Adding images in musicxml

I have a question that is more related to musicXML, but I figured maybe you would know the answer.

I want to embed an image in an xml file and be able to show it in musescore.

I believe the musicxml standard currently does not support this feature, I know mscz does, but if possible I would prefer not the write a converter in my software. Perhaps you would know if this is at all possible (however unlikely).

Basically what I want to achieve is to display a sort of plot with a tension value over the score. If the above is not possible, maybe anybody has an idea on how to best achieve that?

Thanks for any insights!
Dorien