Hemodynamics of distal cerebral arteries are associated with functional outcomes in symptomatic ischemic stroke in middle cerebral artery territory: A 4D flow CMR study.

Background: Cerebrovascular hemodynamics are believed to play an important role in the development of ischemic stroke (IS). However, the relationships between hemodynamics and prognosis are not fully understood. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) enables comprehensive characteristics of cerebrovascular hemodynamics. This study aims to investigate the associations of the different hemodynamics derived from 4D flow CMR with IS functional outcomes.
Methods: 91 patients (median age 64 years, 62 males) with unilateral IS in middle cerebral artery (MCA) territory were included. All subjects underwent a CMR scan, including 4D flow, three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA), 3D whole brain black-blood high-resolution vessel wall imaging (HR-VWI) of the MCA. Six hemodynamics, including flow rate, velocity, pulsatility index, time-averaged WSS (TAWSS), oscillatory shear index and relative residence time (RRT) were calculated for the lesion site, pre-bifurcation M1 (pM1) segment and the distal M1 and/or first branches of M2 (dM1/M2) segments. Vessel characteristics such as lumen area, vessel area, wall area, maximum wall thickness and the degree of stenosis were calculated at the most stenotic lesion site. The modified Rankin Scale (mRS) scores were assessed at 90 days and one year, and a mRS >2 was considered as a poor functional outcome.
Results: Lower segment-level TAWSS (OR:0.24, P=0.006 and OR: 0.29, P=0.014), higher RRT (OR: 2.74, P=0.007 and OR: 2.40, P=0.011) of dM1/M2 segments and lower segment- and lesion-level velocity (OR: 0.40, P=0.019 and OR: 0.41, P=0.025; OR: 0.41, P=0.030 and OR: 0.42, P=0.040) of pM1 segment were observed to be associated with poor functional outcome at both 90 days and one year. Using the cut-off value of 3.58Pa and 0.29, respectively, TAWSS and RRT of dM1/M2 segments showed moderate estimate performance in distinguishing poor functional outcome from favorable outcome (AUCs range from 0.642-0.687) both at 90 days and one year.
Conclusion: Distal segmental TAWSS and RRT of dM1/M2 segments were associated with poor functional outcomes. Such alterations of hemodynamics might help for the identification of patients with potential unfavorable prognosis.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2025 The Author(s). Published by Elsevier Inc. All rights reserved.)