%0 Journal Article %A T. HEINICKE %A E. WARDELMANN %A T. SAUERBRUCH %A H.J. TSCHAMPA %A A. GLASMACHER %A H. PALMEDO %T Very Early Detection of Response to Imatinib Mesylate Therapy of Gastrointestinal Stromal Tumours Using 18Fluoro-Deoxyglucose-Positron Emission Tomography %D 2005 %J Anticancer Research %P 4591-4594 %V 25 %N 6C %X Aim: To investigate whether 18F-FDG-PET allows early assessment of response to imatinib mesylate in GIST patients. Patients and Methods: Five gastrointestinal stromal tumour (GIST) patients and one patient with a KIT-positive small cell cancer were studied. Treatment consisted of 400 mg imatinib mesylate daily. 18F-deoxyglucose-positron emission tomography (18F-FDG-PET) scans were done before and one week after starting imatinib mesylate therapy. Results: Metabolic responses were detected after only one week of therapy in all GIST patients (four partial and one complete response). The mean decrease of the standardised uptake value was 60% (range 43 to 77%). In contrast, the tumour of the non-GIST patient was metabolically stable. Four of the 5 GIST patients achieved a partial response on CT after a mean duration of 23 weeks (range 6 to 48 weeks). Conclusion: 18F-FDG-PET is a valuable method for the detection of response to imatinib mesylate in patients with KIT-positive tumours as early as one week after starting therapy. Copyright© 2005 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved %U https://ar.iiarjournals.org/content/anticanres/25/6C/4591.full.pdf