MRI Brain — with gadolinium
As for the routine brain study, with the enhanced series matched in plane and thickness to the unenhanced T1.
Typical, not policy
Timings, volumes and delays here are representative values drawn from published guidance. Scanner generation, injector, cardiac output and local preference all move them. Confirm against your department's own protocol before you rely on a number.
When to use it
- Suspected intracranial infection, including abscess, meningitis with complications and encephalitis.
- Suspected leptomeningeal or dural disease, including drop metastases and hypertrophic pachymeningitis.
- Characterisation of an abnormality found on an unenhanced study.
- Suspected or known intracranial metastatic disease outside a dedicated tumour follow-up protocol.
- Suspected intracranial hypotension, where dural enhancement is a core sign.
Technique
- Unenhanced T1 must be acquired in the same plane and geometry as the post-contrast T1, otherwise subtle enhancement cannot be distinguished from intrinsic T1 shortening.
- 3D T1 gradient-echo post-contrast improves small-lesion detection and allows reformatting; 2D spin-echo T1 gives better grey-white contrast for some questions and centres differ on which is standard.
- Fat saturation on post-contrast T1 helps for skull base, orbital and scalp disease but costs signal and is sensitive to field inhomogeneity.
Where it goes wrong
- No matched pre-contrast T1: subacute blood, melanin, fat and mineralisation all mimic enhancement.
- Imaging immediately after injection, which under-calls leptomeningeal and small metastatic enhancement.
- Repeating gadolinium at every follow-up when the target lesion never enhanced in the first place.
- Fat saturation failure at the skull base creating spurious signal that is read as enhancement.
Clinical questions that reach this study
Known or suspected lung cancer — stagingSuspected acute ischaemic strokeSuspected intracranial haemorrhage (non-traumatic)Suspected subarachnoid haemorrhageFirst unprovoked seizureDrug-resistant epilepsy — pre-surgical assessmentSuspected brain metastasesSuspected primary brain tumourSuspected multiple sclerosis or first demyelinating eventSuspected meningitis or encephalitisHeadache with red flag featuresHeadache without red flags (migraine, tension-type, chronic stable)Suspected normal pressure hydrocephalusCognitive impairment or suspected dementiaHead injury in childrenSuspected inflammatory spinal cord lesion (transverse myelitis)Chronic rhinosinusitis and pre-operative sinus CTSuspected physical abuse in a child — skeletal survey
Contrast
Gadolinium, intravenous
A macrocyclic gadolinium-based agent at a typical single dose of about 0.1 mmol/kg, followed by a saline flush. Confirm agent, dose and injection rate against the local formulary.
- Post-contrast T1 imaging is usually acquired a few minutes after injection; a short delay improves conspicuity of leptomeningeal and small parenchymal enhancement.
Acquisition
- Breathing
- Free breathing.
- Preparation
- No fasting or bowel preparation for an unenhanced brain study. Establish whether gadolinium is actually needed before booking an IV slot — most brain questions do not require it. Young children and patients unable to keep still for 20-30 minutes need a sedation or general anaesthetic pathway agreed in advance.
Safety checks this protocol carries
Derived from the contrast agent and phases above, not authored here — which is why they cannot drift apart from what the protocol actually does.
- MR safety screening for implants and foreign bodies· radiographer at scan
- Sedation or anaesthesia for a child· nurse pre scan