Neuroradiology Flashcards
what appears dark, bright, black and grey on the T1W MRI?
Dark: Fluid - CSF, Edema, most lesions
Bright: Fat - Blood (metGb), gadolinium (Gd,contrast)
Black: no water or fat protons: air, calcium, dense bone
Grey: gray and white matter
what is the T1 MRI useful for?
- borders b/w the brain and CSF (e.g. sulci, ventricles, cysts)
- not very sensitive to lesions
- pre-contrast images
how to recognise a MRI?
- repeated multiple orientations
- looks like CT
> ventricles: dark
> scalp: bright - orbits(tracts attaching the eye socket to optic nerves): bright, globes(eye socket): black
- vessels normally not seen
what are the uses of T1W images with Gd contrast?
useful for visualisation of:
- normal vessels
- vassalar changes
- disruption of BBB
how to recognise T1W with Gd?
like non-contrast T1 but with bright arteries and veins
what appears dark, bright, black and grey on the T2W MRI?
bright: fluid - CSF, blood, edema and most lesions
dark: white and grey matter
black: air, calcium, dense bone, flow
what are the uses of T2W MRI?
- brain anatomy (shows CSF spaces)
- most brain lesions
- cannot distinguish lesions from CSF (ventricles, sulci)
how to recognise the T2W MRI?
- > CSF(ventricles, cisterns, sulci) - bright
- > Scalp - bright
- > eyes - bright
- > vessels - black (flow void)
what is a FLAIR scan?
- fluid attenuated inversion recovery
- same as T2 except free CSF
- most pathology: bright
what is the T2W useful for?
- same as T2
- most lesions
- especially good for lesions near ventricles or sulci (MS)
- improves gray/white distinction
how to recognise a FLAIR?
- superficially resembles T1
- bright pathology
- often bright areas around ventricles
what is DWI?
- diffusion weighted imaging
- sensitive to passive diffusion of water
- areas of restricted diffusion - BRIGHT
- restricted diffusion occurs in cytotoxic edema: ischemia (within mins), seizures, abscess, tumours, vascogenic edema
what is an ADC map?
- apparent diffusion coefficient map
- areas of restricted diffusion are dark
what is the difference between DWI and ADC?
areas of restricted diffusion
DWI - BRIGHT
ADC - DARK