Reich DS, Smith SA, Zackowski KM, Gordon-Lipkin EM, Jones CK, Farrell JA, Mori S, van Zijl PC, Calabresi PA. Multiparametric magnetic resonance imaging analysis of the corticospinal tract in multiple sclerosis.Neuroimage. 2007 Nov 1;38(2):271-9.

TITLE

Multiparametric magnetic resonance imaging analysis of the corticospinal tract in multiple sclerosis

AUTHORS

Daniel S. Reich, Seth A. Smith, Kathleen M. Zackowski, Eliza M. Gordon-Lipkin, Craig K. Jones, Jonathan A.D. Farrell, Susumu Mori, Peter C.M. van Zijl, Peter A. Calabresi

ABSTRACT
Background/Purpose: Muscle weakness is an important feature of multiple sclerosis and is responsible for much of the disability associated with that condition. Here, we describe the quantitative magnetic resonance imaging (MRI) attributes of the major intracerebral motor pathway – the corticospinal tract – in multiple sclerosis. To do so, we develop an intuitive method for creating and displaying spatially normalized tract-specific imaging data.

Methods: In 75 individuals with multiple sclerosis and 29 healthy controls, the corticospinal tracts were reconstructed from diffusion tensor imaging at 3 T. Multiple MRI indices – T2 relaxation time; fractional anisotropy; mean, longitudinal, and transverse diffusivity; and magnetization transfer ratio – were examined within the reconstructed tracts. Spatially normalized tract profiles were created to compare, across subjects, the variation in MRI index as a function of tract position.

Results: Each index’s tract profile had a characteristic shape. Individual subjects had markedly abnormal tract profiles, particularly at lesion sites. On average, tract profiles were different between patients and controls, particularly in the subcortical white matter and corona radiata, for all indices examined except for fractional anisotropy. Magnetization transfer ratio was further decreased in subjects with secondary progressive disease. Tract asymmetry was increased in multiple sclerosis compared to controls.

Conclusion: Multiparametric MRI allows rapid detection, localization, and characterization of tract-specific abnormalities in multiple sclerosis. Tract profiles bridge the gap between whole-brain imaging

LINKS
http://www.ncbi.nlm.nih.gov/pubmed/17870615?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

CATEGORIES

Year Published
-2007 (paper)

Authors
-Reich DS, Smith SA, Zackowski KM, Gordon-Lipkin EM, Jones CK, Farrell JA, Mori S, van Zijl PC, Calabresi PA.

Affiliations/Departments
Department of Neurology, Johns Hopkins University, 600 N Wolfe St, Baltimore, MD 21287, USA

Department of Radiology, Johns Hopkins University, 600 N Wolfe St, Baltimore, MD 21287, USA

Department of Physical Medicine and Rehabilitation, Johns Hopkins University, 600 N Wolfe St, Baltimore, MD 21287, USA

F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, 707 N Broadway, Baltimore, MD 21205, USA

Department of Physical Medicine and Rehabilitation, Kennedy Krieger Institute, 707 N Broadway, Baltimore, MD 21205, USA

Funding
National Multiple Sclerosis Society Collaborative Center Award

National Multiple Sclerosis Society TR-3760- A-3

NIH RR15241, RO1EB3543, AG20012, and EB000991

The Nancy Davis Center without Walls

Dr. Craig K. Jones is supported by a grant from Philips Medical
Systems to the Kennedy Krieger Research Institute.

Dr. van Zijl is a paid lecturer for Philips Medical Systems, an arrangement that has been approved by Johns Hopkins University in accordance with its conflict of interest policies

Journal
-NeuroImage

Neuroscientific Applications
- Multiple Sclerosis (MS)

-Brain, Corticospinal Tract (Spinal Cord)

Technology

Diffusion Tensor Imaging (DTI), Magnetization Transfer (MT), T2 Relaxation Time (T2)

TITLE
Effects of signal-to-noise ratio on the accuracy and reproducibility of diffusion tensor imaging-derived fractional anisotropy, mean diffusivity, and principal eigenvector measurements at 1.5 T.

AUTHORS
Jonathan A.D. Farrell, Bennett A. Landman, Craig K. Jones,Seth A. Smith, Jerry L. Prince, Peter C.M. van Zijl, Susumu Mori

AFFILIATIONS
F.M. Kirby Research Center for Functional Brain Imaging, Kennedy
Krieger Institute, Baltimore, Maryland, USA.
The Russell H. Morgan Department of Radiology and Radiological
Science, The Johns Hopkins University School of Medicine, Baltimore,
Maryland, USA.
Department of Biophysics and Biophysical Chemistry, The Johns Hopkins
University School of Medicine, Baltimore, Maryland, USA.
Department of Biomedical Engineering, The Johns Hopkins University
School of Medicine, Baltimore, Maryland, USA.
Department of Electrical and Computer Engineering, Johns Hopkins
University, Baltimore, MD, USA.

ABSTRACT
PURPOSE: To develop an experimental protocol to calculate the precision and accuracy of fractional anisotropy (FA), mean diffusivity (MD), and the orientation of the principal eigenvector (PEV) as a function of the signal-to-noise ratio (SNR) in vivo.

MATERIALS AND METHODS: A healthy male volunteer was scanned in three separate scanning sessions, yielding a total of 45 diffusion tensor imaging (DTI) scans. To provide FA, MD, and PEV as a function of SNR, sequential scans from a scan session were grouped into nonintersecting sets. Analysis of the accuracy and precision of the DTI-derived contrasts was done in both a voxel-wise and region of interest (ROI)-based manner.

RESULTS: An upward bias of FA and no significant bias in MD were present as SNR decreased, confirming results from simulation-based studies. Notably, while the precision of the PEV became worse at low SNR, no bias in the PEV orientation was observed. Overall, an accurate and precise quantification of FA values in GM requires substantially more SNR than the quantification of white matter (WM) FA values.

CONCLUSION: This study provides guidance for FA, MD, and PEV quantification and a means to investigate the minimal detectable differences within and across scan sessions as a function of SNR.

LINKS
http://www.ncbi.nlm.nih.gov/pubmed/17729339?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

CATEGORIES
Year Published (Paper/Abstract): 2007, Paper

Authors: Jonathan A.D. Farrell, Bennett A. Landman, Craig K. Jones, Seth A. Smith, Jerry L. Prince, Peter C.M. van Zijl, Susumu Mori

Author Affiliations/Departments: Kirby Center, KKI, Radiology, JHMI, Biophysics, Radiology, Biomedical Engineering, Electrical & Computer Engineering

Funding: NIH/NCRR P41 RR 15241; NIH R01 G20012, U24 RR021382-02.

Journal: Journal of Magnetic Resonance Imaging

Neuroscientific Applications:
Pathology/Disease: Normal
Structures: Brain

Technology/Methods: Diffusion Tensor Imaging (DTI)

Landman BA, Farrell JA, Jones CK, Smith SA, Prince JL, Mori S.
Effects of diffusion weighting schemes on the reproducibility of DTI-derived fractional anisotropy, mean diffusivity, and principal eigenvector measurements at 1.5T. Neuroimage. 2007 Jul 15;36(4):1123-38

TITLE

Effects of diffusion weighting schemes on the reproducibility of DTI-derived fractional anisotropy, mean diffusivity, and principal eigenvector measurements at 1.5T

AUTHORS

Bennett A. Landman, Jonathan A.D. Farrell, Craig K. Jones, Seth A. Smith, Jerry L. Prince, Susumu Mori

ABSTRACT
Diffusion tensor imaging (DTI) is used to study tissue composition and architecture in vivo. To increase the signal to noise ratio (SNR) of DTI contrasts, studies typically use more than the minimum of 6 diffusion weighting (DW) directions or acquire repeated observations of the sameset of DW directions. Simulation-based studies have sought to optimizeDTI acquisitions and suggest that increasing the directional resolutionof a DTI dataset (i.e., the number of distinct directions) is preferable to repeating observations, in an equal scan time comparison. However, it is not always clear how to translate these recommendations into practice when considering physiological noise and scanner stability. Furthermore, the effect of different DW schemes on in vivo DTI findings is not fully understood. This study characterizes how the makeup of a DW scheme, in terms of the number of directions, impacts the precision and accuracy of in vivo fractional anisotropy (FA), mean diffusivity (MD), and principal eigenvector (PEV) findings. Orientation dependence of DTI reliability is demonstrated in vivo and a principled theoretical framework is provided to support and interpret findings with simulation results. As long as sampling orientations are well balanced, differences in DTI contrasts due to different DW schemes are shown to be small relative to intra-session variability. These differences are accentuated at low SNR, while minimized at high SNR. This result suggests that typical clinical studies, which use similar protocols but different well-balancedDW schemes, are readily comparable within the experimental precision.

LINK
http://www.ncbi.nlm.nih.gov/pubmed/17532649?ordinalpos=3&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
CATEGORIES

Year Published
-2007 (paper)

Authors
-Landman BA, Farrell JA, Jones CK, Smith SA, Prince JL, Mori S.

Affiliations/Departments
Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA

The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA

F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205, USA

Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA

Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21205, USA

Funding
NIH grants NCRR P41RR15241, RO1AG20012, U24 RR021382-02 (Morphometry group of the Biomedical Informatics Research Network (BIRN), and 1R01NS056307

Dr. Craig K. Jones is supported by a grant from Philips Medical
Systems to the Kennedy Krieger Research Institute

Journal
-NeuroImage

Neuroscientific Applications
-Healthy Volunteer, Brain

Technology: Diffusion Tensor Imaging (DTI)

TITLE
Pulsed magnetization transfer imaging with body coil transmission at 3 Tesla: feasibility and application.

AUTHORS
Seth A. Smith, Jonathan A.D. Farrell, Craig K. Jones, Daniel S. Reich, Peter A. Calabresi, Peter C.M. van Zijl

ABSTRACT
Pulsed magnetization transfer (MT) imaging has been applied to quantitatively assess brain pathology in several diseases, especially multiple sclerosis (MS). To date, however, because of the high power deposition associated with the use of short, rapidly repeating MT prepulses, clinical application has been limited to lower field strengths. The contrast-to-noise ratio (CNR) of MT is limited, and this method would greatly benefit from the use of higher magnetic fields and phased-array coil reception. However, power deposition is proportional to the square of the magnetic field and scales with coil size, and MT experiments are already close to the SAR limit at 1.5T even when smaller transmit coils are used instead of the body coil. Here we show that these seemingly great obstacles can be ameliorated by the increased T1 of tissue water at higher field, which allows for longer maintenance of sufficiently high saturation levels while using a reduced duty cycle. This enables a fast (5–6 min) high-resolution (1.5 mm isotropic) whole-brain MT acquisition with excellent anatomical visualization of gray matter (GM) and white matter (WM) structures, and even substructures. The method is demonstrated in nine normal volunteers and five patients with relapsing remitting MS (RRMS), and the results show a clear delineation of heterogeneous lesions.

LINKS
http://www.ncbi.nlm.nih.gov/pubmed/16964602?ordinalpos=4&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

CATEGORIES
Year Published: 2006, paper
Authors: Seth A. Smith, Jonathan A.D. Farrell, Craig K. Jones, Daniel S. Reich, Peter A. Calabresi, Peter C.M. van Zijl
Affiliations: Kirby Center, JHU, Neurology, Biophysics, Radiology, KKI
Funding
Johns Hopkins University General Clinical Resource Center (GCRC); Grant number: 5M01-RR000052-43;
Grant sponsor: NIH/NIBIB; Grant number: EB000991;
Grant sponsor: NIH/NCRR; Grant number RR015241;
Grant sponsor: National MS Society; Grant numbers: CA 1029-A-2; TR 3760-A-3;
Grant sponsor: Nancy Davis Center Without Walls.
Journal: Magnetic Resonance in Medicine (MRM)
Neuroscientific Applications: Multiple Sclerosis (MS), Brain
Technology: MT: Magnetization Transfer Imaging

TITLE
Magnetization transfer weighted imaging in the upper cervical spinal cord using cerebrospinal fluid as intersubject normalization reference (MTCSF imaging).

AUTHORS
Seth A. Smith, Xavier Golay, Ali Fatemi, Craig K. Jones, Gerald V. Raymond, Hugo W. Moser, Peter C.M. van Zijl

AUTHOR AFFILIATIONS/DEPARTMENTS

F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, Maryland, USA
Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland, USA
Neurogenetics Research Center, Kennedy Krieger Institute, Baltimore, Maryland, USA

ABSTRACT
The magnetization transfer ratio (MTR) is a reliable measure of MT effects because it employs an internal standard that allows quantitative comparison between subjects, independent of other contrasts, coil loading, and coil sensitivity profiles. However, at very high spatial resolution in the spinal cord at 1.5 T, the use of MTR quantification has been hampered by low signal-to-noise ratio (SNR) and acute sensitivity to motion. Here, the suitability of cerebrospinal fluid (CSF) as an alternative inter-subject MT signal intensity reference for the spine is evaluated. Contrary to MTR, this so-called MTCSF internal standard does not remove interfering T1, T2, and spin density contrast and is not expected to be able to discriminate between myelination and inflammation effects. However, it can detect initial changes in myelination when signal alterations are not yet detectable by conventional MRI. As a first example, this is demonstrated for the noninflammatory spinal cord white matter disease adrenomyeloneuropathy.

FUNDING
JHU GCRC; Grant Number: 5M01-RR000052-43
NIH/NIBIB; Grant Number: EB00991-01
Philips Medical Systems to Kennedy Krieger Research Institute

LINKS
http://www.ncbi.nlm.nih.gov/pubmed/15968676?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

CATEGORIES
Year Published: 2005 Paper
Author Names: Seth Smith, Xavier Golay, Ali Fatemi, Craig Jones, Gerald Raymond, Hugo Moser, Peter van Zijl
Affiliations/Departments: Kirby Center, KKI, JHMI, JHU, Biophysics, Radiology, Neurogenetics
Funding: JHU GCRC, NIH/NIBIB, Philips Medical Systems
Grant Number: JHU GCRC 5M01-RR000052-43, NIH/NIBIB EB00991-01, Philips Medical Systems to KKI
Journal: MRM: Magnetic Resonance in Medicine
Neuroscientific Applications:
Pathology/Disease/Healthy Volunteers: AMN: Adrenomyeloneuropathy
Structures: Spinal Cord
Technology: MTCSF, MT: Magnetization Transfer