^18F-FDGPET／CT影像特征对甲状腺结节的诊断效能

Diagnostic efficiency of ^18F-FDG PET/CT for indeterminate thyroid nodules

目的研究甲状腺结节^18F-FDGPET／CT影像特征对甲状腺结节良恶性的鉴别诊断效能。方法回顾性研究68例[男24例，女44例，平均年龄（52．8±10．58）岁]2006年1月至2012年12月间经PET／CT检查发现甲状腺结节且有术后病理结果的患者，分析其PET／CT图像特征并获得特征参数，包括结节边界清晰度、密度均匀性、钙化情况、包膜情况、平均CT值、结节大小及SUVmax。以术后病理结果为“金标准”，采用Mann-Whitney u检验、x^2检验及ROC曲线对各参数的诊断效能进行统计分析。结果68例患者中，病理结果显示恶性18例，良性50例。结节密度是否均匀、有无钙化灶、有无包膜对于甲状腺结节良恶性鉴别均无统计学意义（x^2=0．21、0．01、0．43，均P〉0．05），结节平均CT值及结节大小亦无鉴别意义（均AUC〈0．5）。结节边界是否清晰对良恶性结节鉴别有统计学意义（x^2=8．06，P〈0．05），其诊断灵敏度、特异性及准确性分别为55．6％（10／18）、80．0％（40／50）和73．5％（50／68）。良性结节SUVmax为3．16±1．84，恶性结节SUVmax为8．53±7．09，差异有统计学意义（u=-4．281，P〈0．01）。以SUVmax为评价指标，其ROC的AUC为0．841（95％CI：0．726—0．955），最大约登指数（0．562）对应SUVmax为4．25，其诊断灵敏度、特异性及准确性分别为72．2％（13／18）、84．0％（42／50）和80．9％（55／68）。结论可依据^18F—FDGPET／CTSUVmax对甲状腺结节良恶性进行判断，但同机CT影像特征价值有限。

Objective To investigate the diagnostic efficiency of ^18F-FDG PET/CT imaging for indeterminate thyroid nodules. Methods Sixty-eight patients （24 males, 44 females, age： （52.8±10.58） years） with indeterminate thyroid nodules who underwent ^18F-FDG PET/CT imaging from January 2006 to December 2012 were analyzed retrospectively. The imaging characteristic including clearity of boundary, uniform density, calcification, capsule, mean CT value, nodular size and SUVmax of thyroid nodules were evaluated. The gold standard was postoperative pathological results. Mann-Whitney u test, x^2 test and ROC curve analysis were performed to investigate the diagnostic efficiency. Results Among 68 patients with indeterminate thyroid nodules, 18 were malignant and 50 were benign according to pathological results. Uniform density, calcification, capsule （x^2 =0.21, 0.01, 0.43, all P〉0.05）and mean CT value, nodular size （all AUCs〈0.5） could not differentiate benign from malignant thyroid nodules. However, whether the nodules had clear boundary was significant to differentiate benign from malignant nodules （x^2= 8.06,P〈0.05）, and the sensitivity, specificity and accuracy were 55.6% （ 10/18）, 80.0% （40/50） and 73.5% （ 50/68）, respectively. The mean SUVmax of benign and malignant thyroid nodules was 3.16±1.84 and 8.53±7.09, respectively （ u = - 4.281, P 〈 0.01 ）. AUC of SUVm~ was 0.841 （ 95% CI： O. 726- O. 955 ）. According to the maximal Youden index（0. 562）, 4.25 was chosen as the SUVmax, threshold, and its sensitivity, specificity and accuracy were 72. 2%（ 13/18）, 84.0%（42/50） and 80.9%（55/68）, respectively. Conclusion Among different characteristics of ^18F-FDG PET/CT imaging, SUVmax of thyroid nodules plays an important role in the differ- ential diagnosis of undetermined thyroid nodules, but CT image features have limited value.