Does the choice of radiopharmaceutical affect the rate of incidental diagnosis of cardiac amyloidosis by bone scintigraphy?

BackgroundCardiac radiopharmaceutical uptake during bone scintigraphy is a specific finding of cardiac amyloidosis, particularly transthyretin amyloid. There is little evidence to guide the optimum choice of technetium labelled radiopharmaceutical in protocols to detect cardiac amyloid. In our practice, different radiopharmaceuticals were used based on external factors such as availability and pricing. We wished to use this natural experiment to examine the rate of incidental cardiac uptake in clinically indicated bone scintigraphy. MethodsBone scintigraphy for non-cardiac indications was examined over a three-year period. Radiopharmaceutical and demographic data were recorded, and scans were evaluated retrospectively using the Perugini scale. ResultsOne thousand four hundred seventy-three scans were examined, and of these, the radiopharmaceutical used was: 209 DPD, 175 HDP, 51 HMDP, and 1038 MDP. There were no significant differences between radiopharmaceutical groups regarding patient demographics or indications for imaging. The rate of radiopharmaceutical cardiac uptake (Perugini grade >1) was 2.4% for DPD, 0% HDP, 0% HMDP, and 0.3% MDP (Fisher exact test p=0.011). ConclusionsDPD may confer higher sensitivity than other radiopharmaceuticals to diagnose cardiac amyloid. These results encourage a direct comparison of radiopharmaceuticals to detect cardiac amyloid.