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Updated: Feb 24, 2026
3D Cine Magnetic Resonance Imaging of Respiratory Motion in Mechanically Ventilated Mice and Rats
Published on: September 19, 2025
MR-based respiratory and cardiac motion correction for PET imaging
Thomas Küstner1, Martin Schwartz2, Petros Martirosian3
1Institute of Signal Processing and System Theory, University of Stuttgart, Stuttgart, Germany; Department of Radiology, University of Tübingen, Tübingen, Germany.
Purpose:
To develop a motion correction for Positron-Emission-Tomography (PET) using simultaneously acquired magnetic-resonance (MR) images within 90 s.
Methods:
A 90 s MR acquisition allows the generation of a cardiac and respiratory motion model of the body trunk. Thereafter, further diagnostic MR sequences can be recorded during the PET examination without any limitation. To provide full PET scan time coverage, a sensor fusion approach maps external motion signals (respiratory belt, ECG-derived respiration signal) to a complete surrogate signal on which the retrospective data binning is performed. A joint Compressed Sensing reconstruction and motion estimation of the subsampled data provides motion-resolved MR images (respiratory + cardiac). A 1-POINT DIXON method is applied to these MR images to derive a motion-resolved attenuation map. The motion model and the attenuation map are fed to the Customizable and Advanced Software for Tomographic Reconstruction (CASToR) PET reconstruction system in which the motion correction is incorporated. All reconstruction steps are performed online on the scanner via Gadgetron to provide a clinically feasible setup for improved general applicability. The method was evaluated on 36 patients with suspected liver or lung metastasis in terms of lesion quantification (SUVmax, SNR, contrast), delineation (FWHM, slope steepness) and diagnostic confidence level (3-point Likert-scale).
Results:
A motion correction could be conducted for all patients, however, only in 30 patients moving lesions could be observed. For the examined 134 malignant lesions, an average improvement in lesion quantification of 22%, delineation of 64% and diagnostic confidence level of 23% was achieved.
Conclusion:
The proposed method provides a clinically feasible setup for respiratory and cardiac motion correction of PET data by simultaneous short-term MRI. The acquisition sequence and all reconstruction steps are publicly available to foster multi-center studies and various motion correction scenarios.
Insights
This study introduces a novel motion correction technique for Positron-Emission-Tomography (PET) using simultaneous magnetic-resonance (MR) imaging. The method significantly improves lesion quantification, delineation, and diagnostic confidence in PET scans.
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.
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