Monitoring of therapeutic effect in heart failure patients: a clinical application of 123I MIBG imaging?

Labelling of metaiodobenzylguanidine (MIBG) with ¹²³I allowsscintigraphic visualization of the cardiac sympathetic nervoussystem and ¹²³I MIBG was the first radiopharmaceutical thatallowed imaging of cardiac neurotransmission by single photonemission computed tomography. Norepinephrine (NE) is the majorneurotransmitter of the sympathetic nervous system. ¹²³I MIBG,an analogue of NE, and NE have similar molecular structures,and use the same uptake and storage mechanisms in the pre-synapticsympathetic nerve ending. Uptake-1 is the most important uptakemechanism of MIBG in human, and is sodium- and energy-dependent.Other uptake mechanisms are the non-neuronal uptake-2 mechanism,which is sodium- and energy-independent, and diffusion. The cardiac sympathetic nervous system is mainly involved inpreserving circulatory homeostasis during environmental stress.Increase of sympathetic nervous activity or a rise in