Cerebral blood flow territory instability in patients with atherosclerotic intracranial stenosis.

Background Stroke risk stratification in patients with symptomatic intracranial atherosclerotic arterial disease (ICAD) remains an important clinical objective owing to the high 14-19% recurrent stroke rate in these patients on standard-of-care medical management. There thus remains a need for hemodynamic markers that may allow for the selection of personalized therapies for high-risk symptomatic patients. Purpose To determine if shifting of cerebral blood flow (CBF) territories in response to changes in cerebral perfusion pressure (CPP) may provide a marker for stroke risk in ICAD patients. Study Type Prospective. Population Twenty ICAD patients who experienced a stroke within 45 days of study enrollment and 10 healthy controls. Sequence 3.0T MRI including anatomical imaging (T-1-weighted, T-2-weighted/FLAIR), 3D MR angiography, and normocapnic and hypercapnic vessel-encoded CBF-weighted arterial spin labeling. Assessment Patients were scanned within 45 days of overt stroke and monitored (duration = 13.2 +/- 4.4 months) for the endpoint of non-cardioembolic stroke or transient ischemic attack. Flow territory shifting (shifting index) was calculated from the first scan by determining whether a voxel shifted from its primary arterial source from normocapnia to hypercapnia. Statistical Tests A Mann-Whitney U-test (significance: P < 0.05) was performed to determine whether patients meeting the endpoint had greater shifting indices relative to controls or patients not meeting the endpoint. Results Shifting indices (mean +/- standard error) were significantly higher in patients meeting endpoint criteria relative to controls (P = 0.0057; adjusted P = 0.036) and patients not meeting endpoint criteria (P = 0.0047; adjusted P = 0.036). Data Conclusion Flow territory shifting may provide a marker of recurrent stroke risk in symptomatic ICAD patients on standard-of-care medical management therapies. Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019.