46 Brain imaging

Question 1

If the brain parenchyma is isodense, the CSF is ______________ in CT.

Answer 1

hypotense (dark)

Question 2

If the brain parenchyma is isodense, the skull is ______________ in CT.

Answer 2

hyperdense

bright

Question 3

How to differentiate white and gray matter in CT?

Answer 3

white matter looks dark and gray matter looks bright.

Question 4

Why is there a need to insert contrast in CT angiogram and venogram?

Answer 4

Blood vessels appears to be isodense without contrast and become hyper dense with contrast.

Question 5

Trauma can be easily identified in CT, what can be observed?

Answer 5

Hyperdense blood (haemorrhage)

Question 6

How will stroke infract appears to be in CT?

Answer 6

Infarct is hypotenuse (dark)

due to obstruction of the artery> no blood supply > edema > swollen

Question 7

MRI descriptions are made in terms of?

Answer 7

signal intensity:

isointense, hyperintense, hypointense

Question 8

What colour does it different intensities appear?

Answer 8

depends on sequence (T1/T2)

Question 9

In T1 sequence, gray matter appears to be _____________ and white matter appears to be ___________.

Answer 9

Hypointense;

Hyperintense

Question 10

In MRA/MRV, it only picks up moving blood. Is contrast needed?

Answer 10

no

Question 11

Use of MRI especially in tumors?

Answer 11

Excellent location (in/ outside of the brain parenchyma) which CT cannot provide

Question 12

General rule of use of CT and MRI?

Answer 12

CT: Trauma and stroke
MRI: tumour