Evaluation of Left and Right Ventricular Ejection Fraction and Volumes from Gated Blood-Pool SPECT in Patients with Dilated Cardiomyopathy: Comparison with Cardiac MRI

This prospective study evaluated the accuracy of electrocardiogram-gated blood-pool SPECT (GBPS) for the assessment of left ventricular (LV) and right ventricular (RV) ejection fraction (EF), end-diastolic volume (EDV), and end-systolic volume (ESV) in patients with dilated cardiomyopathy (DCM), using cardiac magnetic resonance (CMR) imaging as the reference standard. Methods: Thirty-two patients (24 men and 8 women; mean age, 51 y) with a diagnosis of idiopathic DCM underwent GBPS and CMR. LV and RV parameters including EDV, ESV, and EF from GBPS were calculated using fully automated gradient software and compared with those obtained by CMR. Results: Biventricular volumes were underestimated by GBPS, compared with CMR (P < 0.001). We found no statistical difference between these 2 methods in the assessment of LV EF (P = 0.23), whereas RV EF was overestimated by GBPS (P < 0.001 vs. CMR). Regression analysis yielded significant correlations between GBPS and CMR in the assessments of biventricular parameters (r = 0.83 for LV EDV, 0.88 for LV ESV, 0.89 for LV EF, 0.86 for RV EDV, 0.86 for RV ESV, and 0.62 for RV EF; all P < 0.001). Comparison of the deviations of RV indices between GBPS and CMR with the ratio of RV EDV to LV EDV showed that there was a statistically significant trend for RV volumes to be underestimated and for RV EF to be overestimated as the biventricular volumetric ratio decreased (r = 0.61 for RV EDV, 0.68 for RV ESV, and -0.55 for RV EF; all P < 0.001). Conclusion: For patients with DCM, GBPS correlated well with CM R for the assessment of biventricular parameters, but RV indices should be cautiously interpreted. Key Words: dilated cardiomyopathy; gated blood-pool SPECT; cardiac magnetic resonance imaging; ventricular function