April 30, 2003

ACR Radiology Coding Source™ March-April 2003

MRI of the Internal Auditory Canal (IAC)

There has been much discussion by insurance carriers at the local level about how to appropriately code for an MRI of the brain and an MRI of the internal auditory canal (IAC) if both studies are performed, and if a specific number of sequences needs to be performed before coding for both.

If a complete MRI of the brain study is performed in conjunction with a complete study of the IACs, it is appropriate to code for two MRI of the brain studies; a "–59" modifier should be appended to the second MRI brain code to indicate that separate and distinct services were provided. On the other hand, if a complete MRI of the brain is done with just a few extra sequences focused on the IACs, the extra sequences would be considered part of the base study, and only one MRI of the brain study should be coded.

It would be difficult to set the reimbursement rate for a limited MRI study based on the number of additional sequences, because each patient study has its own protocol. The number of sequences needed to fully evaluate the patient's condition, injury or disease varies and is part of the original MRI study ordered.

Note that a radiology group rarely performs a full MR of the brain with a separate and distinct study of the IACs; therefore, the ACR does not see the need to develop a new CPT® code that describes MRI of the IACs. Instead, Medicare carriers and other third-party payers should allow radiologists to submit two MRI of the brain codes when it is medically necessary to perform separate and distinct studies and when appropriate documentation is provided.