unit 5 Flashcards
facial nerve studies are usually done for
the trigeminal nerve (CN V)
plotting the coronal for a facial nerve study :
cover the top of the 4th ventricle & align with the nasal septum
on axials for facial nerve studies cover through
the parotid gland
CSF studies are done to
determine if patient has aqueduct stenosis or hydrocephalus
aqueduct stenosis
blockage of fluid
when doing a brain for CSF flow you use a _______ on patient
peripheral gating probe to synchronize the MRI signal to the cardiac cycle
what happens to blood & CSF during systole
blood flows into brain & CSF flows down the aqueduct of sylvius
when setting up a sagittal for CSF brain flow
set up as a single midline slice , parallel to & through the 4th ventricle
axial slices for CSF brain flow are set up
perpendicular to & through the aqueduct of sylvius
one of patient’s complaints when getting IAC’s scanned
tinnitus (ringing in ears)
when setting up a sagittal for an IAC coverage includes
the foramen magnum through the superior body of the corpus callosum
thin slices for the coronal IAC include
posterior border of the cerebellum to the clivus
IAC thin slices use a _____ FOV
small
exams with thin slices are usually _______ exams (IAC)
long
proptosis
protrusion of the eyeball
protocol tips for orbit imaging
- remove eye makeup
- fine matrix
- STIR , usually needed to visualize orbit well due to high fat content of globe
thin axial slices of the orbit are angled with
the optic nerve
thin coronal orbit slices include
the posterior globe to the posterior aspect of the optic chiasm
for artifacts due to blinking use
FSE (fast spin echo)
to prevent flow motion, sometimes from circle of willis, use
sat bands , placed superior and posterior
inferior- reduces carotid flow
when doing orbits if contrast is used ,
do at least one sequence of entire brain
MRA
magnetic resonance angiography
3D TOF (time of flight) provides
higher spatial resolution than 2D
- longer scan time & generally less artifacts
3D TOF usually done for
circle of willis
- great for flow visualization
Blood shows bright
3D TOF uses a ______ TR
short
contrast is ______ used in MRA exams
not usually
MRV
magnetic resonance venography
MRV’s are looking at
venous flow of the brain
fMRI usually uses the
BOLD (blood oxygen level dependent) sequences
fMRI measures function of different areas of the brain like
language
motor
passive/thinking
allows for planning of surgery , to see what cortex they will pass through & possible damage caused
fMRI
which cranial nerve is associated with the optic nerve
CN II
this technique is becoming the standard of care in neurological work
functional MRI (fMRI)
what is NOT true regarding phase contrast MRA
it suffers from more background tissue being represented
when performing an MRA of the cerebral arteries, a saturation band should be placed _______ to the axial slices
superior
which MRA technique is typically used to evaluate the venous structures of the head
PC MRA
an example of examining blood flow within a vascular network is
MRA
which cranial nerves run through the IACs
VII & VIII
