tc-99m-pyrophosphate scintigraphy for the diagnosis of attr cardiac amyloidosis: comparison of quantitative and semi-quantitative approaches

Attr cardiac amyloidosis (ca) can be diagnosed with tc-99m-pyp scintigraphy. there are two recommended interpretative approaches: the quantitative heart-to-contralateral lung ratio (h/cl) at 1 hour and the semi-quantitative visual system at 3 hours. this study’s aim was to compare both approaches and to apply the semi-quantitative method at 1 hour. tc-99m-pyp scans of 122 consecutive subjects were reviewed using both approaches. on 1 hour planar images, regions of interest were drawn over the heart and contralateral chest to determine h/cl. myocardial uptake was graded on 1 and 3 hour spect images according to the semi-quantitative method. concordance was examined using kappa statistics. 31, 10, and 81 studies were positive, negative, and equivocal, respectively, for attr-ca using the h/cl approach. using the grading system, 35, 77, and 10 scans were positive, negative, and equivocal, respectively. the quantitative approach led to a significantly higher proportion of equivocal studies compared to the semi-quantitative approach (p < .0001). these approaches yielded discordant results in 2 subjects; biopsy results were concordant with spect grade. 1 and 3 hour spect grades provided concordant result in 99% of cases. the h/cl approach resulted in a high proportion of equivocal studies. using spect imaging, the semi-quantitative approach minimized this proportion and showed high concordance at 1 and 3 hours.