First Animal Scan on C-SPECT

C-SPECT is designed for dynamic cardiac SPECT of human patients [1] - [4]. It is stationary during acquisition, but its collimation is adaptive through adjustable slat stacks for axial collimation and a selection of slits for transverse collimation. In this study, we performed our first animal scans with quantitative comparison of activity concentration with ex-vivo tissue samples. A 54-kg male Yorkshire swine was sedated, intubated and ventilated mechanically during the procedure, with monitoring throughout. The animal was positioned in the scanner, which was set to high-resolution mode. 21 mCi of ^99m Tc-labeled sestamibi was injected intravenously just after the start of a 300-s acquisition. Five additional static scans were performed with a change of axial FOV for the last. The heart was excised, sectioned according to the 17-segment AHA model, weighed, and assayed to determine true activity concentration. The emission data were reconstructed using an ML-EM algorithm with resolution modeling. The reconstructions were reoriented into traditional cardiac views and concentrations were compared to tissue values. A second 65-kg make Yorkshire pig was imaged using the same procedure with a 22 mCi injection of ^99m Tc-labeled sestamibi. For the first swine, the heart was partially truncated since the animal was positioned low relative to the FOV. Consequently, 10 of 17 segments were available for comparison. The second swine was positioned appropriately and good imaging quality was obtained. In conclusion, despite some positioning problems during the first scan, the overall success of that experiment suggested future experiments to test quantification of myocardial blood flow in comparison with microspheres were feasible. That second experiment with additional microsphere injection was conducted and resulted in good image quality.