Combined use of 18F-FDG and 18F-FMISO in unresectable non-small cell lung cancer patients planned for radiotherapy: a dynamic PET/CT study

摘要

Aim of this study was to evaluate and compare, by means of dynamic and static PET/CT, the distribution patterns and pharmacokinetics of fluorine-18 fluorodeoxyglucose (sup18/supF-FDG) and of fluorine-18-fluoromisonidazole (sup18/supF-FMISO) in non-small cell lung cancer (NSCLC) patients scheduled for intensity modulated radiation therapy (IMRT). Thirteen patients suffering from inoperable stage III NSCLC underwent PET/CTs with sup18/supF-FDG and sup18/supF-FMISO for tumor metabolism and hypoxia assessment accordingly. Evaluation of PET/CT studies was based on visual analysis, semi-quantitative (SUV) calculations and absolute quantitative estimations, after application of a two-tissue compartment model and a non-compartmental approach. sup18/supF-FDG PET/CT revealed all thirteen primary lung tumors as sites of increased sup18/supF-FDG uptake. Six patients demonstrated also in total 43 sup18/supF-FDG avid metastases; these patients were excluded from radiotherapy. sup18/supF-MISO PET/CT demonstrated 12/13 primary lung tumors with faint tracer uptake. Only one tumor was clearly sup18/supF-FMISO avid, (SUVsubaverage/sub = 3.4, SUVsubmax/sub = 5.0). Mean values for sup18/supF-FDG, as derived from dPET/CT data, were SUVsubaverage/sub = 8.9, SUVsubmax/sub = 15.1, Ksub1/sub = 0.23, ksub2/sub = 0.53, ksub3/sub = 0.17, ksub4/sub = 0.02, influx = 0.05 and fractal dimension (FD) = 1.25 for the primary tumors. The respective values for sup18/supF-FMISO were SUVsubaverage/sub = 1.4, SUVsubmax/sub = 2.2, Ksub1/sub = 0.26, ksub2/sub = 0.56, ksub3/sub = 0.06, ksub4/sub = 0.06, influx = 0.02 and FD = 1.14. No statistically significant correlation was observed between the two tracers. sup18/supF-FDG PET/CT changed therapy management in six patients, by excluding them from planned IMRT. sup18/supF-FMISO PET/CT revealed absence of significant tracer uptake in the majority of the sup18/supF-FDG avid NSCLCs. Lack of correlation between the two tracers’ kinetics indicates that they reflect different molecular mechanisms and implies the discordance between increased glycolysis and hypoxia in the malignancy.