3.0T MR超高b值扩散加权成像诊断前列腺癌的临床应用价值

The Clinical Application of 3.0 T MR Ultra High B Value Diffusion Weighted Imaging in Detecting Prostate Cancer

目的探讨3.0 T磁共振超高b值DWI对前列腺癌诊断的临床应用价值。方法 56例经临床病理证实的前列腺疾病患者(前列腺癌32例、前列腺良性病变24例)行MR常规序列(T1WI、T2WI)及DWI扫描(b值=0s/mm2、1000 s/mm2、1500 s/mm2、2000 s/mm2),将常规序列与不同b值DWI进行组合分为3组,即MR常规序列联合DWI b=1000 s/mm2(A组)、b=1500 s/mm2(B组)、b=2000 s/mm2(C组)。采用独立样本t检验比较不同b值时,前列腺癌与前列腺良性病变间ADC值的差别;对A、B、C 3组行受试者工作特性(ROC)曲线分析以确定它们区分前列腺癌与前列腺良性病变的效能。结果当b值分别为1000 s/mm2、1500 s/mm2、2000 s/mm2时前列腺癌组织的平均ADC值均低于前列腺良性病变,两者差异均具有明显统计学意义,P<0.05;随着b值增大,前列腺癌与前列腺良性病变间ADC值重叠范围逐渐减小;C组(b值为2000 s/mm2)鉴别前列腺良恶性病变的ROC曲线下面积(AUC)最大(为0.998),其与B组(b值为1500 s/mm2)及A组(b值为1000 s/mm2)的AUC之间的差异均有统计学意义(Z=11.85,P<0.05;Z=15.42,P<0.05)。结论 3.0 T DWI(b=2000 s/mm2)有助于提高前列腺癌诊断效能;最佳诊断b值为2000 s/mm2,相应最佳临界ADC值为0.87×10-3mm2/s。

Objective To investigate the clinical application of 3.0 T MR ultra high B value diffusion weighed imaging in detecting prostate cancer. Methods A total of 56 patients with clinically- and pathologically-proved prostate lesions were enrolled in this study. The prostate lesions included prostate cancer （ n = 32） and benign prostate lesion （ n = 24 ）. Conventional MRI （T1WI and T2WI） and DWI （b = 0, 1000, 1500 and 2000 s/mm^2） scanning was performed in all pa- tients. Based on the combination of conventional sequence with DWI using different b value, the experiments were divided into three groups. Group A ： conventional MRI plus DWI （ b = 1000 s/mm2 ） ; group B ： conventional MR1 plus DWI （ b = 1500 s/ram2 ） ; and group C ： conventional MRI plus DWI （ b = 2000 s/ram2 ）. ADC values of malignant tissues and benign tissues under different b values were compared by using independent samples t test. Receiver operating characteristic （ROC） curves were used to evaluate the efficacy of the three protocols in differentiating prostate cancer from benign prostate lesions. The results were analyzed. Results The mean ADC of malignant tissue was significantly lower than that of benign lesions when the b value of 1000 s/mm2, 1500 s/mm^2 or 2000 s/mm^2 was used, and the difference was statistically signifi- cant （ P 〈 0.05 ）. With the increasing of b value, the ADC overlapping area of malignant lesions and benign lesions became smaller. The mean area under curve （AUC） in group C （b =2000 s/ram2） was larger than those in group B （b = 1500 s/ mm：） and in group A （b = 1000 s/mm：）, and the differences in AUC between group C and group B as well as between group C and group A were statistically significant （Z = 11.85, P 〈 0. 05 ; Z = 15.42, P 〈 0.05 ）. Conclusion DWI at 3.0 T, when b = 2000 s/mm^2 is employed, can improve the diagnostic accuracy of prostate cancer. The optimal b value is 2000 s/ram： and the best cut off ADC is 0.87 × 10^-3mm^2/s.