Figure 10.

Combined micro-SPECT and micro-CT, demonstrating bone imaging in a mouse model. Micro-CT data (A,C) was acquired over 220° during continuous gantry rotation, with acquisition parameters of 70 kVp and 88 mAs during a total CT acquisition interval of 130 s. The CT image was reconstructed using a modified Feldkamp cone beam algorithm with short-scan weighting, producing a volume image with 100 μm voxel spacing. Micro-SPECT data (B,C) was obtained in the same imaging session, using a multi-pinhole collimator consisting of seven, 1 mm diameter apertures placed at a fixed radius of 32 mm. SPECT data was acquired over 360° by rotating the collimator through 51 steps; reconstruction was performed with an energy acceptance window of 141 ±14 keV. Sub-millimeter spatial resolution in the SPECT image allows the distinction of metabolic activity within individual vertebrae; note in particular the elevated MDP uptake within joints (knee, shoulder) and in the mandible, as indicated by arrows in (d). At the same time, bone density and morphology is easily quantified using the micro-CT data (A,C). Note that, for clarity, bladder activity has been suppressed in this presentation of the SPECT data. Images courtesy of Dr. Tim Morgan, GE Healthcare, London, Ontario.