title: Shear Wave Elastography of Focal Liver Lesion: Intraobserver Reproducibility and Elasticity Characterization.
abstract: OBJECTIVE
  The aim of the study was to evaluate the intraobserver reproducibility and to determine the elasticity characteristics of focal liver lesions (FLLs) by shear wave elastography (SWE).
  
  
  METHODS
  One hundred thirty-six FLLs in 118 patients were examined with SWE for quantitative and qualitative assessment of stiffness. Three SWE images were obtained for each lesion and liver parenchyma by 1 radiologist. Intraobserver reproducibility was assessed by intraclass correlation coefficients (ICCs). Patient and lesion factors that can affect the reproducibility were evaluated. For characterization of the lesion elasticity, the difference in stiffness between the groups of lesions was evaluated.
  
  
  RESULTS
  The mean (SD) diameter and depth of the lesions were 3.98 (2.07) and 4.4 (1.59) cm, respectively. The ICC of intraobserver reproducibility was 0.763. Deep-seated lesions (≥6 cm; ICC, 0.621) showed significantly lower intraobserver reproducibility compared with superficial lesions (ICC, 0.793; P = 0.047). Stiffness values of malignant lesions (n = 85, 60.41 [47.81] kPa) were significantly higher than those of benign lesions (n = 51, 22.05 [17.24] kPa, P < 0.0001). Mean (SD) stiffness of hepatocellular carcinoma (45.72 [35.65] kPa) was significantly lower than that of metastasis (67.43 [43.39] kPa) and was significantly higher than benign FLLs (22.05 [17.24] kPa). However, mean (SD) lesion-parenchyma ratio of hepatocellular carcinoma (3.76 [4]) was not significantly different from that of benign FLLs (3.7 [3.77]).
  
  
  CONCLUSIONS
  Overall, intraobserver reproducibility of SWE in evaluation of FLLs was excellent, but it can be affected by lesion depth. In addition, SWE is helpful in elasticity characterization of FLLs.
authors.affiliation: Department of Radiology, Konkuk University School of Medicine, Seoul, South Korea.
authors.forename: Hee Sun
authors.initials: HS
authors.lastname: Park
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Kim
authors.forename: Mi Hye
authors.initials: MH
authors.lastname: Yu
authors.forename: Sung Il
authors.initials: SI
authors.lastname: Jung
authors.forename: Hae Jeong
authors.initials: HJ
authors.lastname: Jeon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D004548:Elasticity; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008107:Liver Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D055815:Young Adult