Halpern Benjamin S, Dahlbom Magnus, Auerbach Martin A, Schiepers Christiaan, Fueger Barbara J, Weber Wolfgang A, Silverman Daniel H S, Ratib Osman, Czernin Johannes
Department of Molecular and Medical Pharmacology, Ahmanson Biological Imaging Center, UCLA David Geffen School of Medicine, Los Angeles, California 90095-6942, USA.
J Nucl Med. 2005 Apr;46(4):603-7.
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 > or =91 kg (200 lb).
Twenty-five consecutive patients (16 male and 9 female) weighing > or =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.
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.
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.
肥胖患者中高光子衰减和散射会影响图像质量。本研究的目的是优化体重≥91千克（200磅）患者的硅酸镥（LSO）PET图像采集方案。
对25例连续的体重≥91千克（200磅；范围为91 - 168千克[200 - 370磅]）患者（16例男性和9例女性）进行LSO PET/CT研究。静脉注射每千克体重7.77 MBq（0.21 mCi）的18F - FDG后，每个床位进行7分钟的PET发射扫描。从每个床位7分钟的扫描中提取单分钟帧，为每位患者重建1 - 7分钟/床位的扫描。三位阅片者独立分析每位患者的所有7幅重建全身图像。意见不一致时进行共识解读。因此，共分析了175次全身扫描（每位患者7次）的高代谢病变数量。采用感兴趣区方法对图像质量进行定量评估。
在7分钟/床位扫描中识别出的59个高代谢病变作为参考标准。观察者间一致性从1分钟/床位扫描的64%提高到3分钟/床位扫描的70%和4分钟/床位扫描的78%。更长成像时间的一致性率未改变。感兴趣区分析显示，图像噪声从1分钟/床位扫描的21%分别降至4、5和7分钟/床位扫描的14%、13%和11%。与参考标准相比，1分钟/床位扫描漏诊14个病变（24%），而4分钟/床位扫描仅漏诊2个（3%）。5分钟/床位扫描足以检测出7分钟/床位扫描中识别出的所有病变。
5分钟/床位扫描时病变可检测性和阅片者一致性达到峰值，延长PET发射扫描时间未获得进一步的诊断收益。因此，对于肥胖患者使用LSO PET/CT进行最佳病变检测，5分钟/床位扫描就足够了。
