2: Intro to Neuroradiology

Question 1

List the normal gray and white matter structures of the brain that are demonstrable on head CT and MRI. (do not memorize! just know general stuff)

Answer 1

CT: bone, cranial swelling, ventricles, sulci

• -Acute intracranial blood
• -Fractures
• -Brain swelling & mass effect
• -Hydrocephalus

MRI: fine gray and white matter detail

• -Soft tissue subtleties: early swelling, white matter diseases (myelin disorders, scarring)
• -Cortical abnormalities
• -Blood
• -Edema
• -Swelling & mass effect
• -Tumor

Question 2

Describe the pathologic basis for, and appearance of white and gray matter edema on head CT and MRI.

Answer 2

CT: looks darker than parenchyma
–Diffuse edema: no differentiation of gray and white matter

MRI: looks whiter on T2

• -Gray matter edema on outside
• -White matter edema doesn’t touch cortex

Question 3

Describe the appearance of acute hemorrhage on head CT and MRI.

Answer 3

CT: looks white!

MRI: looks different on different sequences and with different ages of hemorrhage

Question 4

Compare and contrast the appearance of subdural vs. epidural vs. subarachnoid hemorrhage on head CT.

Answer 4

Epidural: white, like a bubble

Subdural: white, lens-shaped

Subarachnoid: white fills suprasellar cistern

Question 5

Discuss clinical situations in which IV contrast administration would be indicated or contraindicated when performing a head CT or when performing a brain MRI.

Answer 5

CT:

• -Indicated for cancer, meningiomas
• -CONTRAINDICATED in subarachnoid hemorrhage

MRI: (same as CT)

Question 6

Discuss which intracranial structures normally enhance (take up IV contrast) on contrast enhanced CT and MRI of the brain, and why they enhance.

Answer 6

CT: increases density of things with blood in them

• -Vessels
• -Meninges
• -Choroid plexus
• -Some related pathologies (cancer)

MRI: (same as CT)

Question 7

Explain why multiple pulse sequences are obtained when performing an MRI of the brain, instead of one acquisition as is done in CT.

Answer 7

Gives a more complete image

Can get T1, T2, and/or FLAIR to see different structures of interest

Question 8

Explain why certain structures are visible on an MRI of the brain that cannot be seen on CT. List three.

Answer 8

MRI has much better soft tissue contrast

1. Cortex abnormalities
2. White matter abnormalities
3. Acute infarcts

Question 9

Compare and contrast CT and MRI of the brain with respect to the length of image acquisition, cost, and risk to the patient.

Answer 9

CT:

• -Exposes patient to IR
• -Accessible, fast
• -$$
• -Better for bone

MRI:

• -No radiation
• -Slower
• -$$$$
• -Better soft tissue contrast