When I try to enter J149A the system says it's an invalid code. I think I should be able to use this code for ultrasound guidance of para/thora procedures.
Please note that J149A is not a valid code. There are two components of J149 service code, Technical and Professional, please see SOB G11. As such the suffix can either be B (Technical) or C (Professional). Please refer to SOB, G11 for the definition of Technical and Professional to see which applies to you, and bill accordingly.
Also note that this service code requires a Service Location Indicator. To do this you will need to enable the "Service Code Location" under MY PREFERENCES (tab) --> My Preferences --> Specific to Medical Disciplines