Abstract WP168: Association of Stenosis, Proximal Flow and Distal Perfusion in Subjects With Middle Cerebral Artery Stenosis

Abstract

Introduction: Hemodynamic compromise caused by intracranial artery stenosis is one of the critical factors contributing to ischemic stroke. However, the association between flow and stenosis has not been well determined quantitatively, nor its correlation with distal perfusion. The purpose of this study was to investigate the association of blood flow in different grades of stenosis, as well as its association with distal brain tissue perfusion. Methods: Intracranial 4D flow and perfusion were obtained in 33 patients (mean 56 years old) with different grades of unilateral middle cerebral artery (MCA) stenosis. GTFlow was used to measure the flow at the proximal of stenosis and the symmetrical location of contralateral side (Fig 1a). Olea was accessed to calculate the perfusion parameters in MCA area. The average net flow at the proximal of stenosis was compared in patients with different grades(<30%,30-49%,50-69%, and ≥70%) of stenosis. Correlation between relative flow(stenosis/contralateral) and perfusion parameters were also compared in different pial collateral status. Results: Blood flow at the proximal of stenosis changes with the grades of stenosis increasing (Fig 1b, p =0.01). Subjects with <50% and ≥50% stenosis differ in MCA flow, rCBF and rTTP, but not in rCBV (Fig 1c).Spearman correlation analysis indicated that the relative flow was also associated with rTTP shown in distal brain tissue in subjects with poor collateral (Fig 1d, r=-0.69, p =0.02), but not in patients with good collateral. No association between relative flow and rCBF was detected in this group of population. Conclusion: In conclusion, decreased flow at the proximal of stenosis could result in the delay of perfusion in distal brain tissue in patients with poor collateral. Association of flow and stenosis, as well as its relationship with distal perfusion need further study, collateral status and potential compensatory mechanism should be considered in future study.