Computerized Angiographic Occlusion Rating for Ruptured Clipped Aneurysms is Superior to Subjective Estimation

Background and Purpose: Computerized occlusion rating (COR) to estimate angiographic occlusion of embolized aneurysms is superior to subjective occlusion rating (SOR). In this study, we compared the two methods in the analysis of aneurysms clipped after subarachnoid hemorrhage. Material and Methods: The pre- and postoperative angiographic images (DSA) of 95 selected patients were analyzed and stratified in four groups (group 0 for 100%, group I for <100–90%, group II for <90–70%, and group III for < 70% occlusion) using SOR and COR. For SOR, the occlusion rate was estimated, whereas for COR the “occluded” and “nonoccluded” aneurysm areas were automatically calculated in mm² after outlining the ideal occlusion line. Results: With SOR, 75 (78.9%), 12 (12.6%), 7 (7.4%), and 1 (1.1%) and with COR 45 (47.4%), 24 (25.3%), 20 (21.0%), and 6 (6.3%) patients had aneurysms stratified to the Groups 0, I, II, and III, respectively. The interobserver variation was significant with SOR but not with COR. SOR overestimated aneurysm occlusion in 30 (31.6%) patients. Mean values were: SOR 97.5 ± 6.3% and COR 93.5 ± 9.7% (p ≤ 0.0001). No patient rebelled and four patients underwent re-treatment during 36 months ± 38. 9; the predictive value (log-rank, Kaplan–Meier) of SOR and COR with respect to re-treatment was highly significant for both methods (SOR: chi-square 29.65; p < 0.0001; COR: chi-square 35.57, p < 0.0001). Conclusion: The two methods showed remarkable differences in the estimation of the angiographic occlusion rates of clipped aneurysms. The significantly lower interobserver variation of COR versus SOR indicates a superiority of COR.