Imaging of Neuro system Flashcards
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.
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)
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
All of the above
plus field of view
What are 2 other names for the interarcuate ligament?
yellow ligament
ligamentum flavum
Where does the dural sac end in dogs? Cats?
Dog L6/7
(conus medularis may extend to L7-S1 in small dogs)
Cat as far as first sacral segment
what metal can cause streaking artifact on CT, but is ok on MRI?
Lead:
a non-ferromagnetic metal is relatively small on MR, but large streaking artifact on CT
What is the hounsfield unit measurement for fat versus water versus air?
Fat = -100 water = 0 air = -1000 Brain = 30-40 white matter slightly lower to grey matter
Hemorrhage, mineral and metal are ___attenuating on CT?
HYPERattenuating
T/F: Short repetition time (TR) accentuated T1 and Long echo time (TE) maximize T2 contrast for MRI
true
How do you suppress fluid or fat in an MRI?
INversion recovery (T1 flair, T2 Flair, STIR) STIR --> suppression of fat
At what age does the grey and white signal intensity reverse?
16 weeks
myelination of white matter progresses
What are 3 forms of edema in the brain?
Vasogenic
cytotoxic
interstitial
What is the concentration of iohexal aka omnipaque?
240 mgI/mL
nonionic contrast media
What is another name for rhombencephalon? What 3 parts does it contain?
hindbrain = an anatomic division
Metencephalon = pons
cerebellum
myelencephalon = medulla oblongata
What structures are in the Diencephalon? (2)
hypothalamu
thalamus
What do the 3 pairs of peduncles do?
Connects the white matter of the arbor vitae to the brainstem
rostral = efferent + afferent
middle = afferent only
caudal = efferent + afferent
what is the tentorium cerebelli?
separation between cerebral hemispheres and cerebellum (with ossous tentorium)
Which cranial nerves pass through the orbital fissure?
III oculomotor
IV trochlear
V ophthalmic br trigeminal
VI abducens
Where do cranial nerves IX-XI exit?
tympano-occipital fissure
Where does the facial nerve enter skull and exit?
internal acoustic meatus
stylomastoid foramen
True or false? The maxillary branch of the trigeminal leaves through the round foramen, and the mandibular branch through the oval foramen?
true
Where is the epidural space?
between the dura matter and ligamentum flavum
What % are relevant in the Monroe-kellie doctrine?
Brain = 80-85%
CSF = 7-10%
Cerebral blood volume = 5-8%
how do you calculate cerebral perfusion pressure?
MAP - ICP(mean)
how do you calculate cerebral blood flow?
CPP/CVR
cerebral perfusion pressure
cerebral vascular resistance
What may be damaged if there is generalized hyperesthesia? localized hyperesthesia?
thalamus
usually focal to where the lesion is
What structure is abnormal in osseous cervical spondylomyelopathy?
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”
what 3 factors contribute to Doberman CSM?
“vertebral canal stenosis, pronounced TORSION of the caudal cervical intervertebral column leading to intervertebral disc degeneration, and protrusion of larger volume intervertebral discs”
What is the ligament seen in a cervical ventral slot?
dorsal longitudinal ligament
what and where is myelography?
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
What is spina bifida? consequences?
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
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
true
Which of the following are congential spinal neurologic disorders?
a. Spina bifida
b. Hemivertebrae
c. Subarachnoid diverticula
d. Dysraphism
e. all of the above
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
