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Estimation of mutual information objective function based on Fourier shift theorem: an application to eddy current
Udomchai Techavipoo1, John Lackey, Jianrong Shi
1Department of Radiology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Magnetic Resonance Imaging
|July 18, 2009
Summary
Eddy current distortion in diffusion tensor imaging is corrected using a novel mutual information (MI) estimation method. This Fourier shift theorem-based approach eliminates artifacts, improving diffusion-weighted image quality.
Area of Science:
- Medical Imaging
- Image Processing
- Neuroimaging
Background:
- Diffusion tensor imaging (DTI) is crucial for visualizing white matter tracts.
- Eddy currents induce distortions in diffusion-weighted images (DWIs), compromising image quality and analysis.
- Existing retrospective correction methods using linear or partial volume interpolation introduce artifacts into the mutual information (MI) objective function.
Purpose of the Study:
- To develop an artifact-free method for retrospective eddy current distortion correction in DWIs.
- To improve the accuracy and efficiency of distortion correction in DTI.
- To optimize algorithm parameters for enhanced diffusion tensor image quality.
Main Methods:
- Estimated the MI objective function using interpolation based on the Fourier shift theorem, avoiding traditional interpolation artifacts.
- Improved computational efficiency by approximating pixel values using nearest neighbors in an up-sampled spatial domain.
- Investigated the impact of quantization levels and Parzen window filtering for MI objective function smoothing to optimize parameters.
Main Results:
- The proposed Fourier shift theorem-based interpolation successfully eliminated artifacts present in previous MI estimation methods.
- The nearest neighbor approximation in the up-sampled domain significantly increased computational efficiency without degrading correction performance.
- Optimized algorithm parameters through systematic investigation of quantization levels and smoothing filters.
- Visually significant improvements in diffusion tensor image quality were observed after applying the proposed distortion correction.
Conclusions:
- The Fourier shift theorem-based method provides an effective and artifact-free approach for eddy current distortion correction in DTI.
- The enhanced computational efficiency makes this method more practical for clinical and research applications.
- This technique substantially improves the overall quality and reliability of diffusion tensor imaging data.
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