Normalization of the binding PET images. (A) Rigid co-registration of perfusion-like PET images to MRI (transformation matrix t1). Spatial normalization of MR images in original image space (OIS) into MNI space (t2). Combination of t1 and t2 to normalize the binding PET images into the MNI space. (B) Direct transformation of binding PET images to MNI space by normalization to the raclopride PET template.