MR弥散加权成像在甲状腺结节良恶性鉴别中的应用价值

目的：探讨MR弥散成像（DWI）在甲状腺结节良恶性鉴别中的应用价值。方法回顾性分析35例甲状腺良性单发结节和13例恶性单发结节实性部分的ADC值（b值取200、500、800s/mm2），比较其差异，绘制ROC曲线，分析实验的诊断效能。结果 b值取200和500s/mm2时恶性组平均ADC值显著低于良性组（P＜0.01）。b值取800s/mm2时良恶性组平均ADC值差异无统计学意义。b值分别为200,500,800 s/mm2时ADC值判断甲状腺恶性结节的曲线下面积分别为0.98,0.94,0.66。b值为200s/mm2时价值最大，诊断阈值1.92×10-3mm2/s时，诊断敏感度为100.0％，特异度为91.4％，准确率为93.7％。结论 DWI对甲状腺良恶性结节鉴别有重要的临床应用价值，b值取200s/mm2时更有助于甲状腺良恶性结节的鉴别。

Value of diffusion-weighted MR imaging in differential diagnosis of malignant thyroid nodules

Objective To assess the value of MR diffusion weighted imaging （DWI） in differential diagnosis of malignant thyroid nodules. Methods The imaging findings of Thirty- five patients with solitary thyroid nodules （13 malignant and 35 benign nodules） who underwent DWI were analyzed retrospectively. The apparent diffusion coefficient （ADC） values （b=200, 500, 800 s/mm2） of thyroid nodules were measured. The differences were compared between malignant and benign thyroid nodules. Re-ceiver operating characteristics （ROC） analyses were also performed. Results When the b values were 200 and 500s/mm2, the ADC values were significantly lower in malignant nodules compared with those in the benign nodules （P〈0.01）. However, there was no difference between malignant and benign nodules in mean ADC value when b value was 800s/mm2. Areas under the ROC curve for identification of malignant nodules were 0.98 （b=200s/mm2）, 0.94 （b=500s/mm2）, and 0.66 （b=800s/mm2）, respectively. When b was 200s/mm2 and taking ADC 1.92×10-3mm2/s as the cutoff value in differentiating malignant from benign nodules, the sensitivity, specificity and accuracy were 100.0%, 91.4% and 93.7%, respectively. Conclusion DWI is a promising method for differentiation between malignant and benign thyroid nodules and when b value is 200s/mm2 ADC provides higher diagnostic performance.