[Quantitative myocardial perfusion assessment with magnetic resonance imaging in patients with coronary artery disease].

Aim: To elucidate feasibility of the absolute myocardial blood flow (MBF), total coronary resistance (TCR), and myocardial blood flow reserve (MBFR) quantification using MRI in patients with coronary artery disease (CAD).
Material and Methods: A total of 19 patients with angiographically documented CAD and 9 healthy subjects were studied by MRI using double-slice saturation-recovery Turbo-FLASH sequence for monitoring myocardial first pass kinetics of Gd-DTPA-BMA at rest and during hyperemia (dipyridamole 0.56 mg/kg). The signal intensity curves were acquired within ROI for perfusion beds of the three main coronary arteries (LAD, LCX and RCA) and left ventricle cavity. Eighty five myocardial segments were included in final analysis (group 1 - supplied by <<normal>> coronary arteries, n=26; group 2 - supplied by arteries with non-significant diameter stenoses <50%, n=27; group 3 - supplied by arteries with significant stenoses >/=50%, n=32). Sixteen segments were revascularized subsequently (PCI or CABG). One-compartment model and slope-method were used for flow calculation. Myocardial and blood signal intensities were converted to concentration of Gd-DTPA-BMA according to the <<in vitro>> calibration curve.
Results: MBF was similar in groups at baseline (group 1 - 0.98+/-0.54, group 2 - 1.24+/-0.53 and group 3 - 1.28+/-0.48 ml/g/min) but significantly lower in group 3 during hyperemia (2.57+/-1.23, 2.99+/-1.14 vs. 1,79+/-0.94 ml/g/min, p<0.05). MBFR (the ratio of flow during hyperemia to flow at baseline) was significantly lower in group 3 than in groups 2 and 1 (1.4+/-0.7 vs. 2.7+/-1.3 vs. 2.9+/-1.2, respectively, p<0.01). Receiver-operator characteristic analysis of MBFR (value </=1.6) revealed sensitivity and specificity of 81% and 85%, respectively, for detection of CAD as defined by quantitative coronary angiography (stenosis diameter >/=50%). TCR (mean arterial pressure divided by flow) significantly decreased (78.8+/-42.2 vs. 41.3+/-17.3 mm Hg ґ min ґ g/ml, p<0.01), MBF accordingly increased (1.61+/-0.77 vs. 2.58+/-0.91 ml/g/min, p<0.01) during hyperemia and MBFR <<normalized>> (1.3+/-0.6 vs. 3.0+/-1.3, p<0.00l) in myocardial segments after revascularization.
Conclusion: Absolute MBF and MBFR calculation by first-pass contrast perfusion MRI are feasible in patients with CAD before and after revascularization.