Other radionuclides include iodine-123 (I-123) - labeled fatty acids, which produces cold spots where myocardium is ischemic; gallium citrate-67 (Ga-67), which accumulates in sites of active inflammation (eg, in acute inflammatory cardiomyopathy); and I-123 metaiodobenzylguanidine, a neurotransmitter analog taken up and stored in neurons of the sympathetic nervous system and used in research to evaluate heart failure, diabetes, pheochromocytoma, certain arrhythmias, and arrhythmogenic right ventricular dysplasia.