Correction of motional artifacts in diffusion-weighted MR images using navigator echoes

Ordidge, Roger J.; Helpern, Joseph A.; Qing, Z.X.; Knight, Robert A.; Nagesh, Vijaya

doi:10.1016/0730-725x(94)92539-9

Cited by 319 publications

(233 citation statements)

References 9 publications

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“…The exploited center slice was measured ϳ580 msec after peak systole, which is close to the value suggested by Mü rtz et al (7). For each excitation pulse a navigator echo was also acquired (16).…”

Section: Methodsmentioning

confidence: 99%

Diffusion tensor MRI of the human kidney

Ries

Jones

Basseau

et al. 2001

Magnetic Resonance Imaging

223

153

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This study characterizes the diffusion anisotropy of the human kidney using a diffusion-weighted, single-shot echo planar imaging (EPI) sequence in order to access the full apparent diffusion tensor (ADT) within one breathhold. The fractional anisotropy (FA) of the cortex and the medulla were found to be 0.22 ؎ 0.12 and 0.39 ؎ 0.11, respectively (N ‫؍‬ 10), which emphasizes the need for rotationally invariant diffusion measurements for clinical applications. Additional limitations for clinical diffusion imaging on the kidney are the strong susceptibility variations within the abdomen that restrict the use of imaging techniques employing long echo trains, and the severe motion sensitivity that limits the available imaging time to one breath-hold. To overcome these problems an isotropic, diffusion-weighted, segmented EPI protocol that facilitates the acquisition of high-resolution diffusion-weighted images within a single breath-hold was implemented. Using this method, the apparent diffusion coefficient (ADC) of the cortex and medulla were found to be 2. 89 Index terms: diffusion; magnetic resonance imaging; kidney; EPI; fractional anisotropy WATER TRANSPORT is the predominant phenomenon throughout the kidney due to the kidney's major role in water reabsorption and concentration-dilution functions. These movements are mainly located in the tubular cells and are controlled either by active or passive mechanisms, depending on their location in the nephrons. Consequently, the measurement of the diffusion characteristics of the kidney may provide useful insights into the mechanisms of various renal diseases, including chronic renal failure, renal artery stenosis, and uretral obstruction. However, renal diffusion imaging is very challenging due to the extreme motion sensitivity of diffusion-weighted sequences, and the clinical use of this technique has been hampered by both the severe motion artifacts caused by arterial pulsations and respiratory motion. Diffusion-weighted single-shot-EPI (DW-SSEPI) (1), in conjunction with single breath-hold imaging (2-6) and peripheral pulse unit (PPU) triggering, (7) has been suggested as a possible means of overcoming these problems. However, the restriction of the diffusion experiment to a single breathhold limits the possible spatial resolution and the precision of the diffusion measurement (the number of directions for the diffusion weighting, the number of b-values, and the number of averages). As a result, most studies in the literature have measured the ADC in only one direction (2,4 -7), and hence have implicitly assumed that the diffusion characteristics of the kidney are isotropic. Hydration has been shown to increase global ADC values (3), while renal artery stenosis or ureteral obstruction decreased the values (2,3). In cases of acute or chronic renal failure, the cortical and medullary ADC values were significantly lower than in normal kidneys, and the cortical values were highly correlated with the serum creatinine levels (2).Although some studies have implied that t...

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Section: Methodsmentioning

confidence: 99%

Diffusion tensor MRI of the human kidney

Ries

Jones

Basseau

et al. 2001

Magnetic Resonance Imaging

223

153

View full text Add to dashboard Cite

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“…This problem has been only partially addressed by incorporating navigator echoes in the DWI pulse sequence. 68,69 However, artifacts due to other physiological motion, for example, eye movements or pulsation of cerebrospinal fluid, are more difficult to correct. While these artifacts are mitigated by the use of fast echo-planar DWI sequences and cardiac gating, no general theoretical approach has been developed to model and correct for them.…”

Section: Artifacts In Dt-mri Subject Motionmentioning

confidence: 99%

Diffusion‐tensor MRI: theory, experimental design and data analysis – a technical review

2002

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This article treats the theoretical underpinnings of diffusion-tensor magnetic resonance imaging (DT-MRI), as well as experimental design and data analysis issues. We review the mathematical model underlying DT-MRI, discuss the quantitative parameters that are derived from the measured effective diffusion tensor, and describe artifacts thet arise in typical DT-MRI acquisitions. We also discuss difficulties in identifying appropriate models to describe water diffusion in heterogeneous tissues, as well as in interpreting experimental data obtained in such issues. Finally, we describe new statistical methods that have been developed to analyse DT-MRI data, and their potential uses in clinical and multi-site studies.

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“…These newer techniques include: (1) diffusion weighted radial acquisition of data (DIFRAD) (Trouard et al, 1999); (2) slab scan diffusion imaging (SSDI) (Maier, 2001); (3) segmented EPI with navigator echoes correction (Ordidge et al, 1994); and (4) single-shot EPI with parallel imaging (Bammer et al, 2002). DTI acquisitions are generally performed on high field, high performance gradient systems where 3-4 Tesla magnets are becoming more and more popular in clinical research.…”

Section: Acquisition Of Diffusion Tensor Images In the Brainmentioning

confidence: 99%

A review of diffusion tensor imaging studies in schizophrenia

Kubicki

McCarley

Westin

et al. 2007

Journal of Psychiatric Research

691

532

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Both post-mortem and neuroimaging studies have contributed significantly to what we know about the brain and schizophrenia. MRI studies of volumetric reduction in several brain regions in schizophrenia have confirmed early speculations that the brain is disordered in schizophrenia. There is also a growing body of evidence suggesting that a disturbance in connectivity between different brain regions, rather than abnormalities within the separate regions themselves, are responsible for the clinical symptoms and cognitive dysfunctions observed in this disorder. Thus an interest in white matter fiber tracts, subserving anatomical connections between distant, as well as proximal, brain regions, is emerging. This interest coincides with the recent advent of diffusion tensor imaging (DTI), which makes it possible to evaluate the organization and coherence of white matter fiber tracts. This is an important advance as conventional MRI techniques are insensitive to fiber tract direction and organization, and have not consistently demonstrated white matter abnormalities. DTI may, therefore, provide important new information about neural circuitry, and it is increasingly being used in neuroimaging studies of psychopathological disorders. Of note, in the past five years 18 DTI studies in schizophrenia have been published, most describing white matter abnormalities. Questions still remain, however, regarding what we are measuring that is abnormal in this disease, and how measures obtained using one method correspond to those obtained using other methods? Below we review the basic principles involved in MR-DTI, followed by a review of the different methods used to evaluate diffusion. Finally, we review MR-DTI findings in schizophrenia.

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Correction of motional artifacts in diffusion-weighted MR images using navigator echoes

Cited by 319 publications

References 9 publications

Diffusion tensor MRI of the human kidney

Diffusion tensor MRI of the human kidney

Diffusion‐tensor MRI: theory, experimental design and data analysis – a technical review

A review of diffusion tensor imaging studies in schizophrenia

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