title: O-(2-[18F]fluoroethyl)-L-tyrosine PET for monitoring the effects of convection-enhanced delivery of paclitaxel in patients with recurrent glioblastoma.
abstract: OBJECTIVE
  Convection-enhanced delivery (CED) of paclitaxel is a new locoregional approach for patients with recurrent glioblastoma. The aim of this study was to evaluate O-(2-[(18)F]fluoroethyl)-L-tyrosine (FET) positron emission tomography (PET) in monitoring the effects of this type of direct drug delivery.
  
  
  METHODS
  Eight patients with recurrent glioblastoma underwent CED of paclitaxel, which was infused over stereotactically placed catheters into the tumour. FET PET and MRI were performed before and 4 weeks after therapy and then at 3-month intervals to document follow-up. For quantitative evaluation, SUV(max)(tumour)/SUV(mean)(background) ratios were calculated.
  
  
  RESULTS
  At baseline all tumours showed gadolinium enhancement and high FET uptake (SUV(max)/BG 3.2+/-0.8). Four weeks after CED, a statistically significant decrease in FET uptake was seen (SUV(max)/BG-17%; p<0.01). During follow-up, no recurrence was observed within the CED area. Two out of eight patients with extended tumours died 4 and 5 months after treatment, most probably from local complications. Temporarily stable disease with stable FET uptake was observed in six of eight patients; this was followed by progression and increasing FET uptake ratios (+46%) distant from the CED area in five of the six patients 3-13 months after CED. One patient still presents stable FET uptake 10 months after CED. MRI showed unchanged/increasing contrast enhancement and oedema without ability to reliably assess disease progression.
  
  
  CONCLUSIONS
  FET PET is a valuable tool in monitoring the effects of CED of paclitaxel. In long-term follow-up, stable or decreasing FET uptake, even in contrast-enhancing lesions, is suggestive of reactive changes, whereas increasing ratios appear always to be indicative of recurrence. Therefore, FET PET is more reliable than MRI in differentiating stable disease from tumour regrowth.
authors.affiliation: Department of Nuclear Medicine, Klinikum Grosshadern, University of Munich, Marchioninistrasse 15, 81377 Munich, Germany. Gabriele.Poepperl@med.uni-muenchen.de
authors.forename: G
authors.initials: G
authors.lastname: Pöpperl
authors.forename: R
authors.initials: R
authors.lastname: Goldbrunner
authors.forename: F J
authors.initials: FJ
authors.lastname: Gildehaus
authors.forename: F W
authors.initials: FW
authors.lastname: Kreth
authors.forename: P
authors.initials: P
authors.lastname: Tanner
authors.forename: M
authors.initials: M
authors.lastname: Holtmannspötter
authors.forename: J C
authors.initials: JC
authors.lastname: Tonn
authors.forename: K
authors.initials: K
authors.lastname: Tatsch
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D018481:Convection; D016503:Drug Delivery Systems / Q000379:methods; D005260:Female; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D006801:Humans; D036502:Infusions, Intralesional / Q000379:methods; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D017239:Paclitaxel / Q000008:administration & dosage*; D049268:Positron-Emission Tomography / Q000379:methods; D011379:Prognosis; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014443:Tyrosine / Q000031:analogs & derivatives*
chemical_list: D000970:Antineoplastic Agents; C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D014443:Tyrosine; D017239:Paclitaxel