RT Journal Article SR Electronic T1 Quantitative evaluation of 99mTc-pyrophosphate SPECT/CT in the diagnosis of transthyretin amyloid cardiomyopathy JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1607 OP 1607 VO 61 IS supplement 1 A1 Satoru Watanabe A1 Hiroto Yoneyama A1 Kenichi Nakajima A1 Hiroshi Wakabayashi A1 Anri Inaki A1 Junji Komatsu A1 Shohei Yoshida A1 Takahiro Konishi A1 Seigo Kinuya YR 2020 UL http://jnm.snmjournals.org/content/61/supplement_1/1607.abstract AB 1607Objectives: Quantitative uptake evaluation of 99mTechnetium-pyrophosphate (PYP) has been proved robust for the diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM). However, conventional quantitative methods were based on two-dimensional planar imaging and had some inherent limitations. The aim of this study was to evaluate the feasibility of quantitative PYP SPECT/CT for differentiating ATTR-CM patients from non-ATTR-CM patients. Methods: We retrospectively evaluated all patients who underwent PYP SPECT/CT at our hospital between October 2018 and December 2019. Among them, only 21 patients underwent endomyocardial biopsies (15/21) and/or TTR gene tests (14/21) and were included in this study. Thirteen patients were diagnosed as ATTR-CM (9 variant types and 4 wild types) and 8 patients were diagnosed as non-ATTR-CM (control: 1 light chain cardiac amyloidosis, 1 cardiac sarcoidosis, and 6 other myocardial disorders). There was no significant difference in age between two groups. We evaluated myocardial PYP uptake using standardized uptake values (SUVmean and SUVmax) calculated with xSPECT Quant. In addition, we evaluated blood pool PYP uptake using SUVmean in the ascending aorta at the level of the main pulmonary artery. Myocardial SUVmean and SUVmax were normalized to the blood pool activity and defined as normalized SUVs (nSUVmean and nSUVmax, respectively). As a conventional method, we calculated a heat to contralateral lung ratio (H/CL) on planar imaging as the fraction of heart mean count to contralateral lung mean count. Accuracy of determining abnormal or normal uptake was examined using receiver operating characteristic analysis and the area under the curve (AUC) was calculated. Results: Myocardial SUVmean, myocardial SUVmax, and H/CL were significantly higher in patients with ATTR-CM than in control patients (p = <0.0001, 0.01, and 0.0003, respectively; AUC = 0.93, 0.81, and 0.89, respectively). Both nSUVmean and nSUVmax were also significantly higher in patients with ATTR-CM than in control patients (p = <0.0001 and 0.0007, respectively; AUC = 0.97 and 0.89, respectively). Among these uptake parameters, nSUVmean achieved the highest AUC for discriminating ATTR-CM from control. Using the cutoff value of 0.91 for diagnosing ATTR-CM, nSUVmean showed sensitivity and specificity of 92% and 100%, respectively. Using the cutoff value of 1.4 for diagnosing ATTR-CM, H/CL showed sensitivity and specificity of 85% and 100%, respectively. Myocardial SUVmean strongly correlated with myocardial SUVmax (r = 0.83, p <0.0001) and H/CL (r = 0.77, p <00001). There were no significant differences in myocardial SUVmean, myocardial SUVmax, and H/CL between patients with variant type ATTR-CM (n = 9) and patients with wild type ATTR-CM (n = 4). Conclusions: A novel three-dimensional quantitative assessment of PYP SPECT/CT could accurately differentiate ATTR-CM patients from non-ATTR-CM patients, which should be studied in a larger prospective manner.