“Squashing peanuts and smashing pumpkins”: How noise distorts diffusion‐weighted MR data
Open Access
- 26 October 2004
- journal article
- research article
- Published by Wiley in Magnetic Resonance in Medicine
- Vol. 52 (5), 979-993
- https://doi.org/10.1002/mrm.20283
Abstract
New diffusion-weighted imaging (DWI) methods, including high-b, q-space, and high angular resolution MRI methods, attempt to extract information about non-Gaussian diffusion in tissue that is not provided by low-b-value (b ≈ 1000 s mm−2) diffusion or diffusion tensor magnetic resonance imaging (DT-MRI). Additionally, DWI data with higher spatial resolution are being acquired to resolve fine anatomic structures, such as white matter fasciculi. Increasing diffusion-weighting or decreasing voxel size can reduce the signal-to-noise ratio so that some DWI signals are close to the background noise level. Here we report several new artifacts that can be explained by considering how background noise affects the peanut-shaped angular apparent diffusion coefficient (ADC) profile. These include an orientationally dependent deviation from Gaussian behavior of the ADC profile, an underestimation of indices of diffusion anisotropy, and a correlation between estimates of mean diffusivity and diffusion anisotropy. We also discuss how noise can cause increased gray/white matter DWI contrast at higher b values and an apparent elevation of diffusion anisotropy in acute ischemia. Importantly, all of these artifacts are negligible in the b-value range typically used in DT-MRI of brain (b ≈ 1000 s mm−2). Finally, we demonstrate a strategy for ameliorating the rectified noise artifact in data collected at higher b values. Magn Reson Med 52:979–993, 2004. Published 2004 Wiley-Liss, Inc.Keywords
This publication has 28 references indexed in Scilit:
- Characterization of anisotropy in high angular resolution diffusion‐weighted MRIMagnetic Resonance in Medicine, 2002
- Relationships between diffusion tensor andq‐space MRI†Magnetic Resonance in Medicine, 2002
- Anisotropy in high angular resolution diffusion‐weighted MRIMagnetic Resonance in Medicine, 2001
- Highly diffusion‐sensitized MRI of brain: Dissociation of gray and white matterMagnetic Resonance in Medicine, 2001
- Analysis of partial volume effects in diffusion‐tensor MRIMagnetic Resonance in Medicine, 2001
- Water diffusion compartmentation and anisotropy at high b values in the human brainMagnetic Resonance in Medicine, 2000
- Three-dimensional tracking of axonal projections in the brain by magnetic resonance imagingAnnals of Neurology, 1999
- Diffusion tensor MR imaging of the human brain.Radiology, 1996
- Estimation of the Effective Self-Diffusion Tensor from the NMR Spin EchoJournal of Magnetic Resonance, Series B, 1994
- Early detection of regional cerebral ischemia in cats: Comparison of diffusion‐ and T2‐weighted MRI and spectroscopyMagnetic Resonance in Medicine, 1990