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Skeletal muscle perfusion during exercise using Gd-DTPA bolus detection
A T Nygren1, D Greitz, L Kaijser
1Department of Medical Laboratory Sciences & Technology, Huddinge University Hospital, Karolinska Institutet, Sweden.
Summary
This study assessed magnetic resonance imaging (MRI) for measuring skeletal muscle perfusion during exercise. While MRI signal intensity did not fully quantify blood flow, it showed potential for studying muscle conditions like ischemia.
Area of Science:
- Physiology
- Radiology
- Biomedical Engineering
Background:
- Skeletal muscle perfusion significantly changes during exercise.
- Accurate, non-invasive methods are needed to quantify muscle blood flow.
- Contrast-enhanced MRI offers potential for assessing tissue perfusion.
Purpose of the Study:
- To evaluate the utility of MRI with a gadolinium-based contrast agent (Gd-DTPA) for determining skeletal muscle perfusion during exercise.
- To compare MRI-derived parameters with ultrasonography measurements of blood flow.
Main Methods:
- Utilized a fast spoiled gradient echo (T1-weighted) MRI sequence with intermittent imaging during one-legged plantar flexion exercise.
- Measured blood flow in the popliteal artery using ultrasonography for comparison.
- Analyzed MRI parameters including signal intensity (SImax), upslope, downslope, mean transit time, and integrated curve area.
Main Results:
- Ultrasonography showed muscle perfusion increased from 4 ml/100g/min at rest to 110 ml/100g/min at high workload.
- MRI parameters, particularly signal intensity, showed trends related to blood flow but did not quantitatively mirror perfusion.
- MRI visually differentiated between exercising, non-exercising, and low-activity muscles.
Conclusions:
- The signal intensity curve from fast spoiled gradient echo MRI does not fully quantitatively reflect skeletal muscle perfusion during exercise.
- However, MRI signal intensity may correlate with blood flow velocity within a specific range (15-60 cm/s).
- This MRI technique could be valuable for studying skeletal muscle ischemia or endothelial dysfunction during physical activity.