Myocardial Perfusion Imaging with a Solid State Camera: Simulation of a Very Low Dose Imaging Protocol

摘要

High sensitivity dedicated cardiac systems cameras provide an opportunity to lower injected doses for SPECT myocardial perfusion imaging (MPI), but the exact limits for lowering doses have not been determined. List mode data acquisition allows for reconstruction of various fractions of acquired counts, allowing a simulation of gradually lower administered dose. We aimed to determine the feasibility of very low dose MPI by exploring the minimal count level in the myocardium for accurate MPI.MethodsSeventy nine patients were studied (mean body mass index 30.0 ± 6.6, range 20.2–54.0 kg/m²) who underwent 1-day standard dose ^99mTc-sestamibi exercise or adenosine rest/stress MPI for clinical indications employing a Cadmium Zinc Telluride dedicated cardiac camera. Imaging time was 14-min with 803 ± 200 MBq (21.7 ± 5.4mCi) of ^99mTc injected at stress. To simulate clinical scans with lower dose at that imaging time, we reframed the list-mode raw data to have count fractions of the original scan. Accordingly, 6 stress equivalent datasets were reconstructed corresponding to each fraction of the original scan. Automated QPS/QGS software was used to quantify total perfusion deficit (TPD) and ejection fraction (EF) for all 553 datasets. Minimal acceptable count was determined based on previous report with repeatability of same-day same-injection Anger camera studies. Pearson correlation coefficients and SD of differences with TPD for all scans were calculated.