title: MRI-suspected low-grade glioma: is there a need to perform dynamic FET PET?
abstract: OBJECTIVE
  Since differentiation between low-grade glioma (LGG) and high-grade glioma (HGG) remains challenging according to MRI criteria alone, we investigated the discriminative value of additional dynamic FET PET in patients with MRI-suspected LGG.
  
  
  METHODS
  Included in this retrospective study were 127 patients with newly diagnosed MRI-suspected LGG and dynamic FET PET prior to histopathological assessment. FET PET lesions were visually classified as having reduced, normal, or increased tracer uptake. Maximal tumour uptake scaled to the mean background uptake (SUV(max)/BG), mean tumour uptake (SUV(mean)/BG), biological tumour volume and kinetics were evaluated and correlated with individual histopathological findings.
  
  
  RESULTS
  Histopathological analysis revealed 71 patients with LGG, 47 patients with HGG (including 5 glioblastoma multiforme), 2 patients with low-grade ganglioglioma and 7 patients with non-neoplastic lesions. Of the 127 patients, 97 had lesions with increased FET uptake, of which 93 were neoplastic. Increased uptake was found in 49/71 LGG (69 %) and 42/47 HGG (89 %). None of the conventional uptake parameters differed significantly between the HGG and LGG groups. Kinetic analysis reliably identified HGG (sensitivity 95 %, specificity 72 %, PPV 74 %, NPV 95 %). Normal tracer uptake was observed in 19 patients (15 with LGG, 1 with HGG and 3 with non-neoplastic lesions) and reduced uptake in 11 patients (7 with LGG and 4 with HGG).
  
  
  CONCLUSIONS
  Among the MRI-suspected LGG, kinetic but not conventional analysis of FET uptake enabled remarkably high sensitivity for detection of HGG. This held true even for lesions with low or diffuse tracer uptake. Lesions with reduced tracer uptake must be interpreted with caution, as they can also harbour HGG tissue.
authors.affiliation: Department of Nuclear Medicine, Ludwig-Maximilians-University Munich, Marchioninistr 15, 81377 Munich, Germany.
authors.forename: Nathalie L
authors.initials: NL
authors.lastname: Jansen
authors.forename: Vera
authors.initials: V
authors.lastname: Graute
authors.forename: Lena
authors.initials: L
authors.lastname: Armbruster
authors.forename: Bogdana
authors.initials: B
authors.lastname: Suchorska
authors.forename: Juergen
authors.initials: J
authors.lastname: Lutz
authors.forename: Sabina
authors.initials: S
authors.lastname: Eigenbrod
authors.forename: Paul
authors.initials: P
authors.lastname: Cumming
authors.forename: Peter
authors.initials: P
authors.lastname: Bartenstein
authors.forename: Jörg-Christian
authors.initials: JC
authors.lastname: Tonn
authors.forename: Friedrich Wilhelm
authors.initials: FW
authors.lastname: Kreth
authors.forename: Christian
authors.initials: C
authors.lastname: la Fougère
mesh_terms: D001692:Biological Transport; D015331:Cohort Studies; D005260:Female; D005910:Glioma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D049268:Positron-Emission Tomography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: C545932:(18F)fluoroethyltyrosine; D014443:Tyrosine