Correction of Respiratory and Cardiac Motion in Cardiac PET/MR Using MR-Based Motion Modeling

This proof-of-concept study implemented an MR image-based motion correction algorithm for cardiac PET/MR — simultaneously correcting for respiratory and cardiac motion in 8 patients undergoing clinical cardiac imaging.

Motion-corrected PET/MR improved visual alignment of tracer uptake patterns, enhanced target-to-background ratios, and improved contrast-to-noise ratios compared with uncorrected images. The MR-derived motion model was applied retrospectively to the PET data without additional scan time or radiation.

Combined PET/MR holds theoretical appeal for cardiac imaging: simultaneous acquisition of metabolic (PET) and structural/functional (MRI) data without the ionizing radiation of PET/CT and with superior soft tissue contrast. Motion correction is a critical technical challenge because the heart moves continuously during the minutes-long PET acquisition — motion blurring degrades both spatial resolution and quantitative accuracy. This study demonstrates that MR-derived motion modeling can address the challenge.

The proof-of-concept scale (n=8) and the qualitative/quantitative image metrics used — without clinical outcomes comparison — limit the conclusions. Motion-corrected cardiac PET/MR remains a research technique with high acquisition complexity and cost.

We rate the evidence limited. A small proof-of-concept study demonstrating technical feasibility of MR-based motion correction for cardiac PET — a methodological step in advanced hybrid cardiac imaging development.