*Refers to the appropriateness rating in the American College of Radiology (ACR) Appropriate Use Criteria (AUC) where the MRI is rated “Usually appropriate” and CT is rated “May be appropriate”. # ACR AUC only considers initial imaging evaluation, and thus the CT scan is scored "May be appropriate". Because of the exponential complexity, the ACR does not nest AUC to provide recommendations after the initial imaging is complete. However, given the diagnosis of vestibular schwannoma from the MRI, the CT to better assess the skull base is routinely performed and I expect it would be reimbursed. & The secondary code 73677 may be added to the MRI or the CT scan. However, if either is performed an an angiography, 73677 could not be added.