Google Script : How to add an image to a CheckboxItem choice programmatically?

in a Google Form, you can manually add an image to the choices in an checkbox item (there is a little icon appearing on the right when you manually edit one choice). I would like to do that programmatically but I could not find any way in the reference guide.

I need it because using getChoices and setChoices of the CheckboxItem makes the manually set images vanished every time I need to filter its choices.

Is it just not possible or is it only for some sort of premium users?

Thank you for your help.