CT Head — Other Acute Indications
CTVaries
EDInpatient
All imaging requests must be justified by an IR(ME)R practitioner (radiologist or radiographer)Subarachnoid haemorrhage (SAH)
— ANY of the following
- Thunderclap headache or features suggesting SAH
- CT sensitivity near 100% within 6 hoursNICE NG228
- If CT negative within 6 hours: do NOT routinely offer LPNICE NG228 Rec 1.1.8
- If CT negative >6 hours: consider LP ≥12 hours after onsetNICE NG228 Rec 1.1.9
- If SAH confirmed: CTA immediatelyNICE NG228 Rec 1.1.12
Raised intracranial pressure (ICP)
— ANY of the following
- CT to exclude raised ICP before LP
Space-occupying lesion (SOL)
— ANY of the following
- CT as initial investigation; MRI preferred for characterisation
Meningitis
— ANY of the following
- CT only to exclude raised ICP before LP — do NOT delay LP for CT if no clinical features of raised ICP
Cerebral venous sinus thrombosis (CVST)
— ANY of the following
- CT with CT venography if MRI/MRV unavailable
- MRI with MRV preferred
Notes
Information
CT sensitivity for SAH near 100% within 6 hours
NICE NG228Information
If CT negative within 6 hours, LP not required
NICE NG228Information
CTA if SAH confirmed on NCCT
Local preference
MRI with MRV preferred over CT for CVST
Radiation Dose
CT head ~2 mSv
Modality Preference
CT preferred. CT is first-line for acute indications; MRI preferred for CVST and tumour characterisation
Source: NICE NG228; NG99
Change Log
v1.02026-03-05Initial publication
v2.02026-03-08CVST section added. Meningitis LP guidance clarified. NG228 SAH LP criteria confirmed.