DWI在乳腺肿瘤鉴别诊断中的应用价值及b值优化

Value of diffusion-weighted imaging with different b values in the diagnosis of breast tumor

目的探讨1.5T MRI的扩散加权成像(DWI)在乳腺肿瘤鉴别诊断中的应用价值,并对b值进行优化。方法回顾性分析经术后病理确诊的66例乳腺肿瘤的DWI图像,b值分别为0、400、800 s/mm 2。比较不同b值DWI图像质量,测量正常组织、肿瘤组织的对比噪声比(CNR)及表观扩散系数(ADC)值,并以病理诊断为金标准,以不同b值恶性病灶均ADC值的95%可信区间上限为阈值,计算其诊断的敏感性、特异性及准确性。结果不同b值DWI图像质量主观评分差异无统计学意义(P>0.05);不同b值时病灶的CNR差异有统计学意义(P<0.05),且b值为800 s/mm 2病灶的CNR较高;当b值相同时,正常组均ADC值>良性组均ADC值>恶性组均ADC值,三组间均ADC值差异有统计学意义(P<0.05),且两两比较差异有统计学意义(P<0.05)。不同b值时,每组内ADC值差异有统计学意义(P<0.05);当b=400、800 s/mm 2时,恶性病灶均ADC值的95%可信区间上限阈值分别为1.51×10-3 mm 2/s、1.21×10-3 mm 2/s,其诊断的敏感性、特异性、正确性分别为75.0%、69.2%、72.7%及85.3%、88.0%、86.3%。结论应用DWI鉴别乳腺良恶性病变时,ADC值具有重要诊断价值,且b=800 s/mm 2时病灶CNR较高,值得推荐应用。

Objective To explore the value of 1.5T MR Diffusion-weighted Imaging(DWI)with different b values in the diagnosis of breast tumors.Methods The DWI image of 66 patients with breast tumor by postoperative pathology were retrospectively analyzed with different b values of 0,400 and 800 s/mm 2.Imaging quality score,contrast-to-ratio(CNR)and apparent diffusion coefficient(ADC)of normal,tumorous lesions with the same b values and different b values were compared and analyzed.Sensitivity,specificity and accuracy for the diagnosis of breast malignant lesions with different b values were calculated respectively by the gold standard with pathological diagnosis.The upper threshold was 95%confidence interval of ADC values for malignant lesions with different b values.Results The difference of the image quality score among the different b values was not statistically significant(P>0.05).There were significant differences in CNR of lesions with different b values(P<0.01),and the CNR of lesions was higher when b values was 800 s/mm 2.The average ADC values of normal group was higher than that of benign group,and benign group was higher than that of malignant group.There were significant differences with same b values in the average ADC values among the thtee groups(P<0.05),and between the two(P<0.05).There were significant differences in average ADC values among the thtee groups with different b values(P<0.05).When b value was 400 s/mm 2,800 s/mm 2,the upper threshold of ADC value was 1.51×10-3 mm 2/s,1.21×10-3 mm 2/s.Sensitivity,specificity and accuracy for diagnosis of malignant lesions were 75.0%,69.2%,72.7%and 85.3%,88.0%,86.3%.Conclusion The ADC values had important diagnostic value when we differentiated the benign and malignant breast lesions by DWI.When b values was 800 s/mm 2,the CNR of lesions was higher,which was worthy of recommendation.