Lec 22: Neuroimaging of the Brain and Skull

Question 1

The golden period for stroke patients.

Answer 1

3-4 hours

Question 2

True or False: In CT, gray matter is whiter than white matter.

Answer 2

TRUE.

Question 3

The following changes can indicate an ischemic stroke, EXCEPT:

a. Poor definition of gray-white matter interface
b. Obscuration of lentiform nucleus
c. Effacement of sulci because of edema
d. Presence of hyperattenuating/hyperdense arteries.
e. NOTA

Answer 3

e. NOTA

The other choices are subtle changes that occur when there’s a blockage in certain areas.

• Poor definition of gray and white matter can be an indication of an hyperacute infarct.
• Hyperdense arteries can indicate the presence of a thrombus, calcifications or slow flow of blood.

Question 4

The primary modality of choice in acute trauma to the brain and spine, suspected subarachnoid hemorrhage and conductive hearing loss.

Answer 4

CT Scan

Question 5

TRUE or FALSE: For early hemorrhages, CT is more accurate than MRI.

Answer 5

TRUE. It takes 6-12 hours before an MRI can detect hemorrhage

Question 6

TRUE or FALSE: Conventional MRI is more sensitive and specific than CT for detection of cerebral ischemia during the first few hours after symptom onset.

Answer 6

TRUE. But after 12 hours, specificity and sensitivity are equal.

Question 7

Imaging modality of choice for acute stroke.

Answer 7

MRI

Question 8

You see that the cerebrospinal fluid is white within the ventricles. The imaging modality used was:

a. T1-weighted MRI
b. T2-weighted MRI
c. either
d. neither

Answer 8

b. T2-weighted MRI

Pnemonic: WW2 - “Water is White in T2”

Question 9

A very sensitive imaging modality for acute and hyperacute stroke which can enable differentiation between various differentials and can see the infarct better than a T2-weighted MRI.

Answer 9

Diffusion Weighted Imaging

Question 10

Can be paired with Diffusion Weighted Imaging to further classify infarcts into acute, subacute or chronic.

Answer 10

Attenuated Diffusion Coefficient (ADC) Map

• A hypointense (dark area} represents a hyperacute infarct. Lighter ones means more chronic

Question 11

Used for the detection of hemorrhage/ bleed and produces images with clear areas of hypo/hyper intensity and measurable size.

Answer 11

Gradient Recalled Echo Image

Question 12

What imaging modality should you request that can visualize infarcted areas the best?

Answer 12

Diffusion Weighted Imaging

Question 13

TRUE or FALSE: If suspecting a new stroke, MRI should be used.

Answer 13

TRUE. MRI is better than CT at identifying acute ischemic changes. After 12 hours, you can request for a CT scan instead because the sensitivity becomes similar to when using MRI and 3-4x cheaper.

Question 14

An area of markedly reduced perfusion with loss of function of still viable (salvageable) neurons

Answer 14

Penumbra

Question 15

An imaging modality used for evaluation of blood flow to a specific region of the brain.

Answer 15

Perfusion Imaging

Question 16

Therapeutic window for reperfusion of brain tissue.

Answer 16

3-6 hours.

*can be increased up to 10 hours if vampire bat venom (anticoagulant) is given.

Question 17

TRUE or FALSE: A hypoperfused area of the brain can still be salvaged if there is a matched diffusion-perfusion.

Answer 17

FALSE. The bigger the MISMATCH, the greater the chance that the hypoperfused area of the brain can still be salvaged.

*If the DWI showed a relatively smaller infarct compared to the hypoperfused area in the perfusion imaging, it has a higher chance to be salvaged.

Question 18

Beyond this size, the aneurysm is considered to be HIGH RISK.

Answer 18

> 10mm

Question 19

TRUE or FALSE: Subdural hemorrhage may cross suture lines, dural attachments and tentorial reflections.

Answer 19

FALSE. Subdural hemorrhage can cross suture lines only, not dural attachments or tentorial reflections.

Question 20

The most sensitive modality for subdural hemorrhage.

Answer 20

FLAIR T2

*Fluid-Attenuated Inversion Recovery

Question 21

TRUE or FALSE: FLAIR images are more sensitive than standard spine echo images for the detection of lesions within or adjacent to CSF.

Answer 21

TRUE.

Question 22

Most common cause of subarachnoid hemorrhage aside from trauma.

Answer 22

berry aneurysms

Question 23

Gray-white matter interface is no longer discernible

a. Diffuse axonal injury
b. Cerebral contusion
c. Arachnoid cyst
d. Lymphoma

Answer 23

a. Diffuse axonal injury

Question 24

Diffuse axonal injury tends to occur in these fundamental anatomic areas, EXCEPT:

a. lobar white matter
b. corpus callosum
c. dorsolateral aspect of brainstem
d. subarachnoid space

Answer 24

d. subarachnoid space

Question 25

TRUE or FALSE: For Glioblastoma multiforme, the more heterogeneous-looking the tumor is, the better the prognosis.

Answer 25

FALE. If more hetergeneous-looking, worse prognosis.

Question 26

Pathognomonic of a meningioma

Answer 26

dural tail

Question 27

Anteroposterior elongation of the cranium. a. brachycephaly b. scaphocephaly c. plagiocephaly d. turricephaly

Answer 27

b. scaphocephaly (sagittal synostosis) - brachycephaly - diminished anteroposterior skull - plagiocephaly - sutural assymetry, right-sided harlequin eye - turricephaly - fusion of multiple sutures, weirdly shaped head

Question 28

TRUE or FALSE: A cyclops baby can live if the holoprosencephaly is lobar.

Answer 28

TRUE.

Question 29

A condition wherein the brain has no sulci and the patient can be severely mentally retarded.

Answer 29

Lissencephaly