不同b值范围扩散加权成像定量参数在外周带前列腺癌诊断中的价值比较

Diffusion-weighted imaging in peripheral zone prostate cancer detection:comparison of different mathematical models and different b-value ranges

目的评价不同b值范围扩散模型参数在外周带前列腺癌中的诊断价值。方法本研究纳入56例经病理证实的外周带前列腺癌患者,所有患者均接受21个b值(0~4500 s/mm^2)的扩散加权成像(diffusion weighted imaging,DWI)磁共振成像检查。良性外周带和癌灶组织区的DWI信号强度分别使用单指数、双指数和峰度模型拟合。b值分为四个范围:0~1000,0~2000,0~3200和0~4500 s/mm^2,即组A、B、C和D。计算各兴趣区内A、B、C、D组的ADC、<D>、D*、f、D_(app)和K_(app)值。采用受试者工作特征曲线评价各参数的诊断效能。结果除D*外各组中的所有参数在外周带癌灶组织和良性组织间均有显著差异。ADC值的ROC曲线下面积(area under the curve,AUC)在C和D组中相当(P=0.980),并且显著高于A组和B组(P<0.05)。B和C组中ADC和K_(app)的AUC相近(P=0.07,0.954),并且显著高于其他参数(P<0.001)。D组中ADC的AUC略高于K_(app)(P=0.002),并且两者均显著高于其他参数(P<0.001)。结论在鉴别外周带癌灶组织和良性组织方面,双指数和峰度模型定量参数与单指数定量参数相比没有明显优势。使用b值高达3200 s/mm^2计算的ADC值是诊断外周带前列腺癌的优选参数。

Objective To assess the b-value range dependence and diagnostic performance of conventional mono-exponential apparent diffusion coefficient（ADC）,intravoxel incoherent motion（IVIM）-derived parameters,and diffusion kurtosis imaging（DKI）-derived parameters for differentiation of prostate cancer and normal tissue in the peripheral zone.Methods Diffusion-weighted magnetic resonance imaging（DWI） using 21 b-values（0-4500 s/mm^2） of 56 patients with histologically proven peripheral zone prostate cancer was analyzed.The mean signal intensities of the regions of interest（ROIs） placed in benign and cancerous peripheral tissues on DWI were fitted using mono-exponential,bi-exponential,and kurtosis models.ADC,D ,D＊,f,D_（app）,and K_（app）were estimated using four different ranges of b-values： 0-1000,0-2000,0-3200,0-4500 s/mm^2.Receiver operating characteristic curve（ROC） analysis was performed to evaluate the diagnostic performance of the parameters.Results All parameters except D＊ showed significant differences between cancerous and benign peripheral tissues in all 4 b-value ranges.The areas under the ROC curve（AUCs） of ADCs were comparable in the 0-3200 s/mm^2 and 0-4500 s/mm^2b-value ranges（P=0.980）,and were significantly higher than that of 0-1000 s/mm^2 and 0-2000 s/mm^2b-value ranges（P〈0.05 for all）.The AUCs of ADC and K_（app）in 0-2000 s/mm^2and0-3200 s/mm^2b-value ranges were similar（P =0.07 and P =0.954）,and were significantly higher than that of other parameters（P〈0.001 for all）.The AUC of ADCs in 0-4500 s/mm^2b-value range was significantly higher than that of K_（app）（P=0.002）.The AUCs of both ADCs and K_（app）were significantly higher than that of other parameters（P〈0.001 for all）.Conclusion There is no obvious advantage for IVIM-or DKI-derived parameters compared to ADC for differentiating cancerous from benign prostate tissue.ADC derived from conventional mono-exponential high b-value（3200 s/mm^2） is an optimal parameter for peripheral zone prostate cancer detection.