Single center analysis of cardiac amyloidosis using 99mTc-HMDP imaging for diagnosis and evaluation after tafamidis treatment

Abstract Background The aims of this study were to evaluate the diagnostic performance of 99mTc-HMDP imaging for cardiac amyloidosis and to demonstrate changes in cardiac uptake of 99mTc-HMDP after tafamidis treatment. Seventy-five patients with suspected for cardiac amyloidosis who underwent 99mTc-HMDP imaging were included. We compared clinical data between visually positive and negative groups. We also compared visual Perugini grades and semi-quantitative H/CL (heart-to-contralateral area) ratios and myocardial SUVmax (maximum standardized uptake value) between cardiac transthyretin amyloidosis (ATTR) and amyloid light-chain amyloidosis (AL). Furthermore, H/CL ratio of 99mTc-HMDP and myocardial SUVmax were compared before and after tafamidis administration for cardiac wild-type ATTR. Results Among 75 patients, 20 patients (26.7%) were visually positive based on Perugini grade. Fifteen patients and 3 patients were pathologically identified as cardiac ATTR and AL, respectively. ATTR group (n =15) had significantly higher H/CL ratios of 99mTc-HMDP than AL group (n = 3) (P = 0.003). ATTR group (n =15) had significantly higher myocardial SUVmax of 99mTc-HMDP than AL group (n = 2) (P = 0.015). After tafamidis treatment for cardiac wild-type ATTR, three of the eight patients (37.5%) had more than 15% decrease in H/CL ratios and five of the eight patients (62.5%) had more than 15% decrease in myocardial SUVmax. Conclusions H/CL ratio on planar images and SUVmax on SPECT images in 99mTc-HMDP imaging are useful for diagnosing cardiac ATTR. Myocardial SUVmax might be useful for monitoring changes in cardiac uptake after tafamidis treatment for cardiac ATTR.