| Objectives(1)To comprehend hepatic fat distribution and to find out which segment is closest to the total estimated hepatic fat amount using magnetic resonance imaging-proton density fat fraction(MRI-PDFF).(2)To compare ultrasound attenuation parameter(UAP)using Fibro Touch with MRI-PDFF for diagnosis of hepatic steatosis in patients with nonalcoholic fatty liver disease(NAFLD).Methods(1)410 subjects were enrolled in the study.There were 108 subjects with hepatic steatosis grade 0,110 subjects with hepatic steatosis grade 1,67 subjects with hepatic steatosis grade 2,125 subjects with hepatic steatosis grade 3.MRI-PDFF measurements were performed by placing regions of interest in all liver segments and random largest area.Total hepatic fat was estimated by the weighted mean of each segment reflecting their respective segmental volumes.Spearman correlation coefficient,Kappa statistic and intraclass correlation coefficient were used for statistical analyses.(2)We performed a study with 223 subjects including 123 NAFLD and100 normal control,undergoing UAP measurement and PDFF measurement.All patients received a standard clinical evaluation,including collection of history,anthropometric examination,and biochemical tests.Spearman correlation coefficient,receiver operating characteristics curve and linear regression analyses were used for statistical analyses.Results(1)Intrahepatic fat distribution was heterogeneous.The mean PDFF was higher in the right lobe than the left.In contrast,the PDFF variability was higher in the left lobe than the right.Intrahepatic fat distribution in subjects with hepatic steatosis grade 0 was different from that in subjects with hepatic steatosis grade ≥1.Segment V had the lowest segmental PDFF,while segment VII had the highest in subjects with hepatic steatosis grade 0.Segment I had the lowest segmental PDFF,while segment VIII had the highest in subjects with hepatic steatosis grade ≥1.PDFF of segment V and random largest area were closest to the total estimated hepatic fat amount.Degree of hepatic steatosis was the most important risk factor of hepatic heterogeneity.The variability of intrahepatic steatosis was positively correlated with degree of hepatic steatosis,waist circumference,body mass index,alanine aminotransferase,prealbumin,triglyceride,total cholesterol and low density lipoprotein cholesterol.(2)UAP identified liver MRI-PDFF≥3.71%,≥13.03% and ≥16.37% with area under the receiver operating characteristic curve(AUROC)values of0.87(95%CI: 0.82～0.92),0.89(95%CI: 0.84～0.92)and 0.88(95%CI:0.83～0.92).The best cutoff values were 249.94 d B/m,280.92 d B/m and281.10 d B/m.UAP identified liver PDFF≥5.20%,≥11.30% and ≥17.10% with AUROC values of 0.90(95%CI: 0.85～0.93),0.86(95%CI: 0.80～0.90)and0.88(95%CI: 0.83～0.92).The best cutoff values were 273.07 d B/m,273.92 d B/m and 276.50 d B/m.In general,UAP was positively correlated with PDFF.But UAP had no significant correlation with PDFF when PDFF<3.71%.UAP was positively correlated with degree of hepatic steatosis,waist circumference,BMI and PAB.Degree of hepatic steatosis,variability of intrahepatic steatosis,waist circumference,body mass index,prealbumin,triglyceride and platelet might be associated with discrepancies between UAP and PDFF.ConclusionsIntrahepatic fat distribution was heterogeneous.MRI-PDFF of segment V and random largest area were closest to the total estimated hepatic fat amount.UAP measurement provided a noninvasive,accurate estimation of grading of hepatic steatosis in patients with NAFLD. |
