CAPILLARY TRANSFER CONSTANT OF GD-DTPA IN THE MYOCARDIUM AT REST AND DURING VASODILATION ASSESSED BY MRI

The purpose of this study was to determine whether the capillary trans fer constant (K-i) of gadolinium-DTPA was sensitive to perfusion chang es and whether ischemic regions in the myocardium could be identified using the modified Kety formula. K-i was measured at rest and during d ipyridamole-induced vasodilation in 10 healthy volunteers and in 10 pa tients with ischemic heart disease. K-i increased by a factor of 2.5 /- 1.2 (mean +/- SD) from 55 +/- 16 ml 100 g(-1)min(-1) at rest to 136 +/- 46 ml 100 g(-1)min(-1) (P < 0.01) during vasodilation in the heal thy subjects. In the patients, there were no changes in K-i during vas odilation in ischemic regions (50 +/- 18 versus 49 +/- 30 ml 100 g(-1) min(-1) (P > 0.4)). K-i increased in nonischemic regions by a factor o f 2.0 +/- 0.8 from 44 +/- 17 to 81 +/- 32 mi 100 g(-1)min(-1) during v asodilation (P < 0.02). It is concluded that the capillary transfer co nstant is sensitive to perfusion changes and that regional ischemia ca n be detected with MRI, This noninvasive and quantitative method may p rove useful in the evaluation of patients with ischemic heart disease.