Optimizing sequential dual tracer P.E.T. studies using a combined 2D/3D imaging protocol

We have investigated a combined 2D/3D protocol for minimizing contamination in dual tracer P.E.T. studies in which the tracers are administered on a timescale that is short compared to the half-lives. We have performed a series of phantom studies on an Advance and a Discovery ST (GE Healthcare Technologies), using a torso phantom with cardiac insert (Data Spectrum Corporation) to simulate a combined FDG and NH/sub 3/ scan protocol for a patient with ischemia. The phantom was imaged in a series of alternating 2D/3D acquisitions as it decayed over 6 half-lives. By comparing 2D and 3D images, we have verified that 3D images are of comparable accuracy to 2D images, even with realistic out-of-field activity challenging the 3D scans. Based on scan and image statistical quality, we have recommended optimal doses for maximizing the image quality of both scans.