IODINE-123-LABELED FATTY-ACIDS FOR MYOCARDIAL SINGLE-PHOTON EMISSION TOMOGRAPHY - CURRENT STATUS AND FUTURE PERSPECTIVES

Renewed interest in the clinical use of iodine-123-labelled fatty acid s is currently primarily focused on the use of iodine-123-labelled 15- (p-iodophenyl)pentadecanoic acid (IPPA) and ''modified'' fatty acid an alogues such as 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIP P) which show delayed myocardial clearance, thus permitting single-pho ton emission tomographic imaging, Interest in the use of BMIPP and sim ilar agents results from the differences which have often been observe d in various types of heart disease between regional myocardial uptake patterns of [I-123]BMIPP and flow tracer distribution, Although the p hysiological basis is not completely understood, differences between r egional fatty acid and now tracer distribution may reflect alterations in important parameters of metabolism which can be useful for patient management or therapy planning. These tracers may also represent uniq ue metabolic probes for correlation of energy substrate metabolism wit h regional myocardial viability. The two agents currently most widely used clinically are I-123-labelled IPPA and BMIPP. While [I-123]IPPA i s commercially available as a radiopharmaceutical in Europe (Cygne) an d Canada (Nordion), multicenter trials are in progress in the United S tates as a prelude to approval for broad use. [I-123]BMIPP was recentl y introduced as Cardiodine for commercial distribution in Japan (Nihon Medi-Physics, Inc.), [I-123]BMIPP is also being used in clinical stud ies on an institutional approval basis at several institutions in Euro pe and the United States. In this review, the development of a variety of radioiodinated fatty acids is discussed, The results of clinical t rials with [I-123]IPPA and [I-123]BMIPP are discussed in detail, as ar e the future prospects for fatty acid imaging.