What is Mutual Information

Image registration is the process of determining the correspondence of features between images collected at different times or using different imaging modalities. A wide range of registration algorithms was proposed in literature for solving this task. In this chapter the focus will be on oncology applications, where registration is the prior step of: i) subtraction imaging (to emphasize hyper (or hypo) enhanced structures), ii) fusion imaging (to integrate anatomical and functional information about lesions) and iii) serial imaging comparison (to monitor the progression/regression of a disease). These applications are of great relevance in tumors diagnosis, staging and treatment planning. The goal of this chapter is to provide an overview of registration algorithms considering these different applications in oncology. We discuss the advantages/disadvantages of each algorithm, the results gained and the possible future developments to comply with new requirements.