Dear Dr.Gottschalk:
  Let me describe a little more about my phantom studies for you as a reference.
 1). Hoffman Brain Phantom: SPECT acquired on Triad camera. Manually draw ( not use a
mirror ROIs template ) symmetric RIOs on TV images. Then comparing average counts of
each pair of ROIs. For these SPECTs acquired with 120 degree CCW per head , there is
10 to 20 %  asymmetric difference with a pattern that most higher reading of ROIs on
left side; For these SPECTs acquired with 360 degree CCW per head (same acquisition
time but off course less time per step), there is 5 % (a fewer 7 %) asymmetric
difference with higher left ROIs and higher right ROIs even distributed. I did not
use the cerebral hemisphere as the reference region.
2). Hoffman Brain Phantom and SPECT Phantom: SPECT acquired on Picker Prism 3000. 120
degree CCW per head, 5 scans v/s 360 degree CCW per head, 2 scans (same acquisition
time). I have same result as my study on Triad camera. For the SPECT phantom, I used
only those TVs in uniformity section of the phantom. Since it's uniformity section, I
just random drew muti-ROIs on one side and flipped them over. I have same result from
SPECT phantom.
So both institutes now use the 360 degree protocol instead  120 degree one which it's
usually set by manufacture as default protocol.

"Chris Gottschalk, MD" wrote:

> Drs Glabus and Fang [and I eagerly await Isak's input as well; if he
> doesn't chime in, I will go find him...]
>
>         I am fascinated by this interchange regarding assymtery in *phantom* data
> as opposed to *human beings* deemed "normal". the data from a phantom
> define, I think, what the MINIMUM range of assymetry you should accept for
> your scans, given that a phantom is uniform, by definition. However, whose
> data are we using to define what the normal range of assymetry is in
> [presumably] resting images of people in a gamma camera? Certainly, those
> values will vary according to which structures you are identifying with
> ROIs to define assymetry.
>         Perhaps I envision the wrong thing: are you both referring to percent
> differences between [whole] hemispheric values?
>
> >> I have several questions and statement here related to your E-mail.
> >> 1). Our NM physicians use the 7% based on ' plenty of NM literature '
> >> that the range of asymmetry in SPEC scans of normal population is from
> >> 5% to 10%. They call 7-9 % in borderline and > 9 % as abnormal with
> >> traditional RIO method; I did some phantom studies using
> >> Hoffman Brain Phantom and found there is 5% asymmetry with optimum setting
> >of
> >> acquisition; CERETEC has a 5-10% asymmetry on normal scan according to
> >> Amersham (ECD?). It's almost impossible to get a actual
> >> normal pediatric subject scan and they all come in with some kind of
> >diagnosis.
> >> So Iselected these less than 7 % asymmetry as a control group not a normal
> >> baseline.
> >
> >On the basis of your observation with Ceretec, these thresholds sound
> >reasonable
> >and certainly consistent with observations I've made and with phantom
> >studies
> >using the JB003 brain phantom with Tc99m, but imaged with the Strichman
> >Neuro 900,
> >12-detector system.
> >
> >Routinely clinicians (in Edinburgh) would look for asymmetry of around 20%
> >to be
> >deemed pathological, but opinions vary. *** ISAK PROHOVNIK ***, if you're
> >out there,
> >can you provide some input on this? (Apologies for shouting, but it's a
> >personal
> >"heads up" call...copyright Darren Gitelman)
> >
> >> Do you think that 'no major differences between a custom SPECT and
> >> supplied PET template for normalization results' can be extended to
> >> pediatric patient (assuming supplied PET made from adult)?
> >
> >I'm not sure but it may be prudent to consider making a paediatric template
> >as
> >it's bound to be more unlike the adult (PET) template than an "elderly"
> >adult
> >brain.
> >
> >> 3). When I learnt the SPM from a local spmer, I have been instructed
> >> that I had to do at least Coregister and reslice and Spatial
> >> Normalization (Smooth as an option) on an object image to create a
> >> snr---.img file for Statistics. I have been suggested to use supplied
> >> PET as template then. But I have a impression from your
> >> E-mails that the Coregister step might not be necessary in the process
> >(?).
> >
> >Routinely, one would not normally coregister and reslice a SPECT image
> >in a separate stage from normalisation against (whatever) template image, so
> >I think you may be referring to the issue of "piggy-back" spatial
> >transformations
> >where MRI derived parameters are applied to the SPECT image from the same
> >subject. In theory this should work, but my experience (and of others) has
> >shown
> >it's better to treat these images separately for spatial normalisation. My
> >guess
> >is that errors arise due to poor co-registration between SPECT and MRI
> >images - again
> >the reason is probably that our Neuro 900 have low spatial resolution in the
> >
> >z-plane, with 12-14 slices of 8 - 10 mm slice thickness. If you have a gamma
> >camera
> >which acquires a more complete data set, this may not be an issue.
> >
> >see:
> >"Assessing spatial transformation options in a SPECT and MRI study of
> >elderly
> >depression and dementia using SPM'96". Glabus, M & Ebmeier, K.P., 1999,
> >Neuroimage,9:6:Pt 2 of 2:S149.
> >
> >Regards - Mike
> >--
> >---------------------------------------------
> >Mike Glabus, PhD
> >Visiting Fellow in Functional Neuroimaging
> >Unit on Integrative Neuroimaging,
> >Clinical Brain Disorders Branch, NIMH, NIH
> >Building 10, Rm 4C101, 9000 Rockville Pike
> >Bethesda, MD, 20892-1365, USA
> >Tel: + 301 496 7864    FAX: + 301 496 7437
> >[log in to unmask]
> >
>
> ********************************************************
> Christopher Gottschalk, MD                      *
> Assistant Professor of Neurology & Psychiatry   *
> Yale School of Medicine                 *
>                                                 *
> Mailing Adress:                         *
> VAMC [116-A]            tel [203] 932-5711 x4329*
> 950 Campbell Avenue                 FAX 937-4791*
> West Haven, CT 06516                    *
> ********************************************************



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%