show custom field value in variation tab

For one of my products (canvas with photo on) I added the field 'DPI'.
This field can be configured differently for every canvas size (which is a variation), just like the price.
If I now open the product and I click "manage variations", I see following screen: see attachement

For every variation I see the price and the dimension. Now I want to add the column for DPI too.
Like that I can see the configured DPI without entering the specific variations....

Do you know how I can achieve that?

Thanks