Figure 7a. Scene-based registration. (a) Three-dimensional scenes corresponding to proton-density (PD)–weighted MR images of the head obtained in a patient with multiple sclerosis demonstrate a typical "preregistration" appearance. The scenes were acquired at four different times. (b) Same scenes as in a after 3D registration. The progression of the disease (hyperintense lesions around the ventricles) is now readily apparent. At registration, the scenes were re-sectioned with a scene-based interpolation method to obtain sections at the same location.