Clinical utilities of single-photon biochemical tracers in estimating pathophysiologic processes in heart failure: 123I-BMIPP and 123I-MIBG

Abstract

Information about myocardial perfusion and function has limitations in the assessment of disease severity and prognosis in patients with heart failure. Information about myocardial biochemistry may actually be more important in patient management. In vivo assessment of myocardial biochemistry, which started from the use of positron emission tomography, is now becoming a reality with the use of single-photon emission tomography (SPET). 123I-BMIPP as a fatty acid tracer and 123I-MIBG as a norepinephrine (NE) tracer are already used for clinical assessment here in Japan. In this chapter, based on our experiences, we introduce the utilities of these two tracers in assessing disease severity, the effects of medical treatment and prognosis in patients with heart failure. In 123I-BMIPP imaging, we could not characterize metabolic abnormalities specific for idiopathic dilated cardiomyopathy, but we identified utility in differentiating ischemic from idiopathic dilated cardiomyopathy based on a high prevalence of regional myocardial 123I-BMIPP defects in ischemic cardiomyopathy. In 123I-MIBG imaging, we recognized the utility of the washout rate (WR) of 123I-MIBG from the heart as an index of sympathetic activation. It showed good correlations with the plasma NE concentration and the left ventricular ejection fraction. In addition, we recognized important utilities of WR in evaluating the effectiveness of β-blocker treatment and prognosis in patients with idiopathic dilated cardiomyopathy.