Misc,
Combination of automatic non-rigid and landmark based registration: the best of both worlds
(2003)
Abstract
In particular in medical imaging, registration schemes are known to be valuable tools in various settings, like, e.g., the comparison of pre- and post biopsy images. The currently available schemes in can roughly be divided in two classes: landmark based and intensity based registration schemes. In this paper, we present a rigorous mathematical framework for combining these two techniques, in order to benefit from the advantages of both strategies. Intensity based approaches aim to match images by minimizing an appropriate distance measure, like, e.g., the L2-norm of the difference image or the mutual information of the two images. These techniques are generally full automatic and yield a good registration on the average. However, they may perform poorly for specific, important locations like anatomical landmarks. On the opposite, landmark based registration techniques are designed to accurately match user specified landmarks. A drawback of landmark based registration is the fact that the intensities of the images are completely neglected. Consequently, the registration result away from the landmarks may be very poor. Here, we propose a mathematical framework for combining any distance measure based registration with landmark information. We also present a general numerical procedure for computing the wanted transformation as well as a particular implementation for a specific distance measure based registration technique. The general procedure computes a displacement field which is mathematically guaranteed to produce a one-to-one match between given landmarks and at the same time to minimize an intensity based measure for the remaining parts of the images. The properties of the new scheme are demonstrated for a variety of examples. It is
