title: Comparative assessment of liver tumor motion using cine-magnetic resonance imaging versus 4-dimensional computed tomography.
abstract: OBJECTIVE
  To compare the extent of tumor motion between 4-dimensional CT (4DCT) and cine-MRI in patients with hepatic tumors treated with radiation therapy.
  
  
  METHODS
  Patients with liver tumors who underwent 4DCT and 2-dimensional biplanar cine-MRI scans during simulation were retrospectively reviewed to determine the extent of target motion in the superior-inferior, anterior-posterior, and lateral directions. Cine-MRI was performed over 5 minutes. Tumor motion from MRI was determined by tracking the centroid of the gross tumor volume using deformable image registration. Motion estimates from 4DCT were performed by evaluation of the fiducial, residual contrast (or liver contour) positions in each CT phase.
  
  
  RESULTS
  Sixteen patients with hepatocellular carcinoma (n=11), cholangiocarcinoma (n=3), and liver metastasis (n=2) were reviewed. Cine-MRI motion was larger than 4DCT for the superior-inferior direction in 50% of patients by a median of 3.0 mm (range, 1.5-7 mm), the anterior-posterior direction in 44% of patients by a median of 2.5 mm (range, 1-5.5 mm), and laterally in 63% of patients by a median of 1.1 mm (range, 0.2-4.5 mm).
  
  
  CONCLUSIONS
  Cine-MRI frequently detects larger differences in hepatic intrafraction tumor motion when compared with 4DCT most notably in the superior-inferior direction, and may be useful when assessing the need for or treating without respiratory management, particularly in patients with unreliable 4DCT imaging. Margins wider than the internal target volume as defined by 4DCT were required to encompass nearly all the motion detected by cine-MRI for some of the patients in this study.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Annemarie T
authors.initials: AT
authors.lastname: Fernandes
authors.affiliation: Department of Radiation Oncology, University of Washington, Seattle, Washington.
authors.forename: Smith
authors.initials: S
authors.lastname: Apisarnthanarax
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Lingshu
authors.initials: L
authors.lastname: Yin
authors.affiliation: Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey.
authors.forename: Wei
authors.initials: W
authors.lastname: Zou
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Mark
authors.initials: M
authors.lastname: Rosen
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: John P
authors.initials: JP
authors.lastname: Plastaras
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Edgar
authors.initials: E
authors.lastname: Ben-Josef
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: James M
authors.initials: JM
authors.lastname: Metz
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: kevin.teo@uphs.upenn.edu.
authors.forename: Boon-Keng
authors.initials: BK
authors.lastname: Teo
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D018281:Cholangiocarcinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000556:secondary; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D009068:Movement; D047368:Tumor Burden