SKELETAL-MUSCLE PERFUSION MEASURED BY POSITRON-EMISSION-TOMOGRAPHY DURING EXERCISE

The applicability of (H2O)-O-15-positron emission tomographic (PET) im aging for the assessment of skeletal muscle perfusion during exercise was investigated in five healthy subjects performing intermittent isom etric contractions on a calf ergometer. The workload of the left calf muscles was kept constant in all exercises, while that of the right ca lf muscles was varied. During exercise (H2O)-O-15 distribution in the calf muscles was measured by PET. Radioactivity measured in the left c alf muscles was used as a reference for the radioactivity measured in the right calf muscles. In all studies, muscles were delineated by upt ake of radioactivity. Four subjects demonstrated high radioactivity in the gastrocnemius medialis muscle, in one subject high radioactivity was distributed over the triceps surae muscles. The observed muscles d emonstrated also local foci of radioactivity indicating regionally enh anced tissue perfusion. The right-left ratio of radioactivity in the a ctive muscles increased as a function of the load. We conclude that in ter- and intramuscle perfusion differences can be measured during exer cise by (H2O)-O-15-PET imaging.