Liverpool Hospital, University of New South Wales, Australia.
Hematol Oncol. 2011 Jun;29(2):67-74. doi: 10.1002/hon.955. Epub 2010 Jul 15.
F(18) -2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) has become a well established tool in staging and assessing therapy response in lymphoma. Incidental thyroid uptake on PET is not uncommon and can pose a diagnostic and management challenge. We retrospectively evaluate the prevalence and clinical significance of incidental FDG uptake in the thyroid gland in patients with lymphoma. 1868 lymphoma patients underwent PET and PET-CT between August 2002 and August 2008. 52 patients (2.8%) demonstrated FDG thyroid uptake (M = 17, F = 35; mean age 63 yr). Thyroid uptake was determined as focal or diffuse, maximum standardized uptake values (SUVmax) recorded as well as SUV max ratio compared to background mediastinum activity (SUVR). Corresponding CT findings on PET-CT were evaluated independently. Results were correlated with clinical, histopathological and imaging follow-up. 30 (1.6%) patients had focal thyroid uptake. 16 (53%) had histological confirmation either by surgery (n = 7) or FNA under USS (n = 9). The final diagnosis was benign in 12/30 patients and malignant in 9/30. The malignancy risk for focal thyroid uptake was 30%. Five patients had intercurrent thyroid cancer (four papillary, one microinvasive follicular) and four had lymphomatous involvement. There was no significant difference between the mean sizes of benign (23.7 mm, range 12-34) and malignant nodules (23.6 mm, range 8-48). The mean SUVmax of malignant and benign nodules was 4.4 (range 1.8-10.1) and 3.2 (range 1.8-6.9) respectively with no statistically significant difference. 22 (1.2%) patients had diffuse FDG uptake in thyroid and benign aetiology was found in all with adequate follow-up (15/22). Focal FDG thyroid uptake on PET or PET-CT in lymphoma patients warrants further investigations. The malignancy risk is 30% either due to intercurrent thyroid cancer or lymphomatous involvement. SUVmax, SUVR and CT attenuation characteristics are not helpful in distinguishing between benign and malignant aetiologies. Diffuse thyroid uptake has a benign aetiology.
F(18)-2-氟-2-脱氧-D-葡萄糖（FDG）正电子发射断层扫描（PET）已成为淋巴瘤分期和评估治疗反应的成熟工具。在 PET 上偶然发现甲状腺摄取并不少见，这可能会带来诊断和治疗管理方面的挑战。我们回顾性评估了 2002 年 8 月至 2008 年 8 月期间接受 PET 和 PET-CT 的 1868 例淋巴瘤患者中，甲状腺内偶然摄取 FDG 的发生率及其临床意义。52 例（2.8%）患者出现 FDG 甲状腺摄取（M=17，F=35；平均年龄 63 岁）。甲状腺摄取分为局灶性或弥漫性，记录最大标准化摄取值（SUVmax）和与背景纵隔活性（SUVmax 比值）相比的 SUVR。独立评估 PET-CT 上的相应 CT 结果。结果与临床、组织病理学和影像学随访相关联。30 例（1.6%）患者存在局灶性甲状腺摄取。16 例（53%）经手术（n=7）或在超声引导下 FNA（n=9）证实存在组织学病变。30 例中有 12 例为良性，9 例为恶性。局灶性甲状腺摄取的恶性风险为 30%。5 例患者并发甲状腺癌（4 例为乳头状，1 例为微小浸润滤泡性），4 例为淋巴瘤累及。良性（23.7mm，范围 12-34）和恶性结节（23.6mm，范围 8-48）的平均大小之间无显著差异。恶性和良性结节的平均 SUVmax 分别为 4.4（范围 1.8-10.1）和 3.2（范围 1.8-6.9），无统计学差异。22 例（1.2%）患者甲状腺弥漫性摄取 FDG，所有患者经充分随访后均发现良性病因（22/22）。淋巴瘤患者的 PET 或 PET-CT 上出现局灶性 FDG 甲状腺摄取，需要进一步检查。恶性风险为 30%，可能是由于并发甲状腺癌或淋巴瘤累及。SUVmax、SUVmax 比值和 CT 衰减特征无助于鉴别良性和恶性病因。弥漫性甲状腺摄取提示良性病因。
