Hypoperfusion Intensity Ratio Predicts Malignant Edema and Functional Outcome in Large-Vessel Occlusive Stroke with Poor Revascularization.

BACKGROUND AND OBJECTIVE: Malignant cerebral edema (MCE) is a well-known complication in patients with acute ischemic stroke with core infarcts ≥ 80 mL caused by large-vessel occlusions. MCE can also develop in patients with smaller infarcts with moderate -to-large volume of tissue at risk who do not achieve successful revascularization with endovascular thrombectomy (ET). Features that predict the development of MCE in this population are not well-described. We aim to identify predictors of MCE and 90-day functional outcome in stroke patients with an anterior circulation large vessel occlusion (LVO) and a < 80 mL ischemic core who do not achieve complete reperfusion. METHODS: We reviewed our institutional stroke registry and included patients who achieved unsuccessful revascularization, mTICI 0-2a, after ET and whose baseline imaging was notable for a core infarct < 80 mL, a Tmax > 6 s volume ≥ 80 mL, and a mismatch ratio ≥ 1.8. MCE was defined as ≥ 5 mm of midline shift on follow-up imaging, obtained 6-48 h after the pre-ET perfusion scan. RESULTS: Thirty-six patients met inclusion criteria. Unadjusted analysis demonstrated that younger age, higher systolic blood pressure, larger core volume, and higher hypoperfusion intensity ratio (HIR) were associated with MCE (all p < 0.02). In multivariate logistic regression analysis, age, HIR, and core infarct volume were independent predictors of MCE. The optimal HIR threshold to predict MCE was ≥ 0.54 (OR 14.7, 95% CI 2.4-78.0, p = 0.003). HIR was also associated with 3-month mRS (HIR ≥ 0.54 for mRS of 3-6: OR 10.8, 95% CI 1.9-44.0, p = 0.02). CONCLUSIONS: Younger age, larger core infarct volume, and higher HIR are predictive of MCE in patients with anterior circulation LVO, moderate-to-large tissue at risk, and suboptimal revascularization. HIR is correlated with three-month functional outcomes.

Can diffusion- and perfusion-weighted imaging alone accurately triage anterior circulation acute ischemic stroke patients to endovascular therapy?

BACKGROUND AND PURPOSE: Acute ischemic stroke (AIS) patients who benefit from endovascular treatment have a large vessel occlusion (LVO), small core infarction, and salvageable brain. We determined if diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) alone can correctly identify and localize anterior circulation LVO and accurately triage patients to endovascular thrombectomy (ET). MATERIALS AND METHODS: This retrospective cohort study included patients undergoing MRI for the evaluation of AIS symptoms. DWI and PWI images alone were anonymized and scored for cerebral infarction, LVO presence and LVO location, DWI-PWI mismatch, and ET candidacy. Readers were blinded to clinical data. The primary outcome measure was accurate ET triage. Secondary outcomes were detection of LVO and LVO location. RESULTS: Two hundred and nineteen patients were included. Seventy-three patients (33%) underwent endovascular AIS treatment. Readers correctly and concordantly triaged 70 of 73 patients (96%) to ET (κ=0.938; P=0.855) and correctly excluded 143 of 146 patients (98%; P=0.942). DWI and PWI alone had a 95.9% sensitivity and a 98.4% specificity for accurate endovascular triage. LVO were accurately localized to the ICA/M1 segment in 65 of 68 patients (96%; κ=0.922; P=0.817) and the M2 segment in 18 of 20 patients (90%; κ=0.830; P=0.529). CONCLUSION: AIS patients with anterior circulation LVO are accurately identified using DWI and PWI alone, and LVO location may be correctly inferred from PWI. MRA omission may be considered to expedite AIS triage in hyperacute scenarios or may confidently supplant non-diagnostic or artifact-limited MRA.