The Status of Stress Myocardial Perfusion Imaging Using 99mTc Pharmaceuticals in Japan: Results from a Nationwide Survey

OBJECTIVE(S): To appropriately use one-day myocardial perfusion imaging (MPI) with( 99m)Tc radiopharmaceuticals (i.e. to avoid shine-through artifacts), injection doses need to be optimized and dose ratios between the 1(st) and 2(nd) scans should be maintained at ≥ 3. However, the current state of practice in Japan is unclear. Thus, the aim of this study was to clarify the details of MPI protocols using (99m)Tc radiopharmaceuticals in Japan. METHODS: A nationwide survey was conducted in June and July 2016. Questionnaires about stress MPI protocols using (99)(m)Tc radiopharmaceuticals were sent to 641 nuclear medicine facilities. RESULTS: Responses were received from 246 facilities. One-day protocols were used in 97.1% of the facilities. The most common injection dose ratio was 2.5. Only 18.2% of facilities achieved the recommended injection dose ratio. Stress-only protocols were performed in only 1.7% of facilities; the primary reasons for not performing stress-only protocols were as follows: 1) “The reading-physician cannot interpret the image just after the first scan,” and 2) “Preparation of radiopharmaceuticals and scan arrangements turn out to be complicated.” CONCLUSION: Approximately 80% of nuclear medicine facilities do not follow the recommended injection dose ratio. Stress-only protocols are ideal, but are performed at very few facilities. Both optimization and standardization of stress MPI protocols using (99m)Tc radiopharmaceuticals are needed in Japan.