Non-rigid chest image registration with preservation of topology and rigid structures

Non-rigid image registration of chest CT images acquired at different breathing stages is often necessary in today’s medical practice. Current algorithms take little consideration of physical characteristics of the different tissues during the registration process. In earlier work, we have presented a registration framework based on the elastic transformation model that incorporated additional constraints to preserve topology and rigid structures. In this paper, we extend our previous registration framework to a viscous fluid model using the same constraints. A comparison between the fluid and elastic registrations, with and without the additional constraints, has been performed on 3D chest phantom data. The results show that the fluid registration model using additional constraints is even more successful in keeping the ribs and other bony structures rigid while reducing the amount of folding in the deformation field, thus leading to better preservation of topology.