Hi Griselda,
Sorry no news on the matlab benchmarking - this is because our systems
were hacked just after I got back from my honeymoon, and I've been
reinstalling the system ever since. I'll email the pages to you next
week though.
Your artefact problem could be addressed by prescribing the slices to be
coronal or sagittal, this should reduce the distortions in the frontal
lobe, since the susceptibility effect is mostly S/I (by reducing the
dimension of the pixels in the direction of the suscep artefact). Of
course this doesn't fix your existing data - but might be worth looking
into....
Good luck.
Jon.
_____________________________________________________
Jonathan Brooks Ph.D. (Research Fellow)
Magnetic Resonance and Image Analysis Research Centre
University of Liverpool, Pembroke Place, L69 3BX, UK
tel: +44 151 794 5629 fax: +44 151 794 5635
On Thu, 28 Mar 2002, Griselda J Garrido wrote:
>Dear SPMerīs,
>
>Our data presents EPI distortion in frontal lobe, which includes a priori
>hypothesis of our study:
>http://www.directnet.com.br/users/griselda/EPIdistortion.html
>
>We are seeking for advice as whether the amount of distortion should cause a
>loss of signal, and be a problem to detect effects of interest in SPM
>statistical analysis.
>
>As pointed in
>http://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind0110&L=spm&P=R4662, SPM will
>not correct this distortion. Is there any free utility (field map or
>registration approach) that can be used to correct our data?:
>
>TR=2000 ms
>TE=40 ms
>matrix = 64 x 64
>BOLD-sensitive GE 1.5 T sequence with RTIP
>15 interleaved 7mm/0.7 space slices from cerebellum to vertex
>axial AC-PC alignment (usually slice 6 or 7)
>230 volumes per series were acquired
>
>Any hints are wellcome!
>
>Many Thanks
>Griselda J Garrido
>University of São Paulo - Brazil
>http://www.directnet.com.br/users/griselda/
>
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