Developments in this area include the mathematical aspects of algorithm development, the computer science issues associated with a large cluster-based algorithm, the incorporation of the physics and motion correction, the use of prior information provided from MR images, and the tuning and characterization necessary for practical application for biological studies.
Registration performance itself was evaluated by examining the increase in mutual information from motion correction and registration.
In current motion correction approaches in PET-MRI, motion information from PET data is neglected.
Although for SIMPK more corresponding contours or information were seen, motion correction still failed frequently, especially for the last few frames (data not shown).
As a complementary measure, for each motion correction algorithm run, the difference in mutual information (MI) between the two registered, motion corrected volumes and the original input volumes was calculated.
Functional data were motion corrected offline with the Siemens motion correction protocol.
This could be used for motion correction and gating of PET data without external sensors by incorporation of MR information into the PET list mode data stream, allowing postprocessing of PET data.
Theoretically, the MR information acquired simultaneously with the PET emission data could be used for motion correction of the PET images, improving their diagnostic quality and quantitative information, which could prove to be useful not only for evaluation of the liver, but for all organs affected by respiratory motion.
PET/MR imaging allows for perfectly registered attenuation maps, clinically important complementary MR information, and potentially superior motion correction.
Possible additional advantages of PET/MR over PET/CT are the potential for motion correction, as well as reconstruction driven by anatomic information.
