title: Dynamic respiratory gated (18)FDG-PET of lung tumors - a feasibility study.
abstract: BACKGROUND
  (18)FDG-PET/CT imaging is well established for diagnosis and staging of lung tumors. However, more detailed information regarding the distribution of FDG within the tumor, also as a function of time after injection may be relevant. In this study we explore the feasibility of a combined dynamic and respiratory gated (DR) PET protocol.
  
  
  METHODS
  A DR FDG-PET protocol for a Siemens Biograph 16 PET/CT scanner was set up, allowing data acquisition from the time of FDG injection. Breath-hold (BH) respiratory gating was performed at four intervals over a total acquisition time of 50 minutes. Thus, the PET protocol provides both motion-free images and a spatiotemporal characterization of the glucose distribution in lung tumors. Software tools were developed in-house for tentative tumor segmentation and for extracting standard uptake values (SUVs) voxel by voxel, tumor volumes and SUV gradients in all directions.
  
  
  RESULTS
  Four pilot patients have been investigated with the DR PET protocol. The procedure was well tolerated by the patients. The BH images appeared sharper, and SUV(max)/SUV(mean) was higher, compared to free breathing (FB) images. Also, SUV gradients in the periphery of the tumor in the BH images were in general greater than or equal to the gradients in the FB PET images.
  
  
  CONCLUSIONS
  The DR FDG-PET protocol is feasible and the BH images have a superior quality compared to the FB images. The protocol may also provide information of relevance for radiotherapy planning and follow-up. A patient trial is needed for assessing the clinical value of the imaging protocol.
authors.affiliation: Section for Diagnostic Physics, The Intervention Centre, Oslo University Hospital, Oslo, Norway. ingerid.skjei.knudtsen@ous-hf.no
authors.forename: Ingerid Skjei
authors.initials: IS
authors.lastname: Knudtsen
authors.forename: Jan
authors.initials: J
authors.lastname: Rødal
authors.forename: Odd Terje
authors.initials: OT
authors.lastname: Brustugun
authors.forename: Åslaug
authors.initials: Å
authors.lastname: Helland
authors.forename: Arne
authors.initials: A
authors.lastname: Skretting
authors.forename: Eirik
authors.initials: E
authors.lastname: Malinen
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000473:pathology; D005240:Feasibility Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011379:Prognosis; D019275:Radiopharmaceuticals; D012119:Respiration; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18