CT cisternography

Computed tomography (CT) cisternography is a minimally invasive-invasive imaging technique used to visualise the intracranial CSF cisterns using iodinated contrast medium injected into the subarachnoid space.

Indications

• detect and localise active CSF leaks through the skull base (CSF rhinorrhoea or CSF otorrhoea)
• evaluate intracranial arachnoid cysts for communication with surrounding subarachnoid space
• plan neurosurgery or radiotherapy, especially when MRI is not possible

Contraindications

• hypersensitivityadverse reaction to iodinated contrast media
• severe coagulopathy or thrombocytopenia
• generalised septicaemiasepsis or localised infection at the lumbar puncture site
• compartmentalized increased intracranial pressure
• pregnancy
• recent myelography within previous 1 week

Procedure

Preprocedural evaluation

• obtain medical history relating to medications, allergies, seizures, and bleeding
• review any available spinal imaging
• consider holding medications that decrease seizure threshold
• consider holding anticoagulant/antiplatelet and antiplatelet therapy
• obtain informed consent relating to the risk, benefits, and alternatives of the procedures
• evaluate need for moderate sedation or general anaesthesia
• consider obtaining a noncontrastnon-contrast head CT

Equipment

• standard equipment for fluoroscopy-guided lumbar puncture
• tilt table with device to secure the patient
• contrast media approved for intrathecal use
• 10 mL syringe and needle
• CT scanner

Technique

• fluoroscopy guided lumbar puncture is performed
• optionally, opening pressure can be measured or CSF samples collected
• 3-10 mL of an iodinated non-ionic low-osmolar contrast agent is slowly instilled into the thecal sac under intermittent fluoroscopy
• the spinal needle is withdrawn
• the patient is tilted with foot-end elevation (Trendelenburg position) and intermittently imaged until the contrast column flows into the cervical spinal canal
• the table is returned to horizontal position and the head is flexed into neutral position under imaging to document flow of contrast into the basal cisterns
• CT scan is performed immediately in prone and/or supine positions; concurrent manoeuvres that provoke an active CSF leak, such as head hanging or sneezing, can also be performed

Complications

• headache (common)
• radicular pain or paraesthesia (transient)
• bleeding
• infection
• seizure