1. A method for producing an attenuation-corrected time-gated PET image comprising: obtaining a baseline MR image and a cine MR image of a structure; registering the baseline MR image to the cine MR image to create an image transform; and generating a corresponding cine ACF matrix using the image transform, and time-correlating the ACF matrix to a time-gated PET data set to produce an attenuation-corrected time-gated PET image.