Efficient implementation of Salomir's method from 2003: we use a multi-resolution trick to deal with aliasing.
* more than 6x faster (version of october 2014)
* allows to do simulations in a 2x higher resolution, without memory problems.
Explanation and references:
The presented algorithm is an efficient implementation of the Fourier-based procedure to calculate the susceptibility-induced field-shift if an object with known susceptibility distribution is placed within a strong homogeneous magnetic field (B0).
This method is based on the publication of: Salomir et al, "A fast calculation method for magnetic field inhomogeneity due to an arbitrary distribution of bulk susceptibility" Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering, Volume 19B, Issue 1, pages 26–34, 2003.
A drawback of this method, is that it depends on (inefficient) zero-padding, to prevent the aliasing artefact (periodic wrap-around). See also: Cheng YCN, Neelavalli J, Haacke EM. "Limitations of calculating field distributions and magnetic susceptibilities in MRI using a Fourier based method". Phys Med Biol 2009;54:1169–1189.
In the here presented algorithm, aliasing is removed by calculating this artifact using an additional convolution in a lower resolution, which is does not lead to accuracy loss, due to the smooth decay of the dipole function. For further details the reader is referred to the article: Job G. Bouwman, Chris J.G. Bakker. "Alias subtraction more efficient than conventional zero-padding in the Fourier-based calculation of the susceptibility induced perturbation of the magnetic field in MR" 2012, Magnetic Resonance in Medicine 68:621630 (2012). Please refer to this article when using this script.
인용 양식
Job (2024). Forward field-shift calculation for MRI (https://www.mathworks.com/matlabcentral/fileexchange/37278-forward-field-shift-calculation-for-mri), MATLAB Central File Exchange. 검색됨 .
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줌: MRI simulation using FORECAST: Fourier-based Off-REsonanCe Artifact simulation in the STeady-state
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Start Hunting!버전 | 게시됨 | 릴리스 정보 | |
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1.14.0.0 | 1) Sub-functions are converted into nested functions. This enables / speeds up the convolution of very large susceptibility distributions.
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1.13.0.0 | Screenshot was incorrect |
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1.12.0.0 | Again 30% faster than previous version. Instead of doing two convolutions, the aliasing calculation is done in the imaginary channel of the initial convolution. |
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1.10.0.0 | This version can handle anisotropic voxel sizes. |
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1.7.0.0 | Added a script (FBFC_example.m) for demonstration of the functions FBFC_CC_vZP and FBFC_KF_vZP. This script makes use of the function (FBFC_CC_no_padding.m). |
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1.0.0.0 |