Feasibility of posterior 180° acquisition of bone SPEGT imaging with attenuation correction, scatter correction and resolution recovery

This study aimed to demonstrate the feasibility and usefulness of 180° acquisition of bone SPEGT/CT imaging using iterative reconstruction with several corrections to shorten the acquisition time. We used a dual-head SPECT/CT camera equipped with a low-energy high-resolution collimator and a thoracic spine phantom (SIM2 bone phantom). All SPEGT imaging was performed using 360° and 180° acquisitions with circular and non-circular orbits. The phantom image was reconstructed using the ordered-subset expectation-maximization algorithm with CT-based attenuation correction, scatter correction, and resolution recovery. Percent coefficient of variation (%CV) of the background section, percent contrast, and percentage of detectability equivalence volume (%DEV) of the tumor sections were evaluated using the automatic quantification package 'Hone Graph' for bone SPECT. %CV was higher for 180° acquisition compared with 360° acquisition regardless of automatic contouring. However, there was no significant difference in percent contrast between 180° and 360° acquisitions. %DEV for small spheres (ϕ22 mm, ϕ28 mm) was superior with 180° acquisition (91.5%, 95.4%) compared with 360° acquisition (60.5%, 86.6%). Although 180° acquisition showed inferior uniformity, it was shown to be applicable to bone SPEGT/CT from the perspective of detectability of small lesions, demonstrating its usefulness for shortening acquisition time. (author)