TY - JOUR T1 - Optimizing Imaging Protocols for Overweight and Obese Patients: A Lutetium Orthosilicate PET/CT Study JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 603 LP - 607 VL - 46 IS - 4 AU - Benjamin S. Halpern AU - Magnus Dahlbom AU - Martin A. Auerbach AU - Christiaan Schiepers AU - Barbara J. Fueger AU - Wolfgang A. Weber AU - Daniel H.S. Silverman AU - Osman Ratib AU - Johannes Czernin Y1 - 2005/04/01 UR - http://jnm.snmjournals.org/content/46/4/603.abstract N2 - High photon attenuation and scatter in obese patients affect image quality. The purpose of the current study was to optimize lutetium orthosilicate (LSO) PET image acquisition protocols in patients weighing ≥91 kg (200 lb). Methods: Twenty-five consecutive patients (16 male and 9 female) weighing ≥91 kg (200 lb; range, 91–168 kg [200–370 lb]) were studied with LSO PET/CT. After intravenous injection of 7.77 MBq (0.21 mCi) of 18F-FDG per kilogram of body weight, PET emission scans were acquired for 7 min/bed position. Single-minute frames were extracted from the 7 min/bed position scans to reconstruct 1–7 min/bed position scans for each patient. Three reviewers independently analyzed all 7 reconstructed whole-body images of each patient. A consensus reading followed in cases of disagreement. Thus, 175 whole-body scans (7 per patient) were analyzed for number of hypermetabolic lesions. A region-of-interest approach was used to obtain a quantitative estimate of image quality. Results: Fifty-nine hypermetabolic lesions identified on 7 min/bed position scans served as the reference standard. Interobserver concordance increased from 64% for 1 min/bed position scans to 70% for 3 min/bed position scans and 78% for 4 min/bed position scans. Concordance rates did not change for longer imaging durations. Region-of-interest analysis revealed that image noise decreased from 21% for 1 min/bed position scans to 14%, 13%, and 11% for, respectively, 4, 5, and 7 min/bed position scans. When compared with the reference standard, 14 lesions (24%) were missed on 1 min/bed position scans but only 2 (3%) on 4 min/bed position scans. Five minute/bed position scans were sufficient to detect all lesions identified on the 7 min/bed position scans. Conclusion: Lesion detectability and reader concordance peaked for 5 min/bed position scans, with no further diagnostic gain achieved by lengthening the duration of PET emission scanning. Thus, 5 min/bed position scans are sufficient for optimal lesion detection with LSO PET/CT in obese patients. ER -