Multi-delay arterial spin labeling reveals territorial heterogeneity of perfusion impairment in posterior circulation ischemic stroke.

OBJECTIVE: To evaluate multi-delay arterial spin labeling (m-ASL) for posterior circulation perfusion quantification and characterization of perfusion impairment across different vascular territories in posterior circulation ischemic stroke (PCIS). METHODS: This study included 73 patients with PCIS and 27 healthy controls (HCs). All participants underwent both single-delay ASL (s-ASL) and m-ASL to obtain s-ASL cerebral blood flow (CBF), m-ASL CBF, arterial transit time (ATT), and arterial cerebral blood volume (aCBV). Perfusion parameters were compared between the corresponding vascular territories in HCs and the unaffected side of PCIS patients, as well as between infarct lesions and their contralateral mirror regions. s-ASL and m-ASL ΔCBF were compared within patients. RESULTS: m-ASL CBF values were higher than s-ASL CBF in the posterior circulation territories of HCs and on the unaffected side of patients (all P < 0.05). Compared with HCs, the unaffected side of both the PCA and VBA territories showed lower m-ASL CBF and prolonged ATT (all P < 0.05). In both groups, infarct lesions exhibited lower s-ASL CBF, m-ASL CBF, and aCBV than mirror regions (all P < 0.05), while no significant differences were observed in ATT. m-ASL ΔCBF was greater than s-ASL ΔCBF in the PCA group (P = 0.036), whereas the two measures were comparable in the VBA group. CONCLUSION: m-ASL could reduce the potential underestimation of CBF by s-ASL and provide multiple perfusion parameters, offering a more detailed characterization of perfusion impairment patterns across different posterior circulation territories of patients with PCIS.