MR扩散加权成像鉴别乳腺良恶性病变的研究

The research on distinguishing benign from malignant breast lesions by diffusion-weighted MR imaging

目的探讨磁共振扩散加权成像(diffusion-weighted MR imaging, DW-MRI)的表观扩散系数(apparent diffusion coefficient, ADC)在乳腺病变鉴别诊断中的价值.方法 DW-MRI采用单次激发平面回波成像(echo-planar imaging, EPI)技术, 扩散敏感系数(b值)分别为0、500、1000 s/mm2.计算26个正常乳腺、手术病理证实的24个恶性病灶、30个良性病灶分别在b=1000～0、1000～500、500～0 s/mm2时的ADC值,比较良恶性病变、正常腺体间ADC值差异的统计学意义及b=1000～0、1000～500、500～0 s/mm2间ADC值差异的统计学意义.结果乳腺良、恶性病变、正常腺体间ADC值差异均有统计学意义(F= 565.74,P<0.01),恶性病变ADC值明显低于良性病变和正常腺体组织,良性病变 ADC 值明显低于正常腺体组织;3组b值间ADC值差异均有统计学意义(F=21.30,P<0.01),b值越低,ADC值越大;把恶性肿瘤ADC值95%可信区间上界(1.01×10-3)mm2/s定为良恶性病变鉴别的界值,诊断敏感性为64.0%,特异性为96.7%.结论根据ADC值可以对乳腺良恶性病变做出鉴别诊断,其特异性较高,但敏感性较低.

Objective To investigate the value of apparent diffusion coefficient (ADC) of diffusion-weighted magnetic resonance imaging (DW-MRI) in distinguishing benign from malignant breast lesions. Methods ADC in 26 normal breasts, 24 malignant breast lesions, and 30 benign breast lesions confirmed by operation and pathology were calculated, respectively, and their differentiations in statistics were compared. The differentiations of different ADCs (b=1000-0, 500-0, 1000-500 s/mm2) were also compared. EPI (TR 2900 ms, TE 84 ms, thickness 5 mm) was used in order to acquire the imaging. Results There were significant differences among the ADC values of normal breast tissue, benign, and malignant lesions. The ADC of malignant lesions was lower than those of normal breast tissue and benign lesions, and the ADC of benign lesions was lower than that of normal breast tissue. There were significant differences among the ADC value of b=1000-0, 1000-500, and 500-0 s/mm2. The lower the b value, the higher the ADC. The sensitivity and specificity of ADC for the diagnosis of malignant lesion were 64% and 96.7% if the upper bound of 95% confidence interval was set as a differential level. Conclusion The differentiation of benign from malignant breast lesions by ADC is applicable, although the sensitivity is low, the specificity is high.