拉伸指数模型扩散加权成像对进展期肝纤维化的诊断价值

Value of stretched exponential model diffusion-weighted imaging in diagnosis of advanced liver fibrosis

目的探讨基于拉伸指数模型的扩散加权成像(DWI)诊断进展期肝纤维化的临床价值。方法回顾性收集2015年6月至2020年2月期间在成都医学院第一附属医院行肝脏DWI检查并经病理学检查证实的不同程度肝纤维化的慢性肝病患者,另收集同期同院行上腹部磁共振检查且无肝脏疾病或影响肝功能疾病的患者而需做上腹部磁共振检查的患者作为对照。计算单指数模型拟合的表观扩散系数(ADC)和拉伸指数模型拟合的扩散分布系数(DDC)和扩散异质性指数(α)。肝纤维化分期标准采用Metavir评分系统。比较不同患者间ADC、DDC及α值的差异,采用受试者工作特征曲线下面积(AUC)分析这3个定量参数对进展期肝纤维化的诊断效能。结果本组共收集慢性肝病患者42例,其中轻度纤维化(S1–S2)16例和进展期纤维化(≥S3)24例;对照患者15例。轻度和进展期纤维化患者的ADC、DCC和α值均明显低于对照患者(P<0.05)。ADC、DCC和α值诊断肝纤维化(≥S1)的AUC值分别为0.915、0.974和0.835,在诊断进展期肝纤维化(≥S3)的AUC值分别为0.744、0.869和0.758,但是这3个指标的AUC值比较差异均无统计学意义(P>0.05)。结论基于拉伸指数模型的定量参数DDC对进展期肝纤维化的诊断具有一定的价值。

Objective To investigate the utility of stretched exponential model diffusion-weighted imaging(DWI) for diagnosing of advanced liver fibrosis. Methods The patients with chronic liver disease complicated with vary degrees of fibrosis confirmed by pathological examination underwent DWI using different b-values(0, 50, 600 s/mm2) at the First Affiliated Hospital of Chengdu Medical College from June 2015 to February 2020 were collected. In addition,patients who underwent upper abdominal MRI examination in the same hospital at the same time and had no liver disease or disease affecting liver function were collected as a control group. The apparent diffusion coefficient(ADC) was calculated by using a mono-exponential model. The distributed diffusion coefficient(DDC) and water molecular diffusion heterogeneity index(α) were calculated by using a stretched exponential model. The fibrosis stage was evaluated by using the Metavir scoring system. The ADC, DDC, and α among different fibrosis groups were compared. The receiver operating characteristic(ROC) curve was used to analyze the diagnostic efficacy of these three quantitative parameters for advanced liver fibrosis. Results A total of 42 patients with chronic liver disease were collected in this study, including mild liver fibrosis(S1–S2, n=16) and advanced liver fibrosi(≥S3, n=24);15 patients in the control group. The values of ADC, DDC, and α of the patients with mild liver fibrosis and advanced liver fibrosis were significantly lower than those of the control patients(P<0.05). The area under the ROC curve of ADC, DCC, and α in diagnosing liver fibrosis(≥S1) was0.915, 0.974, and 0.835, respectively, which in diagnosing advanced liver fibrosis(≥S3) was 0.744, 0.869, and 0.758,respectively. However, further the area under ROC curve among these three metrics had no statistical differences(P>0.05).Conclusion DDC based on stretched exponential model is valuable for diagnosis of advanced liver fibrosis.