Nathalie Lassau MD, Presenter: Nothing to Disclose

Serge Koscielny, Abstract Co-Author: Nothing to Disclose

Linda Chami MD, Abstract Co-Author: Nothing to Disclose

Mohamed Chebil MD, Abstract Co-Author: Nothing to Disclose

Alain Roche MD, Abstract Co-Author: Nothing to Disclose

Axel Le Cesne MD, Abstract Co-Author: Nothing to Disclose

To determine the best quantitative parameters of DCE-US for predicting the early functional response at D1, D7, D15 in GIST treated by TKI and to compare the results to the Pet-CT performed at 1 month.

Twenty patients were treated by a targeted treatment AB1010(ABsciences) in phase II. DCE-US was performed before treatment and at 1, 7, 15 days, 1, 2 months and every 2 months. Contrast uptake was acquired using VRI®perfusion software after SonoVue®(Bracco) bolus injection. Time-intensity curves (TIC) were determined using linear raw-data from CHI-Q®(Toshiba) software. Seven parameters were extracted from the modelized TICs: peak intensity, areas under the curve, under the wash-in, under the wash-out, (corresponding all to the blood volume), time to peak intensity, slope of the wash-in (both corresponding to the blood flow), mean transit time. CT ( RECIST) were performed before treatment and at 2 months and every 2 months. Pet-CT were performed before and at 1 month in 14 patients. The variation was estimated between D0 and D1, D7, D15 for each functional DCE-US parameter. A non parametric sum-rank test was used to test the significance of the variation.

Twenty patients were included with a maximal follow-up of 30 months. Nineteen patients were treated at least 1 year. A total of 259 DCE-US were performed. At D 15, 5 parameters were significantly modified: AUC (p=0.004), area under the wash-in (p=0.002), area under the wash-out (p=0.002), time to peak intensity (p=0.005), slope of the wash-in (P=0.003). Among the 14 patients evaluated by Pet-CT, only 11 have a tumoral fixation. Among these, at 1 month : no modification of SUV was found in 4 patients (PFS < 18 months), and SUV was normalized in 7 patients (PFS >18 months). The functional parameters by DCE-US correlated to the blood volume were modified at D7 (increased and decreased for 4 and 7 patients respectively).

This study allows us to determine 5 relevant quantitative functional parameters calculating by DCE-US to early evaluate the targeted treatment in GIST at D15. The decrease of 3 parameters at D7 was able to predict the response on Pet-Ct at 1 month.

DCE-US with quantification performed at D 15 is able to predict the response in GIST treated with targeted treatment. The modification at D 7 is related to the response at 1 month on Pet-CT.

Lassau, N, Koscielny, S, Chami, L, Chebil, M, Roche, A, Le Cesne, A, Quantitative Functional Imaging by DCE-US (Dynamic Contrast Enhanced Ultrasonography) in Patients with GIST Treated by Thyrosine Kinase Inhibitor (TKI): Final Results.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6012423.html