I think I do understand what you are trying to achieve and can even see the point in why you would want to do that. :-) First have a look at the dicominfo function to retrieve some relevant parameters:
dinfo.PixelSpacing(1) * dinfo.Columns;
Using the above values from both your scout and sagital images you can calculate the intersection of the two. This is actually the complicated part I cannot cook up in a minute.
I also suggest to have a real good look at the file exchange because I would expect something like what you are looking for to be present already.