Respiratory motion correction of PET using motion parameters from MR

Respiratory motion during PET acquisition from the chest/abdomen leads to significant image degradation. Combined PET/MR scanners open up the opportunity to correct motion using MR data acquired simultaneously with PET. As simultaneous human chest/abdomen PET/MR images are currently unobtainable, in this preliminary study we determined motion parameters from respiratory-gated MR and then used these to correct pseudo-PET images generated from the MR. The gated MR images were segmented to typical organ FDG SUV values, smoothed to mimic PET resolution, forward projected into the GE advance geometry and reconstructed separately using OSEM. The MR images were registered using a combined affine and non-rigid B-splines algorithm, with mutual information used as the cost function in a multi-resolution approach. Motion corrected images from both post-reconstruction registration and 4D image reconstruction are shown to be superior to those without motion compensation for most organs.