title: 11C-methionine PET, a novel method for measuring regional salivary gland function after radiotherapy of head and neck cancer.
abstract: OBJECTIVE
  Loss of salivary gland function is a distressing side-effect of radiotherapy (RT) for head and neck cancer. The aim of this study was to develop a positron emission tomography (PET) method for measuring regional salivary gland function in the major salivary glands irradiated during RT.
  
  
  METHODS
  Eight head and neck cancer patients were included; two were examined before RT and six after parotid sparing RT. Patients were examined by dynamic 11C-methionine PET of the major salivary glands and parotid gland salivary flow measurements. PET data were analysed using a kinetic model of salivary gland 11C-methionine metabolism, in which salivary gland function was quantified by the net metabolic clearance of 11C-methionine, K. Functional voxel-wise images of K were calculated and matched with the CT-dose-plan for comparing regional salivary gland function with the regional radiation dose.
  
  
  RESULTS
  Parotid gland K correlated positively with parotid gland salivary flow, indicating that K can be used as an index of salivary gland function. K of parotid and submandibular glands was reduced dependent on the median radiation dose. In one patient, receiving a heterogeneous radiation dose to the parotid glands, regional salivary gland function was inversely correlated to the regional radiation dose.
  
  
  CONCLUSIONS
  Salivary gland function can be measured by dynamic 11C-methionine PET. The net metabolic clearance of 11C-methionine of salivary glands was reduced dependent on the radiation dose. Dynamic 11C-methionine PET offers a method for studying the individual response of the major salivary glands to irradiation.
authors.affiliation: PET Centre, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark.
authors.forename: Simon
authors.initials: S
authors.lastname: Buus
authors.forename: Cai
authors.initials: C
authors.lastname: Grau
authors.forename: Ole Lajord
authors.initials: OL
authors.lastname: Munk
authors.forename: Dirk
authors.initials: D
authors.lastname: Bender
authors.forename: Kenneth
authors.initials: K
authors.lastname: Jensen
authors.forename: Susanne
authors.initials: S
authors.lastname: Keiding
mesh_terms: D000328:Adult; D000368:Aged; D002250:Carbon Radioisotopes; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008715:Methionine; D008875:Middle Aged; D010305:Parotid Diseases / Q000000981:diagnostic imaging / Q000209:etiology; D049268:Positron-Emission Tomography / Q000379:methods*; D011832:Radiation Injuries / Q000000981:diagnostic imaging*; D012469:Salivary Glands / Q000000981:diagnostic imaging* / Q000502:physiology / Q000528:radiation effects*
chemical_list: D002250:Carbon Radioisotopes; D008715:Methionine