G9536 HCPCS - DOCUMENTATION OF MEDICAL REASON(S) FOR ORDERING AN ADVANCED BRAIN IMAGING STUDY (I.E., PATIENT HAS AN ABNORMAL NEUROLOGICAL EXAMINATION; PATIENT HAS THE COEXISTENCE OF SEIZURES, OR BOTH; RECENT ONSET OF SEVERE HEADACHE; CHANGE IN THE TYPE OF HEADACHE; SIGNS OF INCREASED INTRACRANIAL PRESSURE (E.G., PAPILLEDEMA, ABSENT VENOUS PULSATIONS ON FUNDUSCOPIC EXAMINATION, ALTERED MENTAL STATUS, FOCAL NEUROLOGIC DEFICITS, SIGNS OF MENINGEAL IRRITATION); HIV-POSITIVE PATIENTS WITH A NEW TYPE OF HEADACHE; IMMUNOCOMPROMISED PATIENT WITH UNEXPLAINED HEADACHE SYMPTOMS; PATIENT ON COAGULOPATHY/ANTI-COAGULATION OR ANTI-PLATELET THERAPY; VERY YOUNG PATIENTS WITH UNEXPLAINED HEADACHE SYMPTOMS)