Dynamic FDG studies in patients with desmoids following imatinib therapy

Abstract

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Objectives: To evaluate the FDG metabolism in patients (pts.) with desmoids prior and after therapy with Imatinib. The treatment effect was assessed with regard to the preliminary clinical results.

Methods: The ongoing evaluation includes 10 patients, 8 of them had a desmoid and two of them an aggressive fibromatosis. The location of the lesions was in the thoracic wall, retrovesical and in the middle abdomen. Five of these patients were studies with FDG prior and three months after onset to Imatinib. The evaluation of dynamic PET studies was based on a 2-tissue compartment model and on a non-compartmental approach. Clinical data served for reference.

Results: Median SUV prior therapy was 3.1 SUV in comparison to 2.7 SUV after chemotherapy, maximal SUV prior was 5.5 in comparison to 5.3. Median influx was 0.037 prior to chemotherapy in comparison to 0.039 following therapy. Most kinetic parameters showed only small changes, only K1 declined after one cycle. This is in accordance to the clinical data, which revealed stable disease in 4/5 patients. One patient did not respond to therapy. This patient showed an increase in the median SUV (from 3.1 to 3.4) and an increase in the influx (0.228 to 0.041).

Conclusions: On the basis of these results, kinetic FDG data are promising for the prediction of early therapy response in patients with desmoids, who are scheduled for Imatinib therapy.