Simplified dual-time-point 99mTc-pyrophosphate scintigraphy in patients with suspected transthyretin amyloid cardiomyopathy: A single center series

Background

There is a lack of consensus regarding the optimal imaging time points and imaging techniques between planar and/or single-photon emission computed tomography (SPECT)/computed tomography (CT) acquisitions for technetium-99 m pyrophosphate (^99mTc-PYP) cardiac scintigraphy. The aim of this study was to investigate correlations between planar and SPECT/CT images and between 1-h and 3-h imaging time points.

Methods

We retrospectively analyzed consecutive patients with clinically suspected transthyretin amyloid cardiomyopathy who underwent ^99mTc-PYP scintigraphy from November 1, 2019 to November 30, 2022. Visual scores were compared between 1- and 3-h imaging time points and between planar and SPECT/CT acquisitions.

Results

A total of 100 patients (66% male; mean age, 65 years) were included, and 1- and 3-h planar and SPECT/CT images were obtained for 97 patients. There was a significant difference in visual grading scores between 1- and 3-h time points on both planar and SPECT/CT imaging, with a downgrade in score in 61 of 99 (61%) cases on planar imaging, and in 14 of 97 (14%) cases on SPECT/CT imaging (p < 0.001). There were significant differences in visual grading scores between planar and SPECT/CT imaging at both time points, with cases being scored higher on planar imaging than on SPECT/CT imaging (81/97 cases for 1-h imaging, and 50/97 cases for 3-h imaging) (p < 0.001).

Conclusion

Simplified 1-h SPECT/CT imaging with visual score and selective use of 3-h SPECT/CT imaging may be an efficient protocol and may reduce the potential for over-scoring and equivocal interpretation. Further validation in larger and more diverse populations is needed.