Multi-Detector row CT urography on a 16-row CT scanner in the ...

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With the introduction of 16-<strong>row</strong> <strong>CT</strong> scanners, the radiologic evaluation of the urinary tract is changing rapidly. The advantages of a 16-<strong>row</strong> <strong>CT</strong> scanner are the following: fast scanning (coverage of at least 48 mm long body sections per second), acquisition of thin collimation and creation of high-resolution multiplanar and threedimensional (3D) reformatted images, with excellent anatomic details [16, 17]. The purpose of our study was to assess the role of multi-detector <strong>row</strong> <strong>CT</strong> <strong>urography</strong>, using a 16-<strong>row</strong> <strong>CT</strong> scanner in the evaluation of patients presenting with painless hematuria, with emphasis placed in the detection of urothelial tumors. Materials and methods This study was a retrospective review of <strong>CT</strong> urographies performed on a 16-<strong>row</strong> <strong>CT</strong> scanner for the evaluation of painless hematuria. The study included 75 consecutive patients (47 men and 28 women) with a mean age of 63 years (age range: 21–87 years), who underwent multidetector <strong>row</strong> <strong>CT</strong> <strong>urography</strong> between March 2004 and January 2005, referred to the department of Radiology for painless hematuria. Five patients were younger than 40 years old. Informed consent for this study was obtained from each patient. The clinical evaluation of the patients included a careful history and clinical examination. The laboratory analysis began with a comprehensive examination of the urine and urine sediment and cytologic analysis. All patients had an ultrasound examination of the abdomen, some performed at an outpatient clinic and the rest at our department. Patients with hematuria and a sonographic examination demonstrating a kidney mass were not included in this study, since they were evaluated with a different protocol tailored for the investigation of renal masses. Cystoscopic examination was carried out in all patients. In patients in whom clinical and imaging evaluation revealed no cause for the hematuria, a follow-up was recommended. This included the repeat of the urinary analysis and urine cytology every month for the first 4 months and thereafter at 6, 12, 24 and 36 months. Immediate reevaluation with repeat of the <strong>CT</strong> examination and/or cystoscopy and urine cytology was recommended if any of the following occurred: development of gross hematuria, abnormal urinary cytologic findings or irritating voiding symptoms in the absence of infection [18]. Technique Examinations were performed on a 16-<strong>row</strong> <strong>CT</strong> scanner with 24 mm scanning span per rotation (Mx8000 IDT, Philips) and a three-phase protocol was used. Unenhanced images were obtained from the kidneys through the urinary bladder using a slice collimation of 16×1.5 mm and a slice thickness of 3 mm. These images were scrutinized to identify urinary tract calculi or calcifications, as well as to assist in the characterization of any detected renal masses. Intravenous non-ionic iodinated contrast material (120 ml, 320 mg I/ml) was subsequently administered at a rate of 3 ml/sec, via mechanical injector, followed by 250 ml of normal saline 0.9%, rapidly infused by intravenous drip. The second phase was the nephrographic phase obtained at 100 sec delay, covering the area from the diaphragm to the iliac crests and the third phase was the excretory phase starting with 10-minute delay, covering the kidneys, ureters and the urinary bladder. The nephrographic phase was chosen for the detection and characterization of renal masses, as well as for staging, while the excretory phase was utilized for the evaluation of abnormalities involving the urothelium. For these two phases a section collimation of 16×0.75 mm and a slice thickness of 1 mm were employed. The nephrographic and excretory phase images were reconstructed at 0.5 mm intervals (50% overlap). All the scans were performed with a pitch of 1.2, at 120 kV, using a rotation time of 0.5 sec. Both dose modulation (DOM) and automatic current setting (DoseRight) were used [19]. No oral contrast material was given, in order to facilitate 3D reformatting. The entire <strong>CT</strong> <strong>urography</strong> examination lasted 15 minutes per patient on the average and every scan lasted 7–12 seconds on the average. Our <strong>CT</strong> protocol is illustrated on Table 1. <strong>CT</strong> data interpretation Image interpretation was done on a workstation (MxView, Philips) and included the study of the axial images of the unenhanced scan. The evaluation of the axial source images of the nephrographic and the excretory phase was Table 1 <strong>CT</strong> protocol for the investigation of hematuria Unenhanced scan Nephrographic phase, 100 sec Excretory phase, 10 min kV, rotation time (sec) 120/0.5 120/0.5 120/0.5 mAsnom/mAssel 200/170 200/175 200/160 <strong>Detector</strong> collimation 16×1.5 16×0.75 16×0.75 (mm) Pitch 1.2 1.2 1.2 Slice thickness (mm) 3 1 1 Reconstruction 3 0.5 0.5 interval (mm) Area Kidneysurinary bladder Diaphragmiliac crests Kidneysurinary bladder Contrast material (iv) 120 ml (320), 3 ml/sec and 250 ml saline 0.9%
difficult, due to the large number (approximately 400–800) of noisy images. For these reasons reformatted images, of 4 mm slice thickness and at 3 mm intervals, usually in the transverse and coronal planes (using the Extended Brilliance V.1.0.1.1. software) were used for interpretation of the nephrographic and excretory phases. The time to generate these images was less than one minute. Wide window settings (bone window settings, W: 1500, L: 500) were also used for the excretory phase, to better visualize caliceal details, as well as filling defects in the urinary collecting system (Fig. 1). Finally, three-dimensional (3D) reconstructions of the excretory phase data were performed, using the volume rendering technique and the same software, obtained in the coronal and/or oblique planes. Volume rendering technique was considered ideal for the creation of the 3D reconstructions [3], especially because it does not obscure superimposed structures, such as the pelvis and the ureters. The time required to create the 3D reformatted images was less than one minute. The main advantage of these images was that they were more familiar to our clinical colleagues, because they closely resemble those of intravenous <strong>urography</strong>. Additionally, these images could be more effectively used for preoperative planning, whenever it was necessary. An important issue on <strong>CT</strong> <strong>urography</strong> is the degree of ureteral opacification. In cases, where excretion of the contrast material was detected on <strong>CT</strong> <strong>urography</strong>, the extent of ureteral opacification was evaluated. The ureter was divided into proximal, middle and distal thirds. The proximal third was defined as the portion of the ureter that extended from the renal pelvis to the superior iliac crests. The middle third was defined as the portion of the ureter between the superior iliac crests and the anterior inferior iliac spines. The lower third was defined as the segment of the ureter located between the anterior inferior iliac spines and the ureterovesical junction. An opacification score from 1 to 3 was assigned for each ureter based on the length of the ureteral portion opacified. A score of 1 indicated opacification of less than one third of the ureter; a score of 2 indicated opacification of less than two thirds of the ureter; a score of 3, opacification of more than two thirds of the ureteral segments up to the entire length of the ureter. <strong>CT</strong> data correlation Findings of MD<strong>CT</strong>U were retrospectively correlated with the results of clinical and imaging follow-up, cystoscopy and/or ureteroscopy, as well as with surgical and histological findings, in surgical cases. More specifically, in patients with urinary tract lithiasis confirmation of the <strong>CT</strong> diagnosis was documented on the basis of other imaging examinations (plain films and ultrasound). Conventional cystoscopy and histologic results were used as standard of reference in patients with urinary bladder carcinomas. Conventional cystoscopy was also used to confirm the presence of benign prostatic hyperplasia (BPH) as the cause of hematuria. In patients with transitional cell carcinoma of the pelvicaliceal system, as well as ureteral lesions, confirmation of the <strong>CT</strong> diagnosis was obtained based on other imaging examinations (IVU, retrograde pyelography), ureteroscopic findings and finally the surgical and histologic findings. Surgery and histologic diagnosis confirmed the presence of other malignancies (renal cancer, pancreatic and prostate cancer). For patients with urinary tract congenital anomalies, the findings of IVU were used for confirming the <strong>CT</strong> diagnosis. The <strong>CT</strong> images were interpreted by one radiologist (A. C. T), blinded to the results of the other examinations. Dosimetry For dosimetry the free-in-air Computed Tomography Dose Index was measured along the axis of rotation using a pencil-shaped ion chamber, type 10×5 10.3 <strong>CT</strong> (Radcal Corp., California, USA). The effective dose was calculated using the ImPA<strong>CT</strong> <strong>CT</strong> Patient Dosimetry Calculator (version 0.99v) [20]. The software used is based on the Fig. 1 A 70-year-old woman with fibroepithelial polyp of the right ureter. Coronal (a) and transverse (b) reformatted images of the excretory phase demonstrate an elongated filling defect (ar<strong>row</strong>), smoothly marginated, involving the intravesical part of the right ureter and prolapsing into the urinary bladder. The lesion is clearly seen with bone window settings
Page 1: Eur Radiol DOI 10.1007/s00330-006-0
Page 5 and 6: Fig. 3 A 73-year old man with TCC o
Page 7 and 8: Fig. 9 A 70-year old man with TCC o
Page 9: 9. Catalano C, Fraoli F, Laghi A, N

Multi-Detector row CT urography on a 16-row CT scanner in the ...

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