Registration of a SPECT brain image with its `nearest normal equivalent´ image

The use of principal components analysis (PCA) applied to image sequences in nuclear medicine is well established. In the paper, PCA is applied to the voxels of regional cerebral blood flow images obtained from single photon emission computed tomography (SPECT). The analysis involves the following stages: (a) acquisition of a series of images obtained from normal control subjects; (b) adoption of one of these as a reference image; (c) registration of each of these images with respect to the reference image; (d) PCA applied to the series of registered images using voxels as variables; (e) registration of subsequent images with respect to the reference image; (f) computation of the nearest normal equivalent image to each subsequent image using the principal components found at stage (d)