Myocardial Imaging in Man with I-123 Meta-Iodobenzylguanidine

Meta-[123I]iodobenzylguanidine (m-[123I]IBG), a guanethidine analog, was used to image the myocardium in five normal male volunteers. Each subject received 2.0 mCi m-[123I]IBG intravenously. Four were given a bolus injection. Multiple myocardial scintigrams were obtained over a 2-hr period. Myocardial uptake was calculated by dividing the decay-corrected global myocardial count rate (after interpolated background correction) by the peak count rate during the first passage of the m-[123I]IBG bolus through the heart. The left ventricle could be visualized within 1-2 min of m-[123I]IBG injection. Mean myocardial uptake was 0.63% (range 0.45-0.78%) of injected dose at 5 min, and 0.76% (range 0.49-0.93%) at 2 hr (n = 4). m-[123I]IBG may provide quantitative information on myocardial catecholamine content.