Inter-observer reproducibility and intra-observer repeatability in 99mTc-pyrophosphate scan interpretation for diagnosis of transthyretin cardiac amyloidosis

Vasvi Singh, Sarah Cuddy, Marie F. Kijewski, Mi Ae Park, Alexandra Taylor, Viviany R. Taqueti, Hicham Skali, Ron Blankstein, Rodney H. Falk, Marcelo F. Di Carli, Sharmila Dorbala

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Aim: The purpose of this study was to determine the inter- and intra-observer variability in 99mtechnetium-pyrophosphate (99mTc-PYP) scan interpretation for diagnosis of transthyretin cardiac amyloidosis (ATTR). Methods and Results: Our study cohort comprised 100 consecutive subjects referred for 99mTc-PYP imaging based on clinical suspicion of ATTR cardiac amyloidosis. Myocardial 99mTc-PYP uptake was assessed by both visual (comparison of myocardial to rib uptake) and semi-quantitative (heart-to-contralateral lung uptake ratio, H:CL) methods. Twenty scans were analyzed twice, at least 48 hours apart, by each of two independent observers. Patients with visual scores of ≥ 2 on planar imaging as well as myocardial uptake on SPECT/CT were classified as ATTR positive. Diagnosis of ATTR by visual 99mTc-PYP grade was perfectly reproducible [concordance: positive and negative scans 100% (53/53 and 47/47, respectively). Both inter- and intra-observer correlations for H:CL ratio (r2 = 0.90, 0.99 (Observer 1) and 0.98 (Observer 2), respectively) and repeatability values on Bland–Altman plots were excellent. The coefficient of variation (%) for Observers 1 and 2 was 3.21 (2.14 to 4.29) and 7.49 (4.95 to 10.09), respectively. In addition, there was 100% concordance in positive and negative scan interpretation by visual grading between novice CV imagers (< 3 years’ experience) and an experienced CV imager (10 years’ experience). Conclusions: This study showed excellent inter-observer reproducibility and intra-observer repeatability of 99mTc-PYP visual scan interpretation and H:CL ratio for diagnosis of cardiac ATTR amyloidosis. Cardiac ATTR amyloidosis can be diagnosed reliably using 99mTc-PYP SPECT/CT by novice and experienced CV imagers.

Original languageEnglish (US)
JournalJournal of Nuclear Cardiology
StateAccepted/In press - 2020
Externally publishedYes


  • Amyloid heart disease
  • molecular imaging

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Cardiology and Cardiovascular Medicine


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