104 Chapter 6 DSA All patients underwent catheter DSA (Integris; Philips Medical Systems, Best, the Netherlands). A 4- or 5F catheter was used to perform contrast injections by a power injector (Medrad Inc., Warrendale PA, USA): of 9 ml iobitridol 350 mg/ml (Xenetix®, Guerbet, Villepinte, France) at 5 ml/s for the internal carotid arteries and 8 ml at 4 ml/s for the vertebral arteries. Intracranial branches of the internal carotid arteries were imaged in antero-posterior, lateral and oblique projections and the vertebrobasilar arteries and their branches in antero-posterior and lateral projections. Additional angiographic projections were obtained, if necessary, of the vessels that harbored the aneurysm(s), for better visualization of an eventual recanalization of the aneurysm(s) Evaluation of CEMRA images CEMRA images were independently evaluated by two neuroradiologists experienced in evaluating both MRA and DSA images of coiled aneurysms. They were unaware of the parallel DSA results but the initial DSA images made during the endovascular treatment were at their disposal. The CEMRA acquisition could be interactively assessed on a dedicated workstation (Vitrea; Vital Images, Minnetonka, Minnesota, USA). Scoring criteria were: occlusion status, change compared with initial post-coiling occlusion status, size of recanalization when present, and diagnostic confidence. Occlusion status was graded on the three-point scale described by Roy and Raymond (R&R)23 as follows: R&R Class 1: Complete aneurysm obliteration. R&R Class 2: Residual aneurysm neck. R&R Class 3: residual aneurysm lumen. Discrepancies between the two observers in assessing occlusion status were resolved by joint reassessment to reach consensus. The CEMRA images were compared with the initial post-coiling DSA images to decide whether the occlusion had changed, using a three-point scale: New or increased recanalization (category 1). No change (category 2). Disappearance of, or decrease of remnant (category 3). Confidence of the scoring was given on a three-point scale: ‘poor’, ‘moderate’ and ‘good’. Evaluation of DSA images The report by the radiologist who had performed the follow-up DSA study was used as the standard of reference. Usually the three-point R&R scale was mentioned; if the radiological report did not indicate a specific grading on this scale, the images were re-assessed by a neuro-interventional radiologist and an R&R class was assigned. Size of the aneurysm remnant was estimated by comparison with known diameters of adjacent intracranial arteries. For the assessment of the post-coiling DSA study the same procedure was followed using the original report made by the neuro-interventional radiologist who performed the treatment. Statistical analysis Interobserver agreement was assessed for all CEMRA ratings by kappa statistics with linear weighting for the three-point scale categories.
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