Quantitative evaluation of Scout Accelerated Motion Estimation and Reduction (SAMER) MPRAGE for morphometric analysis
Nelson Gil1, Azadeh Tabari1, Wei-Ching Lo2
1Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
Background:
Three-dimensional (3D) T1-weighted MRI sequences such as the magnetization prepared rapid gradient echo (MPRAGE) sequence are important for assessing regional cortical atrophy in the clinical evaluation of dementia but have long acquisition times and are prone to motion artifact. The recently developed Scout Accelerated Motion Estimation and Reduction (SAMER) retrospective motion correction method addresses motion artifact within clinically-acceptable computation times and has been validated through qualitative evaluation in inpatient and emergency settings.
Methods:
We evaluated the quantitative accuracy of morphometric analysis of SAMER motion-corrected compared to non-motion-corrected MPRAGE images by estimating cortical volume and thickness across neuroanatomical regions in two subject groups: (1) healthy volunteers and (2) patients undergoing evaluation for dementia. In part (1), we used a set of 108 MPRAGE reconstructed images derived from 12 healthy volunteers to systematically assess the effectiveness of SAMER in correcting varying degrees of motion corruption, ranging from mild to severe. In part (2), 29 patients who were scheduled for brain MRI with memory loss protocol and had motion corruption on their clinical MPRAGE scans were prospectively enrolled.
Results:
In part (1), SAMER resulted in effective correction of motion-induced cortical volume and thickness reductions. We observed systematic increases in the estimated cortical volume and thickness across all neuroanatomical regions and a relative reduction in percent error values compared to reference standard scans of up to 66 % for the cerebral white matter volume. In part (2), SAMER resulted in statistically significant volume increases across anatomical regions, with the most pronounced increases seen in the parietal and temporal lobes, and general reductions in percent error relative to reference standard clinical scans.
Conclusion:
SAMER improves the accuracy of morphometry through systematic increases and recovery of the estimated cortical volume and cortical thickness following motion correction, which may affect the evaluation of regional cortical atrophy in patients undergoing evaluation for dementia.
Insights
The Scout Accelerated Motion Estimation and Reduction (SAMER) method effectively corrects motion artifacts in 3D T1-weighted MRI scans. This improves the accuracy of cortical volume and thickness measurements crucial for dementia evaluation.
Area of Science:
- Neuroimaging
- Radiology
- Medical Physics
Background:
- Three-dimensional (3D) T1-weighted MRI, like Magnetization Prepared Rapid Gradient Echo (MPRAGE), is vital for dementia evaluation but suffers from long scan times and motion artifacts.
- The Scout Accelerated Motion Estimation and Reduction (SAMER) method offers retrospective motion correction for MPRAGE scans within clinically feasible computation times.
- SAMER has demonstrated qualitative effectiveness in inpatient and emergency settings.
Purpose of the Study:
- To quantitatively assess the accuracy of morphometric analysis using SAMER motion-corrected MPRAGE images compared to non-corrected images.
- To evaluate SAMER's effectiveness in correcting motion-induced changes in cortical volume and thickness.
- To determine the impact of SAMER on neuroimaging analysis in healthy volunteers and patients evaluated for dementia.
Main Methods:
- Two subject groups were used: 12 healthy volunteers (108 MPRAGE scans) and 29 patients undergoing dementia evaluation.
- Healthy volunteers' scans were manipulated to simulate mild to severe motion corruption to test SAMER's correction capabilities.
- Patients with motion-corrupted clinical MPRAGE scans were prospectively enrolled for analysis.
Main Results:
- SAMER effectively corrected motion-induced reductions in cortical volume and thickness across neuroanatomical regions.
- Systematic increases in estimated cortical volume and thickness were observed, with up to a 66% reduction in percent error for cerebral white matter volume compared to reference scans.
- Statistically significant volume increases were noted in patients, particularly in the parietal and temporal lobes, with general reductions in percent error.
Conclusions:
- SAMER enhances morphometric analysis accuracy by systematically increasing and recovering estimated cortical volume and thickness.
- Motion correction using SAMER can significantly impact the evaluation of regional cortical atrophy in dementia assessment.
- This method holds promise for improving the reliability of neuroimaging biomarkers in clinical dementia evaluation.
