Neuroradiology

Question 1

what appears dark, bright, black and grey on the T1W MRI?

Answer 1

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

Question 2

what is the T1 MRI useful for?

Answer 2

1. borders b/w the brain and CSF (e.g. sulci, ventricles, cysts)
2. not very sensitive to lesions
3. pre-contrast images

Question 3

how to recognise a MRI?

Answer 3

• 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

Question 4

what are the uses of T1W images with Gd contrast?

Answer 4

useful for visualisation of:

1. normal vessels
2. vassalar changes
3. disruption of BBB

Question 5

how to recognise T1W with Gd?

Answer 5

like non-contrast T1 but with bright arteries and veins

Question 6

what appears dark, bright, black and grey on the T2W MRI?

Answer 6

bright: fluid - CSF, blood, edema and most lesions
dark: white and grey matter
black: air, calcium, dense bone, flow

Question 7

what are the uses of T2W MRI?

Answer 7

• brain anatomy (shows CSF spaces)
• most brain lesions
• cannot distinguish lesions from CSF (ventricles, sulci)

Question 8

how to recognise the T2W MRI?

Answer 8

• > CSF(ventricles, cisterns, sulci) - bright
• > Scalp - bright
• > eyes - bright
• > vessels - black (flow void)

Question 9

what is a FLAIR scan?

Answer 9

• fluid attenuated inversion recovery
• same as T2 except free CSF
• most pathology: bright

Question 10

what is the T2W useful for?

Answer 10

• same as T2
• most lesions
• especially good for lesions near ventricles or sulci (MS)
• improves gray/white distinction

Question 11

how to recognise a FLAIR?

Answer 11

• superficially resembles T1
• bright pathology
• often bright areas around ventricles

Question 12

what is DWI?

Answer 12

• 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

Question 13

what is an ADC map?

Answer 13

• apparent diffusion coefficient map

- areas of restricted diffusion are dark

Question 14

what is the difference between DWI and ADC?

Answer 14

areas of restricted diffusion
DWI - BRIGHT
ADC - DARK