3D Computerized Rotational Angiography of the ... - For Members

2001 ASNR Annual Meeting Abstracts01-O-488-ASNR3D Computerized Rotational Angiography of theCarotid ArteryNaik, S. 1 * Fox, A. J. 1 * Pelz, D. M. 1 * Lee, D. H. 1 * Norley, C. J. D. 2 * Hyde, D. E. 2* Holdsworth, D. W. 21 London Health Sciences Centre, London, ON, Canada; 2 John P. Robarts ResearchInstitute, London, ON, CanadaPurposeTo evaluate and validate the utility and efficacy of 3D Computerized Rotational Angiography(CRA) – as compared with Digital Subtraction Angiography (DSA) – in the assessment ofstenoses of the internal carotid artery, for verification of stenosis indications regarding carotidendarterectomy and during carotid angioplasty/stenting.Materials & MethodsSymptomatic patients suspected of carotid stenosis after screening (duplex ultrasound and/or MRangiography) were referred for catheter angiography to confirm stenosis severity for treatmentdetermination (medical vs revascularization). Following informed consent, the angiographicprocedures were carried out using a prototype single-plane, cone-beam CRA angiographicsystem. Conventional DSA included AP, lateral, and oblique projections for both carotid arteries(symptomatic and asymptomatic sides). 3D CRA was performed as an additional commoncarotidcontrast injection, with rotational imaging of 45° per second through an arc of 200°during injection of 4 ml/sec for 6 sec of nonionic contrast material diluted to 200 mg/ml withheparinized saline. Images from both DSA and CRA studies were assessed separately in randomorder for stenosis degree for NASCET-type stenosis measurements by three neuroradiologistsblinded to the side of symptomotology and other interpretations of degree of stenosis. CRAstudies included a search for the narrowest view, determined by interactive evaluation of the 3Ddata set on an imaging workstation.ResultsEighteen carotids have been studied with both DSA and 3D CRA. The additional informationprovided by the 3D CRA often resulted in the designation of a different degree of percentstenosis, compared with the DSA interpretation. This depended upon the type of display of theCRA data set (i.e., maximum intensity projection, surface rendering) and interactive examinationand slicing of a 3D volume. The CRA data also provide the ability to give exact millimetermeasurements of stenosis diameters with 0.4 mm isotropic spatial resolution, as well asquantification of calcification within carotid plaque.ConclusionThree-dimensional CRA provides the ability to accurately visualize the carotid artery at anyprojection view angle after one selective angiographic injection, to assess a carotid stenosis foroptimized measurement leading to a percent stenosis calculation. Additionally, CRA can render

as unnecessary percent stenosis calculations, as it can provide true millimeter stenosismeasurements.References1. Fahrig R, Fox AJ, Lownie S, Holdsworth DW. Use of a C-arm system to generate truethree-dimensional computed rotational angiograms: preliminary in vitro and in vivoresults. AJNR Am J Neuroradiol 1997;18;1507–15142. Fox AJ. How to measure carotid stenosis. Radiology 1993;186;316–3183. Barnett HJ, Taylor DW, Eliasziw M, et al. Benefit of carotid endarterectomy in patientswith symptomatic moderate or severe stenosis. North American Symptomatic CarotidEndarterectomy Trial Collaborators. N Engl J Med 1998;339;1415–1425