title: Prediction and reduction of motion artifacts in free-breathing dynamic contrast enhanced CT perfusion imaging of primary and metastatic intrahepatic tumors.
abstract: OBJECTIVE
  To develop and evaluate a method for predicting and reducing motion artifacts in free-breathing liver perfusion computed tomography (CT) scanning with couch shuttling and to compare tumor and liver parenchyma perfusion values.
  
  
  METHODS
  Thirty patients (23 males, 7 females, median age of 74 years) with primary or metastatic intrahepatic tumors underwent dynamic contrast enhanced CT scans with axial shuttling. A semiautomatic respiratory motion correction algorithm was applied to align the acquired images along the z-axis. Perfusion maps were generated using the dual-input Johnson-Wilson model. Root mean squared deviation (RMSD) maps of the model fit to the pixel time-density curves were calculated.
  
  
  RESULTS
  Precorrection RMSD correlated positively with magnitude of change in functional values resulting from motion. Blood flow, arterial blood flow, and permeability surface product were significantly increased in tumor compared to normal tissue (P < .05), blood volume was significantly reduced in tumor compared to normal tissue (P < .05). In a subgroup of patients with high-amplitude motion significant difference was observed between uncorrected and motion correction blood flow maps.
  
  
  CONCLUSIONS
  Patients can breathe freely during hepatic perfusion imaging if retrospective motion correction is applied to reduce motion artifacts. RMSD provides a regional assessment of motion induced artifacts in liver perfusion maps.
authors.affiliation: Department of Physics & Astronomy, University of Western Ontario, 1151 Richmond Street, London, ON, Canada, N6A 3K7. njensen6@uwo.ca
authors.forename: Nikolaj K G
authors.initials: NK
authors.lastname: Jensen
authors.forename: Michael
authors.initials: M
authors.lastname: Lock
authors.forename: Barbara
authors.initials: B
authors.lastname: Fisher
authors.forename: Roman
authors.initials: R
authors.lastname: Kozak
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Chen
authors.forename: Jeff
authors.initials: J
authors.lastname: Chen
authors.forename: Eugene
authors.initials: E
authors.lastname: Wong
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D001783:Blood Flow Velocity; D001810:Blood Volume; D062485:Breath Holding; D003287:Contrast Media; D005260:Female; D006499:Hepatic Artery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D009068:Movement; D011169:Portal Vein; D012119:Respiration; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media