CT Application 2 Head + Neck Flashcards
function of frontal lobe
judgement, foresight, voluntary movement, smell
function of Broca’s area
speech
function of temporal lobe
intellect & emotions
function of brainstem
involuntary functions = swallow, breathing, waking, heartbeat
function of cerebellum
movement & balance coordination
function of Wernicke’s area
speech
function of occipital lobe
primary visual area
function of temporal lobe
hearing, memory, emotion
function of parietal lobe
language comprehension, temperature, pain, touch
white matter contains high amounts of ___
myelinated axons which are hypodense
grey matter contains high amounts of ___
cell bodies which are hyperdense
mater layers of the brain
dura, arachnoid, pia mater
which are potential spaces
epidural & subdural
which area is filled with CSF
subarachnoid space
where does CSF transfer occur between
arachnoid & pia mater
parts of brainstem
midbrain, pons, medulla oblongata
primary indications for CT Brain
- trauma (GCS < 15)
- haemorrhages
- hydrocephalus
- guidance (pre/post op)
- mental status changes
secondary indications for CT Brain
- developmental delay
- epilepsy
- neurodegenerative diseases
TIA
transient ischemic attack
causes of acute neurological dysfunction
- cerebral infarction
- haemorrhage
- infection
- tumor
patient prep for head & neck CT
- check patient identifiers
- explain & get consent from patient
- co-relate clinical indication
- remove preventable artifacts
- check allergy, renal insufficiency, metformin
- check IV access, chest ports, PICC
PICC
peripherally inserted central catheter
what is tested for renal insufficiency
serum creatinine & eGFR
head & neck positioning
- patient head in first, supine
- arms beside body
- lower leg supported
where to isocenter gantry for CT head
align at EAM and ensure parallel to line between EAM & supraorbital ridge by tucking chin or tilting gantry
scan region of CT brain
base of skull > vertex
recon window for CT brain
brain and skull/bone
WW/WL for CT Brain
80-150/40
2000 - 4000/300-400
what effect does brain algorithm have
smoothing
what effect does bone algorithm have
edge enhancing
HU of bone
+1000
HU of white matter
+20 to +30
HU of muscle
+20 to +40
HU of gray matter
+30 to +40
HU of hemorrhage
+65 to +95
HU of CSF
0
HU of fat
-30 to -70
HU of air
-1000
stroke is the ___ principal cause of death in SG
4th
80% of strokes are ___ & 20% are ___
ischaemic; haemorrhagic
top 5 causes of death in SG
- cancer
- ischaemic heart disease
- pneumonia
- CVS
- hypertensive
epidrual hematoma occurs between ___
skull & dura mater
subdural hematoma occurs between ___
dura & arachnoid mater
how to differentiate between epidrual & subdural hematoma in terms of suture line
subdural hematoma crosses suture line whereas epidural does not
clinical indication of epidrual hemorrhage
loss of consciousness, lucid intervals
identifier of epidrual hemorrhage
sharplyu demarcated biconvex shape
identifier of subdrual hemorrhage
cresent shaped, homogenous hyperdense collection
clinical indication of subdural hemorrhage
trauma, headache, nausea, vomitting, altered mental state
pathophysiology of subarachnoid hemorrhage
85% rupture of intracranial aneurysm, vascular malformations, thunder clap headaches, stiff neck, altered consciousness
where does bleeding of subarachnoid hemorrhage take place in
subarachnoid space (between arachnoid & pia mater)
identifier of subarachnoid hemorrhage
hyperdense filling subarachnoid space commonly around circle of willis
identifier of intracerebral hemorrhage
homogenous hyperdense intraparenchymal collection
most common ischemic strokes
- large artery atherosclerosis
- small vessel occlusion
- cardio-embolism
- cryptogenic
most common hemorrhagic strokes
intracerebral & subarachnoid hemorrhage
ischemic strokes occurs due to ___
sudden obstruction of >1 cerebral arteries due to embolism or thrombosis
what does stroke lead to
significant motor weakness & sensory disturbances
identifiers of acute ischemic stroke
- hypodensity within parenchyma
- loss of gray/white matter
- disappearing basal ganglia
- hyperdense vessel sign
- loss of insular ribbon sign
CT brain + IV indications
lesion, metastasis, arteriovenous malformation, infection, RT planning
CT brain + IV procedure
- patient remains still
- 22/24G cannula used
- wait 1-2 mins post injection then scan
CAVMs
cerebral arteriovenous malformations
GBM
glioblastoma
vasogenic vs cytotoxic edema in terms of location
v: extracellular
c: intracellular
vasogenic vs cytotoxic edema in terms of BBB
v: BBB destroyed
c: BBB intact
vasogenic vs cytotoxic edema in terms of hypodensity
v: only white matter becomes hypodense
c: both grey and white matter becomes hypodense
vasogenic vs cytotoxic edema in terms of grey white differentiation
v: heightened
c: loss
vasogenic vs cytotoxic edema in terms of causes
v: tumor, metastasis, abscess
c: infarction, encephalitis, hypoxic injury
non-contrast CT orbit indications
FB, trauma, blow out #
IV CT orbit indications
- infection/abscess
- tumor
- proptosis/diplopia
- melanoma
proptosis
bulging eye
diplopia
double vision
melanoma
skin cancer
cannula for orbits
22G
recon window for CT orbits
soft tissue + bone
slice thickness for CT orbits
1-2mm
delay timing for CT orbits
1-2 mins after IV injection
non-contrast CT temporal bone indications
- hearing loss
- otalgia
- otitis media
- cholesteatoma
- trauma
- mastoiditis
IV CT temporal bone indications
- pulsatile tinnitus
- paragangliomas
- malignant otitis externa
recon window for temporal bone / IAM CT
soft tissue + bone (inner ear)
recon orientation for temporal bone / IAM CT
axial + sagittal = parallel to falx cerebri
coronal = perpendicular to falx cerebri
indications for CT sinus + facial bones
- sinusitis
- trauma
- polyps
- deviated septum
- surgical planning
- neoplastic diseases / abscesses
indications for IV + CT sinus + facial bones
TRO infection / tumor
scan range for CT sinus
maxillary sinus / hard palate > frontal sinus
scan range for CT facial bone
symphysis menti > frontal sinus
recon window for CT facial bones
soft tissue + bone
recon window for CT sinus
soft tissue + bone
slice thickness for CT facial bones
3mm
slice thickness for CT sinus
3mm
which algorithm to be used for volume rendering of CT sinus / facial bones
smoothest
what part of spine is most mobile
cervical vertebrae
what foramina allows vertebral arteries to pass through
transverse foramen
uniqueness of C1
no body, spinous process but has 2 large lateral masses
function of C1 lateral masses
weight bearing articulation between cranium & vertebral column
uniqueness of C2
large odontoid process that projects upwards
function of uncinate processes of c3-7
prevents lateral movement of c-spine
uniqueness of c3-6
bifid spinous process
what lines must be evaluated in mid-sagittal view of C-spine
- anterior surface of vertebral bodies
- posterior surface of vertebral bodies
- spinolaminar line maintained by ligamentum flavum
- tip of spinous processes
CT neck non-contrast indications
- FB
- salivary stones
- trauma / degenerative changes
- goitres
- dysphagia
dysphagia
swallowing difficulty
goitres
neck swelling from enlarged thyroid gland
CT neck IV-contrast indications
- cyst
- inflammation / abscesses
- lymph nodes
- RT simulation
- tumor
- vocal cord paralysis
scan range of CT neck
base of skull > aortic arch
recon window of CT neck
soft tissue + bone (trauma)
slice thickness & interval of CT neck
3mm
recon orientation of CT neck
soft tissues = axial + coronal
FB & trauma = axial + coronal + sagittal
infarction
blood supply obstruction causing local tissue death
encephalitis
brain inflammation
otalgia
ear pain
otitis media
middle ear infection
Cholesteatoma
destructive & expanding growth of middle ear
mastoiditis
infection of mastoids due to untreated or complicated acute otitis media
otitis externa
ear canal inflammation
polyps
growth in sinus
scan range of CT orbits
floor of orbits > roof of orbits
recon orientation of CT orbits
sagittal recon parallel to optic nerve for each orbit
scan range of CT temporal bone / IAM
superior roof / mid frontal sinus to clear mastoids, parallel to hard palate
