# Changes in arterial flow velocity and pulsatility following endarterectomy for symptomatic high degree carotid artery stenosis: insights from the Carotis7T Study

## TL;DR

This study uses 7T MRI to examine changes in cerebral blood flow after carotid endarterectomy in patients with severe carotid artery stenosis.

## Contribution

The study is among the first to use ultra-high field 7T MRI to assess blood flow velocity and pulsatility in small brain arteries after CEA.

## Key findings

- Carotid endarterectomy did not significantly change blood flow velocity or pulsatility in basal ganglia and semi-oval center perforating arteries.
- There was a non-significant increase in mean blood flow velocity and pulsatility in the middle cerebral artery after surgery.
- Findings suggest limited impact of revascularization on cerebral perfusion in small arteries at three months post-surgery.

## Abstract

•Improved optimal medical therapy (OMT) and surgical experience in carotid interventions have reduced perioperative stroke after carotid endarterectomy (CEA). The 2017 and 2023 European Society of Vascular Surgery guidelines propose imaging criteria to identify patients on OMT who may benefit from CEA. Although symptomatic status affects perioperative diffusion-weighted imaging lesions and cerebral perfusion, specific predictive imaging markers for late stroke remain unclear. Advances in ultra-high field 7T magnetic resonance imaging enable in vivo assessment of blood flow velocity and pulsatility in small perforating brain arteries, offering potential for novel risk markers for stroke.

Improved optimal medical therapy (OMT) and surgical experience in carotid interventions have reduced perioperative stroke after carotid endarterectomy (CEA). The 2017 and 2023 European Society of Vascular Surgery guidelines propose imaging criteria to identify patients on OMT who may benefit from CEA. Although symptomatic status affects perioperative diffusion-weighted imaging lesions and cerebral perfusion, specific predictive imaging markers for late stroke remain unclear. Advances in ultra-high field 7T magnetic resonance imaging enable in vivo assessment of blood flow velocity and pulsatility in small perforating brain arteries, offering potential for novel risk markers for stroke.

Patients with symptomatic high degree carotid artery stenosis often exhibit a reduced perfusion pressure in the cerebral vasculature in absence of sufficient collaterals. The aim of this research was to evaluate changes in mean blood flow velocity and pulsatility within the cerebral perforating arteries following carotid endarterectomy (CEA).

Fifteen patients with symptomatic high degree (>50 %) carotid artery stenosis were included in the monocentre prospective observational Carotis7T study. All patients underwent 7T magnetic resonance imaging (MRI) one day prior to CEA and three months postoperative. Mean blood flow velocity (Vmean) and pulsatility index (PI) were measured in the first segment of the middle cerebral artery (M1 of MCA), and in the perforating arteries of the basal ganglia (BG) and semi-oval centre (CSO), using a 2D phase-contrast 7T MRI sequence. Outcomes on the ipsilateral side were compared between the preoperative and postoperative situation.

A postoperative increase (+14.2 %) in Vmean and (+10.7 %) in PI was seen at the level of the MCA. A slight decrease in Vmean and a slight increase in PI were observed at both the level of the BG (respectively -5.6 % and +12.8 %) and CSO (respectively -13.2 % and +11.0 %) between the preoperative and postoperative situation following CEA. However, these changes were not statistically significant.

In this small single centre patient sample, our findings suggest that revascularization by removal of the stenosis and atherosclerotic plaque does not result in a measurable impact on the brain’s perfusion at BG and CSO level at three months post intervention.