title: The response of human tumors to carbogen breathing, monitored by Gradient-Recalled Echo Magnetic Resonance Imaging.
abstract: OBJECTIVE
  Gradient-Recalled Echo (GRE) Magnetic Resonance Imaging (MRI), which detects changes in blood vessel deoxyhaemoglobin content, has been investigated as a noninvasive monitor of changes in human tumor oxygenation and blood flow, in response to carbogen (95% O2, 5% CO2) breathing.
  
  
  METHODS
  GRE images (TE = 60 ms, TR = 200 ms, alpha = 40 degrees, 256[2] matrix) were acquired from 31 patients with primary and metastatic disease, prior to and during carbogen breathing. Three patients underwent a follow-up examination after radiotherapy.
  
  
  RESULTS
  Seventeen out of 34 tumors showed enhanced image intensity, consistent with an improvement in tumor oxygenation and blood flow, while 11 showed no response; 6 studies were technical failures. In one patient a metastatic node that had eluded orthodox investigation was visualized. A reduction in response was observed in the three patients studied postradiotherapy.
  
  
  CONCLUSIONS
  This method, which can be performed on a standard clinical MRI instrument, provides a noninvasive measurement of tumor response to oxygenation/blood flow modification. In principle, this should enable the clinician to optimize treatment protocols, such as carbogen breathing, for individual radiotherapy patients.
authors.affiliation: CRC Biomedical Magnetic Resonance Research Group, Division of Biochemistry, St. George's Hospital Medical School, London, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Griffiths
authors.forename: N J
authors.initials: NJ
authors.lastname: Taylor
authors.forename: F A
authors.initials: FA
authors.lastname: Howe
authors.forename: M I
authors.initials: MI
authors.lastname: Saunders
authors.forename: S P
authors.initials: SP
authors.lastname: Robinson
authors.forename: P J
authors.initials: PJ
authors.lastname: Hoskin
authors.forename: M E
authors.initials: ME
authors.lastname: Powell
authors.forename: M
authors.initials: M
authors.lastname: Thoumine
authors.forename: L A
authors.initials: LA
authors.lastname: Caine
authors.forename: H
authors.initials: H
authors.lastname: Baddeley
mesh_terms: D000280:Administration, Inhalation; D002245:Carbon Dioxide / Q000008:administration & dosage*; D002294:Carcinoma, Squamous Cell / Q000098:blood supply / Q000378:metabolism; D006801:Humans; D008207:Lymphatic Metastasis / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009369:Neoplasms / Q000098:blood supply* / Q000378:metabolism*; D010100:Oxygen / Q000008:administration & dosage* / Q000378:metabolism*
chemical_list: D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen