title: Combined micro-PET/micro-CT imaging of lung tumours in SPC-raf and SPC-myc transgenic mice.
abstract: BACKGROUND
  SPC-raf and SPC-myc transgenic mice develop disseminated and circumscribed lung adenocarcinoma respectively, allowing for assessment of carcinogenesis and treatment strategies. The purpose of this study was to investigate the technical feasibility, the correlation of initial findings to histology and the administered radiation dose of combined micro-PET/micro-CT in these animal models.
  
  
  METHODS
  14 C57BL/6 mice (4 nontransgenic, 4 SPC-raf transgenic, 6 SPC-myc transgenic) were examined using micro-CT and (18)F-Fluoro-deoxyglucose micro-PET in-vivo. Micro-PET data was corrected for random events and scatter prior to reconstruction with a 3D-FORE/2D-OSEM iterative algorithm. Rigid micro-PET/micro-CT registration was performed. Tumour-to-non-tumour ratios were calculated for different lung regions and focal lesions. Diffuse tumour growth was quantified using a semiautomated micro-CT segmentation routine reported earlier. Regional histologic tumour load was assessed using a 4-point rating scale. Gamma radiation dose was determined using thermoluminescence dosimeters.
  
  
  RESULTS
  Micro-CT allowed visualisation of diffuse and circumscribed tumours in SPC-raf and SPC-myc transgenic animals along with morphology, while micro-PET provided information on metabolism, but lacked morphologic detail. Mean tumour-to-non-tumour ratio was 2.47 for circumscribed lesions. No significant correlation could be shown between histological tumour load and tumour-to-nontumour ratio for diffuse tumours in SPC-raf transgenic animals. Calculation of the expected dose based on gamma dosimetry yielded approximately 140 mGy/micro-PET examination additional to approximately 200 mGy due to micro-CT.
  
  
  CONCLUSIONS
  Combined micro-PET/micro-CT imaging allows for in-vivo assessment of lung tumours in SPC-raf and SPC-myc transgenic mice. The technique has potential for the evaluation of carcinogenesis and treatment strategies in circumscribed lung tumours.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany. Rodt.Thomas@mh-hannover.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Rodt
authors.forename: Matthias
authors.initials: M
authors.lastname: Luepke
authors.forename: Claudia
authors.initials: C
authors.lastname: Boehm
authors.forename: Katja
authors.initials: K
authors.lastname: Hueper
authors.forename: Roman
authors.initials: R
authors.lastname: Halter
authors.forename: Silke
authors.initials: S
authors.lastname: Glage
authors.forename: Ludwig
authors.initials: L
authors.lastname: Hoy
authors.forename: Frank
authors.initials: F
authors.lastname: Wacker
authors.forename: Juergen
authors.initials: J
authors.lastname: Borlak
authors.forename: Christian
authors.initials: C
authors.lastname: von Falck
mesh_terms: D000818:Animals; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D037661:Pulmonary Surfactant-Associated Proteins; D014057:Tomography, X-Ray Computed; D048490:raf Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D016271:Proto-Oncogene Proteins c-myc; D037661:Pulmonary Surfactant-Associated Proteins; D048490:raf Kinases