEJM 2008;359:1317-1329.2. Kassner A et al. AJNR 2005;26:2213-2217.3. Kassner A et al. JMRI 2000;11:103-113.4. Lupo JM et al. AJNR 2005;26:1446-1454.5. Bang OY et al. Ann Neurol 2007;62:170-176.FIG. 1: A ΔR 2 * v. time curve (ΔR 2*measured ), as well as its gamma-variate fit (ΔR 2*fit ). FourDSC parameters were calculated: rR (C/A), Peak Height (A), % Recovery = [100 x (A-B)/A], and Slope = slope of ΔR 2*measured (t) between 50 and 60 s post-injection.41 of 71

University of Toronto Department of Medical Imaging Research Day 2009Characterization of carotid plaque hemorrhage:A CT angiography and MR direct thrombus imaging studyJM U-King-Im, AJ Fox, RI Aviv, P Howard, R Yeung, AR Moody, S SymonsSunnybrook Health Sciences Centre, Toronto, CanadaPurpose: Decision-making regarding revascularization in carotid atherosclerosis isbased on luminal narrowing. There is, however, growing evidence that morphologicalfeatures of vulnerable plaques, such as intraplaque haemorrhage (IPH), ruptured fibrouscap or large lipid core, may be better predictors of stroke risk than luminal stenosis. MR-IPH is a recent but robust technique, able to detect IPH in vivo with excellent diagnosticaccuracy and reproducibility. The main objective of this study was to identify CTangiography (CTA) features which may predict presence of carotid IPH, as defined byMR-IPH.Methods: 167 consecutive patients (Mean age 69, SD 12.8, 58 females) underwent MR-IPH and CTA within 3 weeks. 153 patients were symptomatic, with suspected strokes orTIAs. MR-IPH was performed at 1.5 T, using neurovascular phased-array coil, as acoronal T1-weighted magnetization-prepared 3D GRE acquisition with fat -suppression(TR 10.3 ms, TE 4.0 ms, TI 20 ms, FOV 350 × 300 mm). MR-IPH was reviewed by oneof four neuroradiologists, as to presence or absence of IPH. CTA was performed usingeither a 4 or 64 slice machine, using standard angiography protocols. Images werereviewed in the axial plane and on coronal and sagittal MPR images. CTA was evaluated,blinded to MR-IPH findings, for (1) plaque density (2) presence or absence of plaqueulceration. Plaque density was defined as mean HU of plaque at site of maximumstenosis and two sections above and below, measured using circular ROI in non-calcifiedportions. Plaque ulceration was defined as contrast outpouching into plaque at least 2 mmdeep on any single plane.Results: 15 arteries were excluded due to occlusions or previous surgery, yielding 319arteries for analysis. MR-IPH showed 56 cases of IPH. Mean CT plaque density washigher for plaques with MRI-defined IPH (HU 47) compared to without IPH (HU 43)(p = 0.02). However, significant overlap between distribution of plaque densities suggestthat plaque density is of limited value in distinguishing between the two groups.CT plaque ulceration had excellent diagnostic accuracy for presence of MRI-defined IPH(Sensitivity 80%, Specificity 93%, PPV 72% and NPV 95%).Conclusion: Presence of CT plaque ulceration, but not plaque density, was useful forprediction of MRI-defined IPH.Reference:1. Moody AR et al, Characterization of complicated carotid plaque with MR directthrombus imaging. Circulation 2003 Jun; 107:3047-52.42 of 71

University of Toronto Department of Medical Imaging Research Day 2009DTI and cerebrovascular reactivity MR imagingin the developing swine brainJeff D. Winter 1 , Stephanie Dorner 2 , Joe Fisher 3,4 , Garry Detzler 1 , Andrea Kassner 1,51 Physiology and Experimental Medicine, Hospital For Sick Children;2 Thornhill Research Inc.;3 Department of Anesthesiology, University Health Network, University of Toronto;4 Department of Physiology, University of Toronto;5 Department of Medical Imaging, University of Toronto, Toronto, CanadaIntroduction: The pig brain offers a useful neuroimaging model to investigate pediatricbrain injury and development because it is similar to humans in size, timing of braingrowth, cerebrovasculature and grey:white matter ratio (1). Previous neuroimagingstudies have characterized different aspects of human brain development, includingstructural changes in brain volume, cortical thickness and cortical folding (2). Toinvestigate developmental changes in tissue microstructure, such as myelination,researchers have employed diffusion tensor imaging (DTI), an MRI technique thatquantifies tissue water self-diffusion magnitude and directionality (3). One aspect ofbrain development that has not been fully characterized is vessel function. This can beassessed using cerebrovascular reactivity (CVR), a measure of the cerebral blood flow(CBF) response to a vasoactive stimulus (e.g., carbon dioxide). Using MR measures ofCBF combined with controlled manipulation of the subject’s end-tidal partial pressure ofCO 2 (PetCO 2 ) it is possible to generate high-quality and reproducible CVR images of theentire brain. Although widely used in adults, this method has yet to be applied in animalmodels. Our goal for this study is to demonstrate the feasibility of generating CVRimages using controlled PetCO 2 manipulation in a pig model of normal brain maturation,and to use this method to investigate changes in CVR in relation to DTI measures ofmicrostructural changes.Methods: Seven Yorkshire pigs (1 - 3 months of age) were scanned on a 1.5 T GE SignaMRI scanner. Each animal was induced, intubated and mechanically ventilated.Anesthesia was maintained with an intravenous infusion of ketamine and midazolam. Weperformed DTI with 25 independent diffusion directions (b = 700 s/mm 2 ), echo time (TE)= 72 ms, repetition time (TR) = 5.5 s, field-of-view (FOV) = 160 mm, matrix size =128×128 and slices (4.5 mm thick) = 16. For CVR imaging, we acquired blood-oxygenlevel-dependent(BOLD) MRI data to provide an indirect measure of the changes in CBF.BOLD imaging was performed using standard single-shot echo-planar imaging (EPI) atthe same slice positions as the DTI acquisition. Imaging parameters included: TE = 40ms, TR = 2 s, FOV = 160 mm, matrix size = 64×64, slices (4.5 mm thick) = 16 andvolumes = 270. During BOLD imaging we applied a controlled cerebrovascular stimulusthat consisted of four square-wave cycles of hypercapnia (~ 55 mmHg for 60 s) andnormocapnia (~ 40 mmHg for 60 s). This was achieved using a computer-controlled gasdelivery system in combination with a sequential gas delivery circuit (RespirAct TM ,Thornhill Research Inc., Toronto, Canada), which continuously recorded PetCO 2 (4).43 of 71

University of Toronto Department of Medical Imaging Research Day 2009Diffusion tensor imaging post-processing was performed on the MRI scanner to generatemeasures of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA). Allother post-processing was performed offline using FSL and Matlab scripts. For theBOLD analysis, we matched the PetCO 2 and BOLD MRI time courses by estimating thetime delay between PetCO 2 and whole-brain BOLD signal changes. Once in phase, wecalculated CVR (% ΔMR signal/mmHg CO 2 ) on a pixel-by-pixel basis from the slope ofthe regression of % MR signal with PetCO 2 . Next, we semi-automatically identifiedregions of cortical grey matter (CGM), cortical white matter (CWM), deep GM (DGM)and extracted mean values for CVR, ADC, and FA. We assessed the changes in ADC,FA and CVR during development using curve estimation of these parameters in relationto body weight.Results: Figure 1 provides a representative CVR map and the BOLD MRI time seriesfor all grey matter overlaid with the fitted PetCO 2 model. No trends were observed forADC data. Significant positive log-linear relationships between FA and body weightexisted in the CWM (r = 0.96) and the DGM (r = 0.97) (Figure 2a). In contrast, CVRdemonstrated a negative log-linear relationship with body weight in the DGM (r = 0.79)(Figure 2b).Discussion: In this study we found a significant log-linear FA change duringdevelopment in WM regions, which is similar to human brain maturation. The CVRresults suggest alterations in cerebrovascular function may occur at different stages ofdevelopment. We also demonstrated the feasibility of CVR imaging with controlledPetCO 2 manipulation in an animal model. Together, these results suggest that the pig is apromising model for basic neurodevelopmental research and studies of pediatric braininjury and disorders. The ability to collect CVR images in pigs using controlled CO 2manipulation may enhance these future studies with regional information on vascularfunction.References:1. Dobbing J, et al., Early Hum Dev, 3:79-83 (1979).2. Durston S, et al., J Am Acad Child Adolesc Psychiatry, 40:1012:20 (2000).3. Mukherjee P et al., Radiology, 221:349-358 (2001).4. Prisman E et al., JMRI, 27:185-91 (2008).44 of 71

University of Toronto Department of Medical Imaging Research Day 2009Figure 1. Representative CVR map and the correspondingBOLD times-series with the fitted PetCO 2 model for a 2 monthold pig.a)0.4b)0.10Fractional Anisotropy0.3CVR (% MR / mmHg)0.050.20 10 20Body Weight (kg)0.000 10 20Body Weight (kg)Figure 2. Observed FA (a) and CVR (b) changes during pig braindevelopment. The red line represents a log-linear fit to the data points.45 of 71

University of Toronto Department of Medical Imaging Research Day 2009Imaging features of anterior pyriform aperture stenosisand central incisor syndrome including labyrinthine dysplasiaJohanna Monsalve MD 1 , Helen M. Branson MD 1 ,Blake Papsin MD 2 , Grace Yoon 3 , Susan Blaser MD 1,21 Department of Diagnostic Imaging, Division of Pediatric Neuroradiology2 Department of Paediatric Otolaryngology/Head and Neck Surgery3 Department of Medical GeneticsThe Hospital for Sick Children and University of Toronto, Toronto, Ontario, CanadaBackground and Purpose: Congenital pyriform aperture stenosis (CPAS) is an unusual,but well described cause of nasal obstruction, usually in the newborn. CPAS isfrequently associated with single central mega-incisor. Reported CNS features includemidline anomalies such as holoprosencephaly and posterior pituitary ectopia. Otherassociations include midface hypoplasia, triangular shaped palate with midline ridge andseveral multiple congenital anomaly syndromes, including VACTERL, CHARGE and22q11DS. We describe the imaging features in 33 cases and present several new findingsand associations, such as crowding of the maxillary dentition and labyrinthine dysplasia.Materials and Methods: We retrospectively reviewed imaging characteristics of 33patients with a diagnosis of CPAS during the period 1993 to 2008 (16 years).Results: A total of 33 patient with CPAS were identified. There were 16 males and 17females. Eighteen patients underwent both CT and MRI (including one fetus), 8 patientsunderwent CT and 7 patients (including an additional fetus) had only MRI performed.Important findings included: superior central megaincisor (SCMI) in 23/33 (69.7%) ,crowding of the lateral incisors when SCMI was not present in 10/33 (30.3%), narrowednasal pyriform aperture (NPA): 3.9 - 12.1 mm in 32/33, triangular palate in 31/33 (94%)and a midline palatal ridge in 32/33 (97%). Even when SCMI was present, there wascrowding of the remainder of teeth in the triangular shaped palate. Typical features ofPPE in 5/33 (15%) and holoprosencephaly in 4/33 (12% ) were also identified.We also describe dysplasia of the horizontal semicircular canal in 25% of 64 ears.Additional inner ear anomalies included enlarged vestibular aqueduct, small cochlearnerve canal, enlarged vestibule and stenotic internal auditory canal in several patients.Conclusion: New features of CPAS include inner ear dysplasia and crowding of thelateral incisors in patients with two central maxillary incisors, when SCMI was notpresent.46 of 71

University of Toronto Department of Medical Imaging Research Day 2009MRI imaging assessment of parapharyngeal extensionin nasopharyngeal carcinomaA Bharatha, E Yu, AL Thompson, TD Walters, ES BartlettPrincess Margaret Hospital, University of TorontoPurpose: Nasopharyngeal carcinoma (NPC) has a tendency for early parapharyngealextension (PPE). As part of the current American Joint Committee on Cancer (AJCC-TNM) staging of NPC, the presence of PPE differentiates T1/T2a from T2b disease, andis associated with worse prognosis. However, the radiologic definition of PPE lacksconsensus. The AJCC staging system defines PPE as tumor extension posterolateral tothe pharyngobasilar fascia (PBF). The purpose of this study is: 1.) to determine whetherPPE can be reliably assessed by different readers; 2.) to evaluate several potentialindicators of PPE; and, 3.) to highlight potential issues in the current AJCC stagingdefinition of PPE.Materials and Methods: Initial staging MR studies from 50 consecutive pre-treatmentNPC patients were identified. The nasopharyngeal/parapharyngeal tissues were separatedinto right/left sides and assessed separately. Three radiologists independently reviewedeach side in a randomized blinded fashion for the presence of PPE based on the AJCCstaging definition. PPE's relationship to 1.) presence of pharyngobasilar fascia attenuationor disruption; and 2.) tumor extension beyond a previously described "line" joining themedial pterygoid plate and the lateral ICA was evaluated. In addition, we also examinedthe relationship of the AJCC PPE definition to tumor involvement of six structuresadjacent to the PBF [1. levator veli palatini (LvP); 2. tensor veli palatini (TvP);3. neurovascular bundle (NVB); 4. prestyloid parapharyngeal fat (PsF); 5. prevertebralmusculature (PvM); and 6. pterygoid process marrow signal change (PtM). Data werecompared using the Kappa statistic and McNemar's Test.Results: Tumor was present in 83/100 sides, with PPE present in 47 (57%). There wasgood inter- and intra-observer agreement for PPE. In normal sides, the PBF was alwaysdetected. Attenuation or disruption of the PBF was a very good proxy for PPE(Sensitivity 99%, Specificity 94%, kappa 0.95, p

University of Toronto Department of Medical Imaging Research Day 2009improved by incorporating more specific reference to standard radiologic spaces andlandmarks.Table 1: Relationship of PPE cases (n=47) to tumor involvement of six structuresadjacent to the PBFLvP TvP NVB PsF PvM PtMn 22 10 22 5 36 17% 47 21 47 11 77 3648 of 71

University of Toronto Department of Medical Imaging Research Day 2009Vascular andInterventional Imaging49 of 71

University of Toronto Department of Medical Imaging Research Day 2009Short-term outcomes after varicocele repair by embolizationand microsurgical varicocelectomy: Implications for IVF planningJR Beecroft, A Mujoomdar, G Patry, KC Lo, JR Kachura, K Jarvi, DK RajanPurpose: To compare short term outcomes on sperm parameters following surgicalversus embolization varicocelectomy.Materials & Methods: A retrospective analysis ofpatients (pts) was performed following varicocele repair surgically via microsurgicalinguinal varicocelectomy (Sx) or by embolization (Emb). Semen analysis (S/A) prior totreatment and at 3 and 6 months following repair were evaluated. Primary outcome waschange in the total motile sperm count (TMC= ejaculate volume x concentration of spermx motile fraction). Comparison within and between treatment groups at baseline, 3 and 6-months following treatment was performed using paired and independent T-tests.Results: 56 pts initially evaluated, 28 were in each group. See Table 1 for S/A resultsand results of comparisons within treatment groups. Baseline S/A was comparable inboth groups, p=0.92. At 3 months there was a significant improvement in TMC in theEmb group compared to baseline (p=0.036) but not in the Sx group (p=0.45).Importantly, at 3 months 4 patients who initially were oligospermic became azoospermicin the Sx group (14.3%) compared to none in the Emb group. There was a significantdifference in TMC between Emb and Sx groups at 3 months (p=0.04) but not at 6 months(p=0.27).Conclusion: Embolization offers better short-term outcomes (3-months) versusmicrosurgical varicocelectomy. By 6 months both the Emb and Sx groups had similarimprovements in TMC. Delayed improvement following Sx may be explained bytransient stress to the testis due to anesthesia and surgical procedure itself. These findingsshould be considered among couples planning IVF close to the time of varicocele repair.Table 1: Results TMC, comparison within and between Rx groupsTMC ± SD (millions) at % Increase ± SD at P value vs baseline atBaseline 3 mnths 6 mnths 3 mnths 6 mnths 3 mnths 6 mnthsEmb 12.1 ± 23(n=28)Sx 11.6 ± 15(n=28)20.7 ± 20(n=24)10.4 ±15(n=27)20.2 ± 25(n=23)13.5 ± 15(n=26)P value 0.92 0.04 0.20301 ± 582 285 ± 701 0.02 0.05881 ± 288. 85 ± 208 0.22 0.0250 of 71

University of Toronto Department of Medical Imaging Research Day 2009Interim results of the Celect IVC filter registryMark Otto Baerlocher 1 , Murray R Asch 2 , Andy Myers 2 ,Vincent L Oliva 3 , Gilles Soulez 3 , Deborah van Londen 21 Radiology Residency Training Program, University of Toronto, Toronto, Ontario2Diagnostic Imaging, Lakeridge Health Corporation, Oshawa, Ontario3 Dept de Radiologie, CHUM-Notre-Dame, Montréal, QuébecPurpose: To present interim results of the Canadian Celect TM Inferior Vena Cava FilterRegistry.Materials and Methods: A prospective multi-centre registry using standardized dataforms was created in order to determine the safety and ease-of-retrieval of Cook Inc.’sCelect TM IVC filter .Results: Filters were successfully placed in 40 patients, 58% with deep venousthrombosis and 40% with pulmonary embolic disease (53% male, 47% female; averageage 60.3 years +/- 17.7). 65% of patients had a temporary contra-indication to anticoagulation.95% of filters were placed infra-renally, and 5% were placed supra-renally.33% were tilted upon placement. 38% of patients died of unrelated causes prior toplanned filter retrieval. Filter retrieval was attempted in 53% of patients; of retrievalsattempted, 1 (4%) failed due to orientation of the retrieval hook. The most commonreason that retrieval was not attempted was patient death prior to retrieval attempt (83%).Among those with successful retrieval, the average implantation time was 145 days (+/-149 days; range 5-551 days). Cranial/Caudal filter migration and caval penetrationoccurred in 22% and 14% of patients respectively. Filter tilt occurred in 45% of patients.The mean fluoroscopy time during retrieval was 9.0 min +/-16.6 min (5.7 +/- 3.3 minwith smallest and largest values removed). Radiologists performing the procedures rateddifficulty in filter retrieval as “None” or “Minimal” in 82% of patients. There was noevidence of filter fracture in any of the cases with successful filter removal.Conclusions: Preliminary results demonstrate the Celect TMtechnically easy to retrieve.filter to be safe and51 of 71

University of Toronto Department of Medical Imaging Research Day 2009Vascular and non-vascular mimics of the CT angiography “spot sign”in patients with secondary intracerebral hemorrhageClare Bent, Kong Teng Tan, Dheeraj Rajan, Martin Simons,John Kachura, Kenneth SnidermanPurpose: Unfavorable proximal aortic neck morphology may predispose to an increasedincidence of acute and delayed adverse events after endovascular aortic repair (EVAR).With increasing technical expertise and newer stent-graft design, a greater proportion ofpatients with unfavorable neck anatomy are being offered EVAR. Supra renal fixationEVAR aims to counter adverse neck anatomy and provide secure proximal fixation andsealing. The objective of this study is to evaluate clinical outcomes following supra renalfixation EVAR.Materials & Methods: Between October 2005 and September 2008, 114 supra renalfixation EVAR procedures (77 Cook consisting of 17 Zenith and 60 Zenith ‘FLEX’; 37Medtronic Talent) were performed. Procedural data were collected prospectively andsupplemented with retrospective review of electronic patient records and radiologicalimages. Aortic morphology was assessed using computed tomographic angiography (CTA).Patients were classified as having unfavorable proximal aortic neck anatomy by thefollowing criteria: proximal aortic neck diameter >30mm, neck length 60°, conical neck configuration and circumferential thrombus >50%. Clinical outcomes in45 patients with zero adverse features (non hostile necks) were compared with 69 patientswith one or more adverse features (hostile necks). Mean follow up was 17.8 ± 8.2 months(range: 0.75-39 months).Results: Of 69 patients classified as having a hostile proximal aortic neck, 11 patients hada neck diameter of >30mm (mean: 32.1 ± 1.4mm), 33 patients a short neck (mean length:10.7 ± 2.2mm), 37 patients a markedly angulated neck (mean angle: 70.8 ± 9.6°), 25patients a conical aortic neck and 2 patients had circumferential thrombus of >50%.Twenty-nine patients (42.0%) demonstrated more than one unfavorable anatomical feature.During comparison of the non hostile neck with the hostile neck group, there were nosignificant differences in the incidence of primary technical success (p=1.0), assistedprimary technical success (p=1.0), intra-operative adjunctive procedures (p=1.0), earlyproximal type I endoleak (30 days)(p=1.0), distal type I endoleak (p=0.15), type II endoleak (p=0.45), type III endoleak(p=1.0), secondary interventions (p=1.0), aneurysm sac expansion (p=1.0), or 30 daymortality (p=1.0). No association was demonstrated between the number of hostilecharacteristics or degree of angulation with adverse outcome. Multivariate logisticregression identified no correlation between clinical outcome and the presence of eachhostile neck characteristic.Conclusion: Patients with hostile proximal aortic neck anatomy may be treated with suprarenal fixation EVAR. Early and midterm clinical outcomes are promising. ‘Instruction foruse’ guidelines may be expanded to include patients with hostile proximal aortic neckanatomy.52 of 71

University of Toronto Department of Medical Imaging Research Day 2009Assessment of clinical predictors for endoleaks and complications in patientsundergoing endovascular aneurysm repair (EVAR)Del Dhanoa, Vikram PrabhudesaiIntroduction: During recent years there has been a shift of thoracic and abdominalaneurysm management from an open repair in the operating theatre to an endovascularaneurysm repair (EVAR) (1). This trend is due to the decreases in mortality,postoperative complications and hospital length of stay seen in patients who are treatedusing the endovascular approach (2, 3). EVAR is becoming a new standard for thoracicand abdominal aneurysm repair but the procedure is still relatively new and evolving.Practitioners of EVAR should be cognizant of endoleak and complication rates as theyimprove their EVAR practice over time. Part of the strategy to decrease endoleaks andcomplications is to identify preoperative clinical features that may increase theprobability of EVAR endoleaks and complications. The purpose of this study is toidentify patient demographic features as well as preoperative co-morbidities that maylead to an increase in peri- and postoperative EVAR complications.Objective: To define the preoperative clinical characteristics that identify patients atincreased risk for peri- and postoperative endovascular aneurysm repair (EVAR)endoleaks and complications.Materials and Methods: 114 EVAR patients were retrospectively evaluated over a 10year period (1998-2007). Sources of patient information include demographic data,clinical features, preoperative vascular surgery and anaesthesia consults, operative notes,and postoperative follow-up progress notes. Different demographic parameters wereanalyzed (including age, gender, type of aneurysm) as well as patient comorbidities (suchas diabetes, coronary artery disease (CAD), cerebrovascular accidents (CVA), chronicobstructive lung disease (COPD)) to determine if there was a difference betweencomplication rates with respect to each clinical feature.Measurements and Results: The mean age of the patients being studied was 72.5 yearsold consisting of 102 males (89.5%) and 12 females (10.5%).There were 21 endoleaks of which 4 were type 1 (18%) and 18 were type 2 (82%) and 8occurred within the first 30 days (36%). The rates of endoleak by year were 31% between1998-2004, 26.9% for 2005, 13.5% for 2006, 14.3% for 2007 with a total endoleak rateof 19.3% over a 10 year period. There was no statistical significance of endoleakoccurrence between years (p-value=0.28).The complication rates by year were 12.5% between 1998-2004, 11.5% for 2005, 21.6%for 2006, 11.4% for 2007 with a total complication rate of 14.9% over a 10 year period.There was no statistical significance of complication occurrence between time intervals(p-value=0.58). Early complications, defined as less than 30 days from the date of theprocedure, were quantified as 7%. The 30 day all-cause mortality rate was 0.9%. The53 of 71

University of Toronto Department of Medical Imaging Research Day 2009complications were wound infections (5.3%), myocardial infarctions (2.6%), graftocclusion (1.8%), graft migration (0.9%), ischemic stroke (0.9%), contrast inducednephropathy (0.9%), spinal cord infarct (0.9%), heparin induced thrombocytopenia(0.9%) and pneumonia (0.9%).Complication rates by preoperative clinical feature was 11.5% in 52 smokers versus 18%in 62 non-smokers (p-value=0.33), 13.3% in 15 diabetics versus 15.2% in 99 nondiabetics(p-value=0.85), 8.3% in 12 renal insufficiency patients versus 15.8% in 101non-renal insufficiency patients (p-value=0.5), 15% in 60 CAD patient versus 15.1% in53 non-CAD patients (p-value=0.99), 14.3% in 14 CVA patients versus 15.2% in 99 non-CVA patients (p-value=0.93), 22.7% in 22 cancer patients versus 13.2% in 91 non-cancerpatients (p-value=0.27) and 8.7% in 23 COPD patients versus 16.7% in 90 non-COPD(p-value=0.35). There was no statistical significance between endoleak or complicationrates and respective preoperative co-morbid clinical feature.Conclusion: We conclude that among patients undergoing EVAR repair endoleakoccurrence and postoperative complications cannot be predicted by the presence ofreadily identifiable preoperative clinical characteristics.References:1. TF Lindsay. Canadian Society for Vascular Surgery consensus statement onendovascular aneurysm repair. Canadian Medical Association Journal. 2005 March29:172 (7).2. F Aarts, S van Sterkenburg, JD Blankensteijn. Endovascular aneurysm repair versusopen aneurysm repair: Comparison of treatment outcome and procedure-relatedreintervention rate. Annals of Vascular Surgery. 2005 Sept;19(5), 699-704.3. WA Lee, JW Carter, G Upchurch, JM Seeger, TS Huber. Perioperative outcomesafter open and endovascular repair of intact abdominal aortic aneurysms in the UnitedStates during 2001. Journal of Vascular Surgery. 2004 Mar;39(3):491-6.54 of 71

University of Toronto Department of Medical Imaging Research Day 2009Combined prophylactic internal iliac artery balloon occlusion anduterine artery embolization in the management of invasive placentaDonna L. D'Souza 1 , John R. Kachura 1 , Rob Beecroft 1 ,Rory C. Windrim 2 , John C. Kingdom 21 Interventional Radiology, Mount Sinai Hospital, Toronto, ON2 Obstetrics, Mount Sinai Hospital, Toronto, ONPurpose: To evaluate the safety and efficacy of combined intra-operative internal iliacartery balloon occlusion and post-operative uterine artery embolization in patients withinvasive placenta undergoing caesarean delivery.Materials and Methods: Between 2002 and 2008, 14 patients with invasive placentaunderwent pre-operative prophylactic insertion of bilateral internal iliac artery occlusionballoons, intra-operative inflation of the balloons, and post-operative bilateral uterineartery embolization using absorbable gelatin sponge. All patients had concomitantplacenta previa, were multiparous, and 93% had previous caesarean section. Invasiveplacenta was confirmed by pre-delivery MRI (8 had placenta percreta and 6 had placentaincreta). Via retrospective chart review, the following outcomes were evaluated: intraoperativeblood loss, transfusion requirement, hysterectomy rate, major complicationsand fluoroscopy time. Major complications were defined as those requiring furtherendovascular or surgical intervention.Results: All patients in the study group (n=14) underwent caesarean section: 2 patientsunderwent planned caesarean hysterectomy and 12 patients were planned for uterinepreservation. Mean maternal age was 34 years (range 23-39), and mean gestational age atdelivery was 35 weeks (range 30-38). Mean fluoroscopy time for pre-delivery ballooninsertion was 5.4 minutes (range 2.0-16.5), and for post-operative embolization was 10.6minutes (range 3.3-15.9). The mean estimated intra-operative blood loss was 1250 mL(range 400-4000). 4/14 (28.6%) patients required a blood transfusion with mean volumeof 2.25 units packed red blood cells (range 1-4). There were no major complications inthe 2 patients who had planned caesarean hysterectomy. Within the group planned foruterine preservation, 5/12 (36%) had a major complication: post-partum hemorrhage(5/5), DIC (2/5) and endomyometritis (2/5). 4 of these patients required hysterectomy tocontrol the post-partum hemorrhage. The hysterectomy rate in the uterine preservationgroup was therefore 33% (4/12), and successful uterine preservation was achieved in67% (8/12).Conclusion: The use of combined prophylactic bilateral internal iliac artery balloonocclusion and uterine artery embolization is safe and effective in controlling intraoperativeblood loss and preserving the uterus in patients with invasive placentaundergoing caesarean delivery.55 of 71

University of Toronto Department of Medical Imaging Research Day 2009Molecular imaging of atherosclerotic plaqueKT Tan, SG Pasian, J Zhan, S Chiu, G Leung, AR MoodyBackground: The imaging of atherosclerosis has, up until the past few years, beenlimited to the study of luminal size. Recently, there has been an interest in the descriptionof plaque morphology/ constituents. However, macroscopic changes are always precededby changes in the molecular expression of various molecules. Vascular cell adhesionmolecule-1 (VCAM-1) is an adhesion molecule that is upregulated in atherosclerosis andplays an important role in atherogenesis. The long term goal of our group is to synthesiseultrasound and MRI contrast agents that can detect VCAM-1 expression in vivo in arabbit model of atherosclerosis.Hypotheses(1) VCAM-1 is expressed in our rabbit model of atherosclerosis.(2) A VCAM-1 antibody binding microbubble contrast agent can be synthesized inour laboratory.(3) An anti-VCAM-1 targeted iron oxide particle can be imaged ex vivo using MRI.Methods: Aortic arch segments from a rabbit model of atherosclerosis are studiedhistologically for the expression of VCAM-1. For ultrasound imaging, perflurobutane isencased in a phospholipid-polyethylene glycol shell to form a microbubble. An antibodydirected against VCAM-1 is then attached to the microbubble.The same anti-VCAM-1 antibody can also be attached to iron oxide particles. TheVCAM-1 targeted iron oxide particle is then used to perfuse an ex vivo rabbit aortic archprior to MR imaging. Histological confirmation of iron oxide staining will be obtained.Results: Histological examination has confirmed the presence of VCAM-1 expression inthe aorta of our rabbit model of atherosclerosis. VCAM-1 can be found in both theluminal and neovascular endothelium. There is also VCAM-1 expression by vascularsmooth muscle cells.Preliminary ex-vivo results from using the VCAM-1 targeted iron oxide particles in theMRI scanner suggest that they are capable of detecting VCAM-1 expression in rabbitaortic arch. Histological confirmation is pending.An anti-VCAM-1 antibody binding microbubble has been synthesized in our department.This has been confirmed by both flow cytometry and microscopy.Conclusions: Although in its early stages, this work suggests that the MR imaging ofVCAM-1 expression is feasible. We will be doing further studies using cell culture todetermine the optimal binding conditions for the targeted iron oxide particle.The results from the ultrasound contrast experiments are promising. At present, we are inthe process of fine tuning our contrast agent, in order to obtain microbubbles of uniformsize. Further in vitro work using cell culture is also planned to study the interactionbetween the targeted microbubble with endothelial cells.56 of 71

University of Toronto Department of Medical Imaging Research Day 2009Radiofrequency ablation of renal cell carcinoma: Mid-term resultsJohn R. KachuraDivision of Vascular and Interventional Radiology, Department of Medical Imaging,University Health Network and Mount Sinai Hospital, University of TorontoPurpose: To evaluate the mid-term efficacy and safety of radiofrequency ablation (RFA)of renal cell carcinoma (RCC).Materials and Methods: The medical records and imaging of all patients with RCCtreated with RFA from January 1, 2004 to December 31, 2008 were reviewed. Thepatient cohort consisted of 75 patients (57 male, 18 female) with a mean age of 61 years(range 28-89 years). Each patient had an outpatient percutaneous RFA procedure undercombined ultrasound and CT guidance with conscious sedation using a 3.5 cm or 4 cmarray multi-tined expandable LeVeen electrode. All patients except one had significantcomorbidities (n=60), renal dysfunction (n=28), previous nephrectomy (n=8), and/or vonHippel Lindau syndrome (n=9). In total, 81 tumors were ablated with a mean size of 2.8cm (range 1.0-7.4 cm). More than 80% of tumors were pathologically proven to be RCC.Successful ablation was defined as no tumor enhancement and no growth on follow-upcontrast-enhanced CT, MRI, and/or US.Results: Mean follow-up was 27 months (range 1-58 months). Successful ablation wasnoted in 73 of the 75 patients after a single RFA procedure (primary treatmenteffectiveness = 97%). One of the 2 patients with residual viable tumor was successfullyablated after a second RFA procedure using a Cool-tip straight needle electrode(secondary treatment effectiveness = 99%). Recurrent viable tumor after successfulablation has not been encountered thus far, but 2 patients developed enhancing soft tissueat the ablation zone pathologically proven to represent inflammation. There were 4 majorcomplications (one abscess, 3 ureteral strictures) and 3 minor complications (one splenichematoma, 2 patients with leg pain from psoas injury despite thermal protection with airor dextrose). One patient’s renal dysfunction continued to worsen at an unchanged rate,eventually requiring dialysis.Conclusions: Mid-term results show that RFA of RCC using a multi-tined expandableelectrode is a safe and effective one-time outpatient procedure performed without generalanesthesia. Long-term follow-up is required before considering RFA of RCC in patientswho are candidates for surgical resection.57 of 71

University of Toronto Department of Medical Imaging Research Day 2009Bland hepatic artery embolization for symptomaticneuroendocrine tumor metastases: An 11-year experienceKebby F.G. King, John R. KachuraPurpose: To evaluate the safety and efficacy of bland hepatic artery embolization for thepalliation of symptomatic neuroendocrine tumor metastases, and to assess radiologicresponse.Materials and Methods: Between 1998 and 2009, 50 hepatic artery embolizationprocedures using polyvinyl alcohol particles or tris-acryl gelatin microspheres wereperformed at 2 hospitals for 28 patients with unresectable, biopsy-confirmed hepaticmetastases from carcinoid or neuroendocrine tumors. A retrospective review wasperformed to evaluate symptomatic response, major complications, and radiologicresponse. Radiologic assessment was performed using RECIST and EASL criteria.Results: The patient cohort consisted of 15 females and 13 males, with a mean age of 61years (range 37-79). Indications for embolization included abdominal pain and distention(n= 18), flushing and/or other hormonal symptoms (n=5), fatigue (n=4), and rapid tumorprogression (n=1). Mean clinical follow-up was 25 months (range 0.5-69). Of the 27patients for whom clinical follow-up information was available, 19 patients experiencedsignificant symptomatic improvement (70%). There were no treatment-related deaths.Major complications occurred in 4 patients: 2 had sepsis, one had a large hematoma, andone had encephalopathy for which no etiology was found.Using RECIST criteria, no progression was noted after 35 procedures (35/48= 73%). Ofthese, partial response was seen after 14 and stable disease after 21 procedures.Progressive disease was noted after 13 procedures (13/48= 27%). The mean time toprogression was 13 months (range 0-23).EASL necrosis criteria were used to quantify necrosis. 0%, less than 50%, greater than50% and 100% necrosis was seen initially after 3, 14, 14, and 15 procedures (7%, 30%,30%, 33%) respectively. No increase in enhancement throughout follow-up was notedafter 22 procedures (22/46 =48%). The mean length of time to show increasedenhancement from the initial post-embolization CT was 8 months (range 1-25).After 11 of the 50 embolization procedures, an initial increase in tumor size was noted,but with 6 of these 11 cases (55%) there was greater than 50% necrosis.Conclusions: Bland hepatic artery embolization for neuroendocrine tumor metastases issafe and effective for the palliation of symptoms. Most patients demonstrated radiologicstability or improvement that persisted on average for 13 months, when using sizecriteria. In a minority of patients, size criteria were discordant with response as measuredby tumor necrosis.58 of 71

University of Toronto Department of Medical Imaging Research Day 2009Efficacy of stent-graft placement for salvage ofdysfunctional hemodialysis fistulasD.K. Rajan, C.L. Bent, M. Simons, K. Tan, R. Beecroft,J. Jaskolka, J. Kachura, K. SnidermanUniversity Health Network, University of TorontoPurpose: To retrospectively determine the clinical efficacy of stent-graft placement forsalvage of dysfunctional autogenous hemodialysis fistulas.Material and Methods: Between September 2006 and June 2008, 24 Fluency stentgrafts(Cr Bard, Tempe, AZ) were inserted in 17 patients (12 men and 5 women; meanage: 67 years, range 25 - 85 years) with failing autogenous hemodialysis fistulas (tworadiocephalic, 12 brachiocephalic and three brachiobasilic). Six fistulas were thrombosedat presentation. Indications for stent-graft insertion included: one venous occlusion, 9resistant stenoses, six pseudoaneurysms and one rupture following fistuloplasty. Fistulafunction pre and post intervention was assessed using ultrasound dilution technique.Results: Of the 17 fistulas intervened on, 9 were considered unsalvageablepercutaneously. Initial technical success was 100%. Clinical success was 100%. Theprimary patency rates at 3, 6 and 12 months were 94.1%, 88.2% and 64.7% respectively.With the Kaplan-Meier method, the primary patency rates with standard errors of theestimate at 3 and 6 months were 94% (0.82 - 1.06), and at 12 months, 94% (0.79 - 1.08).Secondary patency rates were equal to primary patency rates. No accesses were lost andno patients were lost to follow up over the study period. The binary re-stenosis rate at 6months was 5.9%. The percentage of fistulas with concurrent lesions treated at the timeof stent-graft placement was 41.2%. The mean transonic flow rate prior to interventionwas 959.3 ml/min. Post intervention was 2186.8 ml/min (p=0.01). No complicationsoccurred associated with stent-graft deployment.Conclusion: Stent-graft placement in dysfunctional autogenous fistulas, some of whichwere considered unsalvageable with traditional percutaneous methods is technicallyfeasible. Stent-graft placement was effective in preserving function and preventing accessabandonment with patency rates that exceed historical patencies with angioplasty and/oruncovered stents.59 of 71

University of Toronto Department of Medical Imaging Research Day 2009Retrospective review of non-vascular findings in peripheral CT angiographyAhmed Farooq, Jeff JaskolkaObjectives: The purpose of this study was to evaluate the incidence and significance ofextravascular findings in patients undergoing CT angiography (CTA) of the abdomen,pelvis and lower extremities.Methods: A retrospective review of patients examined between March 2006 and Aug2008 was performed. Patients underwent either CTA of the abdomen and pelvis alone orCTA of the abdomen, pelvis and lower extremities. Images where reviewed by a boardcertified radiologist and all extravascular findings recorded and compared with thecorresponding dictated radiologist reports. Extravascular findings were divided into 3categories: incidental, clinically important but probably benign, and serious/suspicious.The patients’ electronic medical records and radiology reports were reviewed todetermine the impact of these findings on patient management and the outcome of anyfollow-up imaging studies or other diagnostic evaluation.Results: A total of 76 patients were imaged in the study period, of which 52 were male(68.4%). 70% of patients showed extravascular findings. Of these, 46 patients (61%)had incidental findings, 10 (13%) had clinically significant but probably benign findingsand 5 (7%) had serious/suspicious findings. In the patients with serious/suspiciousfindings, 2 were confirmed to have neoplastic disease on follow up imaging whilemalignancy was ruled out in the other 3 patients. All significant findings were seen in theabdomen or pelvis rather than the images of the extremities. Imaging findings in theretrospective review were concordant with the patients’ dictated reports in all cases.Conclusion: CTA is a useful tool in assessing vascular disease, however CTA of theabdomen can also uncover a significant number of extravascular findings. Almost 20% ofincidental findings were clinically significant or resulted in a serious diagnosis such asneoplasm requiring further treatment. Proper review of all images in a CTA examinationis important for the detection of these abnormalities to ensure patients can receiveappropriate diagnostic workup or treatment.60 of 71

University of Toronto Department of Medical Imaging Research Day 2009Limb perfusion: Characterization of a new techniqueJoe Barfett, Edmund Ng, Jeff JaskolkaPurpose: In patients with critical limb ischemia, wound and ulcer healing are dependentupon adequate blood flow. The goal of this study was to quantify skeletal muscleperfusion in the feet of normal subjects with dynamic perfusion CT, taking advantage ofthe 16cm scan range of the Toshiba Aquilon One TM 320-multidetector scanner.Materials and Methods: 6 healthy male subjects, aged 22-50, were enrolled in thestudy. Dynamic CT was performed from the ankle to the plantar aspect of the foot afterbolus injection of intravenous contrast at 5mL/sec. Contrast transit to the ankle wasdetermined with a timing bolus of 20mL, injected at 5mL/sec. Restraints were used inthe later patients to reduce motion artifact. IV contrast dose was varied between 50-90mLand radiation dose varied from low (~2.7mSv total dose) to standard (~4.4mSv) for thetotal exam. Several acquisition protocols were tested. Perfusion analysis was performedusing both deconvolution by single value decomposition on a commercial workstationand calculation of perfusion index by a compartmental model with custom software.Results: Each foot was analyzed separately, giving 12 datasets. Beam hardening artifactlimited evaluation of the time density curve in patients one to four, scanned using the lowradiation dose protocol and lower contrast volumes of 50 and 70mL. Perfusion index wascalculated with a variation of the Mullani-Gould formula in patients five and six in themuscles of the plantar compartment, plantar fat and bone of the distal tibial epiphysisafter standard dose CT and 90mL of contrast. Analysis of the entire plantar compartmenten bloc with compartmental analysis was more efficacious than individual voxel timedensity analysis by deconvolution. Perfusion index estimates ranged between 0.17 and1.01 /s in the muscular compartment. The use of restraints reduced patient motion andfacilitated analysis.Conclusion: Beam hardening artifacts associated with low radiation and contrast doseprotocols, as well as low contrast uptake in muscle in general, limit reliable estimation ofsoft tissue enhancement. Dynamic acquisitions with serial CT examinations of normalradiation dose are needed to perform quantification of muscle perfusion, and injection of90mL of iodinated contrast allows estimation of Perfusion Index in the plantarcompartment. We are now undertaking a larger study with these optimized parameters.61 of 71

University of Toronto Department of Medical Imaging Research Day 2009Abdominal, GU, and GIImaging62 of 71

University of Toronto Department of Medical Imaging Research Day 2009CT urography: Image quality and accuracyfor upper tract urothelial cancerME O’Malley, E Maheshwari, S Ghai, M Staunton, C MasseyDivision of Abdominal Imaging, Joint Department of Medical ImagingPurpose: To assess the quality and diagnostic accuracy of CT urography using a splitbolustechnique.Materials and Methods: We identified 200 consecutive patients (119 men, 81 women;median age 58 years, range, 18 – 89) with a history of hematuria who had CTU betweenJanuary 2004 and December 2006. The majority of patients were scanned on a 64-sliceCT scanner. CTU protocol included anatomic coverage from top of kidneys to bladderbase. The first set of images was obtained without IV contrast. Then 50 ml of contrastwas injected at 3 ml/sec. Five minutes after injection, an additional 80 ml of contrast wasinjected at 3 ml/sec and a second set of images was acquired 100 seconds after the secondinjection. Images were displayed in axial (3 x 1.5mm) and coronal (3 x 3mm) planes.Images were independently reviewed by two radiologists blinded to final diagnosis.Upper urinary tracts were divided into 4 segments. To determine quality of CTUprotocol, degree of opacification of each segment was recorded as follows: 0-unopacified, 1- less than 50%, 2- 50 to 99%, and 3- 100%. For diagnostic accuracy ofupper tract tumors (UTT), each study was subjectively scored as follows: 0 - negative, 1 -probably negative, 2 - indeterminate, 3 - probably abnormal, 4 - definitely abnormal.Standard of reference included all clinical and laboratory data up to 12 months followingCTU.Results: For reviewers 1 and 2, 85.1% and 84.5% of segments were at least 50%opacified, respectively. For hematuria, the final diagnosis was: no cause, 123 (61.5%);urothelial cancer, 27 (13.5%); nonmalignant 49 (24.5%) and indeterminate 4 (2%)patients. There were 9 UTT. Sensitivity, specificity, and accuracy for UTT forprospective interpretation, reviewer 1, and reviewer 2 were: 88.9, 99.0, 98.5%; 100, 99.5,99.5%; and 88.9, 99.0, 98.5%, respectively.Conclusion: CT urography using a split-bolus technique provided high quality studiesand was accurate for detection of UTT.63 of 71

University of Toronto Department of Medical Imaging Research Day 2009Microbubble DCE-US, DCE-CT, and DCE-MRI imaging for theassessment of tumor response to Sunitinib treatmentof renal cell carcinoma: Preliminary resultsM Atri, D Cheng, PN Burns, G Stanisz, R Williams,G Lueck, J Hudson, C Bailey, G BjarnasonPurpose: To evaluate three imaging modalities; dynamic contrast enhanced-US (DCE-US), dynamic contrast enhanced-CT (DCE-CT), dynamic contrast enhanced-MRI (DCE-MRI) to predict anti-angiogenic response to Sunitinib (Sutent) for treatment of metastaticRCC.Materials and Methods: A cohort of patients with biopsy proven RCC received Sutentfor 4 weeks. Following the protocol, 13 patients had baseline DCE-US, DCE-CT, DCE-MRI, 11 had DEC-US and DCE-MRI 2 weeks into treatment, 7 had DCE-US, 8 DCE-CTat 4 weeks, and 10 had DCE-US one week post treatment. DCE-US was performed on anIU22 Phillips machine during drip infusion of 1.1 ml Definity/50 mL 9% saline usinghigh MI disruption/low MI replenishment, DCE-CT on a 64 slice MDCT using 1 mL/kgof Visipaque at 5 mL/s covering 4 cm at 8 x 5 mm collimation, 1 scans/s for 1 minute, 1scans/5s for 1 minute, and DCE-MRI on a 1.5T GE using 0.1 mL/kg Gadodiamide, 3DLAVA, 12 coronal scans at 8 mm slice thickness at 1 scan/5s for 7 minutes. Relativeblood volume was calculated by DCE-US, Blood flow (BF), blood volume (BV),permeability surface area (PS) by DCE-CT, Ktrans (min-1), and Ve (mL) (volume of theextra-cellular extra-vascular space) by DCE-MRI.Results: At 2 week into treatment, DCE-US showed 61% drop in BV (p=0.001), DCE-MRI 3.4% drop in Ve (p>0.05), and 53% drop in Ktrans (p=0.03). At 4 weeks intotreatment DCE-US showed 75% drop in BV (p=0.01), DCE-CT 82% drop in BF(p=0.008), 72% drop in BV (p=0.008), and 61% drop in PS (p=0.008). At 1 week posttreatment DCE-US showed 13% drop in BV (p>0.05).Conclusion: Both DCE-US and DCE-CT showed significant drop in BV duringtreatment. Vessel permeability significantly dropped during treatment as shown on PS byDCE-CT and Ktrans on DCE-MRI. DCE-US showed a rebound of BV post treatment.64 of 71

University of Toronto Department of Medical Imaging Research Day 2009Radiology resident on-call productivity during a night shift schedule:A pilot projectDavid Kelton, Ashish Mahajan, Anthony HanbidgeDepartment of Medical Imaging, University of TorontoPurpose: There is increasing focus on emergency department (ED) patient workflowand safety. This in part due to recent studies examining the impact of trainee duty hourson patient and resident safety, as well as recent government initiatives to improve EDpatient wait times in Ontario. The purpose of this study is to compare radiology residenton-call productivity during a night shift schedule with current call schedules.Methods: An R1 and R3 resident performed on-call radiology duties within a modifiedschedule. The pilot project schedule included one resident on a weekday (Monday toFriday) block of evenings, 5pm-10pm, and the second resident on a weekday block ofnights, 10pm-8am. This was organized within the current on-call point distributionsystem used at the University of Toronto and performed at Sunnybrook Hospital.Primary outcome was time from cross-sectional study (CT, MRI) to preliminary report.Secondary outcome was preliminary report accuracy compared to final report. The R1resident was blinded to study outcomes. The daily on-call total case volume, traumavolume, and ultrasound volumes were recorded to control for potential sources of reportdelay. Analysis was performed using an unpaired 2 tailed T-Test.Results: Reporting times at night during the pilot project were 46±31 minutes for allstudies and 66±53 minutes during the regular call schedule (P=0.02). Reporting times forhead CT, body CT, and CTA were 20±11 min, 53±23 min, 73±39 min during the pilotschedule and 45±37 min, 72±47 min, 117±112 min during the regular call schedule.During the pilot project period, there was an average of 25 cross-sectional studiesbetween 5pm-8am (range 17-34), with an average of 10 studies between the hours of10pm-8am (range 4-13). Total cases, ultrasound, and trauma volumes were similarbetween both schedules. Accuracy was high during both call periods.Conclusion: Radiology resident preliminary reporting times for emergency crosssectionalimaging can be significantly decreased using a block-call schedule whilemaintaining high accuracy.65 of 71

University of Toronto Department of Medical Imaging Research Day 2009Biliary anatomy of potential donor for living donorliver transplantation: The utility of CT cholangiographyin cases with indeterminate results on MRCPSean E. McSweeney, Tae Kyoung Kim, Hyun-Jung Jang, Korosh KhaliliPurpose: This study is to determine the efficacy of CT cholangiography (CTC) forevaluating biliary anatomy in potential donors for living-donor liver transplantation(LDLT) when MRCP is inconclusive.Materials and Methods: Over a 2-year period, contrast-enhanced (Cholografin) CTCwas performed in 41 potential living liver donors who showed inconclusive results onMRCP. Twenty of the 41 patients subsequently underwent partial liver donation and wereincluded in this study. Two independent, blinded radiologists retrospectively reviewedboth MRCP and CTC with 1-month interval and documented the types of bile ductbranching patterns, diagnostic confidence (3-point scale), and visualization score ofintrahepatic bile ducts (4-point scale). MRCP and CTC findings were compared with thegold standard of intraoperative cholangiography and surgical findings.Results: There were no complications associated with CTC examinations. CTC correctlyclassified the types of biliary anatomy in 17/20 (85%) including 7/9 typical branchingtypes and 10/11 anomalous branching types whereas MRCP correctly classified in 14/20(60%) including 5/9 typical branching types and 7/11 anomalous branching types. All 3misclassified cases by CTC were false identification of an accessory right intrahepaticduct joining the CBD. CTC showed higher diagnostic confidence (mean, 2.9) than MRCP(mean, 2.1) (P = .002). CTC also showed higher visualization score (mean, 3.9) thanMRCP (mean, 2.6) (P < .001).Conclusions: CTC accurately depicts biliary tract anatomy in LDLT donors and can beeffectively used when MRCP is inconclusive.66 of 71

University of Toronto Department of Medical Imaging Research Day 2009The impact in abdominal imaging with the introductionof a dedicated emergency CTRicha Mittal, Josée Sarrazin, Alan MoodyPurpose: The need for emergency (ER) radiological examinations is increasing rapidlyas the standard of care for patients presenting to the emergency department continues toevolve. Computed tomography (CT) is the main imaging modality to be requested. Thisplaces more pressure and demand on radiology resources. Many institutions haveinstituted a CT scanner dedicated to the ER department; however there have been nostudies that have examined the impact of this to patient management and radiologyresource utilization. To better understand the trends in emergency imaging, this studyexamines several aspects of the abdominal CT examinations completed for patientspresenting to the ER department. The utilization of CT was compared before and afterthe introduction of a dedicated ER CT scanner.Methods and Materials: All of the reports for CTs completed from patients in the ERdepartment at the time of referral were examined for a period of 6 months before andafter the introduction of a dedicated ER CT (which was March 2007). Data was collectedfrom August 1 2006 to January 31 2007 and August 1 2007 to January 31 2008. Datawas compiled from the imaging reports and electronic data records of the emergencyvisit. The following data was collected: total number of CTs, number of CTs that hadfindings concurring with the referring indication, the number of patients dischargedhome, admitted or had surgery after imaging, the indication for the imaging, whetherother imaging was performed before or after the CT and any incidental findings. Adatabase was complied in an excel spreadsheet, which was then analyzed utilizing SPSS12.0 software (SPSS Inc, Chicago, IL).Results: A total of 950 patients received an abdominal CT scan during the study period,referred from the ER department. 484 were male, 266 were female with an average age of55 years. The total number of CT requests did not significantly change with 507 beforeand 443 after the introduction of the dedicated CT scanner (p=0.543). The number ofCTs which had findings concurring with the referring indication did not significantlychange either going from 42.0 % to 38.4 % (p=0.513). The number of patients admittedor undergoing surgery did not significantly change either. The most common indicationfor CT was renal colic in both groups with up to 18.5% of all scans completed for thisindication. The number of CTs done related to malignancy staging decreased in thesecond group from 16.0 % to 12.2 % (p=0.003). There was no change in the number ofpatients receiving imaging before or after the CT, nor the number of incidental findings(p= 0.226 and p=0.0.91 respectively).Conclusion: Due to the increasing volume of imaging requested by the ER department,many hospitals have introduced a dedicated ER CT scanner. This study indicates thatthe introduction of a dedicated CT scanner for the emergency department does notincrease the number of studies requested by the ER department, nor does change thenumber of CTs with positive results. As well, non emergency imaging, such asmalignancy staging, has decreased in volume, indicating better utilization of imaging foremergency patients.67 of 71

University of Toronto Department of Medical Imaging Research Day 2009Pseudoenhancement within local ablation zone of hepatic tumorsdue to nonlinear artifact on contrast-enhanced ultrasoundHojun Yu, Hyun-Jung Jang, Tae Kyoung Kun, Korosh Khalili,Ross Williams, Gord Lueck, Peter BurnsPurpose: Pseudo-enhancement of an avascular region on CEUS often occurs within anechogenic region of radiofrequency ablation (RFA) zone. The purpose of this study wasto describe imaging features of this artifact and confirm its origin as nonlinear ultrasoundpropagation.Materials and Methods: Twenty-six patients with no tumor recurrence within RFAzones were included. Three radiologists assessed CEUS pseudo-enhancement in thearterial (90 seconds): presence,degree, time to first appearance, progression over time, and location, correspondinggreyscale echo (hypo/iso/hyperechoic) and lesion depth.Results: Fourteen (14/26, 54%) lesions showed pseudo-enhancement on CEUS. All(14/14) of them corresponded to the hyperechoic area within the RFA zone on gray-scaleUS and were non-marginal in location. Pseudo-enhancement more frequently occurred indeep lesions (≥5 cm) than superficial lesions (

University of Toronto Department of Medical Imaging Research Day 2009Magnetic resonance imaging of liver disease inhereditary hemorrhagic telangiectasiaA Moktassi, L Wu, J O'Rourke, ME FaughnanDepartment of Medical Imaging and Department of Medicine,St. Michael’s Hospital, University of Toronto, CanadaBackground/Aims: To describe findings, including flow quantification, obtained withmagnetic resonance imaging (MRI) of the liver in patients with hereditary hemorrhagictelangiectasia (HHT).Methods: MRI was performed in 35 patients [20 females; mean age, 49 years (range,15–75 years)] seen in the HHT Clinic, during a 2-year period. The protocol was designedto retrospectively evaluate the morphologic changes seen in HHT and evaluate flows.The study protocol was approved by our Review Board in accordance with therecommendations of the Human Research Committee. The presence of shunts, hepaticperfusion disorders, telangiectases, other vascular lesions, and flow abnormalities withinthe celiac and hepatic artery were evaluated by two radiologists in consensus.Results: Thirty-one/35 patients (89%) had a definite clinical diagnosis of HHT (CuracaoCriteria). Genetic mutation was available in 16/35 (49%). Nine/35 (25%) weresymptomatic of hepatic vascular malformations. Hepatic vascular abnormalities werefound in 23/35 (66%) patients. Arteriosystemic shunts were present in 17/35 (49%)patients and arterioportal shunts in 4 of 35 (11%). In 17/35 (49%) patients, parenchymalperfusion disorders were detected. Telangiectases were found in 18/35 (51%) patients. In14/35 (41%) patients, large confluent vascular masses were visualised. In 13/33 (39%)patients, the celiac artery flow volume exceeded 2L/min. The flows ranged from 2-7L/min. In 12 of 31 patients (39%) the hepatic artery flow volume exceeded 1L/min, withflows ranging from 1-4 L/min.Conclusions: MRI allows for the characterization of hepatic involvement in patientswith HHT.69 of 71

University of Toronto Department of Medical Imaging Research Day 2009Interval growth of focal nodular hyperplasia in the liver on MR imagingJaydeep Halankar, Tae Kyoung Kim, Hyun-Jung Jang,Korosh Khalili, Masoom HaiderPurpose: To determine the incidence of interval growth of focal nodular hyperplasia(FNH) in the liver.Materials and Methods: The subjects retrospectively included 120 consecutive patientsfor 2 years who were diagnosed to have FNH by characteristic imaging findings on Gd-BOPTA-enhanced MR imaging and had multiple MR examinations separated by over 6months. There were 25 men and 95 women (age range, 18-80 years; mean, 45 years).Images were retrospectively reviewed for interval growth of FNH. The maximum size ofthe lesion was measured on axial arterial-phase images of the initial and last MRexaminations. An interval increase in diameter over 10% of the initial diameter wasconsidered positive growth. The use of oral contraceptives was also documented.Results: Eleven of 120 patients (9%), comprising 10 female and 1 male, showed aninterval growth for a period ranging from 7 months to 84 months (mean, 29 months). Theinterval change of the size ranged from 0.4 to 2.0 cm (mean, 0.8 cm). The percent changeof the size ranged from 11% to 133% (mean, 49%). Only 2/10 (20%) female patientswith growing FNH and 30/85 (35%) female patients with non-growing FNH had ahistory of oral contraceptives intake.Conclusions: Progressively growing liver masses for a long-term imaging follow-upcannot exclude the diagnosis of FNH as an interval growth can be seen in 9% of cases.70 of 71

University of Toronto Department of Medical Imaging Research Day 2009No significant difference between nuchal translucency (NT) in weeks 11-13 +6of singleton pregnancies conceived spontaneously and by IVF/ICSIPM O’Donoghue 1 , BR Hoffman 2 , LI Bromberg, 2EM Greenblatt 3 KW Fong 1 , A Toi 1 , N Okun 41 Department of Medical Imaging, Mount Sinai Hospital and UniversityHealth Network, University of Toronto, Toronto, Canada.2 Laboratory Medicine and Pathobiology, University of Torontoand Pathology and Laboratory Medicine, Mount Sinai Hospital.3 Reproductive Biology Unit, Mount Sinai Hospital, Division of ReproductiveSciences, Department of Obstetrics and Gynaecology, Mount Sinai Hospitaland University Health Network, University of Toronto, Toronto, Canada4 Department of Obstetrics and Gynaecology, Mount Sinai Hospital andUniversity Health Network, University of Toronto, Toronto, CanadaBackground: If IVF/ICSI compared to spontaneous conception appreciably influencesNT, then this must be taken into account to calculate reliable Downs prenatal screenrisks. Whether IVF/ICSI actually affects NT in the first trimester is currentlycontroversial.Aim: To compare week 11-13 NT of singleton IVF/ICSI and spontaneous pregnancieseliminating potential confounders by matching NTs by sonographer, gestational age(CRL) and date of measurement (DOM).Methods: METHODS: This is a retrospective matched case control study. 449 selfreportedIVF/ICSI singleton pregnancies screened (2006-09) for Downs using NT wereidentified and the delta NT and MoM NT related to the expected (median) NT ofgestation matched (CRL) non- trisomic pregnancies were recorded. Non IVF/ICSIpregnancy delta/MoM NTs of NTs measured by the same sonographer were matched tothose of each IVF/ICSI pregnancy and ranked by proximity of their DOM (max ±90 day)and associated CRL (max ±5 mm) to those of the IVF/ICSI pregnancy. Ranked matchedNTs in order of rank were retained if not already matched to another IVF/ICSI pregnancyand if fewer than 4 matches. The final database contained 411 IVF/ICSI pregnancies(7 with only 3 matches) along with 1637 non-IVF/ICSI pregnancies. Delta and MoM NTwere separately compared between the two pregnancy groups by Students T Test.Results: The mean MoM NT (SD) of IVF/ICSI and spontaneous singleton pregnancieswas 1.04 (0.28) and 1.03 (0.35), respectively. Corresponding data for the delta NT was0.07 (0.43) and 0.05 (0.52). In neither case was the difference statistically (or clinically)significant.Conclusion: Week 11-13+6 NT does not differ significantly between IVF/ICSI andspontaneous pregnancies thereby obviating the need to apply special IVF/ICSI correctionfactors to the expected NT in order to calculate reliable Downs prenatal screen risk. Thisstudy is distinguished by its careful matching of potential confounders and inclusion of alarge number of pregnancies.71 of 71