磁共振弥散加权成像及表观扩散系数值分析在乳腺良恶性结节鉴别诊断中的价值

目的 评价磁共振弥散加权成像（diffusion-weighted imaging,DWI）及其表观扩散系数（apparent diffusion coefficient,ADC）在乳腺良、恶性结节鉴别诊断中的价值.方法 回顾性分析56例患有乳腺结节性疾病患者及13例健康女性志愿者（对照组）乳腺MRI资料,所有病例全部行MRI常规成像、DWI检查,扩散敏感系数（b值）取0、500、1000 s/mm.观察分析病变在MRI常规平扫、DWI图像的信号特征,测量不同b值感兴趣区（ROI）的ADC值.根据手术病理,按照恶性结节、良性结节、正常腺体分为三组,比较各组之间的ADC值,采用单因素方差分析统计分析,并绘制ROC曲线检验诊断效能,计算不同阈值下,ADC值诊断的敏感度、特异度、准确度,并与形态学评价相结合,确定合适的b值和阈值.结果 当b =500、1000 s/mm2时,恶性结节、良性结节及正常腺体的平均ADC值两两之间均有统计学差异（P＜0.05）.同一b值下,乳腺恶性结节较良性结节和正常腺体明显低,而良性结节平均ADC值较正常腺体低.通过受试者工作特征曲线（ROC curve）,确定不同b值下诊断乳腺良、恶性结节的ADC阈值,当b=500 s/mm2阈值为1.202×10-3mm2/s;b=1000 s/mm2阈值为1.117×10-3 mm2/s.结论 ADC值分析结合DWI图像对乳腺良、恶性结节的鉴别诊断有重要价值.

The value of MRI diffusion-weighted imaging and ADC values analysis in differential diagnosis between benign and malignant breast nodules

Objective To evaluate the value of MRI diffusion-weighted imaging （DWI） and apparent diffusion coefficient（ADC） values analysis in differential diagnosis between benign and malignant breast nodules. Methods Breast MRI findings were analysized of 56 patients suffering from breast nodular disease and 13 healthy female volunteers （control group） retrospectively. All subjects were tested with conventional imaging of MRI, and DWI, with diffusion-sensitive coefficients （b-value） being set at 0,500,1000 s/mm^2. The signal characteristics of the lesions observed in a conventional MRI scan, DWI image were analyzed. The ADC values of regions of interest, ROI were measured at different b-values. According to the surgical pathology, Malignant nodules, benign nodules and normal glands were divided into 3 categories. The ADC values among the 3 categories were compared using one-way ANOVA. Receiver Operating Characteristic curves （ROC） were drawn to evaluate the diagnostic performance. The diagnostic sensitivity, specificity, and accuracy of ADC values were evaluated under different thresholds, which combined with morphological evaluations, in order to determine appropriate b-value and threshold. Results Using b =500 and 1000 s/mm^2 ,there were significant statistical difference in mean ADC values between any two groups of the 3 categories（P 〈 0. 05）. The mean ADC values in malignant and benign nodules were lower than that in normal gland tissue with the same b-value. The ADC threshold was determined to diagnose benign and malignant breast nodules under different b-values with ROC curves. When using b = 500 s/mm^2 ,threshold = 1. 202 × 10^-3 mm^2/s or when using b = 1000 s/mm^2 ,threshold = 1. 117× 10^-3 mm^2/s. Conclusion ADC values combined the imagings of DWI were of important significance for differentiating benign from malignant breast nodules.