Visual Differentiation Between Triglyceride Deposit Cardiomyovasculopathy and Old Myocardial Infarction Using Count-Washout Rate Polar Map in Iodine-123-β-Methyl-p-Iodophenyl-Pentadecanoic Acid Scintigraphy.

Background: In nuclear cardiology, tracer uptake and washout rate (WR) are key parameters for evaluating cardiac pathophysiology. However, WR is influenced by counts in the early image, making it difficult to evaluate pathophysiology based on WR value alone. To differentiate cardiovascular diseases involving count and WR variations, such as triglyceride deposit cardiomyovasculopathy (TGCV) and old myocardial infarction (OMI), we proposed a method to simultaneously evaluate both. Methods: We newly developed the Count-Washout Rate Polar Map (CWRM), a graphical representation of the count and WR values in a polar coordinate system. CWRM consists of two axes: count in the early image and WR. Given the variety of diseases characterized by count and WR, Iodine-123-β-methyl-p-iodophenyl-pentadecanoic acid was selected as the radiotracer. We examined patients without cardiovascular disease (normal) and patients with TGCV, OMI, and TGCV with OMI. CWRMs for each disease were visually evaluated. Results: In the normal case, sufficient counts were observed in the early image, and WR did not decrease; CWRM showed light blue. In TGCV, sufficient counts were observed in the early image, but WR markedly decreased; CWRM showed orange evenly. In non-TGCV with OMI, regions with decreased and preserved counts coexisted; CWRM showed light blue in the normal region and black in the OMI region. In TGCV with OMI, CWRM showed orange in the TGCV myocardium and black in the OMI region. Conclusion: CWRM is useful for at-a-glance differentiation of patients with TGCV, OMI, and TGCV with OMI, thereby showing potential as a new diagnostic indicator.