Effect of a patient-specific minimum activity in stress myocardial perfusion imaging using CZT-SPECT: Prognostic value, radiation dose, and scan outcome

Spect myocardial perfusion imaging (mpi) is associated with a relatively high radiation burden and decreasing image quality in heavy patients. patient-specific low-activity protocols (plaps) are suggested but follow-up data is lacking. our aim was to compare the use of a standard fixed-activity protocol (fap) with a plap in cadmium zinc telluride (czt)-spect mpi. we retrospectively included 1255 consecutive patients who underwent czt-spect stress-optional rest mpi. 668 patients were scanned using fap (370 mbq) and 587 patients using plap (2.25 mbq·kg−1). percentage of scans interpreted as normal, radiation dose, and 1-year follow-up including hard event rates (all-cause death or non-fatal myocardial infarction) were collected and compared. the percentage of scans interpreted as normal was 67% in fap and 70% in plap groups (p = .29). the annualized hard event rates in these patients were 1.0% in the fap and 0.9% in the plap group (p = .86). however, the mean radiation dose decreased by 23% for stress-only and by 15% to 2.6 msv for stress-optional rest mpi after introduction of the plap (p<0.001). introduction of a patient-specific low-activity protocol does not affect the percentage of scans interpreted as normal or prognosis but significantly lowers the radiation dose for czt-spect mpi.