I would like to define the size of my ROI's using the values given in the property window. However, I can not find any documentation that says, "any value displayed (e.g. radius) is equivalent to a particular measurable value" such as mm or inches etc.

For every point value, how many mm. does this correlate to in Trackvis? In other words, If my region of interest has a radius of 6, how many mm is this?

I am new to DTI analysis, and any help would be appreciated. Thanks.