Dual gradient-echo MRI of post-contraction changes in skeletal muscle blood volume and oxygenation.

Damon BM, Hornberger JL, Wadington MC, Lansdown DA, Kent-Braun JA
Magn Reson Med. 2007 57 (4): 670-9

PMID: 17390346 · PMCID: PMC4437703 · DOI:10.1002/mrm.21191

Analysis of post-contraction MRI signal intensity (SI) transients may allow noninvasive studies of microvascular reactivity and blood oxygenation recovery. The purpose of this study was to determine the physiological basis for post-contraction changes in short-echo (6 ms) and long-echo (46 ms) gradient-echo (GRE) MRI signals (S(6) and S(46), respectively). Six healthy subjects were studied with the use of dual GRE MRI and near-infrared spectroscopy (NIRS). S(6), S(46), total hemoglobin concentration ([THb]), and oxyhemoglobin saturation (%HbO(2)) were measured before, during, and after 2 and 8 s dorsiflexion maximal voluntary contractions, and 5 min of proximal arterial occlusion. The changes in S(6) and [THb] after the 2-s contractions were similar to those following 8-s contractions, but changes in %HbO(2) and S(46) were greater following 8-s contractions than after the 2-s contractions. [THb] and S(6) did not change during and following 5 min of arterial occlusion, but %HbO(2) and S(46) were both significantly depressed at similar occlusion durations. Also, distance measures indicated similarity between S(6) and [THb] and between S(46) and %HbO(2). We conclude that following brief human skeletal muscle contractions, changes in S(6) primarily reflect changes in blood volume and changes in S(46) primarily reflect changes in blood oxygenation.

MeSH Terms (13)

Analysis of Variance Blood Volume Female Hemoglobins Humans Magnetic Resonance Imaging Male Microcirculation Muscle, Skeletal Muscle Contraction Oxygen Regional Blood Flow Spectroscopy, Near-Infrared

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