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Functional Tumor Shape Characterization On Baseline 18F-FDG PET Images Predicts Response to Concomitant Radio-Chemotherapy in Esophageal Cancer

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F Tixier

F Tixier1*, M Hatt1, C Cheze Le Rest2, D Visvikis1, (1) INSERM, Brest,(2) CHU Miletrie, Poitiers

TU-A-WAB-9 Tuesday 8:00AM - 9:55AM Room: Wabash Ballroom

Purpose: The development of robust 18F-FDG PET tumor volume delineation methodologies has led to the investigation of several image-derived parameters for tumor characterization, including metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tracer heterogeneity quantification. Their potential clinical value regarding patient outcome (response to therapy and/or survival) prediction has been recently investigated in several cancer models. They have often demonstrated superior value over standard measurements such as SUVmax or SUVpeak. However, the value of shape characterization (SC) parameters has not been extensively investigated as yet. We therefore studied the predictive value of 7 parameters derived from SC of PET image functional tumor activity distributions within the context of esophageal cancer treated by concomitant radio-chemotherapy.

Methods: Baseline 18F-FDG PET scans of 50 patients with locally advanced esophageal cancer were retrospectively analyzed. Primary tumors were delineated with the fuzzy locally adaptive bayesian algorithm and 7 features describing the shape of the delineated volumes were extracted. Response to therapy (complete (CR), partial (PR) and non-response (NR)) was evaluated according to RECIST criteria 1 month after the end of treatment. The correlation between SC parameters was assessed using Pearson coefficients and their corresponding predictive value was evaluated with receiver operating characteristic (ROC) curves analysis.

Results: 3D surface and MTV were highly correlated (r=0.97). All other SC parameters were moderately correlated (r<0.75). Maximum diameter within the MTV, as well as the smoothness of its surface allowed the identification of NR (vs. PR+CR) or CR (vs. PR+NR) with areas under the ROC curves of 0.78 and 0.80 respectively.

Conclusion: Baseline PET image derived parameters characterizing the shape of the functional tumor uptake may help in predicting response to radio-chemotherapy in locally advanced esophageal cancer. Future studies will investigate their potential combination with other parameters previously demonstrated as predictive of response, such as intra-tumor heterogeneity quantification.

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