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A semiautomated measure of whole-brain atrophy in multiple sclerosis
Robert A Bermel1, Jitendra Sharma, Christopher W Tjoa
1University at Buffalo, State University of New York, USA.
Abstract:
Brain atrophy is a proposed MRI marker of irreversible pathologic damage in multiple sclerosis (MS). The brain parenchymal fraction (BPF) is the ratio of brain parenchymal volume to the total volume within the surface contour. We developed a semiautomated measure of BPF using commercially available edge-finding and thresholding software (30-min analysis time per patient). We measured BPF in 78 patients with MS and 17 healthy controls. BPF was lower in a cohort of patients with MS (n=50) (0.843+/-0.042, range 0.743-0.906) age-matched to controls (0.877+/-0.020, range 0.835-0.901) (p<0.001). BPF correlated inversely with third ventricular width (r=-0.785, p<0.001), and total T1 hypointense lesion volume (r=-0.347, p=0.011), but not with total T2 hyperintense lesion volume (r=-0.213, p=0.13). BPF correlated negatively with expanded disability status scale (EDSS) score (r=-0.391, p=0.0006) and disease duration (r=-0.281, p=0.01). Stepwise regression compared the relative abilities of MRI variables to predict clinical data. By regression of age, BPF, third ventricular width, T2 lesions, and T1 lesions, BPF was the best predictor of disability score (R(2)=0.204, p<0.001). Third ventricular width was the best predictor of disease duration (R(2)=0.316, p<0.001). None of the MRI variables differed between relapsing-remitting (RR) (n=60) and secondary progressive (SP) (n=18) disease course (p>0.05). The intrarater, interrater, and scan-rescan BPF variability (COV) was 0.31%, 0.34%, and 0.41% and the accuracy against a phantom was 99.1%. We conclude that whole-brain atrophy in MS can be reliably and readily quantified by a semiautomated approach. Longitudinal studies are warranted to determine if this method provides a sensitive biologic marker of the MS disease process.
Insights
Brain atrophy, measured by brain parenchymal fraction (BPF), is lower in multiple sclerosis (MS) patients. This MRI marker reliably quantifies atrophy and predicts disability, aiding MS research.
Area of Science:
- Neurology
- Radiology
- Biomarker Discovery
Background:
- Brain atrophy is a key indicator of irreversible damage in multiple sclerosis (MS).
- The brain parenchymal fraction (BPF) quantifies atrophy by measuring brain volume relative to total intracranial volume.
- Accurate and reliable measurement of BPF is crucial for understanding MS progression.
Purpose of the Study:
- To develop and validate a semiautomated method for measuring BPF in MS patients.
- To assess the correlation between BPF and clinical/MRI measures of MS severity.
- To evaluate BPF as a potential imaging biomarker for MS.
Main Methods:
- A semiautomated BPF measurement technique was developed using standard image analysis software.
- BPF was measured in 78 MS patients and 17 healthy controls.
- Correlations between BPF, third ventricular width, lesion volumes, disability scores (EDSS), and disease duration were analyzed.
Main Results:
- Patients with MS exhibited significantly lower BPF compared to healthy controls (p<0.001).
- BPF showed strong inverse correlations with third ventricular width (r=-0.785) and disability score (r=-0.391).
- BPF was the strongest MRI predictor of clinical disability (R(2)=0.204).
Conclusions:
- Semiautomated BPF measurement is a reliable and efficient method for quantifying whole-brain atrophy in MS.
- BPF serves as a sensitive imaging biomarker for MS disability.
- Further longitudinal studies are recommended to validate BPF's role in tracking MS progression.