Discovery of Radioiodinated Monomeric Anthraquinones as a Novel Class of Necrosis Avid Agents for Early Imaging of Necrotic Myocardium
Assessment of myocardial viability is deemed necessary to aid in clinical decision making whether to recommend revascularization therapy for patients with myocardial infarction (MI) Dianthraquinones such as hypericin (Hyp) selectively accumulate in necrotic myocardium, but were unsuitable for early imaging after administration to assess myocardial viability. Since dianthraquinones can be composed by coupling two molecules of monomeric anthraquinone and the active center can be found by splitting chemical structure, we propose that monomeric anthraquinones may be effective functional groups for necrosis targetability. In this study, eight radioiodinated monomeric anthraquinones were evaluated as novel necrosis avid agents (NAAs) for imaging of necrotic myocardium. All 131I anthraquinones showed high affinity to necrotic tissues and 131I rhein emerged as the most promising compound. Infarcts were visualized on SPECT/CT images at 6 h after injection of 131I rhein, which was earlier than that with 131I Hyp. Moreover, 131I rhein showed satisfactory heart to blood, heart to liver and heart to lung ratios for obtaining images of good diagnostic quality. 131I rhein was a more promising "hot spot imaging" tracer for earlier visualization of necrotic myocardium than 131I Hyp, which supported further development of radiopharmaceuticals based on rhein for SPECT/CT (123I and 99mTc) or PET/CT imaging (18F and 124I) of myocardial necrosis.
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