| Re: minimum intensity projection [message #40032] |
Fri, 02 July 2004 08:15 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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maarten writes:
> I am trying to perform a minimum intensity projection on a 3d MRI
> dataset, and I was hoping if anyone ever wrote an algortithm to perform
> this. Because I am having some problems implementing this myself.
When we want a minimum projection image of one of our volumes,
we simply do this:
min_image = Min(volume, Dimension=3)
We have had some discussion with doctors about whether
this *means* anything, but it's easy enough to do, so
why not. :-)
More often they are interested in the maximum intensity
projection, which--of course--is done like this:
max_image = MAX(volume, Dimension=3)
If we are calculating a MIP Cine image, we will
do a bit a weighting of the values, otherwise
as the image rotates it is very difficult to
distinguish front from back.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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| Re: minimum intensity projection [message #40034 is a reply to message #40032] |
Fri, 02 July 2004 08:01  |
Dick Jackson
Messages: 347
Registered: August 1998
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Senior Member |
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Hi Maarten,
"maarten" <user@domain.invalid> wrote in message
news:40E56C55.90001@domain.invalid...
> Hello everybody,
>
> I am trying to perform a minimum intensity projection on a 3d MRI
> dataset, and I was hoping if anyone ever wrote an algortithm to
perform
> this. Because I am having some problems implementing this myself.
>
> thanks in advance,
>
> Maarten
I believe that "maximum intensity projection" is more common, and is
found in a few places in IDL. Use IDL Online Help's "Search" function
for the words "intensity projection" and you get several routines that
might do just what you want: SLICER3, VOXEL_PROJ, and in IDL 6.0,
IVolume.
I suppose if you really wanted minimum intensity projection you could
invert your data and then use maximum intensity projection:
newData = 255B - oldData ; Assumes that you have 1-byte data
I hope this helps you.
Cheers,
--
-Dick
Dick Jackson / dick@d-jackson.com
D-Jackson Software Consulting / http://www.d-jackson.com
Calgary, Alberta, Canada / +1-403-242-7398 / Fax: 241-7392
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