Vol 8: Isotropic non-white matter partial volume effects in constrained spherical deconvolution.Report as inadecuate



 Vol 8: Isotropic non-white matter partial volume effects in constrained spherical deconvolution.


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This article is from Frontiers in Neuroinformatics, volume 8.AbstractDiffusion-weighted DW magnetic resonance imaging MRI is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter WM of the brain. Significant partial volume effects PVEs are present in the DW signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter GM and cerebrospinal fluid CSF, and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging HARDI methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution CSD. Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios SNRs, fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35–50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM–GM interface is especially important. We suggest acquiring data with high diffusion-weighting 2500–3000 s-mm2, reasonable SNR ~30 and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD.



Author: Roine, Timo; Jeurissen, Ben; Perrone, Daniele; Aelterman, Jan; Leemans, Alexander; Philips, Wilfried; Sijbers, Jan

Source: https://archive.org/







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