Artifacts and pitfalls in diffusion MRI

Bihan, Denis Le; Poupon, Cyril; Amadon, Alexis; Lethimonnier, Franck

doi:10.1002/jmri.20683

Cited by 695 publications

(577 citation statements)

References 67 publications

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“…The susceptibility artifact generates a local imaging distortion or signal dropout [10]. Because of the use of a relatively low phaseencoding BW, a severe artifact can occur in EPI acquisition along the phase-encoding axis when a local frequency shift happens [11]. However, as this study shows, the selection of readout-encoding (or frequency-encoding) BW and the corresponding ES should be one of the factors that need to be optimized when designing a DT-MRI protocol.…”

Section: Discussionmentioning

confidence: 93%

“…The directional diffusion properties of tissue water are quantified by repeating the experiment with diffusion-weighting gradients applied along at least six different directions. However, artifacts induced by eddy current [9] and susceptibility distortions [10] are common artifacts in EPI, complicating accurate measurements and quantifications of DT-MRI data [11]. In addition to eddy currents and susceptibility distortions, N2 ghosting can distort apparent diffusion coefficients [12].…”

Section: Introductionmentioning

confidence: 99%

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Diffusion anisotropy indexes are sensitive to selecting the EPI readout-encoding bandwidth at high-field MRI

Jahng

Weiner

Schuff

2008

Magnetic Resonance Imaging

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Diffusion tensor magnetic resonance imaging (DT-MRI) is generally performed using an echo planar imaging (EPI) acquisition to map directional water diffusion. However, the oscillating magnetic field gradients of the EPI acquisition can result in considerable mechanical vibrations, which lead, in turn, to magnetic field fluctuations causing Nyquist ghosting in the EPI data. The objective of this study was to investigate effects of EPI readout gradient modulation frequency, which is directly associated with the EPI readout bandwidth (BW), on the accuracy of DT-MRI measurements in a high magnetic field system. A spherical water phantom was used to study the relationship between the EPI BW and the Nyquist ghost for a spin-echo EPI acquisition with a matrix size of 128×128, complemented by diffusion sensitization gradients of up to b=800 s/mm 2 along six directions for DT-MRI. Nine volunteers (four males and five females) were studied using EPI at different BW acquisitions. Analysis of variance was used to investigate the EPI BW effects. The phantom studies demonstrated a systematic relationship between BWs and the intensities of Nyquist ghosts. In the human brain studies, EPI BW variations substantially corrupted diffusion anisotropy indexes (i.e., fractional anisotropy and relative anisotropy) (F=10.5, P=.0001) but were unrelated to diffusion-encoding directions (F=0.14, P=.98). It was possible to minimize BW dependence (F=1.48, P=.25) by tuning the modulation frequency of the EPI readout gradient. In conclusion, diffusion anisotropic indexes are sensitive to the readout BW of EPI due to associated Nyquist ghosting. However, the effect can be minimized by tuning the modulation frequency of the EPI readout gradient, that is, the EPI BW, to a range outside the harmonics of mechanical gradient vibrations.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Diffusion anisotropy indexes are sensitive to selecting the EPI readout-encoding bandwidth at high-field MRI

Jahng

Weiner

Schuff

2008

Magnetic Resonance Imaging

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“…Low spatial resolution and certain artifacts are inherent in DWI (21). Motion artifact is the most easily corrected artifact.…”

Section: Discussionmentioning

confidence: 99%

Interobserver and intraobserver variability of the apparent diffusion coefficient in treated malignant hepatic lesions on a 3.0T machine: Measurements in the whole lesion versus in the area with the most restricted diffusion

Meuli

Marques‐Vidal

et al. 2010

Magnetic Resonance Imaging

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Purpose: To assess the inter/intraobserver variability of apparent diffusion coefficient (ADC) measurements in treated hepatic lesions and to compare ADC measurements in the whole lesion and in the area with the most restricted diffusion (MRDA). Materials and Methods:Twenty-five patients with treated malignant liver lesions were examined on a 3.0T machine. After agreeing on the best ADC image, two readers independently measured the ADC values in the whole lesion and in the MRDA. These measurements were repeated 1 month later. The Bland-Altman method, Spearman correlation coefficients, and the Wilcoxon signed-rank test were used to evaluate the measurements. Conclusion: A limited variability in ADC measurements does exist, and it should be considered when interpreting ADC values of hepatic malignancies. This is especially true for the measurements of the minimal ADC.

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“…Diffusion-weighted MRI (DWI) assesses the Brownian motion of water molecules and provides information about tissue structure and intra/extracellular space via the "apparent diffusion coefficient" ADC [15]. DWI shows broad clinical application in diagnosis of acute cerebral infarction, characterization and therapy monitoring of tumours, and differentiation of gliomas from brain abscesses or lymphomas [16].…”

Section: Diffusion-weighted Mrimentioning

confidence: 99%