title: Dynamic Volume Assessment of Hepatocellular Carcinoma in Rat Livers Using a Clinical 3T MRI and Novel Segmentation.
abstract: OBJECTIVE
  In vivo liver cancer research commonly uses rodent models. One of the limitations of such models is the lack of accurate and reproducible endpoints for a dynamic assessment of growing tumor nodules. The aim of this study was to validate a noninvasive, true volume segmentation method using two rat hepatocellular carcinoma (HCC) models, correlating magnetic resonance imaging (MRI) with histological volume measurement, and with blood levels of α-fetoprotein.
  
  
  METHODS
  We used 3T clinical MRI to quantify tumor volume with follow-up over time. Using two distinct rat HCC models, calculated MRI tumor volumes were correlated with volumes from histological sections, or with blood levels of α-fetoprotein. Eleven rats, comprising six Buffalo rats (n = 9 scans) and five Fischer rats (n = 14 tumors), were injected in the portal vein with 2.5 × 105and 2.0 × 106syngeneic HCC cells, respectively. Longitudinal (T1) relaxation time- and transverse (T2) relaxation time-weighted MR images were acquired.
  
  
  RESULTS
  The three-dimensional (3D) T1-weighted gradient echo had 0.35-mm isotropic resolution allowing accurate semi-automatic volume segmentation. 2D T2-weighted imaging provided high tumor contrast. Segmentation of combined 3D gradient echo T1-weighted images and 2D turbo spin echo T2-weighted images provided excellent correlation with histology (y = 0.866x + 0.034, R² = 0.997 p < .0001) and with α-fetoprotein (y = 0.736x + 1.077, R² = 0.976, p < .0001). There was robust inter- and intra-observer reproducibility (intra-class correlation coefficient > 0.998, p < .0001).
  
  
  CONCLUSIONS
  We have developed a novel, noninvasive contrast imaging protocol which enables semi-automatic 3D volume quantification to analyze nonspherical tumor nodules and to follow up the growth of tumor nodules over time.
authors.affiliation: a Divisions of Abdominal and Transplantation Surgery, Hepato-Pancreato-Biliary Centre, Department of Surgery , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Lorenzo A
authors.initials: LA
authors.lastname: Orci
authors.affiliation: a Divisions of Abdominal and Transplantation Surgery, Hepato-Pancreato-Biliary Centre, Department of Surgery , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Graziano
authors.initials: G
authors.lastname: Oldani
authors.affiliation: a Divisions of Abdominal and Transplantation Surgery, Hepato-Pancreato-Biliary Centre, Department of Surgery , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Lacotte
authors.affiliation: a Divisions of Abdominal and Transplantation Surgery, Hepato-Pancreato-Biliary Centre, Department of Surgery , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Florence
authors.initials: F
authors.lastname: Slits
authors.affiliation: b Division of Radiology , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Iris
authors.initials: I
authors.lastname: Friedli
authors.affiliation: c Institute of Anatomy, Paracelsus Medical University , Salzburg , Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wirth
authors.affiliation: a Divisions of Abdominal and Transplantation Surgery, Hepato-Pancreato-Biliary Centre, Department of Surgery , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Toso
authors.affiliation: b Division of Radiology , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Vallée
authors.affiliation: b Division of Radiology , University Hospitals of Geneva and Faculty of Medicine, University of Geneva , Geneva , Switzerland.
authors.forename: Lindsey A
authors.identifier: http://orcid.org/0000-0002-2044-1220
authors.initials: LA
authors.lastname: Crowe
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008099:Liver / Q000000981:diagnostic imaging* / Q000473:pathology; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051381:Rats; D011915:Rats, Inbred BUF; D011916:Rats, Inbred F344; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D013997:Time Factors; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays
keywords: 3T; MRI; hepatocellular carcinoma; histology; quantitative; rat; volume segmentation