title: Four-Dimensional Magnetic Resonance Imaging With 3-Dimensional Radial Sampling and Self-Gating-Based K-Space Sorting: Early Clinical Experience on Pancreatic Cancer Patients.
abstract: OBJECTIVE
  To apply a novel self-gating k-space sorted 4-dimensional MRI (SG-KS-4D-MRI) method to overcome limitations due to anisotropic resolution and rebinning artifacts and to monitor pancreatic tumor motion.
  
  
  METHODS
  Ten patients were imaged using 4D-CT, cine 2-dimensional MRI (2D-MRI), and the SG-KS-4D-MRI, which is a spoiled gradient recalled echo sequence with 3-dimensional radial-sampling k-space projections and 1-dimensional projection-based self-gating. Tumor volumes were defined on all phases in both 4D-MRI and 4D-CT and then compared.
  
  
  RESULTS
  An isotropic resolution of 1.56 mm was achieved in the SG-KS-4D-MRI images, which showed superior soft-tissue contrast to 4D-CT and appeared to be free of stitching artifacts. The tumor motion trajectory cross-correlations (mean ± SD) between SG-KS-4D-MRI and cine 2D-MRI in superior-inferior, anterior-posterior, and medial-lateral directions were 0.93 ± 0.03, 0.83 ± 0.10, and 0.74 ± 0.18, respectively. The tumor motion trajectories cross-correlations between SG-KS-4D-MRI and 4D-CT in superior-inferior, anterior-posterior, and medial-lateral directions were 0.91 ± 0.06, 0.72 ± 0.16, and 0.44 ± 0.24, respectively. The average standard deviation of gross tumor volume calculated from the 10 breathing phases was 0.81 cm(3) and 1.02 cm(3) for SG-KS-4D-MRI and 4D-CT, respectively (P=.012).
  
  
  CONCLUSIONS
  A novel SG-KS-4D-MRI acquisition method capable of reconstructing rebinning artifact-free, high-resolution 4D-MRI images was used to quantify pancreas tumor motion. The resultant pancreatic tumor motion trajectories agreed well with 2D-cine-MRI and 4D-CT. The pancreatic tumor volumes shown in the different phases for the SG-KS-4D-MRI were statistically significantly more consistent than those in the 4D-CT.
authors.affiliation: Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, California. Electronic address: wensha.yang@cshs.org.
authors.forename: Wensha
authors.initials: W
authors.lastname: Yang
authors.affiliation: Biomedical Imaging Research Institute, Department of Biomedical Sciences, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Fan
authors.affiliation: Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Richard
authors.initials: R
authors.lastname: Tuli
authors.affiliation: Biomedical Imaging Research Institute, Department of Biomedical Sciences, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.affiliation: Biomedical Imaging Research Institute, Department of Biomedical Sciences, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Jianing
authors.initials: J
authors.lastname: Pang
authors.affiliation: Department of Imaging, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Ashley
authors.initials: A
authors.lastname: Wachsman
authors.affiliation: Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Robert
authors.initials: R
authors.lastname: Reznik
authors.affiliation: Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Howard
authors.initials: H
authors.lastname: Sandler
authors.affiliation: Biomedical Imaging Research Institute, Department of Biomedical Sciences, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Debiao
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, California.
authors.forename: Benedick A
authors.initials: BA
authors.lastname: Fraass
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D005260:Female; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D008875:Middle Aged; D009068:Movement; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D011446:Prospective Studies; D012119:Respiration; D047368:Tumor Burden