MRI quantitative myocardial perfusion with compartmental analysis: A rest and stress study

K 1 (first‐order transfer constant from arterial plasma to myocardium for Gd‐DTPA) and Vd (distribution volume of Gd‐DTPA in myocardium) were measured in vivo in a canine model ( n = 5) using MRI‐derived myocardial perfusion curves and a compartmental model. Perfusion curves were obtained after a bolus injection of Gd‐DTPA (0.04 m M /kg) with an inversion‐prepared fast gradient echo sequence. Myocardium and blood signal intensity were converted to a concentration of Gd‐DTPA, according to a model appropriate for short (<1 s) interimage intervals characteristic of cardiac‐triggered acquisitions. Before dipyridamole‐induced stress, K 1 and Vd , obtained from the fit of the MRI‐derived perfusion curves, were 6.2 ± 1.4 (mHz) and 17.5 ± 4.2%, respectively. After dipyridamole infusion, a K 1 increase of a factor of 2.82 ± 0.72 was measured ( P = 0.003). No change was observed in Vd ( P = 0.98). These results suggest that the K 1 increase after dipyridamole reflects a flow‐related effect that can be useful to quantity the MRI‐derived perfusion curves.