title: Identifying hypoxia in human tumors: A correlation study between 18F-FMISO PET and the Eppendorf oxygen-sensitive electrode.
abstract: BACKGROUND
  Polarographic oxygen-sensitive electrodes have demonstrated prognostic significance of hypoxia. However, its routine application is limited. (18)F-FMISO PET scans are a noninvasive approach, able to measure spatial and temporal changes in hypoxia. The aim of this study was to examine the association between measures of hypoxia defined by functional imaging and Eppendorf pO(2) electrodes.
  
  
  METHODS
  A total of 18 patients were included, nine squamous cell carcinoma of the head and neck and nine soft tissue tumors. The tumor volume was defined by CT, MRI, (18)FDG-PET or by clinical examination. The oxygenation status of the tumors was assessed using (18)F-FMISO PET imaging followed by Eppendorf pO(2) electrode measurements. Data were compared in a 'virtual voxel', resulting in individual histograms from each tumor.
  
  
  RESULTS
  The percentages of pO(2) ≤ 5 mmHg ranged from 9 to 94% (median 43%) for all 18 tumors. For (18)F-FMISO PET the T/M ratio ranged from 0.70 to 2.38 (median 1.13). Analyzing the virtual voxel histograms tumors could be categorized in three groups: Well oxygenated tumors with no hypoxia and concordance between the (18)F-FMISO data and the Eppendorf measurements, hypoxic tumors likewise with concordance between the two assays and inconclusive tumors with no concordance between the assays.
  
  
  CONCLUSIONS
  This study analyzed the relationship between (18)F-FMISO PET and Eppendorf pO(2) electrode measurements by use of a virtual voxel model. There was a spectrum of hypoxia among tumors that can be detected by both assays. However no correlation was observed, and in general tumors were more hypoxic based on Eppendorf pO(2) measurements as compared to (18)F-FMISO PET.
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark. lsm@oncology.dk
authors.forename: Lise Saksø
authors.initials: LS
authors.lastname: Mortensen
authors.forename: Simon
authors.initials: S
authors.lastname: Buus
authors.forename: Marianne
authors.initials: M
authors.lastname: Nordsmark
authors.forename: Lise
authors.initials: L
authors.lastname: Bentzen
authors.forename: Ole Lajord
authors.initials: OL
authors.lastname: Munk
authors.forename: Susanne
authors.initials: S
authors.lastname: Keiding
authors.forename: Jens
authors.initials: J
authors.lastname: Overgaard
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002294:Carcinoma, Squamous Cell / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D006258:Head and Neck Neoplasms / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D008839:Microelectrodes; D008920:Misonidazole / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D009369:Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D010100:Oxygen / Q000032:analysis* / Q000493:pharmacokinetics; D049268:Positron-Emission Tomography / Q000379:methods*; D012509:Sarcoma / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D012983:Soft Tissue Neoplasms / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology
chemical_list: C031843:fluoromisonidazole; D008920:Misonidazole; D010100:Oxygen