Assessment of reactive hyperaemia using real time zonal echo-planar flow imaging

Area of Science:

• Cardiovascular physiology
• Medical imaging
• Vascular biology

Background:

• Limb blood flow measurement, particularly during reactive hyperemia, is crucial for assessing vascular health and endothelial function.
• Flow-mediated dilation, a key indicator, is challenging to measure with cardiovascular magnetic resonance due to short-lived flow increases.
• Noninvasive techniques are needed to accurately quantify dynamic changes in blood flow.

Purpose of the Study:

• To evaluate a real-time, single-shot zonal echo-planar imaging (ZEPI) method for measuring reactive hyperemia in the femoral artery.
• To assess the feasibility of using ZEPI for noninvasive cardiovascular magnetic resonance assessment of vascular reactivity.

Main Methods:

• Utilized a real-time, single-shot zonal echo-planar imaging (ZEPI) technique.
• Measured flow velocity in the femoral artery of five healthy volunteers every 78 milliseconds during reactive hyperemia.
• Analyzed changes in peak forward flow velocity during systole and minimum flow velocity.

Main Results:

• Demonstrated significant changes in peak forward flow velocity (580 vs. 390 mm/sec, p < 0.01) and minimum flow velocity (160 vs. 100 mm/sec, p < 0.01) during reactive hyperemia.
• The ZEPI method allowed for high temporal resolution measurement of femoral artery blood flow dynamics.
• Observed rapid changes consistent with reactive hyperemia were successfully captured.

Conclusions:

• The real-time ZEPI technique shows promise for accurate, noninvasive measurement of femoral artery blood flow during reactive hyperemia.
• This method facilitates the study of vascular health and endothelial function by capturing rapid flow dynamics.
• Future improvements in spatial resolution will enable precise determination of total flow, flow profile, and peak velocities in real time.