What does CPT Assistant (Jun 96:6, Dec 05:3, Aug 09:3, Jun 12:16, Jun 13:14, Jan 14:10) say about ABI? CPT states that this code can be billed with a modifier 59 on the additional level. But Medicare has a MUE of 1. I am doing some auditing and the MUE's typically make sense but this one is throwing me off. Any suggestions on why this would be MUE of 1 when CPT states to use -59 on the additional level?