QUANTITATIVE SCINTIGRAPHIC ANALYSIS OF I-123 MIBG BY POLAR MAP IN PATIENTS WITH DILATED CARDIOMYOPATHY

To evaluate sympathetic dysfunction of the heart, one of the factors r esponsible for heart failure in patients with dilated cardiomyopathy ( DCM), we performed I-123-metaiodobenzylguanidine (I-123-MIBG) myocardi al single photon emission tomography (SPET) in 22 cases of DCM. There were significant relationships between severity scores and defect scor es for the early and delayed images. When the data acquired by I-123-M IBG myocardial SPET were compared with left ventricular function, the extent score (r = -0.754, P < 0.01) and severity score (r = -0.693, P < 0.01) for the early images were both significantly correlated with l eft ventricular ejection fraction (LVEF). For the delayed images also, a good correlation was obtained between LVEF and extent score (r = -0 .704, P < 0.01) and between LVEF and severity score (r = -0.801, P < 0 .01). The washout rate for the entire left ventricle, calculated from the early and delayed images, also correlated with LVEF (r = -0.643, P < 0.01). Since the I-123-MIBG defect on the early images was shown to be significantly related to left ventricular function, a decrease in neuronal uptake at sympathetic nerve endings appears in the main to ac count for the I-123-MIBG defect on the early images. The regional wash out rate was increased compared to that in the control group (P < 0.01 ). It was particularly high in the inferior wall, suggesting that acce leration of turnover and poor retention in the area of the I-123-MIBG defect on the early images and then the entire left ventricle was stro ngly associated with the I-123-MIBG defect on the delayed images. Our results suggest that I-123-MIBG myocardial SPET may be useful in deter mining the severity of DCM.