title: The value of PET, CT and in-line PET/CT in patients with gastrointestinal stromal tumours: long-term outcome of treatment with imatinib mesylate.
abstract: OBJECTIVE
  Gastrointestinal stromal tumours (GIST) are mesenchymal neoplasms of the gastrointestinal tract that are unresponsive to standard sarcoma chemotherapy. Imaging of GIST patients is done with structural and functional methods such as contrast-enhanced helical computed tomography (ceCT) and positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG). The aim of this study was to compare the prognostic power of PET and ceCT and to evaluate the clinical role of PET/CT imaging.
  
  
  METHODS
  All patients with GIST undergoing PET or PET/CT examinations were prospectively included in this study, and the median overall survival, time to progression and treatment duration were documented. The prognostic significance of PET and ceCT criteria of treatment response was assessed and PET/CT was compared with PET and ceCT imaging. Data for 34 patients (19 male, 15 female, 21-76 years) undergoing PET or PET/CT for staging or restaging were analysed.
  
  
  RESULTS
  In 28 patients, PET/CT and ceCT were available after introduction of treatment with the tyrosine kinase inhibitor imatinib mesylate (Gleevec; Novartis, Basel, Switzerland). Patients without FDG uptake after the start of treatment had a better prognosis than patients with residual activity. In contrast, ceCT criteria provided insufficient prognostic power. However, more lesions were found on ceCT images than on PET images, and FDG uptake was sometimes very variable. PET/CT delineated active lesions better than did the combination of PET and ceCT imaging.
  
  
  CONCLUSIONS
  Both PET and PET/CT provide important prognostic information and have an impact on clinical decision-making in GIST patients. PET/CT precisely delineates lesions and thus allows for the correct planning of surgical interventions.
authors.affiliation: Division of Nuclear Medicine, University Hospital Zurich, Raemistrasse 100, 8091, Zurich, Switzerland. gerhard.goerres@usz.ch
authors.forename: G W
authors.initials: GW
authors.lastname: Goerres
authors.forename: R
authors.initials: R
authors.lastname: Stupp
authors.forename: G
authors.initials: G
authors.lastname: Barghouth
authors.forename: T F
authors.initials: TF
authors.lastname: Hany
authors.forename: B
authors.initials: B
authors.lastname: Pestalozzi
authors.forename: E
authors.initials: E
authors.lastname: Dizendorf
authors.forename: P
authors.initials: P
authors.lastname: Schnyder
authors.forename: F
authors.initials: F
authors.lastname: Luthi
authors.forename: G K
authors.initials: GK
authors.lastname: von Schulthess
authors.forename: S
authors.initials: S
authors.lastname: Leyvraz
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001549:Benzamides; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis* / Q000188:drug therapy* / Q000401:mortality; D006801:Humans; D000068877:Imatinib Mesylate; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011743:Pyrimidines / Q000627:therapeutic use*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013557:Switzerland / Q000453:epidemiology; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000068877:Imatinib Mesylate