Imaging of Neuro system

Question 1

Which of the following is correct?
• Gadolinium is an iodinated contrast used in MRI
• Vasogenic edema migrates along the grey matter more readily
• Necrotic lesions can always be identified on an MRI with a contrast ring effect
• Images obtained immediately after IV admin of contrast can be used to evaluate vasculature, and a delay of a few minutes to evaluate distribution.

Answer 1

D is correct

gadoliunium chelates Gd-DTPA and is a paramagnetic substance
white matter: vasogenic edema
(contrast enhancement can also be found within the necrotic lesion, don’t depend on it for necrotic lesions)

Question 2

Which of the following is important for MRI image quality?
•	Magnetic field and gradient strength
•	Number of excitations
•	Matrix size
•	Slice thickness
•	All of the above

Answer 2

All of the above

plus field of view

Question 3

What are 2 other names for the interarcuate ligament?

Answer 3

yellow ligament

ligamentum flavum

Question 4

Where does the dural sac end in dogs? Cats?

Answer 4

Dog L6/7
(conus medularis may extend to L7-S1 in small dogs)
Cat as far as first sacral segment

Question 5

what metal can cause streaking artifact on CT, but is ok on MRI?

Answer 5

Lead:

a non-ferromagnetic metal is relatively small on MR, but large streaking artifact on CT

Question 6

What is the hounsfield unit measurement for fat versus water versus air?

Answer 6

Fat = -100
water = 0
air = -1000
Brain = 30-40 white matter slightly lower to grey matter

Question 7

Hemorrhage, mineral and metal are ___attenuating on CT?

Answer 7

HYPERattenuating

Question 8

T/F: Short repetition time (TR) accentuated T1 and Long echo time (TE) maximize T2 contrast for MRI

Answer 8

true

Question 9

How do you suppress fluid or fat in an MRI?

Answer 9

INversion recovery (T1 flair, T2 Flair, STIR)
STIR --> suppression of fat

Question 10

At what age does the grey and white signal intensity reverse?

Answer 10

16 weeks

myelination of white matter progresses

Question 11

What are 3 forms of edema in the brain?

Answer 11

Vasogenic
cytotoxic
interstitial

Question 12

What is the concentration of iohexal aka omnipaque?

Answer 12

240 mgI/mL

nonionic contrast media

Question 13

What is another name for rhombencephalon? What 3 parts does it contain?

Answer 13

hindbrain = an anatomic division
Metencephalon = pons
cerebellum
myelencephalon = medulla oblongata

Question 14

What structures are in the Diencephalon? (2)

Answer 14

hypothalamu

thalamus

Question 15

What do the 3 pairs of peduncles do?

Answer 15

Connects the white matter of the arbor vitae to the brainstem
rostral = efferent + afferent
middle = afferent only
caudal = efferent + afferent

Question 16

what is the tentorium cerebelli?

Answer 16

separation between cerebral hemispheres and cerebellum (with ossous tentorium)

Question 17

Which cranial nerves pass through the orbital fissure?

Answer 17

III oculomotor
IV trochlear
V ophthalmic br trigeminal
VI abducens

Question 18

Where do cranial nerves IX-XI exit?

Answer 18

tympano-occipital fissure

Question 19

Where does the facial nerve enter skull and exit?

Answer 19

internal acoustic meatus

stylomastoid foramen

Question 20

True or false? The maxillary branch of the trigeminal leaves through the round foramen, and the mandibular branch through the oval foramen?

Answer 20

true

Question 21

Where is the epidural space?

Answer 21

between the dura matter and ligamentum flavum

Question 22

What % are relevant in the Monroe-kellie doctrine?

Answer 22

Brain = 80-85%
CSF = 7-10%
Cerebral blood volume = 5-8%

Question 23

how do you calculate cerebral perfusion pressure?

Answer 23

MAP - ICP(mean)

Question 24

how do you calculate cerebral blood flow?

Answer 24

CPP/CVR
cerebral perfusion pressure
cerebral vascular resistance

Question 25

What may be damaged if there is generalized hyperesthesia? localized hyperesthesia?

Answer 25

thalamus

usually focal to where the lesion is

Question 26

What structure is abnormal in osseous cervical spondylomyelopathy?

Answer 26

stenotic vertebral foramina (static)
“Giant breeds usually have severe vertebral foramen stenosis secondary to proliferation of the laminae (dorsally), articular processes (dorsolaterally), or articular processes and pedicles (laterally)”
“cause of compression appears to be a combination of vertebral malformation and osteoarthritic changes at the level of the zygapophyseal joint”

Question 27

what 3 factors contribute to Doberman CSM?

Answer 27

“vertebral canal stenosis, pronounced TORSION of the caudal cervical intervertebral column leading to intervertebral disc degeneration, and protrusion of larger volume intervertebral discs”

Question 28

What is the ligament seen in a cervical ventral slot?

Answer 28

dorsal longitudinal ligament

Question 29

what and where is myelography?

Answer 29

Myelography: contrast study of the subarachnoid space
Injection of water-soluble, non-ionic contrast medium
Invasive and noxious procedure
Adverse effects= bradycardia, tachycardia, seizures, cardiac arrest

Question 30

What is spina bifida? consequences?

Answer 30

Failure of the laminae to fuse dorsally +/-
concomitant neural tube malformation**,
especially meningocele (meninges herniated through the bony defect)
or meningomyelocele (meninges and spinal cord herniated through the bony defect)
Manx cats and screwtail breeds, may be close to open to environment

Question 31

True/false? Pilonidal sinus (dermoid sinus) refers to a congenital condition wherein the skin fails to completely separate from the neural tube during embryonic development

Answer 31

true

Question 32

Which of the following are congential spinal neurologic disorders?

a. Spina bifida
b. Hemivertebrae
c. Subarachnoid diverticula
d. Dysraphism
e. all of the above

Answer 32

E all of the above
Subarachnoid diverticula can also be traumatic/acquired, but congenital more common
dysraphism in Weimarners leads to bunny hopping, not progressive or painful