title: Imaging primary lung cancers in mice to study radiation biology.
abstract: OBJECTIVE
  To image a genetically engineered mouse model of non-small-cell lung cancer with micro-computed tomography (micro-CT) to measure tumor response to radiation therapy.
  
  
  METHODS
  The Cre-loxP system was used to generate primary lung cancers in mice with mutation in K-ras alone or in combination with p53 mutation. Mice were serially imaged by micro-CT, and tumor volumes were determined. A comparison of tumor volume by micro-CT and tumor histology was performed. Tumor response to radiation therapy (15.5 Gy) was assessed with micro-CT.
  
  
  RESULTS
  The tumor volume measured with free-breathing micro-CT scans was greater than the volume calculated by histology. Nevertheless, this imaging approach demonstrated that lung cancers with mutant p53 grew more rapidly than lung tumors with wild-type p53 and also showed that radiation therapy increased the doubling time of p53 mutant lung cancers fivefold.
  
  
  CONCLUSIONS
  Micro-CT is an effective tool to noninvasively measure the growth of primary lung cancers in genetically engineered mice and assess tumor response to radiation therapy. This imaging approach will be useful to study the radiation biology of lung cancer.
authors.affiliation: The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA. david.kirsch@duke.edu
authors.forename: David G
authors.initials: DG
authors.lastname: Kirsch
authors.forename: Jan
authors.initials: J
authors.lastname: Grimm
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Guimaraes
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Wojtkiewicz
authors.forename: Bradford A
authors.initials: BA
authors.lastname: Perez
authors.forename: Philip M
authors.initials: PM
authors.lastname: Santiago
authors.forename: Nikolas K
authors.initials: NK
authors.lastname: Anthony
authors.forename: Thomas
authors.initials: T
authors.lastname: Forbes
authors.forename: Karen
authors.initials: K
authors.lastname: Doppke
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
authors.forename: Tyler
authors.initials: T
authors.lastname: Jacks
mesh_terms: D000818:Animals; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy; D016158:Genes, p53 / Q000235:genetics; D011905:Genes, ras / Q000235:genetics; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy; D051379:Mice; D008822:Mice, Transgenic / Q000235:genetics; D023421:Models, Animal; D011853:Radiobiology; D012119:Respiration; D016896:Treatment Outcome; D047368:Tumor Burden; D055114:X-Ray Microtomography / Q000379:methods*