Characterization of <i>T</i><sub>2</sub>* heterogeneity in human brain white matter

Li, Tie‐Qiang; Yao, Bing; Gelderen, Peter van; Merkle, Hellmut; Dodd, Stephen J.; Talagala, Lalith; Koretsky, Alan P.; Duyn, Jeff H.

doi:10.1002/mrm.22156

Cited by 76 publications

(81 citation statements)

References 28 publications

(36 reference statements)

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“…Interpreting resonance frequency data directly remains challenging, given the presence of multiple contributing mechanisms. Nonetheless, when combined with other information such as T 2 * (33) and magnetization transfer contrast (34), these resonance frequency data could be used to extract microstructural information for use in various clinical and scientific applications (e.g., high-resolution fiber tracking).…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Lee

Shmueli²,

Fukunaga³

et al. 2010

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

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Recent advances in high-field (≥7 T) MRI have made it possible to study the fine structure of the human brain at the level of fiber bundles and cortical layers. In particular, techniques aimed at detecting MRI resonance frequency shifts originating from local variation in magnetic susceptibility and other sources have greatly improved the visualization of these structures. A recent theoretical study [He X, Yablonskiy DA (2009) Proc Natl Acad Sci USA 106:13558–13563] suggests that MRI resonance frequency may report not only on tissue composition, but also on microscopic compartmentalization of susceptibility inclusions and their orientation relative to the magnetic field. The proposed sensitivity to tissue structure may greatly expand the information available with conventional MRI techniques. To investigate this possibility, we studied postmortem tissue samples from human corpus callosum with an experimental design that allowed separation of microstructural effects from confounding macrostructural effects. The results show that MRI resonance frequency does depend on microstructural orientation. Furthermore, the spatial distribution of the resonance frequency shift suggests an origin related to anisotropic susceptibility effects rather than microscopic compartmentalization. This anisotropy, which has been shown to depend on molecular ordering, may provide valuable information about tissue molecular structure.

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Section: Discussionmentioning

confidence: 99%

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Lee

Shmueli²,

Fukunaga³

et al. 2010

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

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249

316

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“…Previously published work suggests that this is, at least in part, due to microscopic susceptibility effects in white matter associated with large concentrations of myelin. 63 The effects of bulk magnetic susceptibility on resonance frequency and other characteristics of the water resonance are often dependent on orientation relative to B 0 . Lee et al 64 demonstrated that rotating parallel white matter nerve bundles 90…”

Section: Discussionmentioning

confidence: 99%

3D high spectral and spatial resolution imaging of ex vivo mouse brain

et al. 2015

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Purpose: Widely used MRI methods show brain morphology both in vivo and ex vivo at very high resolution. Many of these methods (e.g., T 2 * -weighted imaging, phase-sensitive imaging, or susceptibility-weighted imaging) are sensitive to local magnetic susceptibility gradients produced by subtle variations in tissue composition. However, the spectral resolution of commonly used methods is limited to maintain reasonable run-time combined with very high spatial resolution. Here, the authors report on data acquisition at increased spectral resolution, with 3-dimensional high spectral and spatial resolution MRI, in order to analyze subtle variations in water proton resonance frequency and lineshape that reflect local anatomy. The resulting information compliments previous studies based on T 2 * and resonance frequency. Methods: The proton free induction decay was sampled at high resolution and Fourier transformed to produce a high-resolution water spectrum for each image voxel in a 3D volume. Data were acquired using a multigradient echo pulse sequence (i.e., echo-planar spectroscopic imaging) with a spatial resolution of 50 × 50 × 70 µm 3 and spectral resolution of 3.5 Hz. Data were analyzed in the spectral domain, and images were produced from the various Fourier components of the water resonance. This allowed precise measurement of local variations in water resonance frequency and lineshape, at the expense of significantly increased run time (16-24 h). Results: High contrast T 2 * -weighted images were produced from the peak of the water resonance (peak height image), revealing a high degree of anatomical detail, specifically in the hippocampus and cerebellum. In images produced from Fourier components of the water resonance at −7.0 Hz from the peak, the contrast between deep white matter tracts and the surrounding tissue is the reverse of the contrast in water peak height images. This indicates the presence of a shoulder in the water resonance that is not present at +7.0 Hz and may be specific to white matter anatomy. Moreover, a frequency shift of 6.76 ± 0.55 Hz was measured between the molecular and granular layers of the cerebellum. This shift is demonstrated in corresponding spectra; water peaks from voxels in the molecular and granular layers are consistently 2 bins apart (7.0 Hz, as dictated by the spectral resolution) from one another. Conclusions: High spectral and spatial resolution MR imaging has the potential to accurately measure the changes in the water resonance in small voxels. This information can guide optimization and interpretation of more commonly used, more rapid imaging methods that depend on image contrast produced by local susceptibility gradients. In addition, with improved sampling methods, high spectral and spatial resolution data could be acquired in reasonable run times, and used for in vivo scans to increase sensitivity to variations in local susceptibility. C 2015 American Association of Physicists in Medicine. [http://dx

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“…This variability may refl ect distinct pathologic processes. Recent studies (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) of healthy brains both in vivo and postmortem suggest that magnetic susceptibility contrast may have a number of contributors, including myelin and both heme iron (deoxyhemoglobin) and nonheme iron. The tissue concentration of nonheme iron and myelin are particularly relevant to MS as they may be refl ective of the underlying disease process ( 21 ).…”

Section: Neuroradiology: High-field-strength Mr Imaging Of Chronic Mumentioning

confidence: 99%

“…We and others have done this in normal tissue for gray matter and WM ( 28,29 ). Despite the lack of these derived measures of tissue iron ( 12,20 ), have suggested that iron and myelin are the main compounds that contribute to the R2* and phase contrast in WM and cortical gray matter. In particular, in the iron extraction experiment, Fukunaga and colleagues ( 28 ) reported subtle signs of contrast reversal after iron extraction in postmortem brain tissue, suggesting a small opposing frequency shift caused by the remaining myelin.…”

Section: Neuroradiology: High-field-strength Mr Imaging Of Chronic Mumentioning

confidence: 99%

Chronic Multiple Sclerosis Lesions: Characterization with High-Field-Strength MR Imaging

Yao¹,

Bagnato²,

Matsuura³

et al. 2012

Radiology

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124

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Purpose:To elucidate the mechanism of magnetic resonance (MR) imaging contrast in multiple sclerosis (MS) lesion appearance by using susceptibility-weighted imaging and to assess with histologic correlation the role of iron and myelin in generating this MR imaging contrast. Materials and Methods:Each patient provided written consent to a human subject protocol approved by an institutional review board. Highspatial-resolution susceptibility-weighted 7.0-T MR images were obtained in 21 patients with MS. Contrast patterns in quantitative phase and R2* images, derived from 7.0-T data, were investigated in 220 areas defi ned as chronic MS lesions on conventional T2-weighted fl uid-attenuated inversion recovery, T2-weighted, and T1-weighted spin-echo images. The presence of positive or negative phase shifts (ie, decreased or increased MR frequency, respectively) was assessed in each lesion. In addition, postmortem MR imaging was performed at 7.0 T and 11.7 T, and its results were correlated with those of immunohistochemical staining specifi c for myelin, iron, and ferritin. Results:The majority (133 [60.5%] of 220) of the identifi ed lesions had a normal phase and reduced R2*. A substantial fraction of the lesions (84 [38.2%] of 220) had negative phase shift, either uniformly or at their rim, and a variety of appearances on R2* maps. These two lesion contrast patterns were reproduced in the postmortem MR imaging study. Comparison with histologic fi ndings showed that, while R2* reduction corresponded to severe loss of both iron and myelin, negative phase shift corresponded to focal iron deposits with myelin loss. Conclusion:Combined analysis of 7.0-T R2* and phase data may help in characterizing the pathologic features of MS lesions. The observed R2* decreases suggest profound myelin loss, whereas negative phase shifts suggest a focal iron accumulation.q RSNA, 2011Supplemental material : http://radiology.rsna.org/lookup /suppl

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Characterization of T₂* heterogeneity in human brain white matter

Cited by 76 publications

References 28 publications

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

3D high spectral and spatial resolution imaging of ex vivo mouse brain

Chronic Multiple Sclerosis Lesions: Characterization with High-Field-Strength MR Imaging

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Characterization of T2* heterogeneity in human brain white matter

Cited by 76 publications

References 28 publications

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

Sensitivity of MRI resonance frequency to the orientation of brain tissue microstructure

3D high spectral and spatial resolution imaging of ex vivo mouse brain

Chronic Multiple Sclerosis Lesions: Characterization with High-Field-Strength MR Imaging

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Characterization of T₂* heterogeneity in human brain white matter