title: (18)F-fluoromethylcholine (FCho), (18)F-fluoroethyltyrosine (FET), and (18)F-fluorodeoxyglucose (FDG) for the discrimination between high-grade glioma and radiation necrosis in rats: a PET study.
abstract: BACKGROUND
  Discrimination between (high-grade) brain tumor recurrence and radiation necrosis (RN) remains a diagnostic challenge because both entities have similar imaging characteristics on conventional magnetic resonance imaging (MRI). Metabolic imaging, such as positron emission tomography (PET) could overcome this diagnostic dilemma. In this study, we investigated the potential of 2-[(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG), O-(2-[(18)F]-fluoroethyl)-L-tyrosine ((18)F-FET), and [(18)F]-Fluoromethyl-dimethyl-2-hydroxyethylammonium ((18)F-fluoromethylcholine, (18)F-FCho) PET in discriminating high-grade tumor from RN.
  
  
  METHODS
  We developed a glioblastoma (GB) rat model by inoculating F98 GB cells into the right frontal region. Induction of RN was achieved by irradiating the right frontal region with 60 Gy using three arcs with a beam aperture of 3×3 mm (n=3). Dynamic PET imaging with (18)F-FDG, (18)F-FET, and (18)F-FCho, as well as (18)F-FDG PET at a delayed time interval (240 min postinjection), was acquired.
  
  
  RESULTS
  MRI revealed contrast-enhancing tumors at 15 days after inoculation (n=4) and contrast-enhancing RN lesions 5-6 months postirradiation (n=3). On (18)F-FDG PET, the mean lesion-to-normal ratio (LNRmean) was significantly higher in GB than in RN (p=0.034). The difference in the LNRmean between tumors and RN was higher on the late (18)F-FDG PET images than on the PET images reconstructed from the last time frame of the dynamic acquisition (this is at a conventional time interval). LNRs obtained from (18)F-FCho PET were not significantly different between GB and RN (p=1.000). On (18)F-FET PET, the LNRmean was significantly higher in GB compared to RN (p=0.034).
  
  
  CONCLUSIONS
  Unlike (18)F-FCho, (18)F-FDG and (18)F-FET PET were effective in discriminating GB from RN. Interestingly, in the case of (18)F-FDG, delayed PET seems particularly useful.
  
  
  CONCLUSIONS
  Our results suggest that (delayed) (18)F-FDG and (18)F-FET PET can be used to discriminate GB (recurrence) from RN. Confirmation of these results in clinical studies is needed.
authors.affiliation: Department of Nuclear Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Julie
authors.initials: J
authors.lastname: Bolcaen
authors.affiliation: iMinds Medical IT - MEDISIP - Infinity lab, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.
authors.forename: Benedicte
authors.initials: B
authors.lastname: Descamps
authors.affiliation: Department of Radiology, Ghent University Hospital, Ghent, Belgium.
authors.forename: Karel
authors.initials: K
authors.lastname: Deblaere
authors.affiliation: Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium.
authors.forename: Tom
authors.initials: T
authors.lastname: Boterberg
authors.affiliation: Department of Radiopharmacy, Ghent University, Ghent, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: De Vos Pharm
authors.affiliation: Department of Neurosurgery, Ghent University Hospital, Ghent, Belgium.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Kalala
authors.affiliation: Department of Pathology, Ghent University Hospital, Ghent, Belgium.
authors.forename: Caroline
authors.initials: C
authors.lastname: Van den Broecke
authors.affiliation: Department of Basic Medical Sciences-Physiology group, Ghent University, Ghent, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Decrock
authors.affiliation: Department of Basic Medical Sciences-Physiology group, Ghent University, Ghent, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Leybaert
authors.affiliation: iMinds Medical IT - MEDISIP - Infinity lab, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium.
authors.forename: Christian
authors.initials: C
authors.lastname: Vanhove
authors.affiliation: Department of Nuclear Medicine, Ghent University Hospital, Ghent, Belgium. Electronic address: ingeborg.goethals@ugent.be.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Goethals
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000532:radiotherapy; D045744:Cell Line, Tumor; D002794:Choline / Q000031:analogs & derivatives; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000532:radiotherapy; D009336:Necrosis / Q000000981:diagnostic imaging / Q000209:etiology; D060787:Neoplasm Grading; D049268:Positron-Emission Tomography; D011832:Radiation Injuries / Q000000981:diagnostic imaging* / Q000209:etiology; D011849:Radioactive Tracers; D019275:Radiopharmaceuticals; D051381:Rats; D012008:Recurrence; D014443:Tyrosine / Q000031:analogs & derivatives
chemical_list: D011849:Radioactive Tracers; D019275:Radiopharmaceuticals; C516370:fluoromethylcholine; D019788:Fluorodeoxyglucose F18; C545932:(18F)fluoroethyltyrosine; D014443:Tyrosine; D002794:Choline
keywords: (18)F-FCho; (18)F-FDG; (18)F-FET; Glioblastoma; PET; Radiation necrosis