title: Quantitative imaging: quantification of liver shape on CT using the statistical shape model to evaluate hepatic fibrosis.
abstract: OBJECTIVE
  To investigate the usefulness of the statistical shape model (SSM) for the quantification of liver shape to evaluate hepatic fibrosis.
  
  
  METHODS
  Ninety-one subjects (45 men and 46 women; age range, 20-75 years) were included in this retrospective study: 54 potential liver donors and 37 patients with chronic liver disease. The subjects were classified histopathologically according to the fibrosis stage as follows: F0 (n = 55); F1 (n = 6); F2 (3); F3 (n = 1); and F4 (n = 26). Each subject underwent contrast-enhanced computed tomography (CT) using a 64-channel scanner (0.625-mm slice thickness). An abdominal radiologist manually traced the liver boundaries on every CT section using an image workstation; the boundaries were used for subsequent analyses. An SSM was constructed by the principal component analysis of the subject data set, which defined a parametric model of the liver shapes. The shape parameters were calculated by fitting SSM to the segmented liver shape of each subject and were used for the training of a linear support vector regression (SVR), which classifies the liver fibrosis stage to maximize the area under the receiver operating characteristic curve (AUC). SSM/SVR models were constructed and were validated in a leave-one-out manner. The performance of our technique was compared to those of two previously reported types of caudate-right lobe ratios (C/RL-m and C/RL-r).
  
  
  RESULTS
  In our SSM/SVR models, the AUC values for the classification of liver fibrosis were 0.96 (F0 vs. F1-4), 0.95 (F0-1 vs. F2-4), 0.96 (F0-2 vs. F3-4), and 0.95 (F0-3 vs. F4). These values were significantly superior to AUC values using the C/RL-m or C/RL-r ratios (P < .005).
  
  
  CONCLUSIONS
  SSM was useful for estimating the stage of hepatic fibrosis by quantifying liver shape.
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, D1, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: mhori@radiol.med.osaka-u.ac.jp.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, D1, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Okada
authors.affiliation: College of Information Science and Engineering, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Higashiura
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, D1, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Sato
authors.affiliation: College of Information Science and Engineering, Ritsumeikan University, Kusatsu, Shiga, Japan.
authors.forename: Yen-Wei
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, D1, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tonsok
authors.initials: T
authors.lastname: Kim
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, D1, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Onishi
authors.affiliation: Department of Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Eguchi
authors.affiliation: Department of Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nagano
authors.affiliation: Department of Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; Division of Health Science, Osaka University, Suita, Osaka, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Umeshita
authors.affiliation: Department of Pathology, Ishikiriseiki Hospital, Higashiosaka, Osaka, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Wakasa
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, D1, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Tomiyama
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging*; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Quantitative evaluation; cirrhosis; computed tomography, x-ray; diagnosis, computer-assisted; fibrosis, liver