Blood flow and perfusion lateralization in border zone infarct using 4D flow and arterial spin labeling

Hemodynamics may play an important role in border zone infarct (BZI), but macroscopic and microscopic hemodynamics of BZI still remain unclear. This study aims to investigate arterial flow and tissue perfusion differences between BZI and non-BZI in patients with unilateral middle cerebral artery (MCA) territory infarcts.

Subacute ischemic stroke patients with unilateral infarcts at MCA territory were included. Imaging protocols included 4D flow, ASL (arterial spin labeling), and routine clinical brain MRI scan. A total of 56 patients (56.1 ± 11.9 years, 39 male) were included and divided as BZI (n = 26) and non-BZI (n = 30). BZI was further subdivided as cortical BZI (CBZI, n = 9), internal BZI (IBZI, n = 11), and mixed BZI (n = 6). Average blood flow (Flow_avg), regional average cerebral blood flow (CBF_avg) were compared between infarct and contralateral sides to test hemodynamic lateralization. Flow-index and CBF-index (infarct sides/contralateral sides) were compared between groups and subgroups.

Flow_avg and CBF_avg showed significant lateralization in both BZI and non-BZI as well as CBZI and IBZI. Flow-index (0.51 ± 0.37 vs. 0.87 ± 0.36, p < 0.01) and CBF-index (0.70 ± 0.21 vs. 0.90 ± 0.19, p < 0.01) were significantly different between BZI and non-BZI but were not significantly different between CBZI and IBZI.

In summary, hemodynamic lateralization can occur in subacute stroke patients with BZI and non-BZI and the one that occurs in BZI tends to be more severe in view of arterial flow and tissue perfusion.