Non-invasive segmentation of individual watershed areas allows detection of hemodynamic impairments in internal carotid artery stenosis

Motivation: Internal carotid artery stenosis (ICAS) accounts for ≈10% of strokes. Individual watershed areas (iWSA) are especially susceptible to hemodynamic impairments. Currently, iWSA are segmented from contrast agent-based time-to-peak (TTP), limiting applicability. Goal(s): We aimed towards non-invasive iWSA segmentation based on arterial transit time (ATT) from Hadamard-encoded pseudo-continuous ASL. Approach: Overlap of iWSA from ATT and TTP was investigated and agreement of extracted hemodynamic parameter values such as cerebrovascular reactivity (CVR) was evaluated and ICAS-induced parameter-lateralization was investigated. Results: ATT-based and TTP-based iWSAs overlapped well, with excellent agreement in quantitative parameters and significant lateralization of hemodynamic parameters in ICAS within both iWSA delineation approaches. Impact: We successfully segmented iWSA from non-invasive ATT and demonstrated sensitivity to ICAS-related impairments, in agreement with TTP-based iWSA segmentation. ATT-based iWSAs facilitate longitudinal investigation without contrast application in cerebrovascular diseases such as ICAS or Moyamoya.