MR-based respiratory and cardiac motion correction for PET imaging.

Area of Science:

• Medical Imaging
• Radiological Physics
• Nuclear Medicine

Background:

• Motion artifacts significantly degrade the quality of Positron-Emission-Tomography (PET) images.
• Accurate motion correction is crucial for reliable lesion detection and characterization in PET scans.

Purpose of the Study:

• To develop and evaluate a novel, clinically feasible motion correction method for PET imaging.
• To leverage simultaneously acquired, short-duration magnetic-resonance (MR) images for motion modeling and attenuation correction.

Main Methods:

• A 90-second MR acquisition generated cardiac and respiratory motion models.
• Sensor fusion mapped external motion signals to a comprehensive surrogate signal.
• Joint Compressed Sensing reconstruction and motion estimation produced motion-resolved MR images.
• A 1-POINT DIXON method derived motion-resolved attenuation maps.
• The Customizable and Advanced Software for Tomographic Reconstruction (CASToR) system incorporated motion correction, with all steps performed online via Gadgetron.

Main Results:

• Motion correction was successfully applied to all 36 evaluated patients.
• Moving lesions were observed in 30 patients.
• Significant improvements were observed for 134 malignant lesions: 22% in quantification, 64% in delineation, and 23% in diagnostic confidence.

Conclusions:

• The proposed method offers a clinically feasible solution for respiratory and cardiac motion correction in PET using simultaneous, short-term MRI.
• The publicly available acquisition sequence and reconstruction steps facilitate multi-center studies and diverse motion correction applications.