Esen Akkas B, Gökaslan D, Güner L, Ilgin Karabacak N
Ankara Oncology Research and Training Hospital, Department of Nuclear Medicine, Ankara, Turkey.
Rev Esp Med Nucl. 2011 Jan-Feb;30(1):14-8. doi: 10.1016/j.remn.2010.05.006. Epub 2010 Aug 10.
Brown adipose tissue (BAT) is a potential source of false-positive findings on [(18)F] FDG PET. In this report, we have discussed the (18)F-FDG uptake mechanisms in BAT and have aimed to determine if dual time point PET imaging helps to differentiate BAT from malignant lesions.
Patients with dual-time-point PET/CT scans were reviewed retrospectively and 31 cases (11 males, 20 females, age: 28.6±9.7) having hypermetabolic BAT were included for this study. (18)F-FDG uptake in BAT was quantitatively analyzed by maximum standardized uptake values (SUVmax), and average percent change in SUVmax of BAT between early and delayed images was calculated.
Compared to the initial scans, (18)F-FDG uptakes in BAT in delayed images were higher in 26 of the patients, and lower in one patient. In terms of body regions, (18)F-FDG uptake increased in 80.6%, remained unchanged in 5.5% and decreased in 13.9% of the body regions. Mean percent change in SUVmax, including all BAT regions, was 19.8±19.1% while the mean percent increase was calculated as 69±25% in regions where progressive accumulation was observed. The increase in SUVmax correlated with the time interval between the two scans.
Physiologic (18)F-FDG uptake in BAT increases over time and may mimic the behavior of malignant lesions on dual time point PET imaging. Without the exact anatomic definition of the CT scan, false positive interpretation of PET data may be possible in cases with atypical BAT.
棕色脂肪组织（BAT）是[18F]氟代脱氧葡萄糖（FDG）正电子发射断层扫描（PET）出现假阳性结果的一个潜在来源。在本报告中，我们讨论了BAT中18F-FDG的摄取机制，并旨在确定双时相PET成像是否有助于将BAT与恶性病变区分开来。
对进行双时相PET/CT扫描的患者进行回顾性分析，本研究纳入了31例（11例男性，20例女性，年龄：28.6±9.7岁）BAT代谢增高的患者。通过最大标准化摄取值（SUVmax）对BAT中的18F-FDG摄取进行定量分析，并计算早期和延迟图像之间BAT的SUVmax平均变化百分比。
与初始扫描相比，26例患者延迟图像中BAT的18F-FDG摄取更高，1例患者更低。就身体区域而言，80.6%的身体区域18F-FDG摄取增加，5.5%保持不变，13.9%减少。包括所有BAT区域在内的SUVmax平均变化百分比为19.8±19.1%，而在观察到有渐进性积聚的区域，平均增加百分比计算为69±25%。SUVmax的增加与两次扫描之间的时间间隔相关。
BAT中生理性18F-FDG摄取随时间增加，在双时相PET成像上可能模仿恶性病变的表现。如果没有CT扫描的确切解剖定位，在非典型BAT的情况下可能会对PET数据做出假阳性解释。
