Introduction: Patient-level clinical recovery after acute ischemic stroke (AIS) varies even with timely reperfusion therapies. Therefore, imaging markers that potentially predict recovery would benefit treatment decision. MR fingerprinting arterial spin labeling (MRF-ASL) allows simultaneous assessment of cerebral blood flow (CBF), arterial cerebral blood volume (aCBV), and bolus arrival time (BAT). While its value in chronic stroke has been shown, its role in AIS is less explored. In this study, we aim to evaluate its utility in predicting neurological improvement after AIS. Methods: Patients with confirmed AIS were included irrespective of treatments, and underwent MRF-ASL (scan time 5min) and diffusion-weighted imaging (DWI) within 7 days of onset. Derived MRF-ASL parametric maps included: CBF (1- and 2- compartment), aCBV and BAT. Regions-of-interest (ROIs) for ischemic lesions and contralateral healthy tissue were drawn on DWI. Relative differences in MRF-ASL parameters (lesion-normal) were calculated. Stroke severity was scored with NIHSS at admission and discharge. Recovery was indexed as NIHSS shift (discharge-admission), with more negative values denoting better recovery. Paired t-tests were used to compare MRF-ASL parameters between lesion and contralateral tissue. Linear regression was used to examine relationships between NIHSS shift and relative perfusion metrics adjusted for age and sex. Results and Discussion: Twenty-seven AIS patients (13F, age 65.9±15.2 yrs) were studies (Fig 1). Fig 2 presented DWI, MRF-ASL parametric maps, and ROIs from 6 representative AIS cases, with either favorable outcome (NIHSS shift≤-4) or unfavorable outcome (NIHSS shift>-4). Groupwise comparisons showed no lesion-normal differences in MRF-ASL parameters (Fig 3a-d), likely due to variability in treatment outcome. However, regression analyses revealed NIHSS shift correlated positively with BAT diff (P=0.002, Fig 3g), inversely with aCBV diff (P=0.006, Fig 4h), and showed a negative trend with CBF 1cmpt,diff (P=0.05, Fig 3e). These results suggest that shortened BAT and increased aCBV value may serve as predictors of favorable stroke recovery. Elevated aCBV likely indicates a robust compensatory response to ischemia, and is also reflective of the presence of good collaterals. Conclusion: MRF-ASL provides rapid, noninvasive characterization of perfusion in AIS. Specific metrics, particularly BAT and aCBV, show potentials as early markers of neurological recovery.
Hu et al. (Thu,) studied this question.