EFFECT OF CARDIAC FLOW ON GRADIENT RECALLED ECHO IMAGES OF THE CANINEHEART

The effect of coronary flow on the signal intensity of gradient recall ed echo (GRE) MR images of the canine heart was evaluated at 4 T. Usin g a fully instrumented canine model, hyperperfusion (local adenosine i nfusion) and ischemia (local occlusion) were evaluated while coronary blood flow and venous oxygen tension were monitored. These studies dem onstrated an increase in GRE signal intensity with increases in corona ry blood flow and venous oxygenation. A local occlusion resulted in a small decrease in signal intensity in the affected area of the heart. The dependence of the signal changes on TE and TR indicated that the e ffects of high Bow were associated with changes in the apparent T-2 an d T-1. Both relaxation effects could reflect changes in tissue blood v olume associated with the conditions studied. In addition, the apparen t T-2 changes were consistent with alterations in total tissue deoxyhe moglobin concentration and the changes in apparent T-1 were consistent with inflow effects.