Early penumbral FLAIR changes predict tissue fate in patients with large vessel occlusions

Background: In patients with an acute ischemic stroke, the penumbra is defined as ischemic tissue that remains salvageable when reperfusion occurs. However, the expected clinical recovery congruent with penumbral salvage, is not always observed. Aims: We aimed to determine if the Magnetic Resonance Imaging (MRI) defined penumbra includes irreversible neuronal loss that impedes expected clinical recovery after reperfusion. Methods: In the prospective French Acute Multimodal Imaging Study to Select Patients for Mechanical Thrombectomy (FRAME) and an observational cohort of patients with large vessel occlusions undergoing endovascular treatment, we quantified penumbral integrity by FLAIR changes. We studied the influence of recanalization status on the evolution of penumbral FLAIR changes and studied penumbral FLAIR changes as predictor of tissue fate and functional outcome on the 90 days modified Rankin Scale (mRS). Results: Recanalization status did not modify the evolution of rFLAIR signal intensity (SI) over time in the total cohort, but was associated with lower SI in the FRAME subset (b=-0.06, p for interaction=0.04). Median rFLAIR SI was higher at baseline in the subsequently infarcted penumbra compared to the salvaged (ratio=1.07, standard deviation [SD] 0.07 vs 1.03, SD 0.06 p<0.0001, n=150). The severity and extent of rFLAIR SI changes did not predict 90 day functional outcome in univariate (p=0.09) and multivariate logistic regression (p=0.4). Conclusions: Recanalization status did not influence the evolution of penumbral FLAIR changes. FLAIR SI changes in the baseline penumbra were associated with tissue fate, but not functional outcome. Data access statement: The data supporting the study are available upon reasonable request; following a signed data access agreement.