Recalculate DICOM Window Center and Width on Subtraction of Dynamic MRI Sequence

Question

I'm trying to calculate and present the Subtraction images of a Dynamic MRI Sequence. However, I've looked for quite some time and I can't seem to find how to relate the individual Rescale Slope and Intercept and even Window Center and Width fields with the respective fields for the new Subtracted image.

I'm sorry if it is a repost but I can't find the answer for this particular problem.

I guess that for Slope and Intercept I probably should just apply the old ones, subtract the images and make sure they are within uint16 range, but what about Window Center and Width?

Thanks in advance

Answer 1

About Rescale Slope and -Intercept:

You can apply the original values of the slices you subtracted, if they are all equal in the slices you subtract from each other. If they are not equal, you will have to rescale one of the slices to the slope/intercept of the other one before doing the subtraction. Otherwise, the subtraction will yield wrong grayscales. Obviously, the resulting subtracted image will then be assigned the slope and intercept of the slice you rescaled the other one to.

About Window Center and -Width:

There is no answer which is right or wrong. Windowing depends on the taste of the person viewing the images - ask three physicians and receive four different answers ;-) I would rather recommend to calculate new values from the histogram of the subtracted image than trying to calculate them from the orginal slices. Subtraction means that you eliminate tissue. The original values were probably adjusted in such a way that this tissue is visible. Now that you have subtracted it you want to have a window that emphasizes the vessels - the rest is just noise.