18^F-FDG PET／CT全身显像对甲状腺偶发瘤的临床意义

Clinical significance of 18^F-fluorodeoxyglucose PET/CT whole body imaging in detecting thyroid incidentaloma

目的研究18^F-脱氧葡萄糖（FDG）PET／CT显像对甲状腺偶发瘤的检出率及检出恶性病灶的比例、最大标准摄取值（SUVmax）对鉴别诊断良、恶性病变的价值。方法回顾性分析2007年6月-2008年1月1190例无甲状腺癌病史的PET／CT受检者资料，对PET／CT发现的甲状腺偶发瘤行定性、半定量分析。对数据行Kruskal—Wallis检验或Spearman相关分析。结果18^F-FDG PET／CT全身显像对甲状腺偶发瘤的检出率为2．1％（25／1190），其中20例取得病理结果，良性病变9例，恶性病变11例（9例乳头状癌、1例滤泡状癌、1例肺癌转移），恶性比例高达55％（11／20）。良、恶性病变组间SUVmax差异有统计学意义（分别为4．1±1．9和13．3±11．8,Х^2=8．8，P〈0．01）。甲状腺偶发瘤最大径（1．0～4．2cm）与其18^F-FDG摄取（SUVmax为3．0—46．0）之间无相关性（r=0．25，P〉0．01）。结论18^F-FDG PET／CT检查发现甲状腺偶发瘤中甲状腺癌比例很高，其SUVmax对鉴别诊断良、恶性病变有参考价值。

Objective 18^F-fluorodeoxyglucose （FDG） PET/CT is a noninvasive whole-body imaging technique used to evaluate various types of malignancies. Recent advances have rapidly developed it into a diagnostic imaging modality in oncology. The aims of this study were two. One was to estimate the detection rate of thyroid incidentaloma and the risk of thyroid malignancy by 18^F-FDG PET/CT scan and the other was to further understand whether the maximum standardized uptake value （ SUVmax） would be helpful in differentiating benign from malignant thyroid tumor. Methods From June 2007 to January 2008, a total of 1190 subjects who had no previous history of thyroid cancer and had 18^F-FDG PET/CT scan were included. All had visual interpretation and semiquantitative analyses by SUVmax at thyroid incidentalomas detected by FDG PET/CT. Kruskal-Wallis test and Spearman relation analysis were used. Results The prevalence of thyroid incidentaloma on 18^F-FDG PET/CT was 2.1% （25/1190）. Of these 25 tumors, 20 had histologically proven. Of these 20 tumors, 9 were benign and 11 were malignant （ papillary carcinoma of thyroid gland in 9, follicular carcinoma of thyroid gland in 1, metastatic squamous cell carcinoma from lung cancer in 1 ）. Therefore, the cancer risk of thyroid incidentaloma was 55% （11/20）. Significantly higher SUVmax in malignant than in benign nodules were observed （ Kruskal-Wallis test, Х^2 = 8.8, P 〈 0.01 ）. However, the correlation between SUVmax （3. 0-46. 0） and maximal diameter （1.0-4.2 cm） of nodule findings was insignificant （ r = 0. 25, P 〉 0.01 ）. Conclusion Thyroid incidentaloma detected by 18^F-FDG PET/CT has higher risk rate for thyroid malignancy.