The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Sehong Oh - One of the best experts on this subject based on the ideXlab platform.
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evaluation of normal appearing white matter in multiple sclerosis using direct visualization of short Transverse Relaxation Time component vista myelin water imaging and gradient echo and spin echo grase myelin water imaging
Journal of Magnetic Resonance Imaging, 2019Co-Authors: Joon Yul Choi, Sehong Oh, In Hye Jeong, Changhyun Oh, Na Young ParkAbstract:BACKGROUND: In multiple sclerosis (MS), not only lesions but also normal MRI-appearing white matter (NAWM) may undergo demyelination. PURPOSE: To demonstrate the detection of NAWM demyelination using direct visualization of short Transverse Relaxation Time component myelin water imaging (ViSTa-MWI) and to compare the results with those of conventional gradient echo and spin echo (GRASE)-MWI. STUDY TYPE: Control/cohort. POPULATION: Twenty-five MS patients and 18 healthy controls (HC). FIELD STRENGTH/SEQUENCE: 3T/ViSTa and GRASE-MWI. ASSESSMENT: Using ViSTa and GRASE-MWI, myelin water fraction (MWF) of NAWM or normal WM was compared between MS (all patients or early-stage MS patients) and HC. The comparison was performed for a global WM mask and five regional WM masks. STATISTICAL TESTS: A general linear model was applied for the comparison. A statistical power and a minimum sample size for the significant difference were obtained. Spearman's correlation coefficient was calculated between MWF and clinical measures and between ViSTa-MWF and GRASE-MWF for the global WM mask. RESULTS: MWFs of ViSTa were significantly lower in the MS patients than those in the HC in all masks (P < 0.001). GRASE-MWI results revealed reduced MWFs only in global WM, genu, and optic radiation. ViSTa-MWI had higher statistical powers than that of GRASE-MWI (power: ViSTa = 99.2 ± 1.6% and GRASE = 75.5 ± 31.0%; sample size: ViSTa = 18 ± 9 and GRASE = 78 ± 75). In early-stage MS, MWFs of ViSTa were significantly lower than those of the HC in all masks except for centrum semiovale; however, MWFs of GRASE MWI were significantly lower only in optic radiation. Disease duration was correlated with both MWIs (ViSTa; r = -0.437 and GRASE; r = -0.445). ViSTa and GRASE MWFs were significantly correlated in the HC (r = 0.664) and MS (r = 0.768). DATA CONCLUSION: ViSTa-MWI may detect a reduction of MWF in NAWM of MS. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1091-1098.
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probing signal phase in direct visualization of short Transverse Relaxation Time component vista
Magnetic Resonance in Medicine, 2015Co-Authors: Sehong OhAbstract:Purpose: To demonstrate the phase evolutions of direct visualization of short Transverse Relaxation Time component (ViSTa) matches with those of myelin water. Method: Myelin water imaging (MWI) measures short Transverse signals and has been suggested as a biomarker for myelin. Recently, a new approach, ViSTa, has been proposed to acquire short T2* signals by suppressing long T1 signals. This method does not require any ill-conditioned data processing and therefore provides high-quality images. In this study, the phase of the ViSTa signal was compared with the phase of myelin water simulated by the magnetic susceptibility model of hollow cylinder. Results: The phase evolutions of the ViSTa signal were similar to the simulated myelin water phase evolutions. When fiber orientation was perpendicular relative to the main magnetic field, both the ViSTa and the simulated myelin water phase showed large positive frequency shifts, whereas the gradient echo phase showed a slightly negative frequency shift. Additionally, the myelin water phase map generated using diffusion tensor imaging (DTI) information revealed a good match with the ViSTa phase image. Conclusion: The results of this study support the origin of ViSTa signal as myelin water. ViSTa phase may potentially provide sensitivity to demyelination. Magn Reson Med 000:000– 000, 2014. V C 2014 Wiley Periodicals, Inc.
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direct visualization of short Transverse Relaxation Time component vista
NeuroImage, 2013Co-Authors: Sehong Oh, Michel Bilello, Matthew Schindler, Clyde Markowitz, John A DetreAbstract:White matter of the brain has been demonstrated to have multiple Relaxation components. Among them, the short Transverse Relaxation Time component (T2 < 40 ms; T2⁎ < 25 ms at 3 T) has been suggested to originate from myelin water whereas long Transverse Relaxation Time components have been associated with axonal and/or interstitial water. In myelin water imaging, T2 or T2⁎ signal decay is measured to estimate myelin water fraction based on T2 or T2⁎ differences among the water components. This method has been demonstrated to be sensitive to demyelination in the brain but suffers from low SNR and image artifacts originating from ill-conditioned multi-exponential fitting. In this study, a novel approach that selectively acquires short Transverse Relaxation Time signal is proposed. The method utilizes a double inversion RF pair to suppress a range of long T1 signal. This suppression leaves short T2⁎ signal, which has been suggested to have short T1, as the primary source of the image. The experimental results confirm that after suppression of long T1 signals, the image is dominated by short T2⁎ in the range of myelin water, allowing us to directly visualize the short Transverse Relaxation Time component in the brain. Compared to conventional myelin water imaging, this new method of direct visualization of short Relaxation Time component (ViSTa) provides high quality images. When applied to multiple sclerosis patients, chronic lesions show significantly reduced signal intensity in ViSTa images suggesting sensitivity to demyelination.
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Direct visualization of short Transverse Relaxation Time component (ViSTa).
NeuroImage, 2013Co-Authors: Sehong Oh, Michel Bilello, Matthew Schindler, Clyde Markowitz, John A DetreAbstract:White matter of the brain has been demonstrated to have multiple Relaxation components. Among them, the short Transverse Relaxation Time component (T2
Nadine El Tannir El Tayara - One of the best experts on this subject based on the ideXlab platform.
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Transverse Relaxation Time reflects brain amyloidosis in young APP/PS1 transgenic mice.
Magnetic Resonance in Medicine, 2020Co-Authors: Nadine El Tannir El Tayara, Andreas Volk, Marc Dhenain, Benoit DelatourAbstract:Amyloid deposits are one of the hallmarks of Alzheimer's disease (AD), one of the most devastating neurodegenerative disorders. In transgenic mice modeling Alzheimer's pathology, the MR Transverse Relaxation Time (T2) has been described to be modulated by amyloidosis. This modification has been attributed to the age-related iron deposition that occurs within the amyloid plaques of old animals. In the present study, young APP/PS1 transgenic mice without histochemically detectable iron in the brain were specifically studied. In vivo measurements of T2 in the hippocampus, at the level of the subiculum, were shown to reflect the density of amyloid plaques. This suggests that T2 variations can be induced solely by aggregated amyloid deposits in the absence of associated histologically-detectable iron. Thus T2 from regions with high amyloid load, such as the subiculum, is particularly well suited for following plaque deposition in young animals, i.e., at the earliest stages of the pathological process. Magn Reson Med 58:179–184, 2007. © 2007 Wiley-Liss, Inc.
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Transverse Relaxation Time reflects brain amyloidosis in young app ps1 transgenic mice
Magnetic Resonance in Medicine, 2007Co-Authors: Nadine El Tannir El Tayara, Andreas Volk, Marc Dhenain, Benoit DelatourAbstract:Amyloid deposits are one of the hallmarks of Alzheimer's disease (AD), one of the most devastating neurodegenerative disorders. In transgenic mice modeling Alzheimer's pathology, the MR Transverse Relaxation Time (T2) has been described to be modulated by amyloidosis. This modification has been attributed to the age-related iron deposition that occurs within the amyloid plaques of old animals. In the present study, young APP/PS1 transgenic mice without histochemically detectable iron in the brain were specifically studied. In vivo measurements of T2 in the hippocampus, at the level of the subiculum, were shown to reflect the density of amyloid plaques. This suggests that T2 variations can be induced solely by aggregated amyloid deposits in the absence of associated histologically-detectable iron. Thus T2 from regions with high amyloid load, such as the subiculum, is particularly well suited for following plaque deposition in young animals, i.e., at the earliest stages of the pathological process. Magn Reson Med 58:179–184, 2007. © 2007 Wiley-Liss, Inc.
Benoit Delatour - One of the best experts on this subject based on the ideXlab platform.
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Transverse Relaxation Time reflects brain amyloidosis in young APP/PS1 transgenic mice.
Magnetic Resonance in Medicine, 2020Co-Authors: Nadine El Tannir El Tayara, Andreas Volk, Marc Dhenain, Benoit DelatourAbstract:Amyloid deposits are one of the hallmarks of Alzheimer's disease (AD), one of the most devastating neurodegenerative disorders. In transgenic mice modeling Alzheimer's pathology, the MR Transverse Relaxation Time (T2) has been described to be modulated by amyloidosis. This modification has been attributed to the age-related iron deposition that occurs within the amyloid plaques of old animals. In the present study, young APP/PS1 transgenic mice without histochemically detectable iron in the brain were specifically studied. In vivo measurements of T2 in the hippocampus, at the level of the subiculum, were shown to reflect the density of amyloid plaques. This suggests that T2 variations can be induced solely by aggregated amyloid deposits in the absence of associated histologically-detectable iron. Thus T2 from regions with high amyloid load, such as the subiculum, is particularly well suited for following plaque deposition in young animals, i.e., at the earliest stages of the pathological process. Magn Reson Med 58:179–184, 2007. © 2007 Wiley-Liss, Inc.
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Transverse Relaxation Time reflects brain amyloidosis in young app ps1 transgenic mice
Magnetic Resonance in Medicine, 2007Co-Authors: Nadine El Tannir El Tayara, Andreas Volk, Marc Dhenain, Benoit DelatourAbstract:Amyloid deposits are one of the hallmarks of Alzheimer's disease (AD), one of the most devastating neurodegenerative disorders. In transgenic mice modeling Alzheimer's pathology, the MR Transverse Relaxation Time (T2) has been described to be modulated by amyloidosis. This modification has been attributed to the age-related iron deposition that occurs within the amyloid plaques of old animals. In the present study, young APP/PS1 transgenic mice without histochemically detectable iron in the brain were specifically studied. In vivo measurements of T2 in the hippocampus, at the level of the subiculum, were shown to reflect the density of amyloid plaques. This suggests that T2 variations can be induced solely by aggregated amyloid deposits in the absence of associated histologically-detectable iron. Thus T2 from regions with high amyloid load, such as the subiculum, is particularly well suited for following plaque deposition in young animals, i.e., at the earliest stages of the pathological process. Magn Reson Med 58:179–184, 2007. © 2007 Wiley-Liss, Inc.
John A Detre - One of the best experts on this subject based on the ideXlab platform.
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direct visualization of short Transverse Relaxation Time component vista
NeuroImage, 2013Co-Authors: Sehong Oh, Michel Bilello, Matthew Schindler, Clyde Markowitz, John A DetreAbstract:White matter of the brain has been demonstrated to have multiple Relaxation components. Among them, the short Transverse Relaxation Time component (T2 < 40 ms; T2⁎ < 25 ms at 3 T) has been suggested to originate from myelin water whereas long Transverse Relaxation Time components have been associated with axonal and/or interstitial water. In myelin water imaging, T2 or T2⁎ signal decay is measured to estimate myelin water fraction based on T2 or T2⁎ differences among the water components. This method has been demonstrated to be sensitive to demyelination in the brain but suffers from low SNR and image artifacts originating from ill-conditioned multi-exponential fitting. In this study, a novel approach that selectively acquires short Transverse Relaxation Time signal is proposed. The method utilizes a double inversion RF pair to suppress a range of long T1 signal. This suppression leaves short T2⁎ signal, which has been suggested to have short T1, as the primary source of the image. The experimental results confirm that after suppression of long T1 signals, the image is dominated by short T2⁎ in the range of myelin water, allowing us to directly visualize the short Transverse Relaxation Time component in the brain. Compared to conventional myelin water imaging, this new method of direct visualization of short Relaxation Time component (ViSTa) provides high quality images. When applied to multiple sclerosis patients, chronic lesions show significantly reduced signal intensity in ViSTa images suggesting sensitivity to demyelination.
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Direct visualization of short Transverse Relaxation Time component (ViSTa).
NeuroImage, 2013Co-Authors: Sehong Oh, Michel Bilello, Matthew Schindler, Clyde Markowitz, John A DetreAbstract:White matter of the brain has been demonstrated to have multiple Relaxation components. Among them, the short Transverse Relaxation Time component (T2
Andreas Volk - One of the best experts on this subject based on the ideXlab platform.
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Transverse Relaxation Time reflects brain amyloidosis in young APP/PS1 transgenic mice.
Magnetic Resonance in Medicine, 2020Co-Authors: Nadine El Tannir El Tayara, Andreas Volk, Marc Dhenain, Benoit DelatourAbstract:Amyloid deposits are one of the hallmarks of Alzheimer's disease (AD), one of the most devastating neurodegenerative disorders. In transgenic mice modeling Alzheimer's pathology, the MR Transverse Relaxation Time (T2) has been described to be modulated by amyloidosis. This modification has been attributed to the age-related iron deposition that occurs within the amyloid plaques of old animals. In the present study, young APP/PS1 transgenic mice without histochemically detectable iron in the brain were specifically studied. In vivo measurements of T2 in the hippocampus, at the level of the subiculum, were shown to reflect the density of amyloid plaques. This suggests that T2 variations can be induced solely by aggregated amyloid deposits in the absence of associated histologically-detectable iron. Thus T2 from regions with high amyloid load, such as the subiculum, is particularly well suited for following plaque deposition in young animals, i.e., at the earliest stages of the pathological process. Magn Reson Med 58:179–184, 2007. © 2007 Wiley-Liss, Inc.
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Transverse Relaxation Time reflects brain amyloidosis in young app ps1 transgenic mice
Magnetic Resonance in Medicine, 2007Co-Authors: Nadine El Tannir El Tayara, Andreas Volk, Marc Dhenain, Benoit DelatourAbstract:Amyloid deposits are one of the hallmarks of Alzheimer's disease (AD), one of the most devastating neurodegenerative disorders. In transgenic mice modeling Alzheimer's pathology, the MR Transverse Relaxation Time (T2) has been described to be modulated by amyloidosis. This modification has been attributed to the age-related iron deposition that occurs within the amyloid plaques of old animals. In the present study, young APP/PS1 transgenic mice without histochemically detectable iron in the brain were specifically studied. In vivo measurements of T2 in the hippocampus, at the level of the subiculum, were shown to reflect the density of amyloid plaques. This suggests that T2 variations can be induced solely by aggregated amyloid deposits in the absence of associated histologically-detectable iron. Thus T2 from regions with high amyloid load, such as the subiculum, is particularly well suited for following plaque deposition in young animals, i.e., at the earliest stages of the pathological process. Magn Reson Med 58:179–184, 2007. © 2007 Wiley-Liss, Inc.
