Arterial Spin Labeling Reveals Persistent Cortical Hypoperfusion Linked to Cognitive Performance and Radiotherapy Dose in Post-Treatment Glioma Patients

Background: Cognitive impairment is a prevalent long-term sequela in glioma patients, yet its cerebrovascular correlates remain poorly characterized. Arterial spin labeling (ASL) perfusion MRI offers a non-invasive means to quantify cerebral blood flow (CBF) and may serve as a sensitive correlate of radiotherapy (RT)-induced neurovascular injury. Methods: Fifty WHO Grade 2/3 glioma patients and 50 matched healthy controls underwent pseudo-continuous ASL (pCASL) MRI and a standardized cognitive test battery. Regional CBF was compared between patients (n=44, after quality control) and controls (n=50) using ANCOVA with age, sex, and deep white matter CBF as covariates. In irradiated patients (~5 years post-RT), RT dose-CBF associations were assessed using region-wise regression, and regional CBF was compared among controls and low-dose (≤15 Gy) versus high-dose (≥40 Gy) regional RT exposure groups. Cognition-CBF associations were evaluated in a priori domain-specific regions of interest. Results: Compared with controls, patients showed frontoparietal cortical hypoperfusion, with significantly lower CBF in middle frontal and superior/inferior parietal cortices (all q<0.01; partial η-squared=0.128-0.147). Region-wise regression showed no significant linear RT dose-CBF associations after correction. However, subgroup analyses identified RT dose-sensitive regions with ≥40 Gy exposure that showed lower adjusted CBF than controls, most prominently in the left precentral and caudal middle frontal cortices (q<0.01; adjusted-ΔCBF≈-27.2--28.8 mL/100g/min). Perfusion in the left precentral and postcentral gyri of irradiated patients correlated positively with motor performance. Conclusions: pCASL reveals persistent cortical hypoperfusion in glioma patients that spatially corresponds with RT dose exposure and associates with cognitive performance, positioning ASL as a promising non-invasive biomarker of RT-related neurovascular injury.