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MR-assisted PET motion correction in simultaneous PET/MRI studies of dementia subjects
Kevin T Chen1,2, Stephanie Salcedo1, Daniel B Chonde1,3
1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA.
Background:
Subject motion in positron emission tomography (PET) studies leads to image blurring and artifacts; simultaneously acquired magnetic resonance imaging (MRI) data provides a means for motion correction (MC) in integrated PET/MRI scanners.
Purpose:
To assess the effect of realistic head motion and MR-based MC on static [18 F]-fluorodeoxyglucose (FDG) PET images in dementia patients.
Study Type:
Observational study.
Population:
Thirty dementia subjects were recruited.
Field Strength/Sequence:
3T hybrid PET/MR scanner where EPI-based and T1 -weighted sequences were acquired simultaneously with the PET data.
Assessment:
Head motion parameters estimated from high temporal resolution MR volumes were used for PET MC. The MR-based MC method was compared to PET frame-based MC methods in which motion parameters were estimated by coregistering 5-minute frames before and after accounting for the attenuation-emission mismatch. The relative changes in standardized uptake value ratios (SUVRs) between the PET volumes processed with the various MC methods, without MC, and the PET volumes with simulated motion were compared in relevant brain regions.
Statistical Tests:
The absolute value of the regional SUVR relative change was assessed with pairwise paired t-tests testing at the P = 0.05 level, comparing the values obtained through different MR-based MC processing methods as well as across different motion groups. The intraregion voxelwise variability of regional SUVRs obtained through different MR-based MC processing methods was also assessed with pairwise paired t-tests testing at the P = 0.05 level.
Results:
MC had a greater impact on PET data quantification in subjects with larger amplitude motion (higher than 18% in the medial orbitofrontal cortex) and greater changes were generally observed for the MR-based MC method compared to the frame-based methods. Furthermore, a mean relative change of ∼4% was observed after MC even at the group level, suggesting the importance of routinely applying this correction. The intraregion voxelwise variability of regional SUVRs was also decreased using MR-based MC. All comparisons were significant at the P = 0.05 level.
Data Conclusion:
Incorporating temporally correlated MR data to account for intraframe motion has a positive impact on the FDG PET image quality and data quantification in dementia patients.
Level Of Evidence:
3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1288-1296.
Insights
Motion correction using MRI data improves PET imaging in dementia patients. This technique enhances image quality and data accuracy, especially for those with significant head movement during scans.
Area of Science:
- Neuroimaging
- Medical Physics
Background:
- Subject motion during Positron Emission Tomography (PET) studies causes image blurring and artifacts.
- Integrated PET/MRI scanners allow for motion correction (MC) using simultaneously acquired magnetic resonance imaging (MRI) data.
Purpose of the Study:
- To evaluate the impact of realistic head motion and MR-based MC on static [18F]-fluorodeoxyglucose (FDG) PET images in dementia patients.
- To compare MR-based MC with traditional frame-based MC methods.
Main Methods:
- Utilized a 3T hybrid PET/MR scanner to acquire simultaneous PET, EPI, and T1-weighted MRI data.
- Estimated head motion parameters from high temporal resolution MR volumes for PET MC.
- Compared MR-based MC with PET frame-based MC and no MC using standardized uptake value ratios (SUVRs) in brain regions.
Main Results:
- MR-based MC significantly improved PET data quantification, particularly in subjects with larger motion amplitudes.
- Greater improvements were observed with MR-based MC compared to frame-based methods.
- Routine application of MR-based MC resulted in a mean relative change of ~4% at the group level and reduced intraregion variability.
Conclusions:
- Incorporating temporally correlated MR data for intraframe motion correction positively impacts FDG PET image quality and quantification in dementia patients.
- MR-based MC is a valuable tool for improving the accuracy of PET imaging in clinical settings, especially for populations prone to motion artifacts.
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