JiscMail Logo
Email discussion lists for the UK Education and Research communities

Help for SPM Archives


SPM Archives

SPM Archives


SPM@JISCMAIL.AC.UK


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

SPM Home

SPM Home

SPM  June 2008

SPM June 2008

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: Fieldmap toolbox for coronal EPI-SENSE

From:

Chloe Hutton <[log in to unmask]>

Reply-To:

Chloe Hutton <[log in to unmask]>

Date:

Tue, 10 Jun 2008 12:16:49 +0100

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (88 lines)

Dear Bas

We have only ever implemented the FieldMap toolbox for the AP/PA
phase-encode direction. We don't have any plans to collect data with an
LR/RL phase-encode direction in the immediate future so we currently don't
intend to update the toolbox for this.

However, in theory it should be possible to tweak the toolbox to work for
LR phase-encode direction. If you then plan to use the Realign and Unwarp
option to apply the fieldmap, you will also need to tweak this.
Unfortunately, I think both of these tasks (especially the latter) could
be quite fiddly.

If you decide to go ahead with the modifications, I strongly recommend you
acquire phantom data in which there is an obvious distortion (e.g. apply
an additional shim in your phase-encode direction). You can then use this
to test what you've done.

Best wishes
Chloe

On Mon, June 9, 2008 19:59, Bas Neggers wrote:
> Dear list,
>
>
> I am trying to use the fieldmap SPM5 toolbox to correct geometric
> distortions for coronal slices of high resolution (2x2x2) 2DEPI data. The
> 2DEPI acquisition (on a Philips Achieva MR scanner) is accelerated
> with SENSE (eg, sparse K-space sampling) to decrease distortion.  This
> helps, but is not enough due to long readout in case of high-resolution
> data. Phase encoding was in the LR direction. This is the only option,
> because SENSE acceleration can't be done FH since most SENSE headcoil does
> not have opposing coils in that direction.
>
> Now I read in the manual that the Fieldmap toolbox is designed for axial
> slices with phase encoding either AP or PA. Would it be possible to tweak
> the fieldmap toolbox to do corrections for coronal slices the right way?
> The only message I found with a similar question was:
> http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind04&L=spm&O=D&F=&I=-3&S=&P
> =306371
> but unfortunately I could not find an answer...
>
> I tried to simulate SENSE readout when acquiring the required phase maps
> at 2 echo times by doubling voxel size in the phase encoding direction, or
> by adding a 2nd shot. That seems to have worked.
>
> Any help would be appreciated!
>
>
> Cheers,
>
>
> Bas
>
>
> --
> --------------------------------------------------
> Dr. S.F.W. Neggers
> Division of Brain Research
> Rudolf Magnus Institute for Neuroscience
> Utrecht University Medical Center
> Visiting : Heidelberglaan 100, 3584 CX Utrecht
> Room B.01.1.03
> Mail     : Huispost B.01.206, P.O. Box 85500
> 3508 GA Utrecht, the Netherlands
> Tel      : +31 (0)30 2509609
> Fax      : +31 (0)30 2505443
> E-mail   : [log in to unmask]
> Web      : http://www.fmri.nl/people/bas.html
> --------------------------------------------------
>
>


-- 
Dr Chloe Hutton
Wellcome Trust Centre for Neuroimaging
Institute of Neurology
University College London
12 Queen Square
London WC1N 3BG
United Kingdom

Tel. +44-20-7833-7478, (internal ext 4368)
Fax  +44-20-7813-1420

[log in to unmask]

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
2006
2005
2004
2003
2002
2001
2000
1999
1998


JiscMail is a Jisc service.

View our service policies at https://www.jiscmail.ac.uk/policyandsecurity/ and Jisc's privacy policy at https://www.jisc.ac.uk/website/privacy-notice

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager