Metser Ur, Miller Elka, Lerman Hedva, Even-Sapir Einat
Department of Nuclear Medicine, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, 6 Weizman St., Tel-Aviv 64239, Israel.
AJR Am J Roentgenol. 2007 Nov;189(5):1203-10. doi: 10.2214/AJR.07.2083.
The objective of our study was to characterize benign lesions showing increased 18F-FDG uptake and to determine their incidence on whole-body FDG PET/CT performed in oncologic patients. In addition, the performance of PET alone and PET/CT in characterizing lesions as benign was compared.
A retrospective review of 1,134 consecutive reports of PET/CT studies performed in patients with proven or suspected malignancy over a 6-month period yielded 289 patients with 313 lesions that showed increased FDG uptake but were suspected to be benign (nonphysiologic) or indeterminate. Lesions were subjectively categorized on the basis of the intensity of FDG uptake (mild, moderate, or marked) as compared with background activity. For each lesion, a decision was made as to whether a benign diagnosis could be obtained by the CT part of the study, the PET pattern, or clinical correlation, or whether histologic sampling was necessary. The performance of PET alone and PET/CT for characterizing lesions as benign was compared. Two hundred twenty-nine of the lesions were assessed further: 210 were benign and 19, malignant. The final diagnosis was determined by pathology (n = 67), PET/CT follow-up (n = 58), correlative imaging (n = 59), clinical correlation (n = 32), or typical benign pattern on PET/CT (n = 13).
The causes for benign uptake of FDG were inflammatory processes (n = 154, 73.3%), benign tumors (n = 23, 11%), hematoma or seroma (n = 17, 8.1%), fracture (n = 7, 3.3%), fat necrosis (n = 3, 1.4%), and others (n = 6, 2.9%). For lesions with moderate or marked uptake of FDG (n = 117, 55.7%), a benign diagnosis could have been suggested on either PET or CT (e.g., a "hot" osteophyte) in 33 lesions (28.2%), on CT alone (e.g., peritoneal fat necrosis) in 38 lesions (32.5%), on PET alone (e.g., sialadenitis) in 10 lesions (8.5%), or by clinical correlation (e.g., dental abscess) in four lesions (3.4%). A benign diagnosis could not be established without histology (e.g., colonic polyp) in 32 lesions (27.4%). The performance of PET/CT was superior to that of PET alone in characterizing lesions as benign (p < 0.001).
Benign lesions with increased FDG uptake are found in more than 25% of the PET/CT studies performed in patients with proven or suspected malignancy, with inflammation being the most common cause. Lesion characterization on the CT portion of the PET/CT study increases the specificity of PET/CT reporting, especially for lesions with moderate or marked FDG uptake.
本研究的目的是对表现出18F-FDG摄取增加的良性病变进行特征描述，并确定其在肿瘤患者全身FDG PET/CT检查中的发生率。此外，还比较了单独PET和PET/CT在将病变判定为良性方面的表现。
回顾性分析在6个月期间对1134例经证实或疑似患有恶性肿瘤的患者进行的PET/CT研究报告，发现289例患者有313个病变，这些病变显示FDG摄取增加，但被怀疑为良性（非生理性）或性质不确定。根据FDG摄取强度（轻度、中度或显著）与背景活性相比，对病变进行主观分类。对于每个病变，决定是否可以通过研究的CT部分、PET图像或临床相关性获得良性诊断，或者是否需要进行组织学取样。比较了单独PET和PET/CT在将病变判定为良性方面的表现。对其中229个病变进行了进一步评估：210个为良性，19个为恶性。最终诊断通过病理学（n = 67）、PET/CT随访（n = 58）、相关影像学检查（n = 59）、临床相关性（n = 32）或PET/CT上典型的良性表现（n = 13）确定。
FDG摄取为良性的原因包括炎症过程（n = 154，73.3%）、良性肿瘤（n = 23，11%）、血肿或血清肿（n = 17，8.1%）、骨折（n = 7，3.3%）、脂肪坏死（n = 3，1.4%）以及其他（n = 6，2.9%）。对于FDG摄取为中度或显著的病变（n = 117，55.7%），在33个病变（28.2%）中，PET或CT（如“热”骨赘）可提示良性诊断，在38个病变（32.5%）中仅CT（如腹膜脂肪坏死）可提示良性诊断，在10个病变（8.5%）中仅PET（如涎腺炎）可提示良性诊断，在4个病变（3.4%）中通过临床相关性（如牙脓肿）可提示良性诊断。在32个病变（27.4%）中，若无组织学检查（如结肠息肉）则无法确立良性诊断。在将病变判定为良性方面，PET/CT的表现优于单独PET（p < 0.001）。
在经证实或疑似患有恶性肿瘤的患者进行的PET/CT检查中，超过25%发现有FDG摄取增加的良性病变，其中炎症是最常见的原因。PET/CT检查中CT部分对病变的特征描述提高了PET/CT报告的特异性，尤其是对于FDG摄取为中度或显著的病变。
