Systolic versus diastolic acquisition in myocardial perfusion MR imaging.

PURPOSE: To compare myocardial blood flow (MBF) at systole and diastole and determine the diagnostic accuracy of both phases in patients suspected of having coronary artery disease (CAD).
MATERIALS AND METHODS: The study was approved by the regional ethics committee, and all patients gave written informed consent. After coronary angiography, 40 patients (27 men; mean age, 64 years ± 8) underwent stress-rest perfusion magnetic resonance (MR) imaging at 1.5 T, with images aquired simultaneously at end systole and middiastole. Patients were classified as having CAD (stenosis .70%) or no significant CAD. In patients with CAD, myocardial segments were classified as stenosis-dependent (downstream of significant stenosis) or remote. MBF and myocardial perfusion reserve (MPR) were calculated for each segment, and mean values in each phase were compared with paired t tests. The diagnostic accuracy of each phase was determined with receiver operating characteristic (ROC) analysis.
RESULTS: Twenty-one of the 40 patients (53%) had CAD. Resting MBF was similar in both phases for patients with and patients without CAD (P > .05). Stress MBF was greater in diastole than systole in normal, remote, and stenosis-dependent segments (3.75 mL/g/min ± 1.50 vs 3.15 mL/g/min ± 1.10, respectively, for normal segments; 2.75 mL/g/min ± 1.20 vs 2.38 mL/g/min ± 0.99, respectively, for remote segments; 2.49 mL/g/min ± 1.07 vs 2.23 mL/g/min ± 0.90, respectively, for stenosis-dependent segments; P <.01). MPR was greater in diastole than systole in all segment groups (P < .05). The diagnostic accuracies at diastole and systole were similar (area under the ROC curve = 0.79 and 0.82, respectively; P = .30).
CONCLUSION: Myocardial perfusion MR estimates of stress MBF and MPR were greater in diastole than systole in patients with and patients without CAD. However, both phases had similar diagnostic accuracy. These observations may be relevant to other dynamic perfusion methods, including computed tomography and echocardiography. © RSNA, 2012.