title: Identification of residual metabolic-active areas within NSCLC tumours using a pre-radiotherapy FDG-PET-CT scan: a prospective validation.
abstract: It was recently described that high FDG-uptake areas pre-radiotherapy largely correspond with residual metabolic-active areas post-radiotherapy. Here, an independent prospective validation of these results was performed using an overlap-fraction (OF) calculation of various FDG-uptake based thresholds. Data from twelve patients treated at Radboud University Nijmegen Medical Center with lung cancer were analyzed. All patients underwent two FDG-PET-CT scans, one pre-radiotherapy (pre-RT) and one approximately three months after treatment (post-RT). Of the twelve analyzed patients, eight patients showed residual FDG uptake on the post-RT scan and were included for analysis. One of these patients had a residue that was not clearly distinguishable from the surrounding tissue due to FDG avid inflammation. Therefore, seven patients remained for further analysis. The mean volume of the residual metabolic-active areas post-RT was 14.6±10.0% (mean±SD) of the mean volume of the gross tumour volume (GTV) pre-RT. The residual metabolic-active areas largely corresponded with the pre-RT GTV (OF=93.7±7.2%). The pre-RT-scan threshold delineations of 34%, 40% and 50% of the SUV(max) had a large OF with the residual region, 86.9±8.3%, 77.4±8.1% and 67.9±6.8%, respectively. In this independent dataset, we confirmed that the location of residual FDG-uptake areas after radiotherapy corresponds with the high FDG-uptake areas pre-radiotherapy. Therefore, a pre-radiotherapy FDG-PET-CT scan can potentially be used for radiotherapy dose redistribution.
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands. Hugo.Aerts@maastro.nl
authors.forename: Hugo J W L
authors.initials: HJ
authors.lastname: Aerts
authors.forename: Johan
authors.initials: J
authors.lastname: Bussink
authors.forename: Wim J G
authors.initials: WJ
authors.lastname: Oyen
authors.forename: Wouter
authors.initials: W
authors.lastname: van Elmpt
authors.forename: Annemieke M
authors.initials: AM
authors.lastname: Folgering
authors.forename: Daisy
authors.initials: D
authors.lastname: Emans
authors.forename: Marije
authors.initials: M
authors.lastname: Velders
authors.forename: Philippe
authors.initials: P
authors.lastname: Lambin
authors.forename: Dirk
authors.initials: D
authors.lastname: De Ruysscher
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000532:radiotherapy*; D059248:Chemoradiotherapy / Q000379:methods; D002945:Cisplatin / Q000008:administration & dosage; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000532:radiotherapy*; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden / Q000528:radiation effects; D000093542:Gemcitabine
chemical_list: D019275:Radiopharmaceuticals; D003841:Deoxycytidine; D019788:Fluorodeoxyglucose F18; D002945:Cisplatin; D000093542:Gemcitabine