Arterial Spin Labeling‐Based MRI Estimation of Penumbral Tissue in Acute Ischemic Stroke

Abstract

Background: Arterial spin labeling (ASL) has shown potential for the assessment of penumbral tissue in patients with acute ischemic stroke (AIS). The postlabeling delay (PLD) parameter is sensitive to arterial transit delays and influences cerebral blood flow measurements. Purpose: To assess the impact of ASL acquisition at different PLDs for penumbral tissue quantification and to compare their performance regarding assisting patient selection for endovascular treatment with dynamic susceptibility contrast MRI (DSC-MRI) as the reference method. Study Type: Retrospective. Population: A total of 53 patients (59.98 AE 12.60 years, 32% women) with AIS caused by internal carotid or middle cerebral artery occlusion. Field Strength/Sequence: A 3-T, three-dimensional pseudo-continuous ASL with fast-spin echo readout. Assessment: Hypoperfusion volume was measured using DSC-MRI and ASL with PLDs of 1.500 msec and 2.500 msec, respectively. Eligibility for endovascular treatment was retrospectively determined according to the imaging criteria of the Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke trial (DEFUSE 3). Statistical Tests: Kruskal-Wallis tests, Bland-Altman plots, Cohen's kappa, and receiver operating characteristic analyses were used. The threshold for statistical significance was set at P < 0.05. Results: Hypoperfusion volume for ASL with a PLD of 1.500 msec was significantly larger than that for DSC-MRI, while the hypoperfusion volume for a PLD of 2.500 msec was not significantly different from that of DSC-MRI (P = 0.435). Bland-Altman plots showed that the mean volumetric error between the hypoperfusion volume measured by DSC-MRI and ASL with PLDs of 1.500/2.500 msec was À107.0 mL vs. 4.49 mL. Cohen's kappa was 0.679 vs. 0.773 for DSC-MRI and ASL, respectively, with a PLD of 1.500/2.500 msec. The sensitivity and specificity for ASL with a PLD of 1.500/2.500 msec in

Arterial Spin Labeling: Key Concepts and Progress Towards Use as a Clinical Tool

“…Most studies suggest that ASL can be used to assess the presence and size of ischemic lesions, but that it overestimates the lesion size, especially when shorter PLDs are used (e.g. 32 ). The lesion size can be compared to diffusion imaging measures of ischemic core size to determine a mismatch.…”

“…Most reported ASL studies in acute stroke are single center studies with less than 100 subjects and limited randomization to assess the impact of ASL on diagnosis and outcomes. Two notable exceptions are a multi-site comparison of lesion volumes between ASL and contrast 32 and a multi-site comparison of thrombectomy outcomes using ASL and CT perfusion for treatment criteria. 36 The second study showed statistically identical outcomes, though with a trend towards higher complications using ASL.…”

Editorial for “Arterial Spin Labeling Estimation of Penumbral Tissue in Acute Ischemic Stroke”

“…The study by Lyu et al 8 in this issue addresses the existing challenges of ASL in AIS. Unlike previous studies focusing on thresholds for severe hypoperfusion segmentation, the authors investigated the effects of PLD of ASL perfusion on the estimation of penumbra in AIS.…”