3D blood flow characteristics in the carotid artery bifurcation assessed by flow-sensitive 4D MRI at 3T

Area of Science:

• Medical Imaging
• Cardiovascular Research
• Biomedical Engineering

Background:

• Carotid artery bifurcation diseases, particularly internal carotid artery (ICA) stenosis, pose significant stroke risks.
• Accurate assessment of 3D blood flow dynamics is crucial for understanding disease progression and treatment efficacy.

Purpose of the Study:

• To evaluate the feasibility of flow-sensitive 4D MRI for quantifying and visualizing 3D blood flow patterns in the carotid bifurcation.
• To compare flow-sensitive 4D MRI measurements with duplex sonography (DS) in healthy volunteers and patients with ICA stenosis.
• To assess the capability of 3D MRI in detecting altered flow patterns due to stenosis and evaluating post-revascularization changes.

Main Methods:

• Flow-sensitive 4D MRI at 3T was performed on 10 healthy volunteers and 9 patients with ICA stenosis (> or =50%).
• Duplex sonography (DS) measured absolute/mean blood velocities, pulsatility index (PI), and resistance index (RI) in the common carotid arteries (CCAs).
• 3D MRI blood flow patterns in the carotid bifurcation were graded by two independent readers before and after revascularization.

Main Results:

• MRI-derived blood flow velocities were 31-39% lower than DS, while PI and RI showed smaller differences (13-16%).
• Consistent filling and helical flow patterns were observed in volunteers.
• Markedly altered filling and helical flow patterns in the ICA bulb of patients with stenosis were detected, with restoration after revascularization.

Conclusions:

• Flow-sensitive 4D MRI is feasible for quantifying and visualizing physiological and pathological blood flow in the carotid artery bifurcation.
• 3D MRI effectively detects altered flow dynamics in ICA stenosis and evaluates the impact of revascularization.
• This technique offers valuable insights into carotid artery hemodynamics for clinical decision-making.