Dynamic exercise imaging with an MR-compatible stationary cycle within the general electric open magnet

Area of Science:

• Cardiovascular imaging
• Physiology
• Biomedical engineering

Background:

• Muscular ischemia diagnosis often necessitates exercise to reveal symptoms.
• Intermittent claudication requires physiological challenge for accurate diagnosis.
• Cine phase-contrast MRI offers vascular anatomy and blood velocity data for flow quantification.

Purpose of the Study:

• To design, construct, and test an MR-compatible stationary cycle.
• To quantify blood flow in large arteries during lower-limb exercise using MRI.
• To assess the feasibility of exercise-induced flow quantification for diagnosing conditions like intermittent claudication.

Main Methods:

• Development of a novel MR-compatible stationary cycle with adjustable workload and freewheeling capability.
• Utilized cine phase-contrast MRI on a 0.5 T open magnet for simultaneous vascular imaging and velocity acquisition.
• Performed imaging on a healthy male subject at abdominal aorta levels (supraceliac and infrarenal) at rest and during cycling exercise.

Main Results:

• The stationary cycle operated smoothly during MRI acquisition and allowed for workload quantification.
• Achieved an exercise workload of 47.9 W, increasing heart rate from 52 to 78 bpm.
• Demonstrated significant increases in blood flow: supraceliac aorta from 1.7 to 3.7 L/min and infrarenal aorta from 0.4 to 3.2 L/min from rest to exercise.

Conclusions:

• The MR-compatible stationary cycle is a viable tool for exercise-induced blood flow quantification.
• Cine phase-contrast MRI combined with exercise provides valuable data on arterial flow dynamics.
• This methodology shows promise for diagnosing conditions characterized by exercise-induced muscular ischemia, such as intermittent claudication.