多b值MR扩散加权成像对甲状腺乳头状癌甲状腺外侵犯的诊断价值

Preoperative prediction of the extrathyroidal extension of papillary thyroid carcinoma using multi-b values of MR diffusion weighted imaging

目的探讨术前多b值MRDWI及ADC值在甲状腺乳头状癌(PTC)甲状腺外侵犯(ETE)诊断中的价值。方法回顾性分析2013年1月至2017年2月经手术病理证实为PTC的81例患者的MRI平扫、增强和DWI的图像。在工作站上构建ADC图,分别测量伴ETE(微小ETE、广泛ETE)、无ETE的PTC实性区域的ADC值,经独立样本t检验比较其肿瘤实性区域ADC值的差异。结果b值为500s/mm2时,伴ETE及无ETE的PTC实性区域ADC值分别为(1.27±0.17)×10^-3、(2.12±0.72)×10^-3mm^2/s,差异有统计学意义(t=9.126,P=0.000);伴广泛ETE的PTC实性区域ADC值(1.23±0.17)×10^-3mm^2/s低于伴微小ETE的PTC肿瘤实性区域ADC值(1.29±0.16)×10^-3mm^2/s,但差异无统计学意义(t=1.467,P=0.147);以病理为金标准,ADC值诊断PTC伴ETE的ROC曲线下面积为0.887,诊断阈值为1.530×10^-3mm^2/s,诊断敏感度为69.0%、特异度为93.7%、阳性预测值77.6%、阴性预测值77.5%。结论DWI中,伴ETE的PTC实性区域的ADC值明显低于无ETE的PTC实性区域的ADC值,DWI有助于PTC的ETE的鉴别诊断。

Objective To evaluate the diagnostic performance of preoperative multi b values of DWI and ADC for the prediction of extrathyroidal extension (ETE) of papillary thyroid carcinoma (PTC). Methods Between January 2013 and February 2017, MR images including dynamic contrast-enhanced MR imaging (DCE-MRI) and DWI images of 81 patients diagnosed as papillary thyroid carcinoma in the Affiliated Renmin Hospital of Jiangsu University were retrospectively analyzed. ADC values were measured on solid regions of tumors. The differences of ADC were compared between tumors with total ETE(minimal ETE, extensive ETE) and without ETE by independent-samples t test. Results When b=500 s/mm^2, ADC values of PTCs with ETE[(1.27±0.17)×10^-3mm^2/s]were significantly lower than those from PTCs without ETE[(2.12±0.72)×10^-3mm^2/s, (t=9.126,P=0.000)]. ADC values of PTCs with extensive ETE[(1.23±0.17)×10^-3mm^2/s] were significantly lower than those from PTCs with minimal ETE[(1.29±0.16)×10^-3mm^2/s, (t=1.467, P=0.147) ]. When b=500 s/mm2, the cutoff value of ADC to discriminate PTCs with and without ETE was 1.530×10^-3 mm^2/s with a sensitivity of 69.0%, specificity of 93.7%, positive predictive value of 77.6%, negative predictive of 77.5% and ROC curve area of 0.887.