Lab 7

Question 1

Of the following structures found in a normal brain, which has the highest CT number?

CSF
White matter
Grey matter
All the above have the same CT number in a normal head

Answer 1

Grey matter

Question 2

Acutely clotted blood has a CT number of approximately what?

Answer 2

80 HU

Question 3

T/F

Given the small range of densities present within the normal brain tissue, a wide window width setting is appropriate.

Answer 3

False

Question 4

T/F

Hyperacute blood has a higher density than acute clotted blood.

Answer 4

False

Question 5

T/F

A subacute bleed has similar density to that of normal brain parenchyma.

Answer 5

True

Question 6

List 2 signs that are indicative of an acute ischemic stroke in a non-contrast CT head.

Answer 6

Hyperdense vessel sign (earliest CT sign)
Loss of gray white differentiation

Question 7

T/F

Infarcted brain tissue decreases in density over time

Answer 7

True

Question 8

Negative mass effect is associated with what?

Answer 8

Chronic stroke

Question 9

T/F

In the evolution of a stroke, mass effect occurs prior to a negative mass effect.

Answer 9

True

Question 10

T/F

The density of infarcted tissue in a chronic stroke is similar to that of CSF.

Answer 10

True

Question 11

List 2 signs that are indicative of mass effect in brain tissue on a non-contrast CT head

Answer 11

Sulcal effacement and midline shift

Question 12

Explain why a standard brain window (WL = 30 HU, WW = 70 HU) may not be suitable to diagnose acute subdural hematoma.

Answer 12

Using a standard brain window, it allows you to look for large masses and structures within the CSF. With a standard brain window, anything above 65 HU will appear completely white. This is not appropriate for a subdural hematoma since as HU of clotted blood is around 80. This would mean that both bone and a subdural hematoma have the same HU, thus making it very difficult to evaluate if there is blood layering the wall of the of the skull bone. Using a standard brain window is not suitable to diagnose for an acute subdural hematoma.

Question 13

what solution allows for the visualization of acute subdural hematoma and adjacent bone?

Answer 13

The solution for visualization of an acute subdural hematoma is using a blood window.

Question 14

T/F

A stroke window that enhances the visualization of grey-white matter differentiation requires a narrower window width than a standard brain window.

Answer 14

True

Question 15

Which of the following is NOT a part of a multiphasic CT evaluation of acute stroke?
a. Non-contrast CT head
b. CTA (arch to vertex)
c. CTP
d. CTV

Answer 15

D

Question 16

Which of the following vessels is typically designated as the Arterial Input Function (AIF) during CTP post-processing?
a. Internal carotid artery
b. Middle cerebral artery
c. Vertebral artery
d. Anterior cerebral artery

Answer 16

D

Question 17

Which of the following structures is typically designated as the Venous Outflow Function (VOF) during CTP post-processing?
a. Inferior sagittal sinus
b. Superior sagittal sinus
c. Confluence of sinuses
d. Internal jugular vein

Answer 17

B

Question 18

Which of the following is an absolute contraindication to thrombolytic therapy?

a. Acute ICH
b. Middle cerebral artery thrombus
c. Diabetes
d. Anterior cerebral artery aneurysm

Answer 18

A

Question 19

What is the primary purpose of performing a CTP study of the brain in an acute stroke setting?

Answer 19

The purpose of CTP is to access the regional perfusion and to find where the core and where the penumbra is located.

Question 20

What area of the brain must be included in a CTP to ensure the evaluation of areas perfused by the arterial branches of the Circle of Willis?

Answer 20

The area that needs to be included for CTP is from the basal ganglia to cover all anatomy that the circle would feed and include territories supplied by the anterior middle and posterior cerebral arteries