English
 
User Manual Privacy Policy Disclaimer Contact us
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Single, slice-specific z-shim gradient pulses improve T2*-weighted imaging of the spinal cord

Finsterbusch, J., Eippert, F., & Büchel, C. (2012). Single, slice-specific z-shim gradient pulses improve T2*-weighted imaging of the spinal cord. NeuroImage, 59(3), 2307-2315. doi:10.1016/j.neuroimage.2011.09.038.

Item is

Basic

show hide
Item Permalink: http://hdl.handle.net/11858/00-001M-0000-002E-8A26-B Version Permalink: http://hdl.handle.net/21.11116/0000-0003-B017-C
Genre: Journal Article

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Finsterbusch, Jürgen1, 2, Author
Eippert, Falk1, 2, Author              
Büchel, Christian1, 2, Author
Affiliations:
1Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, ou_persistent22              
2Neuroimage Nord, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, ou_persistent22              

Content

show
hide
Free keywords: Spinal cord; fMRI; Magnetic field inhomogeneities; z-shim; Gradient compensation; Temporal resolution
 Abstract: T2*-weighted imaging of the spinal cord suffers from signal dropouts that hamper blood-oxygenation-level-dependent functional magnetic resonance imaging (fMRI). They are due to field inhomogeneities caused by the different magnetic susceptibilities of the vertebrae and the intervertebral disks that vary periodically along the cord and, thus, cannot be compensated appropriately with conventional (constant) shimming. In this study, a single, slice-specific gradient pulse (“z-shim”) is applied in echo-planar imaging of axial sections in order to compensate for the corresponding through-slice signal dephasing without affecting the acquisition time, i.e. the temporal resolution. Based on a reference acquisition sampling a range of compensation moments, the value yielding the maximum signal amplitude within the spinal cord is determined for each slice. Severe N/2 ghosting for larger compensation moments is avoided by applying the gradient pulse after the corresponding reference echoes. Furthermore, first-order flow compensation in the slice direction of both the slice-selection and the z-shim gradient pulse considerably reduces signal fluctuations in the cerebro-spinal fluid surrounding the spinal cord, i.e. would minimize ringing artifacts in fMRI. Phantom and in vivo experiments show the necessity to use slice-specific compensation moments in the presence of local susceptibility differences. Measurements performed in a group of 24 healthy volunteers at 3T demonstrate that this approach improves T2*-weighted imaging of axial sections of the cervical spinal cord by (i) increasing the signal intensity (overall by about 20%) and (ii) reducing signal intensity variations along the cord (by about 80%). Thus, it may help to improve the feasibility and reliability of fMRI of the spinal cord.

Details

show
hide
Language(s): eng - English
 Dates: 2011-09-092011-07-202011-09-142011-09-222012-02-01
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: DOI: 10.1016/j.neuroimage.2011.09.038
PMID: 21979381
Other: Epub 2011
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: NeuroImage
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Orlando, FL : Academic Press
Pages: - Volume / Issue: 59 (3) Sequence Number: - Start / End Page: 2307 - 2315 Identifier: ISSN: 1053-8119
CoNE: /journals/resource/954922650166