拉伸指数模型多b值扩散成像对非酒精性脂肪肝定量诊断的价值

摘要

Objective To evaluate the feasibility of diffusion parameters obtained from mono-exponential and stretched exponential diffusion-weighted imaging models in staging of nonalcoholic fatty liver disease and compare the diagnosis ability of nonalcoholic steatohepatitis.Methods Thirty-two 12-week-old male New Zealand rabbits,about 2.5 kg of each,were randomly divided into five groups.To obtained different severity groups of NAFLD,a variety of diet (from standard to high-fat,high cholesterol chow) were feed for different periods before liver diffusion imaging was performed by using 3.0 T MR imaging system (Discovery 750W GE health care),the value of ADC,stretched exponential model parameters distributed diffusion coefficient (DDC) and α (water molecular diffusion heterogeneity index) were measured.Liver specimens were obtained for pathological grading (NAFLD activity scoring system).The diffusion parameters of each group of NAFLD were compared by ANOVA,LSD-t test was utilized to pairwise comparison between different grades of NAFLD.Spearman rank correlation analysis was used to evaluate the correlation between ADC,DDC,α and different severity groups of NAFLD.ROC curve was compared to evaluate the diagnostic efficiency of MR parameters for NASH.Results α was significant different between borderline and NASH groups (0.65 ± 0.05 vs 0.72 ± 0.07;P＜0.05);ADC and DDC showed no statistical difference between borderline and NASH groups (ADC:(1.09±0.14)× 10-3 vs (1.04±0.24)× 10-3 mm2/s;DDC:(0.73 ± 0.08)× 10-3 vs (0.66 ±0.19)× 10-3 mm2/s;P＞0.05);ADC and DDC were negatively correlated with NAFLD,and the correlation coefficients were-0.552,-0.596,respectively (P＜0.05).α was found to be positively correlated with advancement of NAFLD,the correlation coefficient was 0.729 (P＜0.0S).In terms of the diagnostic efficiency of NASH,the AUC of ADC,DDC and α were 0.736,0.784,0.900,respectively,α was significantly greater than ADC in diagnosis of NASH (P＜0.05).Conclusion Stretched exponential model parameter α (water molecular diffusion heterogeneity index) could be utilized to identify NAFLD.α may provide more information and improve the staging of NASH compared with conventional diffusion parameters.%目的 探讨磁共振多b值扩散成像拉伸指数模型对非酒精性脂肪肝定量分级的诊断价值及早期诊断非酒精性脂肪性肝炎的可行性.方法 32只12周龄雄性新西兰大白兔,体质量2.5 kg,随机分成5组,采用普通饲料和高脂饲养喂养不同周期以获取不同严重等级非酒精性脂肪肝动物模型.采用3.0 T磁共振进行肝脏扩散成像,分别测量肝脏传统扩散成像表观扩散系数(ADC)值、拉伸指数模型参数扩散异质性指数(α)和扩散分布指数(DDC).获取肝脏标本进行非酒精性脂肪性肝病活动度积分(NAS).非酒精性脂肪肝不同等级间的磁共振参数比较采用单因素方差分析,组内两两比较采用LSD法.Spearman等级相关检验ADC值、DDC值及α值与非酒精性脂肪肝等级程度的相关性.采用比较受试者工作特征(ROC)曲线评价各参数对非酒精性脂肪性肝炎的诊断效能.结果 α值在临界组和非酒精性脂肪性肝炎组间差异有统计学意义(0.65±0.05比0.72±0.07,P＜0.05).ADC和DDC在临界组和非酒精性脂肪性肝炎组间差异无统计学意义[ADC:(1.09±0.14) ×10-3比(1.04±0.24)×10-3 mm2/s;DDC:(0.73±0.08)× 10-3比(0.66±0.19)×10-3mmVs,均P＞0.05].ADC值和DDC值与非酒精性脂肪肝病等级程度呈负相关(r=-0.552、-0.596,均P＜0.05).α值与非酒精性脂肪肝病等级程度呈正相关(r=0.729,P＜0.05).对非酒精性脂肪性肝炎诊断效能上,ADC值、DDC值及α值的曲线下面积AUC分别为0.736、0.784、0.900,α值对非酒精性脂肪性肝炎的诊断效能优于ADC值(P＜0.05).结论 拉伸指数模型参数α值可用于非酒精性脂肪肝病的定量分级诊断,α值对非酒精性脂肪性肝炎诊断效能优于传统扩散ADC值.