Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1987
To establish the effect of the paramagnetic contrast agent gadolinium diethylenetriaminepentaacet... more To establish the effect of the paramagnetic contrast agent gadolinium diethylenetriaminepentaacetic acid ([Gd]DTPA) on myocardial magnetic resonance relaxation parameters T1 and T2, and its relationship to myocardial perfusion, we administered [Gd] DTPA 0.2 mM/kg to two groups of dogs. Group I had severe, resting myocardial ischemia induced by coronary occlusion, followed in 2 min by [Gd]DTPA infusion and heart excision 1 min later. Group II had a variable reduction in blood flow. In Group II the coronary vasodilator dipyridamole was infused to enhance blood flow to the normal myocardium before [Gd]DTPA was given. In Group I [Gd]DTPA caused a significant difference in T1 between the normal and severely ischemic zones; changes in T1 correlated with the severity of myocardial ischemia. Although vasodilatation delivered more Gd-DTPA to the normal myocardium in Group II, the lack of further decrease in T1 suggested that it was cleared more rapidly. Thus, [Gd]DTPA permits the detection a...
Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by alteri... more Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed.
PurposeRecent observations of several preferred orientations of diffusion in deep white matter ma... more PurposeRecent observations of several preferred orientations of diffusion in deep white matter may indicate either (a) that axons in different directions are independently bundled in thick sheets and function noninteractively, or more interestingly, (b) that the axons are closely interwoven and would exhibit branching and sharp turns. This study aims to investigate whether the dependence of dMRI Q‐ball signal on the interpulse time can decode the smaller‐than‐voxel‐size brain structure, in particular, to distinguish scenarios (a) and (b).MethodsHigh‐resolution Q‐ball images of a healthy brain taken with s/mm2 for 3 different values of were analyzed. The exchange of water molecules between crossing fibers was characterized by the fourth Fourier coefficient of the signal profile in the plane of crossing. To interpret the empirical results, a model consisting of differently oriented parallel sheets of cylinders was developed. Diffusion of water molecules inside and outside cylinders w...
The tongue is capable of producing intelligible speech because of successful orchestration of mus... more The tongue is capable of producing intelligible speech because of successful orchestration of muscle groupings-i.e., functional units-of the highly complex muscles over time. Due to the different motions that tongues produce, functional units are transitional structures which transform muscle activity to surface tongue geometry and they vary significantly from one subject to another. In order to compare and contrast the location and size of functional units in the presence of such substantial inter-person variability, it is essential to study both common and subject-specific functional units in a group of people carrying out the same speech task. In this work, a new normalization technique is presented to simultaneously identify the common and subject-specific functional units defined in the tongue when tracked by tagged magnetic resonance imaging. To achieve our goal, a joint sparse non-negative matrix factorization framework is used, which learns a set of building blocks and subject-specific as well as common weighting matrices from motion quantities extracted from displacements. A spectral clustering technique is then applied to the subject-specific and common weighting matrices to determine the subject-specific functional units for each subject and the common functional units across subjects. Our experimental results using in vivo tongue motion data show that our approach is able to identify the common and subject-specific functional units with reduced size variability of tongue motion during speech.
Las diversas regiones del cerebro están conectadas por unos 160.000 kilómetros de f... more Las diversas regiones del cerebro están conectadas por unos 160.000 kilómetros de fibras (una longitud equivalente a cuatro veces la circunferencia de la Tierra) que constituyen la denominada sustancia blanca. Imágenes como ésta, revelan por primera vez las rutas específicas relacionadas con determinadas funciones cognitivas. Los haces coloreados en rosa y naranja, por ejemplo, transmiten señales de importancia crítica para el lenguaje
Journal of the Acoustical Society of America, 2017
Amyotrophic Lateral Sclerosis (ALS) is a progressive and irreversible neurological disorder, whic... more Amyotrophic Lateral Sclerosis (ALS) is a progressive and irreversible neurological disorder, which affects upper and lower motor neurons in the motor cortex that control voluntary movements including speech and swallowing. High-resolution MRI (hMRI) and Diffusion Tensor Imaging (DTI) can provide non-invasive imaging of three-dimensional muscle anatomy and fiber myoarchitecture such as fiber orientation within the human tongue, respectively. In this work, we aim to assess anatomical differences of the tongue using both imaging methods by demonstrating the differences in quantities related to fiber connectivity for both normal and ALS subjects. We first manually delineate the genioglossus and superior longitudinal muscles on hMRI, which are aligned to each b0 image of DTI using deformable registration to provide regions of interest. We then compute fractional anisotropy and statistics about fibers connecting each pair of muscles. We apply our framework on five datasets including both ...
Background: The cerebellum is a complex structure that can be affected by several congenital and ... more Background: The cerebellum is a complex structure that can be affected by several congenital and acquired diseases leading to alteration of its function and neuronal circuits. Identifying the structural bases of cerebellar neuronal networks in humans in vivo may provide biomarkers for diagnosis and management of cerebellar diseases. Objectives: To define the anatomy of intrinsic and extrinsic cerebellar circuits using high-angular resolution diffusion spectrum imaging (DSI). Methods: We acquired high-resolution structural MRI and DSI of the cerebellum in four healthy female subjects at 3T. DSI tractography based on a streamline algorithm was performed to identify the circuits connecting the cerebellar cortex with the deep cerebellar nuclei, selected brainstem nuclei, and the thalamus. Results: Using in-vivo DSI in humans we were able to demonstrate the structure of the following cerebellar neuronal circuits: (1) connections of the inferior olivary nucleus with the cerebellar cortex,...
Ralph Kimmlingen, Eva Eberlein, Peter Dietz, Sabrina Kreher, Johann Schuster, Jörg Riegler, Volke... more Ralph Kimmlingen, Eva Eberlein, Peter Dietz, Sabrina Kreher, Johann Schuster, Jörg Riegler, Volker Matschl, Volker Schnetter, Andreas Schmidt, Helmut Lenz, Ernst Mustafa, Daniel Fischer, Andreas Potthast, Ludwig Kreischer , Michael Eberler, Franz Hebrank, Herbert Thein, Keith Heberlein, Philipp Hoecht, Thomas Witzel, Dylan Tisdall, Junqian Xu, Essa Yacoub, Gregor Adriany, Edward Auerbach, Steen Moeller, David Feinberg, Dietmar Lehne, Lawrence L. Wald, Bruce Rosen, Kamil Ugurbil, David van Essen, Van Wedeen, and Franz Schmitt Siemens Healthcare, Erlangen, Germany, Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Boston, United States, Center for Magnetic Resonance Research, University Minnesota, Minneapolis, United States, Helen Wills Inst. of Neurosc., UC Berkeley, CA, United States, Harvard-MIT Division of Health Sciences Technology, Cambridge, United States, Dept. of Anatomy and Neurobiology, Washington U, St. Louis, United States
Proceedings of SPIE--the International Society for Optical Engineering, 2018
Amyotrophic Lateral Sclerosis (ALS) is a neurological disease that causes death of neurons contro... more Amyotrophic Lateral Sclerosis (ALS) is a neurological disease that causes death of neurons controlling muscle movements. Loss of speech and swallowing functions is a major impact due to degeneration of the tongue muscles. In speech studies using magnetic resonance (MR) techniques, diffusion tensor imaging (DTI) is used to capture internal tongue muscle fiber structures in three-dimensions (3D) in a non-invasive manner. Tagged magnetic resonance images (tMRI) are used to record tongue motion during speech. In this work, we aim to combine information obtained with both MR imaging techniques to compare the functionality characteristics of the tongue between normal and ALS subjects. We first extracted 3D motion of the tongue using tMRI from fourteen normal subjects in speech. The estimated motion sequences were then warped using diffeomorphic registration into the b0 spaces of the DTI data of two normal subjects and an ALS patient. We then constructed motion atlases by averaging all war...
The Journal of the Acoustical Society of America, 2018
Amyotrophic Lateral Sclerosis (ALS) is a neurological disorder, which impairs tongue function for... more Amyotrophic Lateral Sclerosis (ALS) is a neurological disorder, which impairs tongue function for speech and swallowing. A widely used Diffusion Tensor Imaging (DTI) analysis pipeline is employed for quantifying differences in tongue fiber myoarchitecture between controls and ALS patients. This pipeline uses both high-resolution magnetic resonance imaging (hMRI) and DTI. hMRI is used to delineate tongue muscles, while DTI provides indices to reveal fiber connectivity within and between muscles. The preliminary results using five controls and two patients show quantitative differences between the groups. This work has the potential to provide insights into the detrimental effects of ALS on speech and swallowing.
Cerebral cortex (New York, N.Y. : 1991), Jan 16, 2017
Brain fiber pathways are presumed to follow smooth curves but recent high angular resolution diff... more Brain fiber pathways are presumed to follow smooth curves but recent high angular resolution diffusion MRI (dMRI) suggests that instead they follow 3 primary axes often nearly orthogonal. To investigate this, we analyzed axon pathways under monkey primary motor cortex with (1) dMRI tractography, (2) axon tract tracing, and (3) axon immunohistochemistry. dMRI tractography shows the predicted crossings of axons in mediolateral and dorsoventral orientations and does not show axon turns in this region. Axons labeled with tract tracer in the motor cortex dispersed in the centrum semiovale by microscopically sharp axonal turns and/or branches (radii ≤15 µm) into 2 sharply defined orientations, mediolateral and dorsoventral. Nearby sections processed with SMI-32 antibody to label projection axons and SMI-312 antibody to label all axons revealed axon distributions parallel to the tracer axons. All 3 histological methods confirmed preponderant axon distributions parallel with dMRI axes with ...
The parameter selection for diffusion MRI experiments is dominated by the "k-q tradeoff"... more The parameter selection for diffusion MRI experiments is dominated by the "k-q tradeoff" whereby the Signal to Noise Ratio (SNR) of the images is traded for either high spatial resolution (determined by the maximum k-value collected) or high diffusion sensitivity (effected by b-value or the q vector) but usually not both. Furthermore, different brain regions (such as gray matter and white matter) likely require different tradeoffs between these parameters due to the size of the structures to be visualized or the length-scale of the microstructure being probed. In this case, it might be advantageous to combine information from two scans - a scan with high q but low k (high angular resolution in diffusion but low spatial resolution in the image domain) to provide maximal information about white matter fiber crossing, and one low q but high k (low angular resolution but high spatial resolution) for probing the cortex. In this study, we propose a method, termed HIgh b-value an...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1987
To establish the effect of the paramagnetic contrast agent gadolinium diethylenetriaminepentaacet... more To establish the effect of the paramagnetic contrast agent gadolinium diethylenetriaminepentaacetic acid ([Gd]DTPA) on myocardial magnetic resonance relaxation parameters T1 and T2, and its relationship to myocardial perfusion, we administered [Gd] DTPA 0.2 mM/kg to two groups of dogs. Group I had severe, resting myocardial ischemia induced by coronary occlusion, followed in 2 min by [Gd]DTPA infusion and heart excision 1 min later. Group II had a variable reduction in blood flow. In Group II the coronary vasodilator dipyridamole was infused to enhance blood flow to the normal myocardium before [Gd]DTPA was given. In Group I [Gd]DTPA caused a significant difference in T1 between the normal and severely ischemic zones; changes in T1 correlated with the severity of myocardial ischemia. Although vasodilatation delivered more Gd-DTPA to the normal myocardium in Group II, the lack of further decrease in T1 suggested that it was cleared more rapidly. Thus, [Gd]DTPA permits the detection a...
Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by alteri... more Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed.
PurposeRecent observations of several preferred orientations of diffusion in deep white matter ma... more PurposeRecent observations of several preferred orientations of diffusion in deep white matter may indicate either (a) that axons in different directions are independently bundled in thick sheets and function noninteractively, or more interestingly, (b) that the axons are closely interwoven and would exhibit branching and sharp turns. This study aims to investigate whether the dependence of dMRI Q‐ball signal on the interpulse time can decode the smaller‐than‐voxel‐size brain structure, in particular, to distinguish scenarios (a) and (b).MethodsHigh‐resolution Q‐ball images of a healthy brain taken with s/mm2 for 3 different values of were analyzed. The exchange of water molecules between crossing fibers was characterized by the fourth Fourier coefficient of the signal profile in the plane of crossing. To interpret the empirical results, a model consisting of differently oriented parallel sheets of cylinders was developed. Diffusion of water molecules inside and outside cylinders w...
The tongue is capable of producing intelligible speech because of successful orchestration of mus... more The tongue is capable of producing intelligible speech because of successful orchestration of muscle groupings-i.e., functional units-of the highly complex muscles over time. Due to the different motions that tongues produce, functional units are transitional structures which transform muscle activity to surface tongue geometry and they vary significantly from one subject to another. In order to compare and contrast the location and size of functional units in the presence of such substantial inter-person variability, it is essential to study both common and subject-specific functional units in a group of people carrying out the same speech task. In this work, a new normalization technique is presented to simultaneously identify the common and subject-specific functional units defined in the tongue when tracked by tagged magnetic resonance imaging. To achieve our goal, a joint sparse non-negative matrix factorization framework is used, which learns a set of building blocks and subject-specific as well as common weighting matrices from motion quantities extracted from displacements. A spectral clustering technique is then applied to the subject-specific and common weighting matrices to determine the subject-specific functional units for each subject and the common functional units across subjects. Our experimental results using in vivo tongue motion data show that our approach is able to identify the common and subject-specific functional units with reduced size variability of tongue motion during speech.
Las diversas regiones del cerebro están conectadas por unos 160.000 kilómetros de f... more Las diversas regiones del cerebro están conectadas por unos 160.000 kilómetros de fibras (una longitud equivalente a cuatro veces la circunferencia de la Tierra) que constituyen la denominada sustancia blanca. Imágenes como ésta, revelan por primera vez las rutas específicas relacionadas con determinadas funciones cognitivas. Los haces coloreados en rosa y naranja, por ejemplo, transmiten señales de importancia crítica para el lenguaje
Journal of the Acoustical Society of America, 2017
Amyotrophic Lateral Sclerosis (ALS) is a progressive and irreversible neurological disorder, whic... more Amyotrophic Lateral Sclerosis (ALS) is a progressive and irreversible neurological disorder, which affects upper and lower motor neurons in the motor cortex that control voluntary movements including speech and swallowing. High-resolution MRI (hMRI) and Diffusion Tensor Imaging (DTI) can provide non-invasive imaging of three-dimensional muscle anatomy and fiber myoarchitecture such as fiber orientation within the human tongue, respectively. In this work, we aim to assess anatomical differences of the tongue using both imaging methods by demonstrating the differences in quantities related to fiber connectivity for both normal and ALS subjects. We first manually delineate the genioglossus and superior longitudinal muscles on hMRI, which are aligned to each b0 image of DTI using deformable registration to provide regions of interest. We then compute fractional anisotropy and statistics about fibers connecting each pair of muscles. We apply our framework on five datasets including both ...
Background: The cerebellum is a complex structure that can be affected by several congenital and ... more Background: The cerebellum is a complex structure that can be affected by several congenital and acquired diseases leading to alteration of its function and neuronal circuits. Identifying the structural bases of cerebellar neuronal networks in humans in vivo may provide biomarkers for diagnosis and management of cerebellar diseases. Objectives: To define the anatomy of intrinsic and extrinsic cerebellar circuits using high-angular resolution diffusion spectrum imaging (DSI). Methods: We acquired high-resolution structural MRI and DSI of the cerebellum in four healthy female subjects at 3T. DSI tractography based on a streamline algorithm was performed to identify the circuits connecting the cerebellar cortex with the deep cerebellar nuclei, selected brainstem nuclei, and the thalamus. Results: Using in-vivo DSI in humans we were able to demonstrate the structure of the following cerebellar neuronal circuits: (1) connections of the inferior olivary nucleus with the cerebellar cortex,...
Ralph Kimmlingen, Eva Eberlein, Peter Dietz, Sabrina Kreher, Johann Schuster, Jörg Riegler, Volke... more Ralph Kimmlingen, Eva Eberlein, Peter Dietz, Sabrina Kreher, Johann Schuster, Jörg Riegler, Volker Matschl, Volker Schnetter, Andreas Schmidt, Helmut Lenz, Ernst Mustafa, Daniel Fischer, Andreas Potthast, Ludwig Kreischer , Michael Eberler, Franz Hebrank, Herbert Thein, Keith Heberlein, Philipp Hoecht, Thomas Witzel, Dylan Tisdall, Junqian Xu, Essa Yacoub, Gregor Adriany, Edward Auerbach, Steen Moeller, David Feinberg, Dietmar Lehne, Lawrence L. Wald, Bruce Rosen, Kamil Ugurbil, David van Essen, Van Wedeen, and Franz Schmitt Siemens Healthcare, Erlangen, Germany, Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Boston, United States, Center for Magnetic Resonance Research, University Minnesota, Minneapolis, United States, Helen Wills Inst. of Neurosc., UC Berkeley, CA, United States, Harvard-MIT Division of Health Sciences Technology, Cambridge, United States, Dept. of Anatomy and Neurobiology, Washington U, St. Louis, United States
Proceedings of SPIE--the International Society for Optical Engineering, 2018
Amyotrophic Lateral Sclerosis (ALS) is a neurological disease that causes death of neurons contro... more Amyotrophic Lateral Sclerosis (ALS) is a neurological disease that causes death of neurons controlling muscle movements. Loss of speech and swallowing functions is a major impact due to degeneration of the tongue muscles. In speech studies using magnetic resonance (MR) techniques, diffusion tensor imaging (DTI) is used to capture internal tongue muscle fiber structures in three-dimensions (3D) in a non-invasive manner. Tagged magnetic resonance images (tMRI) are used to record tongue motion during speech. In this work, we aim to combine information obtained with both MR imaging techniques to compare the functionality characteristics of the tongue between normal and ALS subjects. We first extracted 3D motion of the tongue using tMRI from fourteen normal subjects in speech. The estimated motion sequences were then warped using diffeomorphic registration into the b0 spaces of the DTI data of two normal subjects and an ALS patient. We then constructed motion atlases by averaging all war...
The Journal of the Acoustical Society of America, 2018
Amyotrophic Lateral Sclerosis (ALS) is a neurological disorder, which impairs tongue function for... more Amyotrophic Lateral Sclerosis (ALS) is a neurological disorder, which impairs tongue function for speech and swallowing. A widely used Diffusion Tensor Imaging (DTI) analysis pipeline is employed for quantifying differences in tongue fiber myoarchitecture between controls and ALS patients. This pipeline uses both high-resolution magnetic resonance imaging (hMRI) and DTI. hMRI is used to delineate tongue muscles, while DTI provides indices to reveal fiber connectivity within and between muscles. The preliminary results using five controls and two patients show quantitative differences between the groups. This work has the potential to provide insights into the detrimental effects of ALS on speech and swallowing.
Cerebral cortex (New York, N.Y. : 1991), Jan 16, 2017
Brain fiber pathways are presumed to follow smooth curves but recent high angular resolution diff... more Brain fiber pathways are presumed to follow smooth curves but recent high angular resolution diffusion MRI (dMRI) suggests that instead they follow 3 primary axes often nearly orthogonal. To investigate this, we analyzed axon pathways under monkey primary motor cortex with (1) dMRI tractography, (2) axon tract tracing, and (3) axon immunohistochemistry. dMRI tractography shows the predicted crossings of axons in mediolateral and dorsoventral orientations and does not show axon turns in this region. Axons labeled with tract tracer in the motor cortex dispersed in the centrum semiovale by microscopically sharp axonal turns and/or branches (radii ≤15 µm) into 2 sharply defined orientations, mediolateral and dorsoventral. Nearby sections processed with SMI-32 antibody to label projection axons and SMI-312 antibody to label all axons revealed axon distributions parallel to the tracer axons. All 3 histological methods confirmed preponderant axon distributions parallel with dMRI axes with ...
The parameter selection for diffusion MRI experiments is dominated by the "k-q tradeoff"... more The parameter selection for diffusion MRI experiments is dominated by the "k-q tradeoff" whereby the Signal to Noise Ratio (SNR) of the images is traded for either high spatial resolution (determined by the maximum k-value collected) or high diffusion sensitivity (effected by b-value or the q vector) but usually not both. Furthermore, different brain regions (such as gray matter and white matter) likely require different tradeoffs between these parameters due to the size of the structures to be visualized or the length-scale of the microstructure being probed. In this case, it might be advantageous to combine information from two scans - a scan with high q but low k (high angular resolution in diffusion but low spatial resolution in the image domain) to provide maximal information about white matter fiber crossing, and one low q but high k (low angular resolution but high spatial resolution) for probing the cortex. In this study, we propose a method, termed HIgh b-value an...
Uploads
Papers by Van Wedeen