Non-Invasive functional assessment of severity in cerebral arterial stenosis using cerebral flow fraction: A hemodynamic study.

Intracranial atherosclerotic stenosis (ICAS) is a major cause of ischemic stroke, but current diagnostic indices such as stenotic percentage (SP) and relative cerebral blood flow (rCBF) have limitations. SP lacks functional relevance, and rCBF cannot confirm whether stenosis causes ischemia. We propose a non-invasive method to assess ischemic stroke by computing cerebral fractional flow (cFF), defined as the ratio of distal to inlet pressure across the stenosis. Using cerebrovascular generation algorithms and the Desikan-Killiany atlas, we built 66 personalized whole-brain hemodynamic models to calculate cFF and rCBF, diagnosing ischemia at rCBF ≤ 0.48. cFF showed a stronger correlation with rCBF than SP (r = 1.00 vs. 0.71, p < 0.001). ROC analysis identified a diagnostic threshold of 0.56, yielding 98.48% accuracy, validated against pressure wire and clinical trial data.This proof-of-concept study demonstrates that non-invasive cFF provides superior functional evaluation of ischemic stroke, reflecting both stenosis-induced hemodynamics and compensatory mechanisms. cFF enables accurate identification of stenosis-related ischemia, offering a valuable tool for guiding intervention in ICAS patients.