To evaluate the clinical utility of 123I-labelled 15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid (123I-BMIPP), myocardial scintigraphy using 123I-BMIPP was performed in 13 patients with hypertrophic cardiomyopathy (HCM), and the findings were compared with those of 201Tl. The uptake of each tracer was scored visually from 4 (increased) to 0 (severely decreased) in a total of 13 segments in the apical and basal short axial images, and the long axial images of myocardial single photon emission tomography (SPET). In the comparison of the early images with 123I-BMIPP (taken 15 min after injection) and the 201Tl perfusion images, 70% of the segments showed uncoupled uptake, with the uptake of 123I-BMIPP more often being less. In the hypertrophic regions, 123I-BMIPP demonstrated significantly less uptake than 201Tl, especially in the delayed images (taken 3 h after injection). In the nonhypertrophic regions, there was no significant difference in uptake between the 123I-BMIPP early images and the 201Tl images; the 123I-BMIPP delayed images, however, demonstrated significantly less uptake than the 201Tl images. These results suggest that the uncoupling between the 123I-BMIPP and 201Tl uptakes and the washout (the relative decrease in activity from early to delayed images of 123I-BMIPP) reflect abnormal myocardial fatty acid metabolism in HCM.
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