TriWest has updated the comprehensive list of codes on the Prior Authorization List (PAL). The effective date is January 1, 2011. This update added the new 2011 codes that will need authorization and medical review. Prior Authorization List (PAL) All services listed below, provided by TRICARE civilian providers, must be reviewed for medical necessity and require prior authorization for all TRICARE programs administered by TriWest. LABORATORY Genetic Testing Preservation of Stem Cells RADIOLOGY Brain MRI Breast MRI Spine MRI MRA Pet Scan Cardiac CT Angiography CT Colonoscopy Other UNLISTED CODES In order for TriWest to make an appropriate benefit determination, all services with unlisted codes require prior authorization, and must be submitted with a description.