As an "add-on" code, 64484 is not subject to multiple procedure rules. No reimbursement reduction or modifier 51 is applied. Add-on codes describe additional intraservice work associated with the primary procedure. They are performed by the same physician on the same date of service as the primary service/procedure, and must never be reported as a stand-alone code. Use 64484 in conjunction with 64483. These are unilateral procedures. If performed bilaterally, some payers require that the service be reported twice with modifier 50 appended to the second code while others require identification of the service only once with modifier 50 appended. Check with individual payers. Modifier 50 identifies a procedure performed identically on the opposite side of the body (mirror image). For subarachnoid, subdural, epidural, or caudal injection, see 62310-62319. For transforaminal epidural injections under ultrasound guidance, see 0230T-0231T. Imaging guidance and injection of contrast are inclusive components of 64483 and 64484. (see above)
You probably got the invalid type of bill because you are billing imaging guidance with these transforaminal injections. 64483 and 64484 already include CT and fluoroscopic guidance so you would not be coding 77003 along with these codes for one. I also would not expect to see 72265 unless you had a completely separate report.
Here is what CPT® assistant says:
It is important to note that myelography should not be reported unless a complete myelographic procedure with full RS&I is performed. Myelography is not merely documentation of needle placement