Combined uptake of [18F]FDG and [18F]FMISO correlates with radiation therapy outcome in head-and-neck cancer patients.
OBJECTIVE
FDG PET is frequently used for radiotherapy (RT) planning to determine the tumour extent. Similarly, FMISO is used to assess the hypoxic sub-volume. The relationship between the volumes determined on the basis of FDG and FMISO was investigated. Additionally, the quantitative correlation of the tracers on a voxel basis was studied.


METHODS
Twelve head-and-neck cancer (HNC) patients underwent FDG and FMISO PET examinations prior to RT treatment. The tumour volumes assessed by the two tracers and also the voxel-based joint uptake values were investigated. The characteristic shapes and patterns of the determined scatter plots were analyzed. A number of different variables such as the maximum uptake values of FDG and FMISO, the FDG and FMISO positive volumes, the slope m of the regression line and the scatter width sigma of the scatter plots were tested for their ability to stratify the patient group with respect to treatment outcome.


RESULTS
A diversity of characteristic FDG-FMISO distributions was observed in the patient group. However, no general correlation of enhanced glucose metabolism and FMISO uptake was observed. The maximum uptake of FMISO (p=0.045) showed borderline significance for stratifying the patient group. FDG positive tumour volume, hypoxic fraction, maximum FDG uptake and m were not significant. Sigma turned out to be the most significant variable (p=0.008) to predict treatment success probabilities.


CONCLUSIONS
FMISO and FDG PET data provide independent information about the examined tumour. A quantification of the correlated tracer uptake seems to be meaningful.
Thorwarth
Daniela
D
Section for Biomedical Physics, Clinic for Radiation Oncology, Tübingen, Germany. daniela.thorwarth@med.uni-tuebingen.de <daniela.thorwarth@med.uni-tuebingen.de>
Eschmann
Susanne-Martina
SM
Holzner
Felix
F
Paulsen
Frank
F
Alber
Markus
M
D000368:Aged; D015687:Cell Hypoxia / Q000502:physiology; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005947:Glucose / Q000378:metabolism; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008920:Misonidazole / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D009593:Nitroimidazoles / Q000008:administration & dosage; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D016896:Treatment Outcome
D005462:Fluorine Radioisotopes; D009593:Nitroimidazoles; D019275:Radiopharmaceuticals; C031843:fluoromisonidazole; D019788:Fluorodeoxyglucose F18; C033815:pimonidazole; D008920:Misonidazole; D005947:Glucose