Early effects of irradiation on [(123)I]-IMT and [(18)F]-FDG uptake in rat C6 glioma cells.
BACKGROUND
Single-photon emission computed tomography (SPECT) using 3-[(123)I]-iodo-L-alpha-methyltyrosine ([(123)I]-IMT) and positron emission tomography (PET) using 2-[(18)F]-fluoro-2-deoxy-D-glucose ([(18)F]-FDG) are valuable tools for the distinction between viable tumor and radionecrosis in patients receiving radiotherapy for high-grade gliomas. However, to date, little is known about the early effects of radiation on [(123)I]-IMT and [(18)F]-FDG uptake in gliomas.


METHODS
To determine the early effects of irradiation on [(123)I]-IMT and [(18)F]-FDG uptake in gliomas, in vitro studies were performed using rat C6 glioma cells. The glioma cells were irradiated with 20 Gy which is a common dose applied to patients receiving intraoperative radiotherapy. Subsequently, the early kinetics of [(123)I]-IMT and [(18)F]-FDG uptake in glioma cells were monitored for 3 days.


RESULTS
Micromorphometric examinations of the irradiated glioma cells revealed that about 25% of the viable cells transformed into giant cells. [(123)I]-IMT uptake per 10(5) viable glioma cells was unchanged on the 1st day post irradiation, but showed a significant increase on the 2nd and 3rd day following radiotherapy (p < 0.01). In addition, there was a moderate increase in [(18)F]- FDG accumulation per 10(5) viable glioma cells during the first 3 days after irradiation (p < 0.05). The maximum increase in early [(123)I]-IMT uptake 1 h after application surpassed that of [(18)F]-FDG (p < 0.01).


CONCLUSIONS
Rat C6 glioma cells show an early increase in [(123)I]-IMT and [(18)F]-FDG uptake following irradiation which may be partly due to giant cell formation. These data suggest that [(123)I]-IMT SPECT and [(18)F]-FDG PET may be promising procedures for the early prediction of the therapeutic response of gliomas to radiotherapy.
Riemann
Burkhard
B
Department of Nuclear Medicine, University of Münster, Germany. riemanb@uni-muenster.de
Könemann
Stefan
S
Pöpping
Daniel
D
Kopka
Klaus
K
Weckesser
Matthias
M
Willich
Normann
N
Schober
Otmar
O
D000818:Animals; D001692:Biological Transport / Q000528:radiation effects; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D004195:Disease Models, Animal; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005910:Glioma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008781:Methyltyrosines / Q000493:pharmacokinetics*; D011859:Radiography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats
D007457:Iodine Radioisotopes; D008781:Methyltyrosines; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C030855:3-iodo-alpha-methyltyrosine