Hypoperfusion Intensity Ratio Is Correlated With Patient Eligibility for Thrombectomy

Background and Purpose- Hypoperfusion intensity ratio (HIR) is associated with collateral status in acute ischemic stroke patients with anterior circulation large vessel occlusion. We assessed whether HIR was correlated to patient eligibility for mechanical thrombectomy (MT). Methods- We performed a retrospective cohort study of consecutive acute ischemic stroke patients with a proximal middle cerebral artery or internal carotid artery occlusion who underwent MT triage with computed tomography or magnetic resonance perfusion imaging. Clinical data, ischemic core (mL), HIR (defined as time-to-maximum TMax >10 seconds/TMax >6 seconds), mismatch volume between core and penumbra, and MT details were assessed. Primary outcome was favorable HIR collateral score (HIR 70 mL) and core-penumbra mismatch volumes. Patients who did not meet guidelines were not included. Results- We included 197 patients (145 MT+ and 52 MT-). MT+ patients had a significantly lower median HIR compared with MT- patients (0.4 interquartile range, 0.2-0.5 versus 0.6 interquartile range, 0.5-0.8; P70 mL, and 9 had a National Institutes of Health Stroke Scale 70 mL (0.2 interquartile range, 0.2-0.3 versus 0.7 interquartile range, 0.6-0.8, P<0.001) but their HIR was not significantly different that MT+ patients. Conclusions- Patients who meet American Heart Association guidelines for thrombectomy are more likely to have favorable collaterals (low HIR). HIR may be used as a marker of eligibility for MT triage.