title: (18)F-FET and (18)F-FCH uptake in human glioblastoma T98G cell lines.
abstract: BACKGROUND
  Despite complex treatment of surgery, radiotherapy and chemotherapy, high grade gliomas often recur. Differentiation between post-treatment changes and recurrence is difficult. (18)F-methyl-choline ((18)F-FCH) is frequently used in staging and detection of recurrent prostate cancer disease as well as some brain tumours; however accumulation in inflammatory tissue limits its specificity. The (18)F-ethyl-tyrosine ((18)F-FET) shows a specific uptake in malignant cells, resulting from increased expression of amino acid transporters or diffusing through the disrupted blood-brain barrier. (18)F-FET exhibits lower uptake in machrophages and other inflammatory cells. Aim of this study was to evaluate (18)F-FCH and (18)F-FET uptake by human glioblastoma T98G cells.
  
  
  METHODS
  Human glioblastoma T98G or human dermal fibroblasts cells, seeded at a density to obtain 2 × 10(5) cells per flask when radioactive tracers were administered, grew adherent to the plastic surface at 37°C in 5% CO2 in complete medium. Equimolar amounts of radiopharmaceuticals were added to cells for different incubation times (20 to 120 minutes) for (18)F-FCH and (18)F-FET respectively. The cellular radiotracer uptake was determined with a gamma counter. All experiments were carried out in duplicate and repeated three times. The uptake measurements are expressed as the percentage of the administered dose of tracer per 2 × 10(5) cells. Data (expressed as mean values of % uptake of radiopharmaceuticals) were compared using parametric or non-parametric tests as appropriate. Differences were regarded as statistically significant when p<0.05.
  
  
  RESULTS
  A significant uptake of (18)F-FCH was seen in T98G cells at 60, 90 and 120 minutes. The percentage uptake of (18)F-FET in comparison to (18)F-FCH was lower by a factor of more than 3, with different kinetic curves.(18)F-FET showed a more rapid initial uptake up to 40 minutes and (18)F-FCH showed a progressive rise reaching a maximum after 90 minutes.
  
  
  CONCLUSIONS
  (18)F-FCH and (18)F-FET are candidates for neuro-oncological PET imaging. (18)F-FET could be the most useful oncological PET marker in the presence of reparative changes after therapy, where the higher affinity of (18)F-FCH to inflammatory cells makes it more difficult to discriminate between tumour persistence and non-neoplastic changes. Additional studies on the influence of inflammatory tissue and radionecrotic cellular components on radiopharmaceutical uptake are necessary.
authors.affiliation: Department of Oncohaematology, Nuclear Medicine Unit, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
authors.forename: Marco Giovanni
authors.initials: MG
authors.lastname: Persico
authors.affiliation: Department of Oncohaematology, Nuclear Medicine Unit, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
authors.forename: Federica Eleonora
authors.initials: FE
authors.lastname: Buroni
authors.affiliation: Department of Oncohaematology, Radiotherapy Unit, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Pasi
authors.affiliation: Department of Oncohaematology, Nuclear Medicine Unit, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Lodola
authors.affiliation: Department of Oncohaematology, Nuclear Medicine Unit, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Aprile
authors.affiliation: Department of Biology and Biotecnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Nano
authors.affiliation: Nuclear medicine research department, Iason, Graz, Austria.
authors.forename: Marina
authors.initials: M
authors.lastname: Hodolic