Abstract #1707

Damon B, Hornberger J, Kent-Braun J

Brief MRI signal intensity transients have been reported following short isometric contractions and may be useful indices of vascular function in applied physiology and pathophysiology studies. While generally reflecting a muscle BOLD response, their exact physiological mechanism remains unclear. Using dual gradient-echo EPI acquisitions (TE/TE=1000/6, 46 ms) and near-infrared spectroscopy measurements of total hemoglobin and oxyhemoglobin saturation obtained during 5 min of suprasystolic blood pressure cuff inflation, we show here that short-echo signals reflect changes in blood volume and long-echo signals reflect changes in blood oxygenation.