Short cardiac iodine-123-metaiodobenzylguanidine imaging protocol in heart failure

Background For assessment of cardiac sympathetic nervous activity, the conventional protocol for iodine-123-metaiodobenzylguanidine ( ¹²³I-MIBG) imaging requires several hours. Methods and Results To establish whether it is possible to shorten the conventional ¹²³I-MIBG imaging protocol, anterior planar imaging was performed in 42 heart failure (HF) patients at 5, 15 and 180min. The washout rate of ¹²³I-MIBG from 5 to 15 min(WR5-15min) was calculated as a novel index. WR5-15min closely correlated with the conventional washout rate and inversely correlated with the heart to mediastinum ratio. Univariate Cox analysis revealed that rapid WR5-15min, augmented plasma B-type natriuretic peptide level, and decreased left ventricular ejection fraction (LVEF) were predictors for cardiac events. Multivariate analysis showed WR5-15min and LVEF were independent predictors. The cardiac event rate was markedly higher (73%) in patients when both WR5-15min and LVEF were abnormal. Conclusions WR5-15min obtained from anterior planar imaging is useful for evaluating the severity of HF and clinical outcome, and may shorten the cardiac ¹²³I-MIBG scintigraphy protocol. (Circ J 2008; 72: 1106-1111).