title: Reproducibility of intratumor distribution of (18)F-fluoromisonidazole in head and neck cancer.
abstract: OBJECTIVE
  Hypoxia is one of the main causes of the failure to achieve local control using radiotherapy. This is due to the increased radioresistance of hypoxic cells. (18)F-fluoromisonidazole ((18)F-FMISO) positron emission tomography (PET) is a noninvasive imaging technique that can assist in the identification of intratumor regions of hypoxia. The aim of this study was to evaluate the reproducibility of (18)F-FMISO intratumor distribution using two pretreatment PET scans.
  
  
  METHODS
  We enrolled 20 head and neck cancer patients in this study. Of these, 6 were excluded from the analysis for technical reasons. All patients underwent an (18)F-fluorodeoxyglucose study, followed by two (18)F-FMISO studies 3 days apart. The hypoxic volumes were delineated according to a tumor/blood ratio >or=1.2. The (18)F-FMISO tracer distributions from the two (18)F-FMISO studies were co-registered on a voxel-by-voxel basis using the computed tomography images from the PET/computed tomography examinations. A correlation between the (18)F-FMISO intensities of the corresponding spatial voxels was derived.
  
  
  RESULTS
  A voxel-by-voxel analysis of the (18)F-FMISO distributions in the entire tumor volume showed a strong correlation in 71% of the patients. Restraining the correlation to putatively hypoxic zones reduced the number of patients exhibiting a strong correlation to 46%.
  
  
  CONCLUSIONS
  Variability in spatial uptake can occur between repeat (18)F-FMISO PET scans in patients with head and neck cancer. Blood data for one patient was not available. Of 13 patients, 6 had well-correlated intratumor distributions of (18)F-FMISO-suggestive of chronic hypoxia. More work is required to identify the underlying causes of changes in intratumor distribution before single-time-point (18)F-FMISO PET images can be used as the basis of hypoxia-targeting intensity-modulated radiotherapy.
authors: Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021, USA. nehmehs@mskcc.org
authors: Sadek A
authors: SA
authors: Nehmeh
authors: Nancy Y
authors: NY
authors: Lee
authors: Heiko
authors: H
authors: Schröder
authors: Olivia
authors: O
authors: Squire
authors: Pat B
authors: PB
authors: Zanzonico
authors: Yusuf E
authors: YE
authors: Erdi
authors: Carlo
authors: C
authors: Greco
authors: Gig
authors: G
authors: Mageras
authors: Hai S
authors: HS
authors: Pham
authors: Steve M
authors: SM
authors: Larson
authors: Clifton C
authors: CC
authors: Ling
authors: John L
authors: JL
authors: Humm
mesh_terms: D000368:Aged; D015687:Cell Hypoxia / Q000502:physiology*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008920:Misonidazole / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D049268:Positron-Emission Tomography / Q000379:methods*; D011838:Radiation-Sensitizing Agents / Q000493:pharmacokinetics*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D011838:Radiation-Sensitizing Agents; D019275:Radiopharmaceuticals; C031843:fluoromisonidazole; D019788:Fluorodeoxyglucose F18; D008920:Misonidazole