Attenuation and scatter correction in brain SPECT with Tc-99m labeled receptor-specific radiopharmaceuticals

The main aim of this study was to evaluate the effects of attenuation correction (AC), scatter correction (SC) and collimator resolution on neuroreceptor and neurotransporter imaging using Tc-99m labeled compounds. Accurate measurement of the ratios of target-to-background counts is key for the evaluation of several neuropsychiatric diseases with neuroimaging. For simultaneous emission-transmission scans, a triple-head camera system with a Gd-153 line source was used with low energy high resolution fan beam (LEHR-FB) or ultra-high resolution FB (LEUHR-FB) collimators. Striatal phantom data were acquired with 4, 8 and 12 times the concentration of the background Tc-99m activity and were processed using no correction, uniform AC with a single iteration Chang (UAC), non-uniform AC, and AC+SC. After post-filtering the data, basal ganglia-to-background (BG/B) ratios were calculated using an region-of-interest (ROI) punch biopsy method. In general, the LEUHR-FB collimator produced higher BG/B ratios than the LEHR-FB collimator. Overall, the AC+SC method yielded the most accurate ratios, although the differences in the four processing methods were relatively small.