Myocardial perfusion reserve: assessment with multisection, quantitative, first-pass MR imaging.

PURPOSE: To demonstrate the feasibility of determining myocardial blood flow changes and the myocardial perfusion reserve with magnetic resonance (MR) first-pass imaging, to validate the MR results by means of comparison with radiolabeled microsphere flow measurements in an animal model, and to compare the coronary flow reserve with the perfusion reserve at MR imaging in patients with hemodynamically nonsignificant coronary lesions and angina. MATERIALS AND METHODS: Arrhythmia-insensitive, first-pass, multisection, T1-weighted MR imaging with contrast agent enhancement was performed in eight pigs with acute ischemia and in eight adult patients (six women, two men). In the pigs, microsphere flow measurements were obtained in parallel with the MR measurements. In the patients, the coronary flow reserve was measured with an intracoronary Doppler flow ultrasound probe for comparison with the MR perfusion reserve. RESULTS: In the animal studies, there was linear correlation between MR perfusion indexes and the microsphere flow measurements (r = .88, P < .01). In the patients, the regional perfusion reserve matched the coronary flow reserve (linear regression with a slope of 1.02 +/- 0.09, r = .80). CONCLUSION: The myocardial perfusion reserve can be quantified with first-pass MR imaging. In patients with microvascular dysfunction, the myocardial perfusion reserve matches the reduced coronary flow reserve.

Physiologic assessment of the coronary collateral circulation in transplanted human hearts.

Coronary arteries of transplanted hearts frequently develop a vasculopathy characterized by severe lumenal narrowing in the distal coronary arteries. It has been thought, on the basis of angiographic studies, that the coronary circulation of transplanted hearts with vasculopathy fails to develop collateral vessels normally. To determine the extent of the collateral circulation in transplanted hearts with a significant coronary stenosis, we measured an index of the collateral circulation, the coronary artery occlusion pressure, during single-vessel coronary angioplasty in seven patients with allograft vasculopathy and 18 patients with atherosclerotic disease who did not undergo transplantation. Aortic and coronary artery pressure distal to the stenosis in the epicardial artery were measured during balloon occlusion (> or = 45 seconds). Measurement variability for determination of coronary occlusion pressure was assessed by measuring occlusion pressure on two separate balloon inflations (n = 17). The severity of the dilated stenotic lesion was assessed with quantitative angiography (Reiber-PIE Data method). The indexes of stenosis severity were similar in coronary arteries of transplanted and native hearts. Coronary occlusion pressure measurements were highly reproducible (mean absolute difference between measurements, 1 +/- 1 mm Hg, r = 0.98). Coronary occlusion pressure in transplanted hearts (32 +/- 4 mm Hg) was nearly identical to that measured in coronary arteries of native hearts (29 +/- 2 mm Hg). When vessels with total occlusion were excluded and corrections were made for minor differences in hemodynamics (heart rate and blood pressure) were made, the coronary occlusion pressure in transplanted hearts remained nearly identical to native hearts.(ABSTRACT TRUNCATED AT 250 WORDS)