E1221. Capillary Index Score vs. CT Perfusion for Large Vessel Occlusion Ischemic Strokes in Delayed Time Windows
  1. Sriharsha Voleti; University of Cincinnati Medical Center
  2. Brendan Corcoran; University of Cincinnati Medical Center
  3. Arafat Ali; University of Cincinnati Medical Center
  4. Achala Vagal; University of Cincinnati Medical Center
  5. Thomas Tomsick; University of Cincinnati Medical Center
The recent DAWN and DEFUSE 3 trials established the clinical benefit of endovascular treatment (EVT) in acute ischemic stroke patients presenting in delayed time windows up to 24 hours from stroke onset and promoted the use of CT Perfusion (CTP) in patient selection. Capillary Index Score (CIS) is a recently proposed angiographic method of assessing collateral circulation for EVT patients. The use of CIS has not been studied compared to CTP, especially in delayed time windows. Our objective was to explore correlation of CIS with CTP parameters in delayed time windows.

Materials and Methods:
We retrospectively identified consecutive patients with ICA terminus or M1 large vessel occlusion who underwent EVT 6-24 hours from stroke onset between May 2016 and June 2019. We scored CIS 0 to 3 on pre-treatment diagnostic cerebral angiography (DCA) by identifying the presence/absence of capillary blush in three equal middle cerebral artery territories. We calculated automated CTP parameters using RAPID software including ischemic core volume (relative cerebral blood flow (CBF)<30%) and penumbra volume (Tmax>6sec). We also graded baseline CT Angiography (CTA) collateral status using Tan collateral score (0 = absent; 1 = filling <=50%; 2 = filling >50% & <100%; 3 = filling 100% of occluded vascular territory). We performed Pearson’s correlation to assess associations between CIS and CTA collateral status with CTP parameters.

Among 460 patients who underwent EVT, 26 patients (mean age: 67.2 ± 17.5, 51.9% female) received CTP and adequate baseline DCA including carotid and vertebral artery injections with late venous phase. Median baseline ASPECTS was 8, median CTP core was 12 mL, and median CTP penumbra was 112.5 mL. The correlation coefficients between CIS and CTP core and CTP penumbra were -0.19 (p=0.363) and -0.34 (p=0.092) respectively. The correlation coefficients between CTA collateral status and CTP core and CTP penumbra were -0.42 (p=0.057) and -0.41 (p=0.064) respectively.

While a small sample size prevents drawing significant conclusions, a trend of CIS with CTP penumbra volume is suggested. CIS exhibits potential in assessing collateral circulation of EVT patients in delayed time windows. Stroke investigators would greatly benefit from understanding the methodology and potential use of CIS.