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Neuroradiology

Imaging modalities
Where is the lesion?

Imaging Modalities

There is a tendency these days to do shotgun imaging, but this results in a lot of false positives. It is much better to let differential diagnosis, based on history, physical examination, and basic lab tests, guide your imaging investigations.

Use the modality that will rule in or out the suspected disease

plain films
CT scan
ultrasound
angiography
MRI
PET

plain films

the traditional opening modality

fast, cheap, and accessible
can be used in acute spine trauma because it can be wheeled into the room
- be sure to look down all the way to C7/T1
also good for skull fractures

five basic X-ray densities: air, fat, water, bone, metal

CT scan

shows scalp, skull, brain
good for non-specifici neurological compliants
useful for assessment of acute trauma, stroke, intracranial damage
rules out and follows space-occupying lesions

contrast material

useful for highlighting areas that blood pools, ie tumour
don't use if you're looking for fresh blood, as it will obscure
nephrotoxic, and some risk of allergic reaction

risks

significant radiation exposure
risks associated with contrast enhancement
' a single CT scan on a newborn girl has a 1:800 chance of causing a fatal cancer' - Nature editorial

ultrasound

of limited use in the brain due to the skull.

can be used in infants (with their softer skulls) or also on the carotid to look for stenosis (with doppler

angiography

excellent resultion of small vessels, including dynamic flow
good for characterizing vascular problems such as aneurysms, AVM
best for picking up cerebral vasculitis
good for endovascular therapy