title: Detection and compensation of organ/lesion motion using 4D-PET/CT respiratory gated acquisition techniques.
abstract: OBJECTIVE
  To describe the degradation effects produced by respiratory organ and lesion motion on PET/CT images and to define the role of respiratory gated (RG) 4D-PET/CT techniques to compensate for such effects.
  
  
  METHODS
  Based on the literature and on our own experience, technical recommendations and clinical indications for the use of RG 4D PET/CT have been outlined.
  
  
  RESULTS
  RG 4D-PET/CT techniques require a state of the art PET/CT scanner, a respiratory monitoring system and dedicated acquisition and processing protocols. Patient training is particularly important to obtain a regular breathing pattern. An adequate number of phases has to be selected to balance motion compensation and statistical noise. RG 4D PET/CT motion free images may be clinically useful for tumour tissue characterization, monitoring patient treatment and target definition in radiation therapy planning.
  
  
  CONCLUSIONS
  RG 4D PET/CT is a valuable tool to improve image quality and quantitative accuracy and to assess and measure organ and lesion motion for radiotherapy planning.
authors: Nuclear Medicine, San Raffaele Scientific Institute, Milan, Italy. valentino.bettinardi@hsr.it
authors: Valentino
authors: V
authors: Bettinardi
authors: Maria
authors: M
authors: Picchio
authors: Nadia
authors: N
authors: Di Muzio
authors: Luigi
authors: L
authors: Gianolli
authors: Maria Carla
authors: MC
authors: Gilardi
authors: Cristina
authors: C
authors: Messa
mesh_terms: D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D008991:Monitoring, Physiologic; D009369:Neoplasms / Q000532:radiotherapy*; D049268:Positron-Emission Tomography / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted; D012119:Respiration