L4 Neuroimaging

Question 1

X-ray - characteristics

Answer 1

• lateral and frontal views
• unabsorbed x-rays hit a detector
• high density tissues = white — bone
• low density tissues (nervous system) are not well seen
• nervous pathology is revealed indirectly - calcium deposits

Question 2

X-ray - Advantages vs. Disadvantages

Answer 2

Advantages

• cheap
• commonly available
• sensitive to skill fracture and dense foreign matter

Disadvantages

• exposure to ionizing radiation
• can’t really see structure of the brain

Question 3

Describe pneumoencephalography

Answer 3

• see lateral ventricles

- CSF was replaced with air - very risky and invasive

Question 4

Define Cerebral Angiography (Vasography)

Answer 4

x-ray reabsorption of blood vessels with contrast medium applied through catheter

Question 5

what are the risks and indictations with cerebral angiography (vasography)

Answer 5

risks

• allergic reaction
• arterial spasm–> cerebral infarction

Indictations

• vascular malformation - angioma, aneurysm
• vascular obstruction, stenosis

Question 6

Describe the digital subtraction angiography

Answer 6

native x-ray is taken followed by conventional angiograph. The angiograph is digitally substracts from the native x-ray = dark imagine of hte vessels with attenuation of dark structures - bone

Question 7

Describe myelography

Answer 7

contrast agent via lumbar puncture

irregularities in subarachnoid space may reveal tumor or disk abnormalities

MRI is better

Question 8

Describe CT

Answer 8

can differentiate bone, white matter, grey matter and fresh blood - structural advantage over x-ray

can rule out epi or subdural hemorrhage

Question 9

what does a epidural hemorrhage look it

Answer 9

lemon

Question 10

what does a subdural hemorrhage look like

Answer 10

banana

Question 11

what does a subarachnoid hemorrhage look like

Answer 11

blood goes into the cracks of the brain

Question 12

what does T1 show in MRI

Answer 12

fatty tissue - ventricles are black because its water

good at differentiating white from grey matter

can see infarctions

Question 13

what does T2 show in MRI

Answer 13

watery tissue - eye balls white and white ventricles

good for showing edema

weak differentiation between white and grey matter

Question 14

what does T1 with contrast show?

Answer 14

use paramagnetic gadolinium - shows perforations in BBB maybe in those surrounding tumors

Question 15

what does a T2 weight MRI show?

Answer 15

sensitive to pathology
-MS, AIDS, abcess

a specialized MRI called FLAIRE may better reveal lesions from MS than a standard T2 weighted scan

Question 16

what are the advantages and disadvantages of MRI?

Answer 16

advantages

• excellent structural res.
• sensitive to edema
• no ionizing radiation
• common and accessible

disadvantages

• more expensive than CT
• cannot be used with paramagnetic metals in body - pace makers etc.

Question 17

Describe an MR angiography

Answer 17

contrast agent (gadolinium) is intro to vascular system to reveal normal and abnormal blood vessels - stenosis or aneurysm

Question 18

Positron Emission Tomography (PET)

Answer 18

evaluation of the distribution of radioactive isotopes by a computational method (like CT,MRI) to show metabolism in the brain!

Question 19

disadvantages and indications of PET

Answer 19

disadvantages
-a cyclotron is needed to make radio tracers (short half life) used in PET

indications

• epileptogenic focus
• brain atrophy
• parkinson disease

Question 20

Describe Single Photon Emission Computerized Tomography (SPECT)

Answer 20

evaluation fo the distribution of radioactive isotopes by a computation method (like CT,MRI) to show perfusion in the brain

get info on cerebral blood flow