[Homer-users] Units of HbO, HbR and HbT

[pankaj gupta]

Thanks David, for through response. I need to check again with the Shimadzu
system then, I guess its millimolar.


Regards
Pankaj

On Thu, Sep 25, 2014 at 10:24 PM, David Boas <dboas at nmr.mgh.harvard.edu>
wrote:

> Homer2 gives it in units of micro Molar.
> I don’t know what Shimadzu does.
>
> I like the convention of presenting the concentration changes in units of
> [concentration length],  [mM mm] is often used in the literature
> (milliMolar millimeter). This convention is used in recognition that the
> partial path length of light through the region of brain activation needs
> to be approximated and thus is not necessarily accurately known.
>
> Homer uses assumed path lengths or path lengths provided by the users in
> the hmrOD2Conc function. The default path length factors are 6 for each
> wavelength and this is multiplied by the source-detector separation in
> converting from OD to concentration units.
>
> If I had to guess, I would assume that Shimadzu is using the [mM mm]
> units. If you divide Shimadzu’s 0.1 by a path length of 30mm x 6 where 30
> mm is a typical separation and 6 a typical path length factor, then you get
> ~1 microMolar which is of the same order of magnitude as Homer.
>
>
>
>
>
>
> On Sep 25, 2014, at 3:26 AM, Pankaj Gupta <beckman16 at gmail.com> wrote:
>
> > Hi,
> > I have NIRS device provided by Shimadzu corp. and it gives me Oxygenated
> Hb(HbO), deoxygenated Hb(HbR) and Total Hb(HbT) apart from raw intensity
> values.
> >
> > I use the raw intensity values along with Homer toolkit to obtain
> optical density and then HbO, HbR and HbT values. But these HbO values have
> way much smaller range [-5e-6 5e-6] as compared to [-1e-1 1e-1] of the ones
> that Shimadzu device already gives me.
> >
> > Does anyone know the unit of HbO, HbR and HbT that Homer toolkit gives ?
> > Apologies if its a naive question.
> >
> > Regards
> > Pankaj
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