Comparison of 1-h with 3-h planar 99m Tc-pyrophosphate scintigraphy in patients with suspected transthyretin cardiac amyloidosis using SPECT as a reference standard

• Published in: Annals of nuclear medicine 2023-02, Vol.37 (2), p.99
• Main Authors: Saitou, Toshinori, Aikawa, Tadao, Manabe, Osamu, Nagase, Atsushi, Kudo, Tamaki, Oyama-Manabe, Noriko
• Format: Article
• Language: English
• Subjects: Amyloidosis - diagnostic imaging; Cardiomyopathies - diagnostic imaging; Diphosphates; Humans; Kidney Diseases; Prealbumin; Radionuclide Imaging; Radiopharmaceuticals; Retrospective Studies; Technetium Tc 99m Pyrophosphate; Tomography, Emission-Computed, Single-Photon - methods
• ISSN: 1864-6433

The purpose of this study was to examine the diagnostic value of planar Tc-pyrophosphate (PYP) imaging at 1 and 3 h after tracer administration in patients with suspected transthyretin cardiac amyloidosis (ATTR-CA) using SPECT as a reference standard. We also tested whether blood pool activity of PYP is associated with renal dysfunction. PYP images of 109 consecutive patients with suspected ATTR-CA were retrospectively reviewed. The myocardial PYP uptake was visually graded on a scale of 0 to 3 and quantified with the heart-to-contralateral (H/CL) ratio in accordance with the current expert consensus recommendations. The diagnostic value of planar images for identifying positive PYP SPECT was assessed by a receiver-operating characteristic curve analysis with the area under the curve (AUC). The uptake ratios of the ascending and descending aorta, left atrium, and trapezius muscle divided by the liver uptake were measured on SPECT images and compared to the renal function. A total of 41 patients (38%) had myocardial PYP uptake on SPECT images. In comparison with the visual scores on 1-h anterior planar images, those on 3-h anterior planar images had lower sensitivity (80.5% vs. 97.6%) and higher specificity (86.8% vs. 55.9%) for identifying positive PYP SPECT. The ROC analysis showed that the combination of visual scores on both 1-h and 3-h anterior planar images had significantly higher AUC values in comparison with 1-h anterior planar images alone (0.90 [95% CI 0.83-0.94] vs. 0.83 [95% CI 0.75-0.88]; P  0.05 for all). In the assessment of ATTR-CA using PYP imaging, visual scores on 3-h anterior planar images for identifying positive PYP SPECT had lower sensitivity and higher specificity in comparison with those on 1-h anterior planar images. The diagnostic value of the visual scores on 1-h and 3-h anterior planar images was not improved by adding the H/CL ratio. Blood p