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eLearning

SINAPSE experts from around Scotland have developed ten online modules designed to explain medical imaging. They are freely available and are intended for non-specialists.


Edinburgh Imaging Academy at the University of Edinburgh offers the following online programmes through a virtual learning environment:

Neuroimaging for Research MSc/Dip/Cert

Imaging MSc/Dip/Cert

PET-MR Principles & Applications Cert

Applied Medical Image Analysis Cert

Online Short Courses

An evaluation of the use of passive shimming to improve frontal sensitivity in fMRI

Author(s): R. Cusack, B. Russell, S. M. L. Cox, C. De Panfilis, C. Schwarzbauer, R. Ansorge

Abstract:
The presence of the head in an MRI scanner leads to inhomogeneities in the magnetic field. These cause the 'susceptibility artifacts' of image distortion and signal dropout. In this paper, we evaluate a technique called passive shimming, which has the potential to reduce field inhomogeneities and the resultant artifacts. A piece of a magnetically active material (pyrolytic graphite) is held on the roof of the participant's mouth by a plastic mouth mould. We evaluate the effects in several different ways. We show that the presence of a shim reduces field inhomogeneity across much of the brain. From field maps, we generate simulations of EPI image intensity and BOLD sensitivity. Both of these are mainly improved by the presence of shim, although there were small reductions in some regions. Measured EPI image intensity also mostly increased. Finally, we ran a reward-punishment task in our subjects, and found that the presence of a shim increased functional sensitivity in the orbitofrontal cortex. Using the BOLD sensitivity measure, we provide estimates of the improvement to be expected in functional studies for a range of neural structures. Passive shims are quick to make and reasonably comfortable to wear, and have substantial potential for researchers investigating inferior frontal brain regions using MRI. (C) 2004 Elsevier Inc. All rights reserved.

Full version: Available here

Click the link to go to an external website with the full version of the paper


ISBN: 1053-8119
Publication Year: 2005
Periodical: Neuroimage
Periodical Number: 1
Volume: 24
Pages: 82-91
Author Address: