Left Ventricular Mass Measurement Using Tc-99m MIBI Myocardial Perfusion SPECT: Comparison with Echocardiographic Method

ABSTRACT

BACKGROUND AND OBJECTIVES: A left ventricular mass (LVM) can be used as a prognostic factor in patients with cardiovascular disease, and echocardiographic LVM measurements are most commonly used. We have measured LVM using quantitativel gated myocardial perfusion SPECT (QGS), and compared these results with LVM measured by echocardiography. SUBJECTS AND METHODS: One hundred and sixteen subjects (M/F=66/50, mean age: 58 yrs) underwent both rest QGS with Tc-99m MIBI and echocardiography. On visual interpretation, thirty-six subjects (31%) showed perfusion defects. The myocardial volume was obtained using the AutoQUANT program, and the LVM (LVMSPECT) was calculated by multiplying the volume by the specific gravity of the myocardium. We also measured the echocardiographic LVM (LVMEcho) by the Devereux formula, within one month of the LVMSPECT. RESULTS: The LVMSPECT and LVMEcho were well correlated (r=0.717, p<0.001), but a significant difference was noted between the two values. The mean difference between the LVMSPECT and LVMEcho was 24 g. The LVMEcho was smaller than the LVMSPECT in those subjects with a small LVMEcho, and greater than the LVMSPECT in the subjects with a large LVMEcho. The difference between the LVMEcho and LVMSPECT (LVMEcho-LVMSPECT) was positively correlated with the LVMEcho (r=0.893, p<0.001). CONCLUSION: The LVMs measured by gated myocardial perfusion SPECT and echocardiography were well correlated. But they were significantly different, especially in subjects with large LVMs.