Re: way to look for close proximity?

Posted by Martin Wessendorf on May 18, 2007; 5:52pm
URL: http://imagej.273.s1.nabble.com/way-to-look-for-close-proximity-tp3699409p3699410.html

Rainer Kohler wrote:

> we are imaging two fluorescent markers that are localized in different
> cells but are present in the same tissue according to our theory. The
> data consists of z-stacks of images through the tissue.
> Is there a mathematical way to analyze and support the close proximity
> in the same tissue?
> I guess colocalization studies should not give any colocalization.
> Can it be called "colocalization" in the same tissue or cooccurence in
> the same tissue?

My guess is that there are stereological approaches to this problem.
The probability in a random section that object "x" will appear within
distance "k" of object "y" will be a function of how far apart the
objects actually are.  However, I can't point you to a specific paper.
You might check with your local stereology guru or scan through recent
copies of J. Microscopy.

Also, B. Payne and A. Toga published a paper on "distance fields" in
Neuroimaging back around 1992 or so--it's a means of finding objects
within distance "k" of each other.

Finally, there's the ten-cent solution:

Colocalization studies implicitly define a distance within which the two
labels must occur.  For LM studies this is typically either defined by
the cell membrane, or (when one's interested in protein-protein
interactions), the resolution of the microscope.  However, there's no
reason this size couldn't be bigger.

Suppose you resampled your image so that your voxels were, say, 10 um
cubes, and you didn't see any colocalization.  Now suppose you increased
the voxel size to 20um and you did see colocalization.  Those
observations might allow you to set limits on the closeness of the labels.

You'd need strong labeling (or thresholded images) but it might work....

Good luck!

Martin Wessendorf
--
Martin Wessendorf, Ph.D.                   office: [phone]
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