Neuroradiology Flashcards
How can you tell the difference between a CT and an MRI scan
- MRI has a superior soft tissue anatomic resolution than CT
- The distinction between grey matter and white matter is much greater with T1 and T2 MRI than with CT
- The colour of the white matter on T1 MRI is lighter than grey matter. This relationship is opposite on CT
What are the indications of a CT
Trauma (fractures, haemorrhage) Stroke (initial evaluation) Hydrocephalus Mass effect/midline shift Detect calcification
What are the features of a T1 MRI
CSF = dark WM = white GM = grey Vessels = dark
What are the features of a T1 MRI with contrast
CSF = dark WM = white GM = grey vessels = bright
What is a T1 with contrast useful for
Evaluating blood brain barrier breakdown in the setting of a tumour, infection, MS etc.
What are the features of a T2 MRI
CSF = bright WM = grey GM = lighter than white matter Vessels = dark
What is a FLAIR image useful for
Evaluating areas of edema with CSF subtraction, stands out because CSF is dark
What are the features of a FLAIR image
CSF = dark WM = grey GM = lighter than WM vessels = dark
What are the features of diffusion-weighted imaging
CSF = dark
WM = grey
GM = lighter than WM
Fuzzier than FLAIR
What is DWI useful for
Stroke imaging, abscess and cellular tumours
Why would you need to use apparent diffusion coefficient
Because DWI remains sensitive to T1 and T2 relaxation, it is difficult to tell if a lesion is old or acute
What happens in ADC
restriction of diffusion goes black
use DWI and ADC together and if one is white and one is black then this is an acute stroke
What may the bright white region on a DWI scan be?
The T2 element shining through
What is MR angiography used for
imaging blood vessels
What does perfusion MRI show
The transit time of blood to a location, the flow of blood to a location and the blood volume
