93306 with contrast agent

I am having a disagreement with my physician about billing a saline contrast with a complete Echo(93306). At first she wanted to use 93352 and I told her that she couldn't doe that because it was an add-on code for a stress echo. As near as I can tell an IV drip, venipuncture and saline contrast agent would be included in the procedure. She says that is impossible. Does anyone have any suggestions/

Thanks

One payer opinion

Microcavitation is a technique that utilizes agitated saline as a contrast medium to assess cardiac blood flow patterns. Microcavitation studies may be reported with procedure code 93799 with the narrative “microcavitation study”. The reimbursement for this service includes the infusion, all supplies and the participation of the physician.
https://www.highmarkmedicareservices.com/articles/mac-ab/a47806-r4.html