title: Gd-EOB enhanced MRI T1-weighted 3D-GRE with and without elevated flip angle modulation for threshold-based liver volume segmentation.
abstract: BACKGROUND
  Despite novel software solutions, liver volume segmentation is still a time-consuming procedure and often requires further manual optimization. With the high signal intensity of the liver parenchyma in Gd-EOB enhanced magnetic resonance imaging (MRI), liver volume segmentation may be improved.
  
  
  OBJECTIVE
  To evaluate the practicability of threshold-based segmentation of the liver volume using Gd-EOB-enhanced MRI including a customized three-dimensional (3D) sequence.
  
  
  METHODS
  A total of 20 patients examined with Gd-EOB MRI (hepatobiliary phase T1-weighted (T1W) 3D sequence [VIBE]; flip angle [FA], 10° and 30°) were enrolled in this retrospective study. The datasets were independently processed by two blinded observers (O1 and O2) in two ways: manual (man) and threshold-based (thresh; study method) segmentation of the liver each followed by an optimization step (man+opt and thresh+opt; man+opt [FA10°] served as reference method). Resulting liver volumes and segmentation times were compared. A liver conversion factor was calculated in percent, describing the non-hepatocellular fraction of the total liver volume, i.e. bile ducts and vessels.
  
  
  RESULTS
  Thresh+opt (FA10°) was significantly faster compared to the reference method leading to a median volume overestimation of 4%/8% (P < 0.001). Using thresh+opt (FA30°), segmentation was even faster (P < 0.001) and even reduced median volume deviation of 0%/2% (O1/O2; both P > 0.2). The liver conversion factor was found to be 10%.
  
  
  CONCLUSIONS
  Threshold-based liver segmentation employing Gd-EOB-enhanced hepatobiliary phase standard T1W 3D sequence is accurate and time-saving. The performance of this approach can be further improved by increasing the FA.
authors.affiliation: Klinik für Strahlenheilkunde, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany christian.grieser@charite.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Grieser
authors.affiliation: Klinik für Strahlenheilkunde, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Timm
authors.initials: T
authors.lastname: Denecke
authors.affiliation: Klinik für Strahlenheilkunde, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Jan-Holger
authors.initials: JH
authors.lastname: Rothe
authors.affiliation: Klinik für Strahlenheilkunde, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Geisel
authors.affiliation: Klinik für Strahlenheilkunde, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Stelter
authors.affiliation: Klinik für Strahlenheilkunde, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Thula
authors.initials: T
authors.lastname: Cannon Walter
authors.affiliation: Klinik für Allgemein, Viszeral- und Transplantationschirurgie, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Seehofer
authors.affiliation: Klinik für Strahlenheilkunde, Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Ingo G
authors.initials: IG
authors.lastname: Steffen
mesh_terms: D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement; D021621:Imaging, Three-Dimensional; D008099:Liver / Q000473:pathology*; D008113:Liver Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Gd-EOB; Liver MRI; flip angle; gadoxetic acid; liver segmentation; liver volume