title: [18F]-fluoro-ethyl-L-tyrosine PET: a valuable diagnostic tool in neuro-oncology, but not all that glitters is glioma.
abstract: BACKGROUND
  To assess the sensitivity and specificity of [(18)F]-fluoro-ethyl-l-tyrosine ((18)F-FET) PET in brain tumors and various non-neoplastic neurologic diseases.
  
  
  METHODS
  We retrospectively evaluated (18)F-FET PET scans from 393 patients grouped into 6 disease categories according to histology (n = 299) or distinct MRI findings (n = 94) (low-grade/high-grade glial/nonglial brain tumors, inflammatory lesions, and other lesions). (18)F-FET PET was visually assessed as positive or negative. Maximum lesion-to-brain ratios (LBRs) were calculated and compared with MRI contrast enhancement (CE), which was graded visually on a 3-point scale (no/moderate/intense).
  
  
  RESULTS
  Sensitivity and specificity for the detection of brain tumor were 87% and 68%, respectively. Significant differences in LBRs were detected between high-grade brain tumors (LBR, 2.04 ± 0.72) and low-grade brain tumors (LBR, 1.52 ± 0.70; P < .001), as well as among inflammatory (LBR, 1.66 ± 0.33; P = .056) and other brain lesions (LBR, 1.10 ± 0.37; P < .001). Gliomas (n = 236) showed (18)F-FET uptake in 80% of World Health Organization (WHO) grade I, 79% of grade II, 92% of grade III, and 100% of grade IV tumors. Low-grade oligodendrogliomas, WHO grade II, had significantly higher (18)F-FET uptakes than astrocytomas grades II and III (P = .018 and P = .015, respectively). (18)F-FET uptake showed a strong association with CE on MRI (P < .001) and was also positive in 52% of 157 nonglial brain tumors and nonneoplastic brain lesions.
  
  
  CONCLUSIONS
  (18)F-FET PET has a high sensitivity for the detection of high-grade brain tumors. Its specificity, however, is limited by passive tracer influx through a disrupted blood-brain barrier and (18)F-FET uptake in nonneoplastic brain lesions. Gliomas show specific tracer uptake in the absence of CE on MRI, which most likely reflects biologically active tumor.
authors: Department of Neurology, Wilhelm-Sander Neurooncology Therapy Unit, University Hospital of Regensburg, Universitätsstrasse 84, D-93053 Regensburg, Germany. markus.hutterer@kabelmail.de
authors: Markus
authors: M
authors: Hutterer
authors: Martha
authors: M
authors: Nowosielski
authors: Daniel
authors: D
authors: Putzer
authors: Nathalie L
authors: NL
authors: Jansen
authors: Marcel
authors: M
authors: Seiz
authors: Michael
authors: M
authors: Schocke
authors: Mark
authors: M
authors: McCoy
authors: Georg
authors: G
authors: Göbel
authors: Christian
authors: C
authors: la Fougère
authors: Irene J
authors: IJ
authors: Virgolini
authors: Eugen
authors: E
authors: Trinka
authors: Andreas H
authors: AH
authors: Jacobs
authors: Günther
authors: G
authors: Stockhammer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001812:Blood-Brain Barrier / Q000000981:diagnostic imaging / Q000473:pathology; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D005910:Glioma / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D049268:Positron-Emission Tomography; D011379:Prognosis; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014443:Tyrosine / Q000031:analogs & derivatives*; D055815:Young Adult
chemical_list: C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D014443:Tyrosine