title: Value of the ultrasound attenuation index for noninvasive quantitative estimation of hepatic steatosis.
abstract: OBJECTIVE
  To assess the value of the ultrasound (US) attenuation index for noninvasive estimation of hepatic steatosis and determine its optimal cutoff value for severe steatosis in potential living liver donors.
  
  
  METHODS
  Two hundred forty potential donors underwent US-guided biopsy. The target site was scanned at 4 and 8 MHz. On the sonogram, the observer drew 3 × 3-mm square regions of interest in superficial (3-cm) and deep (5-cm) areas. The attenuation index was defined as the difference between superficial and deep echogenicity/superficial echogenicity × 100. On biopsy specimens, replacement of hepatic parenchyma was evaluated on a percentage scale. Severe steatosis was defined as macrovesicular fatty change of 30% or greater. Spearman rank correlation (ρ) was used to determine correlation coefficients between the attenuation index and steatosis degree; receiver operating characteristic analysis was performed to determine the optimal attenuation index cutoff value for severe steatosis.
  
  
  RESULTS
  The median steatosis degree was 3% (interquartile range [IQR], 0%-10%). Severe steatosis was found in 10 donors. The attenuation index ranged from -27.4 to 36.6 (median, 4.0; IQR, -1.6-10.4) at 4 MHz and -18.0 to 78.1 (median, 14.5; IQR, 7.2-21.9) at 8 MHz. There was a minimal positive correlation between steatosis and the attenuation index at 4 MHz (total steatosis: ρ = 0.339; P < .001; macrovesicular steatosis: ρ = 0.360; P < .001). However, there was a significant moderate correlation between steatosis and the attenuation index at 8 MHz (total steatosis: ρ = 0.669; P < .001; macrovesicular steatosis: ρ = 0.645; P < .001). The optimal attenuation index cutoff value for severe steatosis at 8 MHz was 31.0.
  
  
  CONCLUSIONS
  The US attenuation index at 8 MHz is a useful indicator for noninvasive quantitative estimation of hepatic steatosis and diagnosis of severe steatosis in potential living liver donors.
authors: Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors: Heon-Ju
authors: HJ
authors: Kwon
authors: Kyoung Won
authors: KW
authors: Kim
authors: So Jung
authors: SJ
authors: Lee
authors: So Yeon
authors: SY
authors: Kim
authors: Jong Seok
authors: JS
authors: Lee
authors: Hyoung Jung
authors: HJ
authors: Kim
authors: Gi-Won
authors: GW
authors: Song
authors: Sun A
authors: SA
authors: Kim
authors: Eun Sil
authors: ES
authors: Yu
authors: Jeongjin
authors: J
authors: Lee
authors: Shin
authors: S
authors: Hwang
authors: Sung Gyu
authors: SG
authors: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D001707:Biopsy, Needle; D005234:Fatty Liver / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D061705:Image-Guided Biopsy; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology; D019520:Living Donors / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D014463:Ultrasonography; D055815:Young Adult