Simultaneous gradient-echo and spin-echo imaging showed that the ratio of relaxation rates (deltaR2*/deltaR2) was lower during reactive hyperemia relative to ischemia in human skeletal muscle.
Observational
Does simultaneous gradient-echo/spin-echo EPI provide temporal and spatial information about skeletal muscle perfusion during graded ischemia?
Simultaneous GE/SE EPI imaging can measure changes in relaxation rates during ischemia and reactive hyperemia, potentially providing a measure of the relative distribution of small and large vessels in skeletal muscle.
The goal of this study was to evaluate the usefulness of blood oxygenation level-dependent (BOLD) methodologies to provide temporal and spatial information about skeletal muscle perfusion. A simultaneous gradient echo (GE) and spin-echo (SE) imaging sequence (GE/SE) with alternating TE was used to acquire images of leg skeletal muscle throughout a stepped reactive hyperemia paradigm. The change in both the GE and SE relaxation rates (deltaR2*, deltaR2) measured during ischemia and reactive hyperemia scaled with the duration of cuff inflation (the ischemic period) plateaued for cuff inflations lasting longer than 120 seconds and were greater in soleus muscle than in gastrocnemius. The ratio deltaR2*/deltaR2 was found to be less during the reactive hyperemia period relative to ischemia. Considering that a greater proportion of capillary vessels are perfused during reactive hyperemia than during ischemia, this finding suggests that magnetic susceptibility methodologies, with their dependence on compartment size, may provide a measure of the relative distribution of small and large vessels in skeletal muscle.
Donahue et al. (Tue,) conducted a observational in graded ischemia in human skeletal muscle. Simultaneous gradient-echo/spin-echo EPI was evaluated on change in GE and SE relaxation rates (deltaR2*, deltaR2). Simultaneous gradient-echo and spin-echo imaging showed that the ratio of relaxation rates (deltaR2*/deltaR2) was lower during reactive hyperemia relative to ischemia in human skeletal muscle.