CPT® Code 78635

Cerebrospinal fluid (CSF) flow imaging is a diagnostic procedure that utilizes scintigraphy along with a radiolabeled isotope tracer to visualize the movement of CSF within the central nervous system. This imaging technique is essential for identifying abnormalities in CSF flow, which can include conditions such as communicating and non-communicating hydrocephalus, as well as fistulas that may connect a CSF reservoir, or cistern, to the nasal cavity or ear. The CSF is produced in the lateral ventricles of the brain and flows through various structures, including the foramen of Monro into the third ventricle, and subsequently into the fourth ventricle via the aqueduct of Sylvius. A small volume of CSF is also generated in the spinal canal, which merges with the intraventricular CSF supply in the fourth ventricle. From there, it circulates into the subarachnoid spaces through the medial foramen of Magendie and the lateral foramina of Luschka. The movement of CSF is driven by bulk flow, which occurs from areas of high pressure to those of lower pressure, as well as by pulsatile motion that is influenced by the cardiac cycle of the cerebral arteries. During the procedure, a radiolabeled isotope tracer is introduced into the CSF through a lumbar puncture. The patient is then positioned on an imaging table, with a gamma camera placed over the area of interest. Scanning is conducted at predetermined intervals, capturing the radioactive energy emitted from the tracer, which is then transformed into a visual image for analysis. It is important to note that CPT® Code 78630 is designated for studies focusing on the cisterns (cisternography), while CPT® Code 78635 is specifically used for studies concentrating on the ventricles (ventriculography). Following the imaging, the physician interprets the results and generates a comprehensive written report detailing the findings.