>>>In fact this is a kind of error, I think the model inherited some misplacement when the MRI was done.
How do you think the cplane could help?

Well, the misalignment was giving the things I was trying problems which is why I started suggesting other methods.

It appears that the misalignment may be "Uniform" or universal. (As you said from the original model.

If the "rotation" could be determined then you could add a new Cplane that would make all the geometry "perpendicular" and methods like extrude would work better.

I tried to do some trims of the curves to follow up with my thought, but MoI balked. I WAS on my wifes lessor power computer at the time and I could try to do smaller sections at a time.

I like what your doing and will follow up more to see if my solution could be viable. For me it would be, "What takes longer?" redoing the geometry you have to accomplish your setup, or breaking the curves with a couple horizontal planes and using those pieces to identify the points, then a second set of full wires to assemble.

Can you make the MRI available here?