Probably it's possible with some filter. I don't know exactly which one works.

I need to use it for custom css properties based on Media Description. It will be like:

<img src="image_url" style="width:  60%;" />

or

<img src="image_url" style="width:  80%;" />

Media Description screenshot — http://pixs.ru/showimage/ScreenShot_6110036_3802541.png