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Quantitative abdominal aortic flow measurements at controlled levels of ergometer exercise
E M Pedersen1, S Kozerke, S Ringgaard
1Dept. Cardiothoracic and Vascular Surgery T, MR-Center, Institute of Experimental Clinical Research, Aarhus University Hospital, Skejby Sygehus, Denmark. skejemp@aau.dk
Magnetic Resonance Imaging
|May 7, 1999
Summary
Quantitative MRI accurately measured exercise-induced abdominal aortic flow changes in volunteers. Retrograde flow patterns, linked to atherosclerosis, disappeared during exercise, demonstrating the technique
Area of Science:
- Cardiovascular Physiology
- Medical Imaging
- Biomedical Engineering
Background:
- Measuring exercise-induced arterial flow changes is challenging.
- Quantitative magnetic resonance (MR) flow measurements face artifacts and ECG triggering issues.
- Understanding abdominal aortic flow dynamics during exercise is crucial for cardiovascular health assessment.
Purpose of the Study:
- To quantify exercise-induced flow changes in the abdominal aorta using a novel MR technique.
- To assess the feasibility of rapid quantitative phase contrast (QPC) measurements during a post-exercise window.
- To investigate the impact of exercise on retrograde flow patterns in the abdominal aorta.
Main Methods:
- Employed a fast hybrid phase contrast sequence with K-space segmentation and echo planar imaging readouts.
- Acquired data during a 12-heartbeat, single breathhold post-exercise scanning window after ergometer exercise.
- Quantified heart rate changes to ensure representation of the exercise state during central k-space acquisition.
Main Results:
- Abdominal aortic flow significantly increased from 1.4+/-0.3 L/min at rest to 7.9+/-1.1 L/min at 131 watts.
- Retrograde flow, maximal at rest (1.2 L/min), was largely absent during exercise, except at low workloads in one volunteer.
- Heart rate decrease was minimal (<4% at 6 beats, <14% at 11 beats) during the scanning window, validating the exercise state.
Conclusions:
- Retrograde flow patterns in the abdominal aorta, associated with atherosclerosis risk factors, diminish with increasing exercise intensity.
- Fast quantitative phase contrast MR imaging during a post-exercise window is feasible for representing controlled exercise levels.
- This technique offers a promising approach to study exercise-induced hemodynamic changes non-invasively.