Quantitation vs visual assessment of 99mTc-DPD cardiac uptake in patients with suspected cardiac amyloidosis

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Universitary Clinic Hospital of Valencia Aim Cardiac uptake of 99mTc-DPD has proved its diagnostic efficacy in transthyretin cardiac amyloidosis(ATTR). We compared the usual visual assessment with two quantitative methods to evaluate cardiac activity and its possible relation with clinical follow-up. Methods We have studied 37 successive patients(p):32 men, 52-90 y/o (79.6 ± 9.3), submitted by suspected cardiac amyloidosis TTR by echo/cardiac MRI. After IV administration of 21.5 ± 3.4mCi of 99mTc-DPD, we obtained early (at 5min) and late (at 3h) whole body(WB) planar images and late SPECT. We assessed cardiac uptake in planar images by visual score (0-absent, 1-cardiac uptake lower than bone uptake, 2-equal, 3- higher than bone uptake), considering 2-3 score compatible with ATTR in absence of abnormal light chains on serum-urine. We obtained quantitative evaluation by heart/contralateral thoracic activity ratio (H/CL) in late images and from early and late WB images the heart retention(HR) ratio and heart/whole body(HWB) activity ratio. Clinical follow-up (12.4 ± 8.3 months) considering as cardiac events(CE): cardiac death and heart failure(HF) admissions. Results Visual score 0(11p), 1(2p), 2(4p) and 3(20p), considering group1(0-1) not suggestive of ATTR and group2(2-3) compatible with ATTR. SPECT showed biventricular uptake with septal predominance in group2. H/CL index was 2.23 ± 0.54(group2) vs 1.05 ± 0.10(group1) p