Dual-tracer autoradiography with thallium-201 and iodine-125 MIBG in BIO 14.6 cardiomyopathic Syrian hamsters.

Dual-tracer imaging of the heart with 125I-metaiodobenzylguanicline (MIBG) and 201Tl can simultaneously demonstrate the distribution of sympathetic nerve endings and the underlying myocardial perfusion. A quantitative dual-tracer autoradiographic study with 201Tl and 125I-MIBG was performed to investigate changes in the distribution of cardiac sympathetic innervation with the progression of cardiomyopathy in BIO 14.6 hamsters. The distribution of 201Tl was uniform in control hamsters and BIO 14.6 hamsters at all stages of cardiomyopathy. In contrast, a reduction in MIBG accumulation occurred in the endocardial region of the left ventricular free wall and the left ventricular aspect of the interventricular septum in BIO 14.6 hamsters at 3 and 8 months of age. Thus, there was an uncoupling of the left ventricular distribution of 201Tl and 125I-MIBG in BIO 14.6 hamsters. In addition, interstitial fibrosis was increased in the interventricular septum, the subendocardial region of the left ventricular free wall, and the right ventricular wall, which were the sites of reduced MIBG accumulation. This study shows that dual myocardial imaging with MIBG and 201Tl may be useful for investigating patients with cardiomyopathy.