Effect of axial resolution on PET image data: 2D vs. 3D

The authors compared 12 pairs of cerebral [/sup 18/F]-fluorodeoxyglucose (FDG) 2D/3D image sets from a GE/Advance PET scanner, incorporating the actual corrections used on human subjects. Previously published values for spatial axial resolution in 2D [1] and 3D [2] modes were used to model the differential axial smoothing at each image voxel. This model was then applied to the 2D FDG images as well as to 2D spherical hot-spot phantom images; the resulting smoothed data indicate the published difference in axial resolution between 2D and 3D modes can account for 30-40% of the differences between these image sets. A phantom containing spherical hot- and cool-spots in a warm background was scanned for a variety of time-frame durations (30, 15, 5, 1 min) to mimic a typical human cerebral FDG PET scan. Only for the 1-minute frame (total counts 2D:6M, 3D:30M) is there an advantage to using 3D mode; for the longer frames which are more typical of a human FDG protocol, the reliability for extracting regions-of-interest is the same for either mode while 2D mode shows better quantitative accuracy.