English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  A 200 MHz flexible receive phased array for (f)MRI of macaques in a vertical scanner

Merkle, H., Logothetis, N., & Goense, J. (2008). A 200 MHz flexible receive phased array for (f)MRI of macaques in a vertical scanner. Poster presented at ESMRMB 2008 Congress: 25th Annual Meeting, Valencia, Spain.

Item is

Files

show Files

Locators

show
hide
Description:
-
OA-Status:

Creators

show
hide
 Creators:
Merkle, H, Author           
Logothetis, NK1, 2, Author           
Goense, JBM1, 2, Author           
Affiliations:
1Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497794              
2Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497798              

Content

show
hide
Free keywords: -
 Abstract: Introduction: Since high SNR is necessary for high-resolution FMRI it is advantageous to place the coils close against the monkey’s head whenever
possible. To this end, we designed a flexible 4-channel receive-only phased
array that can be used on monkeys of different sizes as well as for different
cortical areas. In addition, the preamplifiers including control electronics are detachable and can serve a variety of prefabricated and phase-matched fourelement
arrays of different configurations.
Methods: A linear array of 4 circular coils of ~23 mm diameter with gaps of
~11 mm was sutured onto a soft plastic strip (Figure 1). The assembly having
in-line connectors was attached to phase-matched coaxial cables to modified
commercial high reflection coefficient preamplifiers (Stark Contrast
Inc., Erlangen, Germany) via cable traps. Detuning of the individual coils
during RF transmission was achieved using DC currents within the coaxial
cables and pin diode controlled notch filters within the array elements.
Experiments were done on anesthetized monkeys on a vertical 4.7T Bruker
Biospec running ParaVision 5. The array was positioned over the occipital
pole. RF transmission was done with a de-tunable ‘type D’ partial volume
coil. We obtained high-resolution FLASH (Figure 2) and FMRI data using
EPI with and without acceleration (GRAPPA). The stimulus was a full-field
rotating checkerboard. FLASH: resolution 100x100x1000 μm, TE 23 ms, TR
2000 ms, 1 average; FMRI: GE-EPI, resolution 500x500x2000 μm, TE 21 ms,
TR 750 ms, 8 segments with R = 1, or 4 segments with R = 2.
Results: The high-resolution FLASH anatomical images show intracortical
veins and the Gennari line in entire V1, including peripheral V1, which is located
deep in the brain. Using a dual-coil setup, it is only possible to observe
these features in parts of V1 that are close to the surface. The functional map
proofs that the increased coverage allows us to obtain activation in V1-V5 in
both hemispheres at high resolution (Figure 3). SNR was sufficient to also
allow accelerated FMRI at the same resolution.
Discussion: Compared to a dual-coil setup the phased array provides improved
SNR and coverage, which allows for high resolution anatomical imaging
and FMRI of the entire early visual cortex, including better performance
in deep brain areas.

Details

show
hide
Language(s):
 Dates: 2008-10
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: DOI: 10.1007/s10334-008-0126-2
BibTex Citekey: 5484
 Degree: -

Event

show
hide
Title: ESMRMB 2008 Congress: 25th Annual Meeting
Place of Event: Valencia, Spain
Start-/End Date: 2008-10-02 - 2008-10-04

Legal Case

show

Project information

show

Source 1

show
hide
Title: Magnetic Resonance Materials in Physics, Biology and Medicine
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Amsterdam : No longer published by Elsevier
Pages: - Volume / Issue: 21 (Supplement 1) Sequence Number: 917 Start / End Page: 654 - 655 Identifier: ISSN: 0968-5243
CoNE: https://pure.mpg.de/cone/journals/resource/954926245532