Achala Sameer Vagal MD, Presenter: Research Grant, F. Hoffmann-La Roche Ltd Investigator, F. Hoffmann-La Roche Ltd

Bijoy Menon MBBS, MD, Abstract Co-Author: Nothing to Disclose

Anthony Hart Livorine MD, Abstract Co-Author: Nothing to Disclose

Lydia Foster, Abstract Co-Author: Nothing to Disclose

Sharon Yeatts PhD, Abstract Co-Author: Consultant, F. Hoffmann-La Roche Ltd

Emmad Qazi, Abstract Co-Author: Nothing to Disclose

Christopher David d'Esterre BMedSc, Abstract Co-Author: Nothing to Disclose

Junzi Shi, Abstract Co-Author: Nothing to Disclose

Andrew Demchuk MD, Abstract Co-Author: Nothing to Disclose

Michael D. Hill MD, Abstract Co-Author: Nothing to Disclose

David S. Liebeskind, Abstract Co-Author: Consultant, Stryker Corporation Consultant, Covidien AG

Thomas A. Tomsick MD, Abstract Co-Author: Nothing to Disclose

Mayank Goyal MD, FRCPC, Abstract Co-Author: Shareholder, Calgary Scientific, Inc Research Grant, Covidien AG Consultant, Covidien AG Shareholder, NoNO Inc Investigator, Covidien AG

Collateral circulation is an important predictor of outcomes in acute ischemic stroke. Perfusion imaging may provide a unique opportunity to measure collateral flow prior to angiography. Using the IMS III data, we assessed the relationship between CT perfusion (CTP) parameters and leptomeningeal collateral flow.

CTP was not a prerequisite for entry or patient selection in IMS III, however a total of 104 subjects received a baseline CTP study. We analyzed the CTP studies using Olea medical software to quantify core (dual threshold of rCBF less than 30% and Tmax >6 sec ), critically hypoperfused volumes (Tmax >6 sec) and mismatch ratios. Collateral grade on conventional angiograms (DSA) before treatment were assessed on a 5-point scale. Collaterals on baseline CT angiogram (CTA) were categorized as good, intermediate and poor. Spearman correlation test was used to measure the strength of association.

Of total of 104 baseline CTP studies, 95 were diagnostic. 33 patients were randomized to IV tPA only, 62 to endovascular therapy. Of 95 subjects, 85 (89.5%)had a concurrent baseline CTA; 59 (62.1%) had a conventional angiogram. Median age was 69 years, baseline NIHSS17.0, and baseline ASPECTS 8.0. Of 85,76 (89.4%) had baseline intracranial occlusions; 16 ICAT, 39 M1, 17 M2, and 4 other occlusions. The median (range) CTP core volume was 5.8 (0-81.6) ml and hypoperfused volume was 55.8 (0-383.4). Among 53 subjects, the CTA collateral grade was poor in 17 (32.1%), intermediate in 15 (28.3%) and good in 21 (39.6%). Among 41 subjects, the DSA collateral grade was 0 in 3 (7.3%), 1 in 8 (19.5%), 2 in 15 (36.6%), 3 in12 (29.3%) and 4 in 3 (7.3%). Hypoperfused volumes correlated with baseline NIHSS (p =0.0382) and core volumes correlated well with baseline ASPECTS (p <0.0001). Subjects with higher collateral grade (DSA) and intermediate to good collaterals (CTA) had higher mismatch ratios (p<0.0001 and p=0.0215, respectively). Higher CTA collateral status was associated with smaller cores (p=0.0031). There was insufficient evidence of an association between hypoperfused volumes and DSA collateral grade (p=0.8180) or CTA collateral status (p=0.2190).

Higher CTP mismatch ratios and smaller cores were significantly associated with robust baseline collaterals in IMS III.

CTP may be used as a non-invasive tool to predict collateral status, however warrants further investigation.

Vagal, A, Menon, B, Livorine, A, Foster, L, Yeatts, S, Qazi, E, d'Esterre, C, Shi, J, Demchuk, A, Hill, M, Liebeskind, D, Tomsick, T, Goyal, M, CT Perfusion and Collateral Status in the Interventional Management of Stroke (IMS) III Trial.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010713.html