title: Motion freeze for respiration motion correction in PET/CT: a preliminary investigation with lung cancer patient data.
abstract: OBJECTIVE
  Respiratory motion presents significant challenges for accurate PET/CT. It often introduces apparent increase of lesion size, reduction of measured standardized uptake value (SUV), and the mismatch in PET/CT fusion images. In this study, we developed the motion freeze method to use 100% of the counts collected by recombining the counts acquired from all phases of gated PET data into a single 3D PET data, with correction of respiration by deformable image registration.
  
  
  METHODS
  Six patients with diagnosis of lung cancer confirmed by oncologists were recruited. PET/CT scans were performed with Discovery STE system. The 4D PET/CT with the Varian real-time position management for respiratory motion tracking was followed by a clinical 3D PET/CT scan procedure in the static mode. Motion freeze applies the deformation matrices calculated by optical flow method to generate a single 3D effective PET image using the data from all the 4D PET phases.
  
  
  RESULTS
  The increase in SUV and decrease in tumor size with motion freeze for all lesions compared to the results from 3D and 4D was observed in the preliminary data of lung cancer patients. In addition, motion freeze substantially reduced tumor mismatch between the CT image and the corresponding PET images.
  
  
  CONCLUSIONS
  Motion freeze integrating 100% of the PET counts has the potential to eliminate the influences induced by respiratory motion in PET data.
authors.affiliation: Department of Biomedical Imaging and Radiological Science, China Medical University, 91 Hsueh-Shih Road, Taichung City, Taiwan ; Department of Biomedical Informatics, Asia University, Taichung City, Taiwan.
authors.forename: Tzung-Chi
authors.initials: TC
authors.lastname: Huang
authors.affiliation: Department of Biomedical Imaging and Radiological Science, China Medical University, 91 Hsueh-Shih Road, Taichung City, Taiwan.
authors.forename: Kuei-Ting
authors.initials: KT
authors.lastname: Chou
authors.affiliation: Department of Radiation Oncology, China Medical University Hospital, Taichung City, Taiwan.
authors.forename: Yao-Ching
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Moffitt Cancer Center, Tampa, FL, USA.
authors.forename: Geoffrey
authors.identifier: 0000-0001-8548-788X
authors.initials: G
authors.lastname: Zhang
mesh_terms: D016477:Artifacts; D005260:Female; D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008175:Lung Neoplasms / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009038:Motion; D064847:Multimodal Imaging / Q000379:methods*; D010865:Pilot Projects; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity