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Magnetic resonance image registration in multiple sclerosis: comparison with repositioning error and observer-based
I Leng Tan1, Ronald A van Schijndel, Marianne A A van Walderveen
1MR Centre for MS Research and Departments of Radiology, Vrije Universiteit Medical Centre, Amsterdam, The Netherlands.
Journal of Magnetic Resonance Imaging : JMRI
|May 9, 2002
Summary
Image registration using normalized mutual information (NMI) accurately aligns brain MR images for multiple sclerosis (MS) lesion volume analysis. This method shows promise for tracking disease progression in large serial MRI datasets.
Area of Science:
- Medical Imaging
- Neurology
- Biomedical Engineering
Background:
- Accurate measurement of multiple sclerosis (MS) lesion volume is crucial for disease monitoring.
- Image registration techniques are essential for comparing serial magnetic resonance imaging (MRI) data.
- Variability in lesion volume assessment can arise from repositioning errors and observer differences.
Purpose of the Study:
- To evaluate the utility of image registration in analyzing MS lesion volume.
- To compare the accuracy of image registration against repositioning error and observer variability.
Main Methods:
- The normalized mutual information (NMI) algorithm was assessed for accuracy using a phantom.
- NMI was validated on magnetic resonance (MR) data from multiple sclerosis patients.
- Scan-rescan MR data were analyzed to quantify the contributions of registration, repositioning, and quantification to variance.
Main Results:
- Image registration achieved near-perfect accuracy in phantom studies and 0.2-0.3 mm accuracy in vivo.
- In scan-rescan studies, registration accounted for 40.0% of relative variance in lesion volume.
- Repositioning errors contributed 44.4% and quantification 15.6% to the relative variance.
Conclusions:
- Normalized mutual information provides robust and accurate alignment of MR brain images in MS patients.
- Image registration is a valuable tool for detecting changes in MS lesion volume.
- Further evaluation of NMI for large-scale serial MRI analysis in MS is warranted.