Biomechanically guided prone-to-supine image registration of breast MRI using an estimated reference state

The female breast undergoes large scale deformations, when the patient position is changed from the prone position where imaging is usually performed to the supine position, which is the standard surgical setting. To guide the surgical procedure, MRI data need to be aligned between these two positions. Image registration techniques which are purely intensity based usually fail, when prone and supine image data are to be aligned. To address this we use patient specific biomechanical models to provide an initial deformation of the breast prior to registration. In contrast to previous methods, we use these models to estimate the zero-gravity reference state for both the prone and supine configurations and perform the subsequent registration in this space. In this symmetric approach we incorporate non-linear material models and displacement boundary conditions on the chest wall which lead to clinically useful accuracy in the simulation and subsequent registration.