title: Rodent rhabdomyosarcoma: comparison between total choline concentration at H-MRS and [18F]-fluoromethylcholine uptake at PET using accurate methods for collecting data.
abstract: OBJECTIVE
  To compare choline concentration/amount at proton magnetic resonance spectroscopy (H-MRS) and [18F]-fluoromethylcholine (FCH) uptake at positron emission tomography (PET) in a tumour animal model.
  
  
  METHODS
  Twenty-two rats bearing grafted syngenic rhabdomyosarcoma in both thighs were examined on a 3T MR system and on a small animal PET system. Total choline concentration was measured on proton MR spectra using a so-called 'best internal fitting' volume of interest. Choline uptake was expressed as mean and maximum standardized uptake value (SUV and SUVmax, respectively) and as the percent of injected dose (%ID) after tumour delineation on fused PET-MR images. Data sets were displayed on standard scatter plots.
  
  
  RESULTS
  Thirty-six tumours were available for analysis. The area under the curve of the 3.2 ppm choline peak ranged from 69 to 476 (mean, 192) in arbitrary units. Mean SUV values ranged from 0.05 to 0.49 (mean, 0.19) and the %ID from 0.05 to 2.28 (mean, 0.54). Scatter plots failed to reveal quantitative relationship between choline concentration and uptake. Empirically data-driven cut-off lines applied to choline amount (choline concentration x tumour volume) versus choline uptake suggested a paradoxically negative relationship.
  
  
  CONCLUSIONS
  Total choline concentration did not correlate with FCH uptake in a tumour experimental model. A negative feedback of high values of total choline amount on cellular FCH uptake seemed to be present.
authors: Cliniques Universitaires Saint-Luc, Department of Radiology and Medical Imaging, Université Catholique de Louvain, Avenue Hippocrate, 10, 1200 Brussels, Belgium. denis.rommel@uclouvain.be
authors: Denis
authors: D
authors: Rommel
authors: Anne
authors: A
authors: Bol
authors: Jorge
authors: J
authors: Abarca-Quinones
authors: Frank
authors: F
authors: Peeters
authors: Annie
authors: A
authors: Robert
authors: Daniel
authors: D
authors: Labar
authors: Christine
authors: C
authors: Galant
authors: Vincent
authors: V
authors: Gregoire
authors: Thierry
authors: T
authors: Duprez
mesh_terms: D000818:Animals; D002794:Choline / Q000031:analogs & derivatives*; D004195:Disease Models, Animal; D005462:Fluorine Radioisotopes; D009682:Magnetic Resonance Spectroscopy; D049268:Positron-Emission Tomography / Q000379:methods*; D051381:Rats; D012208:Rhabdomyosarcoma / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery
chemical_list: D005462:Fluorine Radioisotopes; C516370:fluoromethylcholine; D002794:Choline