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Background and Purpose— Collateral flow can determine ischemic core and tissue at risk. Using the Interventional Management of Stroke (IMS) III trial data, we explored the relationship between computed tomography angiogram (CTA) collateral status and CT perfusion (CTP) parameters. Methods— Baseline CTA collaterals were trichotomized as good, intermediate, and poor, and CTP studies were analyzed to quantify ischemic core, tissue at risk, and mismatch ratios. Kruskal–Wallis and Spearman tests were used to measure the strength of association and correlation between CTA collaterals and CTP parameters. Results— A total of 95 patients had diagnostic CTP studies in the IMS III trial. Of these, 53 patients had M1/M2 middle cerebral artery±intracranial internal carotid artery occlusion, where baseline CTA collateral grading was performed. CTA collaterals were associated with smaller CTP measured ischemic core volume ( P =0.0078) and higher mismatch ( P =0.0004). There was moderate negative correlation between collaterals and core ( r s =−0.45; 95% confidence interval, −0.64 to −0.20) and moderate positive correlation between collaterals and mismatch ( r s =0.53; 95% confidence interval, 0.29–0.71). Conclusion— Better collaterals were associated with smaller ischemic core and higher mismatch in the IMS III trial. Collateral assessment and perfusion imaging identify the same biological construct about ischemic tissue sustenance.

The importance of time in acute stroke is well-established. Using the Interventional Management of Stroke III trial data, we explored the effect of multimodal imaging (CT perfusion and/or CT angiography) versus noncontrast CT alone on time to treatment and outcomes.We examined 3 groups: 1) subjects with baseline CTP and CTA (CTP+CTA), 2) subjects with baseline CTA without CTP (CTA), and 3) subjects with noncontrast head CT alone. The demographics, treatment time intervals, and clinical outcomes in these groups were studied.Of 656 subjects enrolled in the Interventional Management of Stroke III trial, 90 (13.7%) received CTP and CTA, 216 (32.9%) received CTA (without CTP), and 342 (52.1%) received NCCT alone. Median times for the CTP+CTA, CTA, and NCCT groups were as follows: stroke onset to IV tPA (120.5 versus 117.5 versus 120 minutes; P = .5762), IV tPA to groin puncture (77.5 versus 81 versus 91 minutes; P = .0043), groin puncture to endovascular therapy start (30 versus 38 versus 44 minutes; P = .0001), and endovascular therapy start to end (63 versus 46 versus 74 minutes; P.0001). Compared with NCCT, the CTA group had better outcomes in the endovascular arm (OR, 2.12; 95% CI, 1.36-3.31; adjusted for age, NIHSS score, and time from onset to IV tPA). The CTP+CTA group did not have better outcomes compared with the NCCT group.Use of CTA with or without CTP did not delay IV tPA or endovascular therapy compared with NCCT in the Interventional Management of Stroke III trial.

Introduction: The importance of time in acute stroke is well established. Using the Interventional Management of Stroke (IMS) III trial data, we explored the effect of imaging on time to treatment and outcomes for subjects those receiving multimodal imaging [CT angiogram (CTA) + CT perfusion (CTP) versus CTA alone] versus those who did not. Materials and Methods: Multimodal CT was not a prerequisite for IMS III entry .We examined 3 subgroups; those with baseline CTA alone, CTA + CTP, versus those with no CTA or CTP. The baseline demographics and imaging and treatment time parameters of these 3 subgroups were studied. Results: Of the 656 subjects enrolled, 98 (14.9%) underwent baseline (pre-IV t-PA treatment) CTA+CTP. 8 out of these 98 patients received only CTP. 216 (32.9%) received CTA alone and 342 (52.1%) had neither. Time parameters for the CTA+CTP, CTA alone, and no CTA/CTP groups were as follows: median from stroke onset to IV t-PA (120.5 vs. 117.5 vs 120 min; p=0.5869), median IV t-PA bolus to groin puncture (GP) (78 vs. 81 vs. 91 min; p=0.0043) and median GP to start of endovascular therapy (EVT) (31 vs. 38 vs. 44 min; p=0.0001). Pairwise comparison demonstrated no significant difference in time from IV tPA to GP and time from GP to IA therapy between CTA+CTP and CTA alone groups (p=0. 9883 and p=0.1421, respectively). With removal of drip n’ ship subjects, no statistical differences were seen between groups for time from onset to IV t-PA bolus (p=0.5509) or time from imaging to GP (p=0.8459). Time from GP to start of EVT was still shorter in the CTA+CTP and CTA alone paradigms (p =0.0019). In the IV t-PA treatment arm, no differences in 90d mRS 0-2 outcome were seen in the 3 subgroups (36.4% versus 40.9% versus 38.2%; p=0.8941). In the EVT arm, differences in good outcome were seen (38.5% versus 52.0% versus 33.8%; p=0.0020). CTA alone remained strongly associated with good outcomes in EVT arm (adjusted OR, 2.117; 95% CI, 1.35- 3.30), irrespective of age, stroke severity and time from onset to IV tPA initiation. Conclusion: Multimodal imaging did not delay treatment times in IMS III. The CTA alone group was associated with favorable clinical outcomes in the endovascular arm. The CTA+CTP paradigm resulted in worse outcome over the CTA alone paradigm in the endovascular arm.