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Shape Context Based Deformable Surface Registration for the Gastrointestinal Tract

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Y Lu

Y Lu1*, R Kashani2 , L Henke1 , I Chen1 , A Curcuru1 , P Parikh1 , (1) Washington University in St. Louis, St. Louis, MO, (2) University of Michigan, Ann Arbor, MI.


MO-F-205-8 (Monday, July 31, 2017) 4:30 PM - 6:00 PM Room: 205

Purpose: Deformable image registration (DIR) of the gastrointestinal (GI) tract is of great interest in dose accumulation and contour propagation in abdominal patients. Current intensity based image registration techniques however, are suboptimal due to the complexity of deformation as well as intensity characteristics of the anatomy in this region. In this study, a surface based DIR method was proposed by incorporating the concept of shape context into the framework of DIR.

Methods: The contours in the GI tract were used to create a surface mesh, and the shape context was created at each vertex of the mesh. A point-to-point correspondence was established between the two GI tract volumes acquired at different times. A deformation field following a cubic B-spline function was consequently reconstructed. To evaluate the accuracy of this technique, synthetic datasets mimicking the behaviors of the duodenum including different translations, dilations, rotations, noise levels and bolus fillings, as well as datasets from 10 pancreas patients were analyzed. All clinical data were acquired on a 0.35 Tesla magnetic resonance imaging (MRI) guided radiation therapy system. Statistical analysis on Dice coefficient/Modified Haursdorff Distance (DC/MHD) between the proposed and the conventional intensity based method (a B-spline grid based) was performed.

Results: For the synthetic dataset, the proposed method can register the surfaces of the duodenum at different settings with significantly improved DC/MHD (mm) compared to the intensity based method (0.900.01/1.170.48 vs 0.680.13/4.022.85). For the patient datasets, the proposed method can successfully register the surfaces of stomach, duodenum, small and large bowel with significantly improved DC/MHD (mm) compared to the intensity based method (0.93±0.04/1.93±0.31 vs 0.63±0.13/6.54±2.70, 0.87±0.03/1.79±0.11 vs 0.50±0.19/5.73±2.37, 0.83±0.02/2.05±0.42 vs 0.54±0.11/8.18±2.69, and 0.89±0.03/1.79±0.11 vs 0.52±0.12/7.75±2.24, respectively).

Conclusion: The proposed technique demonstrated its superior performance in deformable registration on the GI tract in MRI-guided adaptive radiation therapy.

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