Hi Natalie,
If by quantitative value you are referring to CBF (in real physical
units of ml/g/min), then no. To convert ASL time-series to CBF you need
to run the data through an appropriate bio-physical model.
cheers,
-MH
On Wed, 2010-10-13 at 08:10 -0400, Natalie Paul wrote:
> Hello,
>
> We have collected a baseline scan (run 6) in addition to our task
> scans (runs 7, 9, 11, and 13). If we subtract our Task ASL - baseline
> ASL, can we do that to get a quantitative value?
>
> Thank you,
>
> Natalie
>
> On Wed, Oct 13, 2010 at 3:12 AM, Stephen Smith <[log in to unmask]> wrote:
> >
> >
> > ----------
> >
> > From: FSL - FMRIB's Software Library on behalf of Stephen
> > Smith[SMTP:[log in to unmask]]
> > Sent: Wednesday, October 13, 2010 3:12:49 AM
> >
> > To: [log in to unmask]
> > Subject: Re: [FSL] ASL ROI analysis
> > Auto forwarded by a Rule
> > Hi, just as with BOLD data, FEAT leaves the mean signal in the data, and
> > the overall (4D) mean is rescaled to be 10000. The units of signal change
> > are therefore either in these scaled units, or in % signal change if that
> > option has been selected in Featquery. I'm not quite sure what you mean by
> > quantitative in this context, as ASL-timeseries data is in general not
> > quantitative without further quantification of the baseline flow level.
> > Cheers.
> >
> >
> >
> > On 11 Oct 2010, at 14:23, Natalie Paul wrote:
> >
> > We did an analysis on our ASL data using FSL feat following the web
> > instructions. We then conducted an ROI analysis using featquery on the
> > perfusion EV (the interaction of control-tag EV with the bold EV). My
> > question is, what unit is used for the mean signal perfusion signal of the
> > ROI? Also, is there a way to get quantitative perfusion measurement from the
> > ROI analysis?
> >
> > Thank you,
> >
> > Natalie Paul
> >
> >
> >
> > ---------------------------------------------------------------------------
> > Stephen M. Smith, Professor of Biomedical Engineering
> > Associate Director, Oxford University FMRIB Centre
> >
> > FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
> > +44 (0) 1865 222726 (fax 222717)
> > [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
> > ---------------------------------------------------------------------------
> >
> >
> >
> >
>
>
>
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