Cardiac and Respiratory Motion Correction for Simultaneous Cardiac PET/MR

Simultaneous cardiac PET/MR is a powerful but technically demanding imaging combination — both modalities are degraded by cardiac and respiratory motion that blurs signal and reduces quantitative accuracy. This single-subject study evaluated a new algorithm for correcting both motion types simultaneously in under five minutes.

The algorithm derived cardiac and respiratory motion fields from MRI navigator data and applied them retrospectively to PET images. In one volunteer, motion correction improved MR image sharpness and PET contrast-to-noise ratio, with good agreement between motion-corrected functional assessments and reference standards.

With a sample size of one, this is foundational methods work. The technical approach is coherent — using the MR component to guide PET correction exploits the strength of each modality — and the proof-of-concept is a necessary step. Clinical validation in patients with coronary disease requires substantially more work.

We rate the evidence limited. A technically innovative single-subject validation; meaningfully informative for imaging physicists and engineers developing PET/MR workflows, but not yet clinically actionable.