Attenuation correction of multiplexed multi-pinhole microSPECT reconstruction

The purpose of this study was to investigate the effect of including attenuation correction in the reconstruction of in vivo rat cardiac SPECT data. CT and SPECT scans of five rats were acquired with a NanoSPECT/CT system (Bioscan, Washington, DC). The CT data were used to estimate the ^99mTc photon attenuation, and the attenuation was modeled in the OS-EM reconstruction loop. For the five rats included in this study, photon attenuation reduced the measured activity in the myocardium by 30±2%. Comparison of the corrected and uncorrected reconstructions showed a mild increase in the measured relative myocardial perfusion in three connected segments in the septal-anterior wall, and a small decrease in three connected segments in the lateral-inferior wall. The overall uniformity of the perfusion, measured as the standard deviation of the relative segment perfusion was not significantly changed (9.1% vs. 8.9%).