Susceptibility phase imaging with comparison to R2* mapping of iron-rich deep grey matter

Walsh, Andrew J.; Wilman, Alan H.

doi:10.1016/j.neuroimage.2011.04.017

Cited by 34 publications

(36 citation statements)

References 43 publications

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“…21,22 Although it does have nonlocal dipole field effects that can potentially be alleviated by susceptibility mapping, it involves fewer assumptions caused by the ill-posed problem of dipole de-convolution, is still widely used by researchers, and is more generally applicable because it is directly available on some scanners. Furthermore, both post-mortem [23][24][25][26] and in vivo 27 studies confirmed associations between the local SWI-filtered phase shift and the underlying magnetic susceptibility, which is affected by the tissue iron content. In the present study, both mean phase (indicative of overall iron content) and mean phase of low-phase voxels (MP-LPV) (indicative of high iron content) measures were used.…”

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confidence: 56%

Effect of Age on MRI Phase Behavior in the Subcortical Deep Gray Matter of Healthy Individuals

Hagemeier

Dwyer

Bergsland

et al. 2013

AJNR Am J Neuroradiol

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mentioning

confidence: 56%

Effect of Age on MRI Phase Behavior in the Subcortical Deep Gray Matter of Healthy Individuals

Hagemeier

Dwyer

Bergsland

et al. 2013

AJNR Am J Neuroradiol

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“…Additionally, there are conflicting results as to the relationship between R 2 *, which is also used as a measure of iron content, and phase. Walsh and Wilman (Walsh and Wilman, 2011) affirmed a relationship between R 2 * and phase in individual structures. On the other hand, (Yan et al, 2012) found no statistically significant correlation between R 2 * and phase in seven structures in the brain, including the SN.…”

Section: Discussionmentioning

confidence: 98%

“…While phase is sensitive to paramagnetic iron species; it is also sensitive to inhomogeneities in the magnetic field, filtering, structure shape (Walsh and Wilman, 2011), orientation of neuronal fibers (Lee et al, 2010), myelin content (Duyn et al, 2007), and the orientation of the brain with respect to the main magnetic field (B 0 ) (Schafer et al, 2009). However, the aforementioned non-iron factors should not significantly affect the phase given that the SN is a grey matter nucleus and the relative proximity of the SN volumes.…”

Section: Discussionmentioning

confidence: 99%

A multicontrast approach for comprehensive imaging of substantia nigra

et al. 2015

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We characterize the contrast behavior of substantia nigra (SN) in both magnetization transfer (MT) imaging, which is believed to be sensitive to neuromelanin (NM), and susceptibility weighted imaging (SWI). Images were acquired with a MT prepared dual echo gradient echo sequence. The first echo was taken as the MT contrast image and the second was used to generate the SWI image. SN volumes were segmented from these two types of images using a thresholding method. The spatial and signal characteristics of the extracted SWI and MT volumes were compared. Both images showed the presence of SN but the volumes of the SN identified in the two are spatially incongruent. The MT volume was more caudal than the SWI volume and with only a 12% overlap between the two volumes. Considering the SN volumes in each hemisphere separately, the average distances between the centers of mass of the volumes from the two types images are 5.1±1.1 mm and 4.1±1.2 mm, respectively. The frequency offsets (homodyne filtered phase/echo time) for the volumes derived from MT (NM) images and SWI images are 0.09±0.32 radians/s and -1.12±0.57 radians/s (p<0.0001), respectively. The MT contrasts for the two volumes are 0.16±0.02 and 0.10±0.03 (p<0.001), respectively. Our results indicate that the two contrasts are sensitive to different portions of the SN, with MT seeing the more caudal portion of the SN than SWI, likely due to variations of NM and iron content in the SN. Despite the small overlap, these regions are complementary. Our results provide a new understanding of the contrast behavior of the SN in the two imaging approaches commonly used to image it and indicate that using both may yield a more comprehensive visualization of the SN.

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“…As a parameter that reflects iron variation in the brain, phase value depends highly on filtering, structure size, shape and local environment. The edge effect could cause the fluctuation of phase values [31] and the difference of the magnetic susceptibility in the surrounding tissue besides the iron content [28], which would reduce the apparent phase shift in large uniform structures such as deep gray nuclei [28], [32]. Furthermore, blood volume as well as higher ferritin content both contributed to the contrast of gray matter and WM in phase imaging [33], and the phase shift also depended on the developmental variation of the cerebral venous system in infants [34].…”

Section: Discussionmentioning

confidence: 99%

Assessment of Iron Deposition and White Matter Maturation in Infant Brains by Using Enhanced T2 Star Weighted Angiography (ESWAN): R2* versus Phase Values

et al. 2014

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Background and PurposeIron deposition and white matter (WM) maturation are very important for brain development in infants. It has been reported that the R2* and phase values originating from the gradient-echo sequence could both reflect the iron and myelination. The aim of this study was to investigate age-related changes of R2* and phase value, and compare their performances for monitoring iron deposition and WM maturation in infant brains.Methods56 infants were examined by enhanced T2 star weighted angiography (ESWAN) and diffusion tensor imaging in the 1.5T MRI system. The R2* and phase values were measured from the deep gray nuclei and WM. Fractional anisotropy (FA) values were measured only in the WM regions. Correlation analyses were performed to explore the relation among the two parameters (R2* and phase values) and postmenstrual age (PMA), previously published iron concentrations as well as FA values.ResultsWe found significantly positive correlations between the R2* values and PMA in both of the gray nuclei and WM. Moreover, R2* values had a positive correlation with the iron reference concentrations in the deep gray nuclei and the FA in the WM. However, phase values only had the positive correlation with PMA and FA in the internal capsule, and no significant correlation with PMA and iron content in the deep gray nuclei.ConclusionsCompared with the phase values, R2* may be a preferable method to estimate the iron deposition and WM maturation in infant brains.

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Susceptibility phase imaging with comparison to R2* mapping of iron-rich deep grey matter

Cited by 34 publications

References 43 publications

Effect of Age on MRI Phase Behavior in the Subcortical Deep Gray Matter of Healthy Individuals

Effect of Age on MRI Phase Behavior in the Subcortical Deep Gray Matter of Healthy Individuals

A multicontrast approach for comprehensive imaging of substantia nigra

Assessment of Iron Deposition and White Matter Maturation in Infant Brains by Using Enhanced T2 Star Weighted Angiography (ESWAN): R2* versus Phase Values

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