title: Prognostic value of O-(2-18F-fluoroethyl)-L-tyrosine PET and MRI in low-grade glioma.
abstract: In glioma of World Health Organization (WHO) grade II (low-grade glioma), the natural course of a particular patient is not predictable and the treatment strategy is controversial. We determined prognostic factors in adult patients with untreated, nonenhancing, supratentorial low-grade glioma with special regard to PET using the amino acid O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) and MRI.
  
  
  METHODS
  In a prospective study, baseline (18)F-FET PET and MRI analyses were performed on 33 consecutive patients with histologically confirmed low-grade glioma. None of the patients had radiation or chemotherapy. Clinical, histologic, therapeutic (initial cytoreduction vs. biopsy), (18)F-FET uptake, and MRI morphologic parameters were analyzed for their prognostic significance. Statistical endpoints were clinical or radiologic tumor progression, malignant transformation to glioma of WHO grade III or IV (high-grade glioma), and death.
  
  
  RESULTS
  Baseline (18)F-FET uptake and a diffuse versus circumscribed tumor pattern on MRI were highly significant predictors of prognosis (P < 0.01). By the combination of these prognostically significant variables, 3 major prognostic subgroups of low-grade glioma patients could be identified. The first of these subgroups was patients with circumscribed low-grade glioma on MRI without (18)F-FET uptake (n = 11 patients, progression in 18%, no malignant transformation and no death). The second subgroup was patients with circumscribed low-grade glioma with (18)F-FET uptake (n = 13 patients, progression in 46%, malignant transformation to a high-grade glioma in 15%, and death in 8%). The third subgroup was patients with diffuse low-grade glioma with (18)F-FET uptake (n = 9 patients, progression in 100%, malignant transformation to a high-grade glioma in 78%, and death in 56%).
  
  
  CONCLUSIONS
  We conclude that baseline amino acid uptake on (18)F-FET PET and a diffuse versus circumscribed tumor pattern on MRI are strong predictors for the outcome of patients with low-grade glioma.
authors.affiliation: Department of Neurosurgery, Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Frank W
authors.initials: FW
authors.lastname: Floeth
authors.forename: Dirk
authors.initials: D
authors.lastname: Pauleit
authors.forename: Michael
authors.initials: M
authors.lastname: Sabel
authors.forename: Gabriele
authors.initials: G
authors.lastname: Stoffels
authors.forename: Guido
authors.initials: G
authors.lastname: Reifenberger
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Riemenschneider
authors.forename: Paul
authors.initials: P
authors.lastname: Jansen
authors.forename: Heinz H
authors.initials: HH
authors.lastname: Coenen
authors.forename: Hans-Jakob
authors.initials: HJ
authors.lastname: Steiger
authors.forename: Karl-Josef
authors.initials: KJ
authors.lastname: Langen
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005910:Glioma / Q000175:diagnosis* / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011446:Prospective Studies
chemical_list: D019788:Fluorodeoxyglucose F18