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.