Assessment of cardiac amyloidosis with 99mTc-pyrophosphate (PYP) quantitative SPECT

Chao Ren; Jingyun Ren; Zhuang Tian; Yanrong Du; Zhixin Hao; Zongyao Zhang; Wei Fang; Fang Li; Shuyang Zhang; Bailing Hsu; Li Huo

doi:10.1186/s40658-020-00342-7

Assessment of cardiac amyloidosis with ^99mTc-pyrophosphate (PYP) quantitative SPECT

EJNMMI Phys. 2021 Jan 7;8(1):3. doi: 10.1186/s40658-020-00342-7.

Authors

Chao Ren¹, Jingyun Ren¹, Zhuang Tian², Yanrong Du¹, Zhixin Hao¹, Zongyao Zhang³, Wei Fang³, Fang Li¹, Shuyang Zhang², Bailing Hsu⁴, Li Huo⁵

Affiliations

¹ Department of Nuclear Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing Key Laboratory of Molecular Targeted Diagnosis and Therapy in Nuclear Medicine, Shuaifuyuan, Dongcheng District, Beijing, 100730, People's Republic of China.
² Department of Cardiology, Peking Union Medical College Hospital, Shuaifuyuan, Dongcheng District, Beijing, People's Republic of China.
³ Department of Nuclear Medicine, Fuwai Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing, People's Republic of China.
⁴ Nuclear Science and Engineering Institute, University of Missouri-Columbia, E2433 Lafferre Hall, Columbia, MO, 65211, USA. bailinghsu@gmail.com.
⁵ Department of Nuclear Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, Beijing Key Laboratory of Molecular Targeted Diagnosis and Therapy in Nuclear Medicine, Shuaifuyuan, Dongcheng District, Beijing, 100730, People's Republic of China. huoli@pumch.cn.

Abstract

Background: ^99mTc-PYP scintigraphy provides differential diagnosis of ATTR cardiomyopathy (ATTR-CM) from light chain cardiac amyloidosis and other myocardial disorders without biopsy. This study was aimed to assess the diagnostic feasibility and the operator reproducibility of ^99mTc-PYP quantitative SPECT.

Method: Thirty-seven consecutive patients who underwent a ^99mTc-PYP thorax planar scan followed by SPECT and CT scans to diagnose suspected ATTR-CM were enrolled. For the quantitative SPECT, phantom studies were initially performed to determine the image conversion factor (ICF) and partial volume correction (PVC) factor to recover ^99mTc-PYP activity concentration in the myocardium for calculating the standardized uptake value (SUV) (unit: g/ml). SUV_max was compared among groups of ATTR-CM, AL cardiac amyloidosis, and other pathogens (others) and among categories of Perugini visual scores (grades 0-3). The intra- and inter-operator reproducibility of quantitative SPECT was verified, and the corresponded repeatability coefficient (RPC) was calculated.

Results: The ICF was 79,327 Bq/ml to convert count rate in pixel to ^99mTc activity concentration. PVC factor as a function of the measured activity concentration ratio in the myocardium and blood-pool was [y = 1.424 × (1 - exp(- 0.759 × x)) + 0.104]. SUV_max of ATTR-CM (7.50 ± 2.68) was significantly higher than those of AL (1.96 ± 0.35) and others (2.00 ± 0.74) (all p < 0.05). SUV_max of grade 3 (8.95 ± 1.89) and grade 2 (4.71 ± 0.23) were also significantly higher than those of grade 1 (1.92 ± 0.31) and grade 0 (1.59 ± 0.39) (all p < 0.05). Correlation coefficient (R²) of SUV_max reached 0.966 to 0.978 with only small systematic difference (intra = - 0.14; inter = - 0.23) between two repeated measurements. Intra- and inter-operator RPCs were 0.688 and 0.877.

Conclusions: ^99mTc-PYP quantitative SPECT integrated with adjustable PVC factors is feasible to quantitatively and objectively assess the burden of cardiac amyloidosis for diagnosis of ATTR-CM.

Keywords: 99mTc-PYP quantitative SPECT; ATTR cardiomyopathy; Diagnostic feasibility; Standardized uptake value; The operator reproducibility.