Comparison of 2D and 3D PET for Cerebral FDG in Human Subjects

The authors compared 12 pairs of cerebral [18F]-fluoro-deoxyglucose (FDG) 2D/3D image sets from a GE/Advance PET scanner, incorporating the actual corrections used on human subjects. Differences in resolution consistent with other published values were found. There is a significant difference in axial resolution between 2D and 3D, and the authors focused on this as it is a scanner feature that cannot be readily changed. Previously published values for spatial axial resolution in 2D and 3D modes were used to model the differential axial smoothing at each image voxel. This model was applied to the 2D FDG images, and the resulting smoothed data indicate the published differences in axial resolution between 2D and 3D modes can account for 30-40% of the differences between these image sets. The authors then investigated the effect this difference might have on analysis typically performed on human FDG data. A phantom containing spherical hot- and cool-spots in a warm background to mimic a typical human cerebral FDG PET scan was scanned for a variety of time durations (30, 15, 5, 1 min). 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

Effect of Axial Resolution on PET Image Data: 2D vs. 3D

The authors compared 12 pairs of cerebral [18F]-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

Multi-Scanner PET 2D/3D Comparison with Cerebral FDG

A comparison was made of 2D and 3D FDG cerebral PET scans acquired on human subjects on two different PET scanners, a CTI ECAT HR+ and a GE Advance. The two scan protocols were part of independent studies and involved a 30 (20) minute 2D scan, a 10 (5) minute transmission scan after (before) injection, and a 10 (10) minute 3D scan for the Advance (HR+). Image reconstruction used each vendor\u27s standard recommendations. The HR+ showed good correlation between 2D and 3D modes, whereas the Advance systematically showed up to a 20% difference between modes, with larger discrepencies for higher pixel values. However, after a major upgrade to the GE/Advance that included replacing all of the detector units, a marked improvement in the 3D quantitative accuracy was noted. A head-sized phantom containing a warm background and various sizes of hot and cool spheres (9, 17, 22mm) was scanned in both scanners. The concentration (0.5 - 0.8 microCi/ml) and volume (∼3 liters) were designed to mimic a typical cerebral FDG scan, and a range of scan durations (1-30 minutes) were acquired to span the range of most FDG protocols. The correlation between 2D and 3D modes showed a similar pattern for each scanner as for the human data. However, the Advance showed somewhat better reliability and slightly better accuracy for recovering activity within the small spheres in 3D mode