Susceptibility map‐weighted imaging (SMWI) for neuroimaging

Gho, Sung Min; Li, Wei; Jang, Ung; Kim, Eung Yeop; Hwang, Dosik; Kim, Dong Hyun

doi:10.1002/mrm.24920

Cited by 43 publications

(45 citation statements)

References 36 publications

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“…In addition, quantitative susceptibility mapping (QSM), which derives the susceptibility distribution from magnetic field variation by solving an inverse problem, makes it possible to evaluate the in vivo susceptibility changes quantitatively . Furthermore, the combination of SWI and QSM, the true susceptibility weighted imaging (tSWI), eliminates the orientation dependence in conventional SWI and improves the delineation of the vessels . However, neither SWI nor QSM is primarily used for in vivo detection of tiny arterioles, where vasculogenic neuropathology often begins .…”

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confidence: 99%

Susceptibility weighted imaging and quantitative susceptibility mapping of the cerebral vasculature using ferumoxytol

Liu

Brisset

et al. 2017

Magnetic Resonance Imaging

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Purpose To demonstrate the potential of imaging cerebral arteries and veins with ferumoxytol using susceptibility weighted imaging (SWI) and quantitative susceptibility mapping (QSM). Materials and Methods The relationships between ferumoxytol concentration and the apparent susceptibility at 1.5T, 3T, and 7T were determined using phantom data; the ability of visualizing subvoxel vessels was evaluated using simulations; and the feasibility of using ferumoxytol to enhance the visibility of small vessels was confirmed in three healthy volunteers at 7T(with doses 1 mg/kg to 4 mg/kg). The visualization of the lenticulostriate arteries and the medullary veins was assessed by two raters and the contrast-to-noise ratios (CNRs) of these vessels were measured. Results The relationship between ferumoxytol concentration and susceptibility was linear with a slope 13.3 ± 0.2 ppm·mg−1·mL at 7T. Simulations showed that SWI data with an increased dose of ferumoxytol, higher echo time (TE), and higher imaging resolution improved the detection of smaller vessels. With 4 mg/kg ferumoxytol, voxel aspect ratio = 1:8, TE = 10 ms, the diameter of the smallest detectable artery was approximately 50µm. The rating score for arteries was improved from 1.5 ± 0.5 (precontrast) to 3.0 ± 0.0 (post-4 mg/kg) in the in vivo data and the apparent susceptibilities of the arteries (0.65 ± 0.02 ppm at 4 mg/kg) agreed well with the expected susceptibility (0.71 ± 0.05 ppm). Conclusion The CNR for cerebral vessels with ferumoxytol can be enhanced using SWI, and the apparent susceptibilities of the arteries can be reliably quantified using QSM. This approach improves the imaging of the entire vascular system outside the capillaries and may be valuable for a variety of neurodegenerative diseases which involve the microvasculature.

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confidence: 99%

Susceptibility weighted imaging and quantitative susceptibility mapping of the cerebral vasculature using ferumoxytol

Liu

Brisset

et al. 2017

Magnetic Resonance Imaging

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“…The resulting QSM was further processed to generate a QSM mask (S mask ) for susceptibility contrast weighting. The following scheme was used for the generation of the mask:

S_{m a s k} (χ) = {\begin{matrix} \begin{matrix} 0, \\ (χ_{t h} - χ) / χ_{t h}, \\ 1, \end{matrix} & \begin{matrix} χ_{t h} < χ \\ 0 < χ < χ_{t h} \\ o t h e r w i s e \end{matrix} \end{matrix}

where X is the quantitative susceptibility value (in units of ppm) calculated in Step 4 and X th is a paramagnetic threshold value. The threshold was determined later using the nigrosome 1 imaging data for an optimal CNR. Finally, the SMWI image was generated by multiplying the multiecho combined magnitude images with the QSM mask.…”

Section: Methodsmentioning

confidence: 99%

“…Alternative susceptibility contrast‐related approaches are GRE phase (or frequency) images and quantitative susceptibility mapping (QSM), both of which have shown a good sensitivity to magnetic susceptibility contrasts and have been widely applied in recent years . More recently, a new method that utilizes susceptibility weighting mask derived from QSM for the magnitude images has been proposed . This approach is similar to SWI but resolves the blooming artifacts of SWI and may potentially provide improved visualization of susceptibility variations.…”

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Imaging of nigrosome 1 in substantia nigra at 3T using multiecho susceptibility map‐weighted imaging (SMWI)

Nam

Gho

Kim

et al. 2016

Magnetic Resonance Imaging

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“…To further enhance the contrast of white matter structures, diamagnetic features predominant in white matter were extracted from the quantitative susceptibility maps and combined with the rescaled T 2 * maps, creating diamagnetic susceptibility map-weighted images (dSMWI) (Gho et al, 2014). The following equation was used in this process:…”

Section: Data Acquisitionmentioning

confidence: 99%

Structure tensor informed fibre tractography at 3T

Chan

Norris

Marques

2018

Human Brain Mapping

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Structure tensor informed fibre tractography (STIFT) based on informing tractography for diffusion-weighted images at 3T and by utilising the structure tensor obtained from gradient-recalled echo (GRE) images at 7T is able to delineate fibres when seed voxels are placed close to the fibre boundaries. However, incorporating data from two different field strengths limits the applicability of STIFT. In this study, STIFT was implemented with both diffusion-weighted images and GRE images acquired at 3T. Instead of using the magnitude GRE data directly for STIFT as in the previous work, the utility of T * maps and quantitative susceptibility maps derived from complex-valued GRE data to improve fibre delineation was explored. Single-seed tractography was performed and the results show that the optic radiation reconstructed with STIFT is more distinguishable from the inferior longitudinal fasciculus/inferior fronto-occipital fasciculus complex when compared to standard diffusion-weighted imaging tractography. We further investigated the quantitative effects of STIFT in a group of five healthy volunteers and evaluated its impact on measures of structural connectivity. The framework was extended to evaluate implementations of STIFT based on T *-weighted and quantitative susceptibility-weighted images in a whole-brain connectivity study. In terms of connectivity, no systematic differences were found between STIFT and diffusion-weighted imaging tractography, suggesting that local improvements in tractography are not translated to the atlas-based structural connectivity analysis. Nevertheless, the reduction in the number of statistically significant connections in the STIFT connectivity matrix suggests that STIFT can potentially reduce the false-positive connections in fibre tractography.

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Susceptibility map‐weighted imaging (SMWI) for neuroimaging

Abstract: SMWI presents an alternative contrast for susceptibility-based imaging. The validity of this method was demonstrated using in vivo data. This proposed method together with denoising allows high-quality reconstruction of susceptibility-weighted image of human brain in vivo.

Cited by 43 publications

References 36 publications

Susceptibility weighted imaging and quantitative susceptibility mapping of the cerebral vasculature using ferumoxytol

Susceptibility weighted imaging and quantitative susceptibility mapping of the cerebral vasculature using ferumoxytol

Imaging of nigrosome 1 in substantia nigra at 3T using multiecho susceptibility map‐weighted imaging (SMWI)

Structure tensor informed fibre tractography at 3T

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