title: Validity of simplified 3'-deoxy-3'-[18F]fluorothymidine uptake measures for monitoring response to chemotherapy in locally advanced breast cancer.
abstract: OBJECTIVE
  Positron emission tomography using 3'-deoxy-3'-[(18)F]fluorothymidine ([(18)F]FLT) has been suggested as a means for monitoring response to chemotherapy. The aim of this study was to evaluate the validity of simplified uptake measures for assessing response to chemotherapy using [(18)F]FLT in locally advanced breast cancer (LABC).
  
  
  METHODS
  Fifteen LABC patients underwent dynamic [(18)F]FLT scans both prior to and after the first cycle of chemotherapy with fluorouracil, epirubicin or doxorubicin, and cyclophosphamide. The net uptake rate constant of [(18)F]FLT, K ( i ), determined by non-linear regression (NLR) of an irreversible two-tissue compartment model was used as the gold standard. In addition to Patlak graphical analysis, standardised uptake values (SUV) and tumour-to-whole blood ratio (TBR) were used for analysing [(18)F]FLT data. Correlations and relationships between simplified uptake measures and NLR before and after chemotherapy were assessed using regression analysis.
  
  
  RESULTS
  No significant differences in both pre- and post-chemotherapy relationships between any of the simplified uptake measures and NLR were found. However, changes in SUV between baseline and post-therapy scans showed a significant negative bias and slope less than one, while TBR did not.
  
  
  CONCLUSIONS
  In LABC, TBR instead of SUV may be preferred for monitoring response to chemotherapy with [(18)F]FLT.
authors.affiliation: Department of Nuclear Medicine & PET Research, VU University Medical Centre, Amsterdam, The Netherlands. mark.lubberink@radiol.uu.se
authors.forename: Mark
authors.initials: M
authors.lastname: Lubberink
authors.forename: Wieteke
authors.initials: W
authors.lastname: Direcks
authors.forename: Jasper
authors.initials: J
authors.lastname: Emmering
authors.forename: Harm
authors.initials: H
authors.lastname: van Tinteren
authors.forename: Otto S
authors.initials: OS
authors.lastname: Hoekstra
authors.forename: Jacobus J
authors.initials: JJ
authors.lastname: van der Hoeven
authors.forename: Carla F M
authors.initials: CF
authors.lastname: Molthoff
authors.forename: Adriaan A
authors.initials: AA
authors.lastname: Lammertsma
mesh_terms: D001943:Breast Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000473:pathology*; D015224:Dideoxynucleosides / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D009367:Neoplasm Staging; D017711:Nonlinear Dynamics; D012044:Regression Analysis; D013223:Statistics as Topic; D016896:Treatment Outcome
chemical_list: D015224:Dideoxynucleosides; C002854:alovudine