Impact of Patient Weight and Emission Scan Duration on PET/CT Image Quality and Lesion

This study was performed to prospectively evaluate fast PET/CT imaging protocols using lutetium oxyorthosilicate (LSO) detector technology and 3-dimensional (3D) image-acquisition protocols. Methods: Fifty-seven consecutive patients (30 male, 27 female; mean age, 58.6 15.7 y) were enrolled in the study. After intra-venous injection of 7.77 MBq (0.21 mCi) of 18F-FDG per kilogram, a standard whole-body CT study (80–110 s) and PET emission scan were acquired for 4 min/bed position in 49 patients and 3 min/bed position in 8 patients. One-minute-per-bed-position data were then extracted from the 3- or 4-min/bed position scans to reconstruct single-minute/bed position scans for each patient. Pa-tients were subgrouped according to weight as follows: 59 kg (130 lb; n 15), 59–81 kg (130–179 lb; n 33), and 82 kg (180 lb; n 9). Three experienced observers recorded numbers and locations of lesion by consensus and independently rated image quality as good, moderate, poor, or nondiagnostic. Results: The observers analyzed 220 reconstructed whole-body PET im-ages from 57 patients. They identified 114 lesions ranging in size from 0.7 to 7.0 cm on the 3- (n 8) and 4-min/bed position images (n 49). Of these, only 4 were missed on the 1-min/bed position scans, and all lesions were identified on the corresponding 2-min/ bed position images. One- and 2-min/bed position image quality differed significantly from the 4-min/bed position image reference (P 0.05). Conclusion: LSO PET detector technology permits fast 3D imaging protocols whereby weight-based emission scan dura-tions ranging from 1 to 3 min/bed position provide similar lesion detectability when compared with 4-min/bed position images. Key Words: lutetium oxyorthosilicate; PET/CT; molecular imagin