Medical imaging
Because CT and MRI are sensitive to different tissue properties, the appearances of the images obtained with the two techniques differ markedly. In CT, X-rays must be blocked by some form of dense tissue to create an image, so the image quality when looking at soft tissues will be poor. In MRI, while any nucleus with a net nuclear spin can be used, the proton of the hydrogen atom remains the most widely used, especially in the clinical setting, because it is so ubiquitous and returns a large signal. This nucleus, present in water molecules, allows the excellent soft-tissue contrast achievable with MRI.
Virtopsy
CT is well suited to show foreign objects, bone and air or gas distribution throughout the body, whereas MRI sequences are strong in detailing organ and soft tissue findings. A comprehensive analysis of both surface and deep tissue findings may require fusion of CT, MRI and 3D surface data.