title: Respiratory-gated positron emission tomography and breath-hold computed tomography coupling to reduce the influence of respiratory motion: methodology and feasibility.
abstract: BACKGROUND
  Respiratory motion causes uptake in positron emission tomography (PET) images of chest and abdominal structures to be blurred and reduced in intensity.
  
  
  OBJECTIVE
  To compare two respiratory-gated PET binning methods (based on frequency and amplitude analyses of the respiratory signal) and to propose a "BH-based" method based on an additional breath-hold computed tomography (CT) acquisition.
  
  
  METHODS
  Respiratory-gated PET consists in list-mode (LM) acquisition with simultaneous respiratory signal recording. A phantom study featured rectilinear movement of a 0.5-ml sphere filled with (18)F-fluorodeoxyglucose ((18)F-FDG) solution, placed in a radioactive background (sphere-to-background contrast 6:1). Two patients were also examined. Three figures of merit were calculated: the target-to-background ratio profile (TBRP) in the axial direction through the uptake (i.e., the sphere or lesion), full-width-at-half-maximum (FWHM) values, and maximized standard uptake values (SUV(max)).
  
  
  RESULTS
  In the phantom study, the peak TBRP was 0.9 for non-gated volume, 1.83 for BH-based volume, and varied between 1.13 and 1.73 for Freq-based volumes and between 1.34 and 1.66 for Amp-based volumes. A reference volume (REF-static) was also acquired for the phantom (in a static, "expiratory" state), with a peak TBRP at 1.88. TBRPs were computed for patient data, with higher peak values for all gated volumes than for non-gated volumes.
  
  
  CONCLUSIONS
  Respiratory-gated PET acquisition reduces the blurring effect and increases image contrast. However, Freq-based and Amp-based volumes are still influenced by inappropriate attenuation correction and misregistration of mobile lesions on CT images. The proposed BH-based method both reduces motion artifacts and improves PET-CT registration.
authors.affiliation: Department of Nuclear Medicine, University Hospital, Amiens, France.
authors.forename: J
authors.initials: J
authors.lastname: Daouk
authors.forename: L
authors.initials: L
authors.lastname: Fin
authors.forename: P
authors.initials: P
authors.lastname: Bailly
authors.forename: M-E
authors.initials: ME
authors.lastname: Meyer
mesh_terms: D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage; D004867:Equipment Design; D005240:Feasibility Studies; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D055425:Respiratory-Gated Imaging Techniques; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D019788:Fluorodeoxyglucose F18