Generalised computational tool for registration

		Registration of MRI and CT scans of the spine. This is a challenging problem, due to the piecewise-rigid nature of the movement of the vertebrae.

In order to compare images of different individuals, study the temporal evolution of a given patient, or fuse the information depicted in images of different modalities for diagnostic purposes, it is necessary to have a means of establishing corresponding locations in two or more images. This process is known as image registration, and it is a key element of image-guided surgical systems. In this project, we aimed at developing a generalised registration tool applicable to rigid structures (e.g. bones), non-rigid tissues (e.g. muscles) and piecewise-rigid structures (e.g. spine)

A multi-level hierarchical registration tool for non-rigid multi-modal registration was developed, based on the maximisation of mutual information (MI) and the use of hierarchical subdivision scheme to build an image pyramid. The nodes of such pyramid are locally rigidly registered and finally integrated into a dense regularised deformation field using elastic thin-plate spline interpolation. The method was tested on both mono-modal and multi-modal cases with images of the leg and head.