CSF Studies (Cisternography, Leak, Shunt)
Radionuclide cisternography uses an intrathecal tracer (¹¹¹In-DTPA) to study cerebrospinal-fluid circulation. It helps characterise normal-pressure hydrocephalus, localise a CSF leak (rhinorrhoea/otorrhoea), and assess ventricular-shunt patency. Cross-sectional CT/MR techniques are often used first, but radionuclide studies uniquely show CSF dynamics over time.
After lumbar intrathecal injection the tracer normally reaches the basal cisterns within ~1 h, the convexities by ~12 h and the parasagittal region (arachnoid villi) by ~24 h, where it is absorbed. Abnormal patterns — ventricular reflux with delayed clearance (NPH), or tracer appearing at a leak site or nasal pledgets — are diagnostic clues.
Indications
- Suspected CSF leak (rhinorrhoea/otorrhoea) — localisation, often with nasal pledgets.
- Normal-pressure hydrocephalus — CSF flow dynamics.
- Ventriculoperitoneal shunt patency assessment (shuntogram).
How to read it
- Normal: tracer ascends over the convexities to the parasagittal region by ~24 h; any early (e.g. 4 h) ventricular entry is transient and gone by 24 h.
- NPH: ventricular reflux persisting at 24–48 h with absent or delayed convexity activity.
- Leak: tracer at the skull-base defect or on nasal/aural pledgets.
- Shuntogram: tracer flow through the shunt into the peritoneum confirms patency.
Protocol
- Sterile lumbar intrathecal injection of ¹¹¹In-DTPA (cisternography) or intra-shunt injection (shuntogram).
- Serial imaging over 24–72 h for cisternography; dynamic imaging for shunt studies.
- Place and count nasal/aural pledgets when a leak is suspected.
Pitfalls
- Invasive (lumbar puncture) with the usual risks.
- Intermittent leaks may be missed if inactive during imaging.
- Slower than CT/MR myelography, which are often first-line for leak localisation.
Evidence & guidelines
- Radionuclide cisternography remains useful for CSF-dynamics and shunt-patency questions.
- CT/MR cisternography/myelography are complementary for precise anatomical leak localisation.
Spotted an error or something out of date? Report an error