Symmetric Biomechanically Guided Prone-to-Supine Breast Image Registration.

Björn Eiben,Norman R Williams,Cristian Lorenz,Thomas Buelow,Sara Reis,Vasileios Vavourakis,David J Hawkes,John H Hipwell,Thomy Mertzanidou,Mohammed Keshtgar,Sven Kabus

doi:10.1007/s10439-015-1496-z

Abstract

Prone-to-supine breast image registration has potential application in the fields of surgical and radiotherapy planning, image guided interventions, and multi-modal cancer diagnosis, staging, and therapy response prediction. However, breast image registration of three dimensional images acquired in different patient positions is a challenging problem, due to large deformations induced to the soft breast tissue caused by the change in gravity loading. We present a symmetric, biomechanical simulation based registration framework which aligns the images in a central, virtually unloaded configuration. The breast tissue is modelled as a neo-Hookean material and gravity is considered as the main source of deformation in the original images. In addition to gravity, our framework successively applies image derived forces directly into the unloading simulation in place of a subsequent image registration step. This results in a biomechanically constrained deformation. Using a finite difference scheme avoids an explicit meshing step and enables simulations to be performed directly in the image space. The explicit time integration scheme allows the motion at the interface between chest and breast to be constrained along the chest wall. The feasibility and accuracy of the approach presented here was assessed by measuring the target registration error (TRE) using a numerical phantom with known ground truth deformations, nine clinical prone MRI and supine CT image pairs, one clinical prone-supine CT image pair and four prone-supine MRI image pairs. The registration reduced the mean TRE for the numerical phantom experiment from initially 19.3 to 0.9 mm and the combined mean TRE for all fourteen clinical data sets from 69.7 to 5.6 mm.

Highlights

Breast cancer is the most common female cancer worldwide
When a woman is diagnosed with breast cancer, surgery is often part of her individual therapy plan which can include additional forms of treatment such as chemotherapy and radiotherapy
The critical time step of the explicit time integration scheme depends on the mesh density and a relatively coarse grid was chosen for the purpose of acceptable computational times

Summary

Introduction

Breast cancer is the most common female cancer worldwide. The lifetime risk for a woman in Europe to develop breast cancer is estimated to be one in eight. Being diagnosed with breast cancer carries a high psychological burden for any patient and improved cancer management strategies are sought which streamline the clinical workflow and could potentially improve the clinical outcome whilst avoiding the risk of over-diagnosis. Where possible lumpectomy combined with radiotherapy is the preferred treatment of choice. This involves removing only the cancerous tissue with a margin of healthy breast tissue, conserving the unaffected parts of the breast. This has potential benefits over mastectomy, the complete removal of breast tissue, of being more acceptable to patients, offering good cosmetic results and comparably low risk of local recurrence.

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Conclusion