Markerless motion tracking and correction for PET, MRI, and simultaneous PET/MRI

Area of Science:

• Medical Imaging
• Neuroscience
• Biomedical Engineering

Background:

• Simultaneous Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) offers advanced diagnostic capabilities but is susceptible to motion artifacts.
• Accurate motion correction (MC) is crucial for reliable PET/MRI data, especially in pediatric patients and for dynamic imaging.
• Existing motion tracking solutions often require markers, limiting their application in PET/MRI environments.

Purpose of the Study:

• To develop and evaluate the first markerless motion tracker compatible with PET, MRI, and simultaneous PET/MRI systems.
• To enable prospective motion correction in MRI and retrospective motion correction in PET brain imaging.
• To assess the tracker's performance in a clinical setting, including pediatric patient studies.

Main Methods:

• Developed a markerless motion tracker with in-bore vision extenders and out-of-bore electronics for PET/MRI compatibility.
• Demonstrated the tracker in a clinical setup with 94 pediatric PET/MRI scans.
• Applied customized Multiple Acquisition Frame method for PET MC and a motion-aware MRI sequence for prospective MC.

Main Results:

• Markerless motion tracking demonstrated good validity for both PET and MRI modalities.
• Motion-induced artifacts were noticeably reduced, with accurate capture of various motion ranges (respiratory to intentional).
• PET/MRI study showed significant image improvement, reducing maximal standardized uptake value differences by 19% for a patient with ±5-10 mm head motion.

Conclusions:

• The first markerless motion tracker for PET/MRI brain imaging was successfully demonstrated.
• The system provides prospective MC for MRI and MC for PET with good tracking validity.
• This technology addresses the growing need for accurate motion tracking in simultaneous PET/MRI scans.