Test-retest reproducibility of myocardial 99mTc-HMDP uptake quantification using SPECT-CT CZT camera in patients with suspected transthyretin-related cardiac amyloidosis

Overview & Synopsis

The aim of this study was to assess the test-retest, intra- and interobserver reproducibility of bone scintigraphy for absolute quantification of cardiac amyloid burden in a population with suspected ATTR cardiac amyloidosis, using a whole-body CZT SPECT-CT camera. 20 patients prospectively included underwent both planar bone scintigraphy and thoracic SPECT CT using CZT camera, repeated twice at oneweek interval. Different metrics were studied (SUVmax, SUVmean, %ID and CAA) within cardiac ventricles volumes of interest manually contoured thanks to CT images. The results demonstrated a high reproducibility of all metrics regarding intra-, interobserver and test-retest. All quantitative parameters were correlated to Perugini score. Furthermore, supplementary test-retest analyses were made using the mean absolute difference (with significant difference only for contoured volume), the COV (in the expected limits for all metrics) and the ICC (good or excellent for all metrics). This study is promising and could help to assess therapeutic response in future studies.