Dual tracer autoradiographic study with thallium-201 and radioiodinated fatty acid in cardiomyopathic hamsters.

To investigate the usefulness of myocardial scintigraphy with radioiodinated 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) in cardiomyopathy, quantitative dual tracer autoradiographic study with 201Tl and [125I]BMIPP was performed in 27 cardiomyopathic Bio 14.6 Syrian hamsters and eight normal hamsters. Furthermore, 16 Bio 14.6 Syrian hamsters aged 21 days were divided into verapamil-treated (during 70 days) and control groups (respectively, n = 8), and autoradiography with 201Tl and [125I]BMIPP was performed. Quantitative autoradiography demonstrated an uncoupling of 201Tl and [125I]BMIPP distributions and a regional heterogeneity of [125I]BMIPP distribution in cardiomyopathic hamsters aged more than 2 mo, while normal hamsters showed only mild heterogeneity of [125I]BMIPP distribution without an uncoupling of tracers. Age-matched comparison between normal and cardiomyopathic hamsters (5-8 mo old) demonstrated that a difference between their [125I]BMIPP distributions are more marked than that between their 201Tl distributions. Furthermore, [125I]BMIPP visualized effects of verapamil on cardiomyopathy more distinctly than did 201Tl. In conclusion, myocardial imaging with [123I]BMIPP could be useful for investigating cardiomyopathy and evaluating the efficacy of therapeutic intervention in patients with cardiomyopathy.