FEM-based MRI deformation algorithm for breast deformation analysis

Breast tissue deformation has recently gained interest in various medical applications. The recovery of large deformations caused by gravity or compression loads and image registration is a non-trivial task. The most effective tool for breast cancer visualisation is Magnetic Resonance Imaging (MRI). However, for MRI scans the patient is in a prone position with the breast placed in signal enhancement coils, while other procedures, i.e. surgery, PET-CT (Positron Emission Tomography fused with Computer Tomography) are performed with the patient in a supine position. The need therefore arises to estimate the large breast deformations caused by natural body movement during examinations or surgery. There is no doubt that a patient's breast in both positions has a different shape and that this influences relationships between intra-breast structures. In this work, we present the fundamentals of a method for transformation of breast images based on Finite Element Methods (FEMs). This 2D model uses the simplest constitutive tissue description, which makes it easily applicable and fast. According to the Jaccard Index, the average accuracy obtained is 95%, the lowest is 87%, and the highest is 99%. The model parameter set is proposed for six different breast size classes, covering the whole population. The algorithm provides reliable breast images in a supine position in a few simple steps. (C) 2020 Nalecz Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.