The synthesis and evaluation of radioiodinated 14-(iodophenyl)-3-(R,S)methyltetradecanoic acid. 
Radiohalogenated fatty acids (FA) labelled with gamma-emitting isotopes have a potentially important application in studies of impaired myocardial perfusion and metabolism.  Evaluation of straight-chain fatty acids radiolabelled in different positions on the FA chain has been reported by many groups.  In this paper we extended our recent studies using the betamethyl branched-chain fatty acid.  The synthesis, labelling and preliminary evaluation of 131I- and 123I-14-(iodophenyl)-3-(R,S)methyltetradecanoic acid (I-PBMTA) are reported.  This radiolabel concentrates in the mouse myocardium with 16% injected dose g-1 and 11% injected dose g-1 at 15 and 30 min, respectively.  The images of the canine heart postinjection indicate a high myocardial extraction of the label with activity retained over an hour.  The rate of washout of the activity from the heart was very low.  This analogue is a potential agent for myocardial imaging studies.