Looking Inside Marine Organisms with MRI and X-ray Tomography

In this chapter we describe computer-based tomographic methods using magnetic resonance imaging (MRI) and X-ray absorption as well as Xray phase-contrast imaging techniques. The latter are based on refraction and near-field diffraction of X-rays and are gaining increased attention due to the increase in sensitivity they offer over conventional, attenuationbased X-ray techniques. The increased sensitivity is of particular interest in marine biology imaging, especially for soft tissue visualization and analysis. The basic principles of the imaging techniques are described, starting with an analysis of the image formation process, followed by a review of several tomography methods, such as MRI or X-ray imaging, and practical guidelines for parameter selection. Finally, two relevant examples of imaging are presented: imaging in marine biology (segmentation and visualization) and small animal (sea horse) imaging. These examples illustrate imaging under different conditions and using different reconstruction options.