Abstract WP1: Evaluation of Clinical and Radiographic Variables Related to False Positive Detection of Tandem Carotid Artery Occlusion on CT Angiography

Abstract

Background and purpose: CT angiography has been shown to result in up to 30% false positive detection of extracranial ICA occlusion in patients with acute ICA terminus occlusion. This may confound planning for acute endovascular intervention and cause inaccurate patient exclusion from related clinical trials of acute stroke therapy. We explored demographic, clinical variables, recanalization rates and outcomes that are associated with this radiographic artifact. Methods: Retrospective review of a prospectively maintained database of acute endovascular therapy at UPMC between 2002 and 2015. Patients with isolated terminus ICA occlusion were selected from a previously derived cohort of cases with or without pseudo-occlusion of the extracranical ICA on pre-procedural CTA (false positives and true negatives). Comparisons between these two groups were evaluated with univariate analysis. Results: We reviewed 69 cases of isolated ICA terminus occlusion. 21 patients had false-positive occlusion of the extracranial ICA (group 1) and 48 patients had adequate CTA diagnosis (true negatives, group 2). Rates of IV tPA (33% vs. 29%) and median CTA to groin puncture time (98 vs. 80 min) were similar between the two groups. Terminus ICA occlusion types were as follows: ICA-I (19% vs 6 %), ICA-L (67% vs. 56%), ICA-T (14% vs. 37%). Manual aspiration thrombectomy was used in 68% of cases in group 1 compared to 38% of cases in group 2 (P=0.03), no difference in use of recanalization devices were found. TICI 2b/3 recanalization was achieved to similar extent (42% vs. 33%). Favorable outcome (90-day modified Rankin Scale ≤ 2) was achieved in 26% vs. 40% between the two groups (P=0.52). Conclusions: Patients with acute terminus ICA occlusion who are misclassified as having tandem ICA occlusions on CTA have similar characteristics than their respective controls in this small cohort. Although future studies with larger sample sizes are needed to tease out preliminary trends, the data support the need for optimization of current screening methods for tandem ICA occlusion in the acute setting.