甲状腺结节性病变MR弥散加权成像诊断价值初探

目的 探讨磁共振弥散加权成像对甲状腺良恶性结节的鉴别诊断价值.方法 搜集2004年11月至2006年2月在天津医科大学总医院及肿瘤医院就诊的甲状腺结节病变患者.采用平面回波成像技术对60例甲状腺结节病变(良恶性各30例)行DWI检查,分别测量b值取0和100、200、300、400 s/mm2时病变的ADC值,比较其间差异.所有病变均经手术病理证实.结果 当选取不同的b值时,所测得的良、恶性结节的ADC值之间均在统计学差异,且恶性结节组的ADC值小于良性结节组的ADC值(P＜0.05).根据兼顾DWI图像的信噪比和能够准确测量ADC值的原则,在多种b值的DWI检查中,宜选择400 s/mm2作为检查甲状腺结节性病变的最佳b值.当b值选择400 s/mm2时,绘制ROC曲线,并选取ADC值1.475×10-3 mm2/s作为阈值,诊断甲状腺恶性结节的敏感性、特异性分别为93.3%、96.7%.结论 甲状腺恶性病变的ADC值低于良性病变.DWI和ADC值在甲状腺结节病变的鉴别诊断中具有重要价值.

Value of diffusion weighted imaging in diagnosis of nodular lesions of thyroid: a preliminary study

Objective To investigate the value of magnetic resonance diffusion weighted imaging (DWI) in the differential diagnoses of malignant and benign thyroid lesions. Methods Using echo planner imaging sequence with b value of 0, 100, 200, 300 and 400 s/mm2 respectively, DWI was performed in 60 patients of focal thyroid lesions. The diagnosis was confirmed by pathological examination (benign, n =30; malignant, n =30). Apparent diffusion coefficient (ADC) values were measured. The differences were analyzed between two groups. Results With b value of 0, 100, 200, 300 and 400 s/mm2 respectively,there were statistical differences in ADC values between benign and malignant lesions. The ADC value of malignant lesions was smaller than that of benign lesions (P ＜ 0. 05). Among different b values, 400 s/mm2 was the most optimal one to diagnose thyroid nodular lesions. DWI with a b value of 400 s/mm2 had a proper signal-to-noise ratio (SNO). And ADC value could be measured correctly. With a b value of 400 s/mm2 and ADC of 1. 475 × 10-3 mm2/s, receiver operating characteristic curve was plotted. In the diagnosis of malignant lesions, the sensitivity and specificity were 93.3% and 96.7% respectively. Conclusions The ADC value of malignant thyroid nodular lesions is smaller than that of benign lesions. The values of DWI and ADC are important in the differential diagnoses of nodular thyroid lesions.