ABSTRACT
In recent years, the number of animal models of human disease has increased and their use is now widespread. The need to study biological processes and morphological features in small-animal models—and to do so noninvasively so that the process can be tracked over time—has stimulated the development of high-resolution biomedical imaging devices. Nowadays, drug development relies heavily on the use of small-animal models and molecular imaging techniques, such as positron emission tomography (PET) or single photon emission computed tomography (SPECT), to provide the required functional information that characterizes the behavior of the drug. However, the results obtained are sometimes difficult to interpret due to the lack of a reliable anatomical localization of tracer uptake. To avoid this problem, registration of PET and SPECT images with accurate anatomical images [1] has proven to be an appropriate choice in new multimodality systems.
