CSF Flow Study (Cerebrospinal Fluid Flow Study), Purpose of CSF Flow Study.

CSF Flow Study (Cerebrospinal Fluid Flow Study) is a specialized MRI technique used to evaluate the movement of cerebrospinal fluid (CSF) within the brain and spinal canal. It is most commonly performed using Phase-Contrast MRI (PC-MRI).

📌 Purpose of CSF Flow Study:

1. Hydrocephalus evaluation

   • To differentiate obstructive (non-communicating) vs. communicating hydrocephalus.

   • Assess aqueductal stenosis.

2. Chiari Malformations

   • To check obstruction of CSF flow at the foramen magnum.

3. Normal Pressure Hydrocephalus (NPH)

   • Helps in predicting response to CSF shunt surgery.

4. CSF Leak suspicion

   • Indirect evaluation of altered CSF circulation.

5. Post-surgical evaluation

   • After shunt placement, decompression, or fenestration surgeries.

 Technique:

• Performed on MRI (1.5T or 3T).

• Phase Contrast MRI (PC-MRI) sequences are applied.

• Usually planned through:

  • Cerebral aqueduct (Sylvian aqueduct).

  • Foramen magnum.

  • Cervical subarachnoid space.

• Uses velocity encoding (VENC) (commonly 10–20 cm/s for CSF).

• Generates both magnitude images and phase images.

📌 Information Obtained:

• Qualitative: Visualization of CSF pulsation and flow voids.

• Quantitative:

  • Flow rate (ml/min)

  • Stroke volume (net CSF flow per cardiac cycle)

  • Velocity of CSF flow

📌 Clinical Importance:

• Chiari I Malformation → Determines whether posterior fossa decompression is needed.

• NPH (Normal Pressure Hydrocephalus) → High aqueductal stroke volume correlates with shunt-responsive patients.

• Obstructive Hydrocephalus → Identifies blockage (e.g., aqueductal stenosis).

• Post-op Assessment → Confirms restoration of CSF flow.