11C-methionine PET, a novel method for measuring regional salivary gland function after radiotherapy of head and neck cancer.
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.
Buus
Simon
S
PET Centre, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark.
Grau
Cai
C
Munk
Ole Lajord
OL
Bender
Dirk
D
Jensen
Kenneth
K
Keiding
Susanne
S
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*
D002250:Carbon Radioisotopes; D008715:Methionine