CT & MRI

Question 1

Axial

Answer 1

Top to bottom

Question 2

Sagittal

Answer 2

Side to side

Question 3

Coronal

Answer 3

Back to front

Question 4

CT windows

Answer 4

Brain, bone

Question 5

CT terminology

Answer 5

Hyper-, iso-, hypoDENSE

Question 6

MRI terminology

Answer 6

Hyper-, iso-, hypoINTENSE

Question 7

T1

Answer 7

Anatomical sequence

Hyperintense - Fat, melanin, subacute blood (metHb), high protein (colloid cyst)

Hypointense - CSF

Question 8

T2

Answer 8

Pathological sequence

Hyperintense - CSF, fat, acute blood (deoxyHb), haemosidrin, physiological iron, mucinous material

Hypointense - Bone, air, moving blood

Question 9

FLAIR

Answer 9

Fluid attenuated inversion recovery

Pathology hyperintense, fluids suppressed

Hyperintense - Infection, tumour, demyelination

Ix - MS

Question 10

STIR

Answer 10

Short tau inversion recovery

Fluids hyperintense, fat suppressed

Hyperintense - pathology

Ix - Discitis

Question 11

T2*

Answer 11

T2 star, gradient echo

Hyperintense - Blood products

Ix - Haemangioma

Question 12

DWI

Answer 12

Diffusion weighted imaging

Pathology hyperintense, water diffusion suppressed

Hyperintense - Low water diffusion (ischaemic infarction, lymphoma, abscess)

Ix - Ischaemic infarction, lymphoma, abscess vs tumour, epidermoid cysts vs arachnoid cysts

Restricted diffusion - hyperintense on DWI and hypointense on ADC (apparent diffusion coefficient)

Hyperintense rim on DWI - abscess, and some tumours. Differentiate by looking on SWI for double rim (abscess)

Epidermoid cysts - Restricted diffusion and T2 shine through (unlike arachnoid cysts)

Question 13

SWI

Answer 13

Susceptibility weighted imaging

Sensitive to compounds distorting the magnetic field

Hypointense - Deoxyhaemoglobin, ferritin, haemosiderin, calcium

Ix - SAH, venous congestion, cavernoma, abscess

Dual rim sign (outer hypointense rim with inner hyperintense rim) - abscess

Question 14

CISS

Answer 14

3D constructive interference in steady state

Image contrast determined by T2:T1 ratio.

Hyperintense - Water, fat

Ix - Hydrocephalus, structures surrounded by CSF e.g. CN, CSF rhinorrhoea, aqueduct stenosis, cavernous sinuses, ventricular system

Hydrocephalus: Request CISS and flow studies

Question 15

TOF

Answer 15

Time of flight

Accentuates contrast between flowing blood and stationary tissues

Hyperintense - Blood vessels

Ix - Blood vessels

Question 16

PC

Answer 16

Phase contrast

Fast moving hyperintense

Hyperintense - arteries (strongly hyperintense), veins (slightly hyperintense)

Ix - Dural venous sinus, CoW, carotid arteries