SPECT/CT Quantification of 99m-TC PYP Uptake to Assess Tafamidis Treatment Response in ATTR Cardiac Amyloidosis.

BACKGROUND

Cardiac imaging with bone-avid tracers for the diagnosis of ATTR cardiac amyloidosis employs only limited quantification, but SPECT/CT acquisition can provide volumetric assessment with quantification of tracer uptake. Tafamidis is routinely used in the treatment of cardiac amyloidosis but there is scant data on changes in imaging results during therapy. The purpose of this study was to perform longitudinal assessment of Tc-99m-PYP imaging to determine if tafamidis therapy results in any change in quantitative measures of tracer uptake.

METHODS

A prospective, single-center study of ATTR patients being treated with tafamidis using Tc-99m-PYP SPECT/CT to quantify cardiac tracer uptake in the whole heart and left ventricle. Standardized uptake values (SUVs) were adjusted for blood pool activity. Comparison of baseline activity was made to values obtained approximately every 6 months during treatment.

RESULTS

Twenty-two patients (77.0 ± 7.5 years old, 86.4% male) were on tafamidis for 15.3 ± 4.0 months with an average time between baseline and final follow-up study of 16.8 ± 4.7 months. Thirteen (59.1%) had multiple follow-up amyloid studies. Statistically significant reductions in total SUVs, SUV volume, and percentage of injected dose were seen. Adjusted for the maximal aortic SUV, the total SUV's in the left ventricle decreased by 36.9%, the SUV volume by 38.7%, and the percentage of injected dose decreased by 34.9% (all p-values ≤0.0001). Over the study duration there was a decrease of 7.7%/month in the measured metrics.

CONCLUSION

The quantitative SUV measurements from Tc-99m-PYP SPECT/CT revealed an overall decrease in scintographic amyloid burden during the course of tafamidis therapy, but additional work is needed to determine the optimal metrics and improve the reproducibility of the quantification.

Informations de copyright

Copyright © 2024 American Society of Nuclear Cardiology. Published by Elsevier Inc. All rights reserved.

Déclaration de conflit d'intérêts

Declaration of Competing Interest ☒ The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: W Lane Duvall reports administrative support was provided by GE Healthcare. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.