Neuroimaging (Part 1)

Question 1

What is the definition of a Cerebral Angiography?

Answer 1

X-ray representation of blood vessels with contrast medium applied through a catheter

Question 2

What are the uses of Cerebral Angiography?

Answer 2

– Vascular malformations: Angioma (vascular tumor), aneurysm
– Vascular obstructions, stenosis

Question 3

Native X-ray diagnostics ______ show pathologies of the brain and spinal cord.

Answer 3

indirectly

Question 4

Digital Subtraction angiography aids in the imaging of what?

Answer 4

Blood Vessels

Question 5

What is examined in Myelography?

Answer 5

spinal cord, nerve roots and the subarachnoid space are examined

Question 6

What do myelographies reveal?

Answer 6

herniated (slipped) intervertebral disks and spinal tumors.

Question 7

What can be indicated through CT scans

Answer 7

• Infarctions and intracranial hemorrhages are readily detected by CT.

(The procedure is initially performed without contrast agents, because contrast may resemble a bleed. A normal CT generally does not show an infarction in the acute stage but is commonly performed to exclude a hemorrhage.)

Question 8

In general, how do MRI’s work?

Answer 8

-the magnetic properties of hydrogen protons are utilized to create horizontal, sagittal, and coronal ‘slices’ of the head and body.

Question 9

Describe a T1 weighted MRI?

Answer 9

-yields images with black CSF and good differentiation of grey and white matter

Question 10

Where are the signal intense protons in a T1 weighted image?

Answer 10

Fatty tissue

Question 11

Where are the signal intense protons in a T2 weighted MRI?

Answer 11

watery tissue

Question 12

T2 weighted MRI reveals what sort of image?

Answer 12

yields images with white CSF.

Question 13

Magnetic resonance angiography (MRA) is used to produce pictures of what?

Answer 13

the arteries, in order to diagnose stenosis or aneurysms

Question 14

What is the paramagnetic contrast medium used in magnetic resonance angiography?

Answer 14

Gadolinium

Question 15

What is measured in a functional MRI?

Answer 15

-different magnetic properties of oxyhemoglobin and deoxyhemoglobin are measured.

Question 16

What is administered in Positron Emission Tomography (PET)

Answer 16

18F-deoxyglucose

Question 17

How does a PET scan show the metabolically active areas of a brain?

Answer 17

• Neurons take up but do not metabolize 18F-deoxyglucose.
• Consequently, 18F-deoxyglucose accumulates in more active neurons.
• Metabolically active neurons therefore emit higher numbers of positrons.
• The emitted positrons eventually collide with electrons, producing a pair of photons (gamma-rays) that move in opposite directions.
• The events are detected and counted by scintillation material in the scanning device. The data generate an image that shows the metabolically active areas of the brain.

Question 18

What is SPECT (Single Photon Emission Computed Tomography). Describe it.

Answer 18

• patient receives an intravenous gamma-ray-emitting radiotracer, usually 99mTc or 123I.
• Tissues with higher perfusion accumulate more of the radiotracer, leading to locally higher gamma-ray emission.
• A gamma camera, rotating around the patient measures the gamma-activity and hence perfusion.
• The data are digitally stored to allow transformation into images.

Question 19

What is SPECT used for?

Answer 19

May be helpful in determining cerebral blood flow.