Towards an in-plane methodology to track breast lesions by using mammograms and patient-specific finite element simulations.

In breast cancer screening or diagnosis, it is usual to combine different images in order to locate a lesion as accurately as possible. These images are generated by using a single or several imaging techniques. As X-ray based mammography is used widespread, a breast lesion is located in the same plane of the image (mammogram), but tracking of a breast lesion across mammograms corresponding to different views is a daring task for medical physicians. According to this, simulation tools and methodologies that use patient-specific numerical models can facilitate the task of fusing information from different images. Additionally, these tools need to be as straightforward as possible to facilitate its translation to the clinical area. This paper presents a patient-specific, finite element (FE) based and semi-automated simulation methodology to track breast lesions across mammograms. A realistic, three-dimensional, computer model of a patient's breast was generated from magnetic resonance imaging (MRI) to simulate mammographic compressions in cranio-caudal (CC, head-to-toe) and medio-lateral oblique (MLO, shoulder-to-opposite hip) directions. For each compression being simulated, a virtual mammogram was obtained and posteriorly superimposed to the corresponding real mammogram, by sharing the nipple as a common feature. Two-dimensional rigid-body transformations were applied, and the error distance measured between the centroids of the tumor previously located on each image was 3.84 mm and 2.41 mm for CC and MLO compression, respectively. Considering that the scope of this work is to conceive a methodology translatable to the clinical practice, the results indicate that it could be helpful to support tracking of breast lesions. .