目的探讨早期乳腺癌在不同b 值下的DWI成像特点及其ADC值改变、与 Ki-67表达的相关性。方法 对35例早期 乳腺癌患者行MRI DWI检查，其b值分别 取为500s/mm2 、800s/mm2 、1000s/mm2 ，分 别测定癌灶在不同b值下扫描后的ADC均 值，分析其DWI信号特点，比较其ADC值 的差异性，并与术后病理Ki-67表达的相 关性进行统计学分析。结果 所有病例均 为早期浸润性导管癌，瘤灶在DWI上均呈 明显高信号。b值500s/mm2 组(b-500组)与 b值800s/mm2 组(b-800组)、b-500组与b值 1000s/mm2 组(b-1000组)间ADC值存在统 计学显著性差异(P值<0.05)；而b-800组 与b-1000组的ADC均值间无统计学显著性 差异(P值>0.05)。b-500组、b-800组、 b-1000组ADC均值分别为1.1416×10-3mm2 / s、0.9258×10-3mm2 /s、0.8668×10-3mm2 / s。不同b值扫描后所测得瘤灶的三组ADC 均值与Ki-67表达间的相关性均无统计学 显著性差异(P>0.05)。结论 早期乳腺癌 不同b值下扫描所测得的ADC值间存在一定 的差异性，选择b值为800s/mm2 时扫描较 为合理。当ADC值低于0.9258×10-3mm2 /s 时提示早期乳腺癌的可能。早期乳腺癌的 ADC值与Ki-67表达之间无明显相关性。

Objective To investigate the features of MR DWI with different b values, changes of ADC value, correlation of ADC value with Ki-67 expression in early breast cancer. Methods 35 patients with early breast cancer underwent MR DWI scanning with different b values, including 500s/mm2 、800s/mm2 、1000s/mm2 .The ADC values of the tumor lesions were measured after scanning with different b values. The DWI signal features of the tumor lesions were analyzed. The differences of the ADC Values were statistically compared, and the correlations of ADC values of the lesions with Ki-67 expressions were statistically analyzed. Results All of the patients were early breast invasive ductal carcinoma. All of the tumor lesions showed obviously high signal in DWI. There were statistically significant differences(P<0.05) between the mean values of the group of b-value 500s/mm2 (group of b-500) with group of b-value 800s/mm2 (group of b-800), Group of b-500 with group of b-value 1000s/mm2 (group of b-1000),respectively. However, there was no statistically significant difference(P>0.05) between the group of b-800 and group of b-1000.The mean ADC values were 1.1416×10-3mm2 / s(group of b-500), 0.9258×10-3mm2 /s (group of b-800), 0.8668×10-3mm2 /s(group of b-1000),respectively. The correlations between the ADC values of the three different b-value groups and the Ki-67 expressions were not statistically different(P>0.05). Conclusion There are certain differences between the ADC values measured after DWI scanning with different b values in early breast cancer. It is more suitable to select b-value 800s/mm2 for DWI scanning in breast cancer. It is possible to diagnose early breast cancer when the ADC value is less than 0.9258×10-3mm2 /s.The ADC value of early breast cancer was not obviously correlative with Ki-67 expression.