title: Use of 11C-methionine PET to monitor the effects of temozolomide chemotherapy in malignant gliomas.
abstract: OBJECTIVE
  The purpose of this study was to monitor the metabolic effects of temozolomide (TMZ) chemotherapy in malignant gliomas by means of repeated positron emission tomography (PET) with [(11)C]methionine (MET).
  
  
  METHODS
  Fifteen patients with histologically proven malignant glioma were treated by TMZ chemotherapy. MET-PET studies were performed before and after the third cycle of TMZ chemotherapy in all patients, and in 12 patients also after the sixth cycle. Gadolinium-enhanced MRI studies were performed in 12 patients before the first and after the sixth cycle. Clinical status was assessed by the modified Rankin scale. Long-term outcome was assessed by calculating the time to progression (TTP) in months.
  
  
  RESULTS
  Decline in MET uptake during therapy corresponded to a stable clinical status. The median TTP was significantly longer in patients with decline in MET uptake than in those with increasing MET uptake (23 vs 3.5 months; p=0.01, log rank test). There was no significant correlation between change in MET uptake and change in contrast enhancement during treatment for all patients.
  
  
  CONCLUSIONS
  The present data demonstrate that clinical stability, which is often achieved under TMZ chemotherapy of malignant glioma, corresponds to a decline in or stability of tumour amino acid metabolism. Tumour responses can already be demonstrated with MET-PET after three cycles of chemotherapy, and absence of progression at that time indicates a high probability of further stability during the next three cycles. A reduction in MET uptake during TMZ treatment predicts a favourable clinical outcome. Molecular imaging of amino acid uptake by MET-PET offers a new method of measurement of the biological activity of recurrent glioma.
authors.affiliation: Department of Neurology, University of Cologne, Cologne, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Galldiks
authors.forename: Lutz W
authors.initials: LW
authors.lastname: Kracht
authors.forename: Lothar
authors.initials: L
authors.lastname: Burghaus
authors.forename: Anne
authors.initials: A
authors.lastname: Thomas
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Jacobs
authors.forename: Wolf-Dieter
authors.initials: WD
authors.lastname: Heiss
authors.forename: Karl
authors.initials: K
authors.lastname: Herholz
mesh_terms: D000328:Adult; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008715:Methionine; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000077204:Temozolomide; D016896:Treatment Outcome
chemical_list: D018906:Antineoplastic Agents, Alkylating; D019275:Radiopharmaceuticals; C086242:carbon-11 methionine; D003606:Dacarbazine; D008715:Methionine; D000077204:Temozolomide