Susceptibility weighted imaging (SWI)

Haacke, E. Mark; Xu, Yingbiao; Cheng, Yu Chung N; Reichenbach, Jürgen R.

doi:10.1002/mrm.20198

Cited by 1,422 publications

(1,222 citation statements)

References 28 publications

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“…We will refer to this filter combination as DORK with SHARP. The three other alternative spatio-temporal filters were: (ii) complex regression of global phase changes in image space (NVR, ); (iii) 2D Gaussian homodyne high-pass filtering of the unwrapped phase with a filter width of 6 mm (homodyne, (Deistung et al, 2008;Haacke et al, 2004;Noll et al, 1991)) and (iv) removal of static phase components by complex division (Tomasi and Caparelli, 2007) in combination with 8 th order 2D polynomial high-pass filtering of the resulting relative phase images (RELPOLY, (Bianciardi et al, 2011)). The time-series from the multiple fMRI runs were co-registered using the FLIRT tool (Jenkinson et al, 2002) by aligning the motion correction reference volumes (i.e.…”

Section: Preprocessing Pipeline Of the Time-seriesmentioning

confidence: 99%

Functional quantitative susceptibility mapping (fQSM)

et al. 2014

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Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is a powerful technique, typically based on the statistical analysis of the magnitude component of the complex time-series. Here, we additionally interrogated the phase data of the fMRI time-series and used quantitative susceptibility mapping (QSM) in order to investigate the potential of functional QSM (fQSM) relative to standard magnitude BOLD fMRI. High spatial resolution data (1 mm isotropic) were acquired every 3 seconds using zoomed multi-slice gradient-echo EPI collected at 7 T in single orientation (SO) and multiple orientation (MO) experiments, the latter involving 4 repetitions with the subject's head rotated relative to B0. Statistical parametric maps (SPM) were reconstructed for magnitude, phase and QSM time-series and each was subjected to detailed analysis. Several fQSM pipelines were evaluated and compared based on the relative number of voxels that were coincidentally found to be significant in QSM and magnitude SPMs (common voxels). We found that sensitivity and spatial reliability of fQSM relative to the magnitude data depended strongly on the arbitrary significance threshold defining "activated" voxels in SPMs, and on the efficiency of spatiotemporal filtering of the phase time-series. Sensitivity and spatial reliability depended slightly on whether MO or SO fQSM was performed and on the QSM calculation approach used for SO data. Our results present the potential of fQSM as a quantitative method of mapping BOLD changes. We also critically discuss the technical challenges and issues linked to this intriguing new technique. seconds using zoomed multi-slice gradient-echo EPI collected at 7 T in single orientation (SO) and multiple orientation (MO) experiments, the latter involving 4 repetitions with the subject's head rotated relative to B 0 . Statistical parametric maps (SPM) were reconstructed for magnitude, phase and QSM timeseries and each was subjected to detailed analysis. Several fQSM pipelines were evaluated and compared based on the relative number of voxels that were coincidentally found to be significant in QSM and magnitude SPMs (common voxels). We found that sensitivity and spatial reliability of fQSM relative to the magnitude data depended strongly on the arbitrary significance threshold defining "activated" voxels in SPMs, and on the efficiency of spatio-temporal filtering of the phase time-series. Sensitivity and spatial reliability depended slightly on whether MO or SO fQSM was performed and on the QSM calculation approach used for SO data.

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Section: Preprocessing Pipeline Of the Time-seriesmentioning

confidence: 99%

Functional quantitative susceptibility mapping (fQSM)

et al. 2014

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“…Several recent studies have shown that the use of MRI signal phase in gradient-echo (GRE) MRI can improve contrast MRI in specific human brain structures, including veins and iron-rich regions (10)(11)(12)(13)(14). Preliminary studies have also shown a substantial contrast between WM and cortical GM (11,15).…”

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confidence: 99%

“…In conventional GRE, a magnitude image combines contributions from transverse (T 2 ) relaxation (which leads to signal decay) as well as from loss of signal because of coherence loss caused by the local resonance frequency offset or B o shift. The latter originates, at least in part, from the magnetic susceptibility differences between tissues (10,11). Phase imaging allows increased dynamic range in detection of these off-resonance effects by directly measuring the change in frequency offset.…”

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confidence: 99%

High-field MRI of brain cortical substructure based on signal phase

Duyn

Gelderen

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

605

750

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The ability to detect brain anatomy and pathophysiology with MRI is limited by the contrast-to-noise ratio (CNR), which depends on the contrast mechanism used and the spatial resolution. In this work, we show that in MRI of the human brain, large improvements in contrast to noise in high-resolution images are possible by exploiting the MRI signal phase at high magnetic field strength. Using gradient-echo MRI at 7.0 tesla and a multichannel detector, a nominal voxel size of 0.24 ؋ 0.24 ؋ 1.0 mm 3 (58 nl) was achieved. At this resolution, a strong phase contrast was observed both between as well as within gray matter (GM) and white matter (WM). In gradient-echo phase images obtained on normal volunteers at this high resolution, the CNR between GM and WM ranged from 3:1 to 20:1 over the cortex. This CNR is an almost 10-fold improvement over conventional MRI techniques that do not use image phase, and it is an Ϸ100-fold improvement when including the gains in resolution from high-field and multichannel detection. Within WM, phase contrast appeared to be associated with the major fiber bundles, whereas contrast within GM was suggestive of the underlying layer structure. The observed phase contrast is attributed to local variations in magnetic susceptibility, which, at least in part, appeared to originate from iron stores. The ability to detect cortical substructure from MRI phase contrast at high field is expected to greatly enhance the study of human brain anatomy in vivo.anatomy ͉ contrast mechanism ͉ cortex

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“…A susceptibility weighted image was acquired with an in‐plane resolution of 0.5 × 0.5mm 2 and a slice thickness of 1.0mm (TR 28ms, TE 20ms, Flip angle 15deg, GRAPPA 2, matrix size 384 × 312 × 52; Haacke et al, 2004; Reichenbach et al, 1997). Finally, a high‐resolution (1.0mm isotropic) anatomical image was acquired using an MPRAGE sequence (TR 2.4s, TE 2.18ms, TI 1040ms, Flip angle 8deg, GRAPPA 2, matrix size 224 × 224 × 192; Mugler and Brookeman, 1990).…”

Section: Methodsmentioning

confidence: 99%

“…Alternatively, susceptibility weighted imaging (SWI) can be used to probe iron and myelin differences in the cortex and, additionally, to locate veins. SWI is a recent MR technique detecting susceptibility differences in the brain (Haacke et al, 2004; Reichenbach et al, 1997). SWI combines magnitude and phase information of the complex T 2 * weighted images to enhance the contrast of paramagnetic substances, such as deoxygenated hemoglobin and iron, with respect to the surrounding diamagnetic tissue.…”

Section: Introductionmentioning

confidence: 99%

Tonotopic maps in human auditory cortex using arterial spin labeling

Gardumi

Ivanov

Havlíček

et al. 2016

Human Brain Mapping

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A tonotopic organization of the human auditory cortex (AC) has been reliably found by neuroimaging studies. However, a full characterization and parcellation of the AC is still lacking. In this study, we employed pseudo‐continuous arterial spin labeling (pCASL) to map tonotopy and voice selective regions using, for the first time, cerebral blood flow (CBF). We demonstrated the feasibility of CBF‐based tonotopy and found a good agreement with BOLD signal‐based tonotopy, despite the lower contrast‐to‐noise ratio of CBF. Quantitative perfusion mapping of baseline CBF showed a region of high perfusion centered on Heschl's gyrus and corresponding to the main high‐low‐high frequency gradients, co‐located to the presumed primary auditory core and suggesting baseline CBF as a novel marker for AC parcellation. Furthermore, susceptibility weighted imaging was employed to investigate the tissue specificity of CBF and BOLD signal and the possible venous bias of BOLD‐based tonotopy. For BOLD only active voxels, we found a higher percentage of vein contamination than for CBF only active voxels. Taken together, we demonstrated that both baseline and stimulus‐induced CBF is an alternative fMRI approach to the standard BOLD signal to study auditory processing and delineate the functional organization of the auditory cortex. Hum Brain Mapp 38:1140–1154, 2017. © 2016 Wiley Periodicals, Inc.

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Susceptibility weighted imaging (SWI)

Cited by 1,422 publications

References 28 publications

Functional quantitative susceptibility mapping (fQSM)

Functional quantitative susceptibility mapping (fQSM)

High-field MRI of brain cortical substructure based on signal phase

Tonotopic maps in human auditory cortex using arterial spin labeling

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