Automatic pre-alignment of multimodality rat brain images using principal axes transformation

Abstract

The use of small animal studies of different modalities isnowadays widespread, since functional studies like positron emission tomography (PET) or single photon emission computed tomography (SPECT) are better analyzed when mapped to the underlying anatomical structure coming from magnetic resonance imaging (MRI) or computed tomography (CT). The different positioning of the animals in the scanners results in the need for automated image registration methods. One important drawback of the existing algorithms is their limited capture range: if case of large initial misregistration (large translations and rotations) the optimization may not converge to the right solution, and the images do not become correctly coregistered. To avoid this problem we propose the use of a pre-alignment step based on the principal axes transformation.