Head And Neck Flashcards
Algorithms
What is it?
Many used based on?
Set of mathematical computations ( rules or direction) used to create an image from acquired raw data from ct scanner. A variety of algorithms can be selected to create optimal images depending on tissue type
Azimuth
- what is it?
- 0 degrees? 90 degrees?
Aka scout
Direction by which the X-ray tube images a patient during scout. Usually given in degrees . Ex 0 degrees = ap scout and 90 degrees = lateral
Contrast resolution
What is?
- what varies?
Ability of a scanner to image as separate object , 2 or more structures vary in density by small amounts
Spatial resolution
- ?
- increases with decrease in?
Ability of a scanner to display as seperate objects, 2 or more structures are close to each other. Increases with decrease in slice thickness
Ct numbers
- aka-
- ?
- range?
- air number?
- bone number?
Number used to designate the X-ray absorption in each pixel ( picture element) of the image. Ct numbers expressed in hounsfield units and are set - 1000 to + 1000. Where ct number for air is -1000 and bone is + 1000
Gray scale
- ?
- air
- water
- bone
Shades of grey assigned to pixels with specific with a ct number ( hounsfield unit)
Air - 1000
Water 0
Bone + 1000
Windowing
- ?
Adjustment of the gray scale to optimize tissue visualization
Window width
?
Range of ct numbers above and below the window level
Window level
Aka
- ?
Aka window center
Center of window width
Pitch
?
- thinner slices means?
- higher ratio is more?
In helical scanning it is the ratio of slice thickness to table movement.
How many times the scanner goes around the patient .
Thinner the slices more times around.
Higher ratio- more mas used
Raw data
Collection of all data acquired during scan within scan field of view. Can by used to later reconstruct images with a different algorithm, slice thickness or display field of view. Usually not archived.
Scan field of view
Field by which the raw data is collected
What is actually used not everything that was scanned
Displayed field of view (dfov)
Size of image on monitor
Effective scan data
Collection of raw data used to create the display image . Usually archived
Noise
-?
4 reasons?
Fluctuation in ct numbers of an object of uniform density. Displayed as graininess. Caused by insufficient photons( not enough mas) , slice thickness, algorithms , and electronic malfunction
Multiplanar reconstruction (mpr)
Simple 3-d technique that enables the visualization of data in any plane
Volume rendering (vr)
3-d visualization technique that provides a 3-d model of all structures in an imaging data set. Used in cta, urograms
Maximum intensity projection (mip)
A volume rendering 3-d technique that displays the voxels with the highest ct number to be displayed. Used in cta to look at vessels
Contrast is out of body in what time frame?
24-48 hrs
Why no contrast with a suspected bleed?
Blood / contrast have same ct number
Routine ct scan of brain, why no contrast used?(5)
Trauma Acute cva Intracranial hemorrhage Hydrocephalus Subdural hematoma less than week
Routine ct brain with contrast
- first with
- 5
First done without contrast with tumors
Vascular malformations Abcess Headache Aneurysm Metastasis
Ct scan brain done intrathecal to evaluate?
Ventricles
Ct scan of brain positioning
Head first Supine Remove head jewelry Head placed into immobilization cradle Cushion under legs for comfort Shield Patient centered midcoronal and midsagital with lasers Have patient close eyes while lasers on
In ct patient needs be shielded ?
All way around
Protocol brain routine
- scout
- Scout 90 degree azimuth ( lateral) from ______ to top of _____approx ___-____ mm total
____mm slices thru posterior ____. Better spatial resolution. Reduces beam hardening artifact
___-____mm slices from base skull to skull apex
Slices angled parallel to ________
Head algorithmn with _____cm display field of view
Reconstruct with a bone algorithmn for ____
Brain windows: ___-____ window width and __-___window level and ___ ww and ____wl for bone when trauma is suspected
Scout 90 degree azimuth ( lateral) from base of skull to top of head, approx 250-300 mm total
1mm slices thru posterior fossa. Better spatial resolution. Reduces beam hardening artifact
2-3 mm slices from base skull to skull apex
Slices angled parallel to orbitomeatal line( oml)
Head algorithmn with 25cm display field of view
Reconstruct with a bone algorithmn for trauma
Brain windows: 90- 120 window width and 0-50 window level and 2500 ww and 500wl for bone when trauma is suspected
______mm throughout entire brain may be used for stereotactic or surgical navigation for tumor localization
1 mm
Know head and brain anatomy out wb
Wb
Pons
Connects cerebellum to medulla oblongota
Vertebral artery merges into ?
Basilar artery
Temporalis muscle
Originates in temporal fossa and inserts on the coronoid process of mandible and elevates the mandible
Basilar artery
Supplies pons, cerebellum, inferior and medial surfaces of temporal occipital lobes with blood
Cerebellum
Coordinates and regulates muscle activity
4th ventricle
Diamond shaped cavity located anterior to the cerebellum and posterior to pons
Pituitary gland
_______ gland connected to the_____.Itās located in the ____ . Called the master gland and Controls and regulates the function of other ____glands
Endocrine gland connected to the hypothalamus. Itās located in the sella turcica . Called the master gland and Controls and regulates the function of other six glands
Internal carotid artery bifurcated at
C4
Internal carotid artery
Supply frontal, parietal , and temporal lobes of brain and orbital structures. Arise from bifurcation of carotid artery
Parts of circle of Willis
Anterior , middle, posterior cerebral artery
Tentorium
Fold of dura mater connects cerebellum and cerebrum
Anterior cerebral artery
Supply blood anterior frontal lobe and medial aspect of parietal lobe. Main branches horizontal segment( a1), vertical segment(a2), and distal segment(a3)
Middle cerebral artery
Largest of cerebral arteries and considered direct continuation of internal carotid artery . Supplies much of the lateral surface of cerebrum, insula, anterior and lateral aspects of temporal lobe, basal ganglia and anterior and posterior internal capsule
Four segments:
Insular (m1)
Opercular( m3)
Cortical ( m4)
Septum pellucidum
Seperate anterior horn and lateral ventricle
Anterior horn lateral ventricle
Pg 93
3rd ventricle
Communicates with 4th ventricle via cerebral aqueduct
Quadrigeminal cistern
Lies between splenium of corpus callosum and superior surface of cerellbelum just posterior to coliculi of midbrain
Field of view (fov)
Size of the image
Ex abdomen 46/48
Corpus callosum
White matter separates left / right hemisphere of brain
Falx cerebri
Separates cerebral hemispheres
Largest and densest bundle white fibers within of cerebrum
Corpus callosum
Internal cerebral vein
Drain deep parts of brain
Choroid plexus
Can be partially calcified and produce csf in ventricles
Fornix
Grey matter both sides hemisphere
Ct scan of paranasal sinus non contrast (4)
Acute or chronic sinusitis
Headache
Trauma
Sinus surgery planning
Ct scan of paranasal sinus contrast exams
If mass is suspected
Ct scan of paranasal sinus intrathecal contrast
In cases of csf leak
Ct scan paranasal sinus positions
Axial and coronal positions
Best ct scan paranasal sinuses for true air fluid level
Coronal
Ct scan of paranasal sinus may be scanned ______ position and reconstructed ______
Axial
Coronally
Isocenter
Middle of scan that gives best data to receptor. Further away less data to receptor
Ct scan paranasal sinus : coronal position
Prone Head first in immobilization cradle Neck hyperextended Cushion under chin Support under legs Jewelry and dental work removed Laser midsagital and midcoronal plane Patient shield
Ct scan paranasal sinus : axial
Supine Head first in immobilization cradle Jewelry and dental work removed Cushion under knees Laser midcoronal and midsagital Patient keeps eyes closed Patient shielded
Coronal paranasal sinus protocol
Scout 90 degree azimuth (lateral) from ________thru _____
___-____mm slices from posterior sella turcica thru the frontal sinus
Slices angled perpendicular to ____
Bone or detail algorithm with ____-____cm dfov
Film either or all bone , air, , or soft tissue windows
Scout 90 degree azimuth (lateral) from posterior skull base thru frontal bone
1-2 mm slices from posterior sella turcica thru the frontal sinus
Slices angled perpendicular to oml
Bone or detail algorithm with 14-20 cm dfov
Film either or all bone , air, , or soft tissue windows
Axial paranasal sinus protocol
Scout 90 degree azimuth ( lateral) from ___thru ____
1-2 mm slices from below ___sinus thru ____sinus
Slices angled parallel ____
Film same as coronal
Reconstruct axial images into ____
Scout 90 degree azimuth ( lateral) from chin thru midbrain
1-2 mm slices from below maxillary sinus thru frontal sinus
Slices angled parallel oml
Film same as coronal
Reconstruct axial images into coronal
Ct scan orbits and facial bones non contrast(3)
Trauma
Gravesā disease - extra fluid in back eyes
Foreign body
Ct scan orbit and facial bones contrast(2)
Suspected mass
Visual disturbances
Scanned axial and coronal
Coronal best true fluid levels
Scanned axial and reconstructedCoronal position orbits and facial bones
Prone Head first in immobilization cradle Neck hyperextended Cushion under chin Support under legs Jewelry and dental work removed Laser midsagital and midcoronal plane Patient shield
Axial position ct scan orbits and facial bones
Supine Head first in immobilization cradle Jewelry and dental work removed Cushion under knees Laser midcoronal and midsagital Patient keeps eyes closed Patient shielded
For orbits have patient ______ reduce rectus muscle motion
Close eyes or stare
Orbit and facial bone protocol: coronal
Scout 90 degree azimuth( lateral) from _______thru bone
1-2 mm slices from posterior _____ thru _____
Slices angled perpendicular to _____
Bone and detail algorithm with a ___-____cm dfov
Film in both bone and soft tissue windows( two different algorithm - bone and soft tissue)
Scout 90 degree azimuth( lateral) from posterior skull base thru bone
1-2 mm slices from posterior sella turcica thru anterior globe of the eye
Slices angled perpendicular to oml
Bone and detail algorithm with a 14-20 cm dfov
Film in both bone and soft tissue windows( two different algorithm - bone and soft tissue)
Axial orbit and facial bone protocol
Scout 90 degree azimuth (lateral) from ____thru mid ____
__-___mm slices from below maxilla or______ thru ___
Slices angled parallel _____
Film as coronal
Reconstruct axial images into coronal
Scout 90 degree azimuth (lateral) from chin thru mid brain
1-2 mm slices from below maxilla or mandible thru superior orbital rim
Slices angled parallel oml
Film as coronal
Reconstruct axial images into coronal
Facial /sinus/ orbit anatomy
Do notebook
Tmj
Condyle and temporal bone joint
Nasal septum
Perpendicular plate of ethmoid and vomer
Anterior clinoid process is in?
Sella turcica
Crista galli is in?
Ethmoid bone
Ct mastoids and internal auditory canals ( iac) non contrast exams(7)
Temporal or petrous bone survey
Hearing loss
Cholesteatoma
Mastoiditis
Chronic Ottis media
Foreign body
Bony destruction
Ct mastoids and internal auditory canals ( iac) contrast exams(3)
Acoustic neuroma
Coronal best for air fluid levels
Scanned axial must be reconstructed
Ct mastoids and internal auditory canals ( iac) and temporal bone coronal protocol
Scout 90 degree azimuth( lateral) from ____thru ____
1-2 mm slices from _____ thru ____
Slices angled perpendicular to _____
Bone or detail algorithm with a ___-___cm dfov
Film either or all bone , air or soft tissue windows
Scout 90 degree azimuth( lateral) from posterior skull base thru frontal bone
1-2 mm slices from posterior mastoid air cells thru sella turcica
Slices angled perpendicular to oml
Bone or detail algorithm with a 14-20 cm dfov
Film either or all bone , air or soft tissue windows
Ct mastoids and internal auditory canals ( iac) and temporal bone Axial protocol
Scout 90 degree azimuth ( lateral) from ___ thru _____
1-2 mm slices from ______ thru ______
Slices angled parallel to _____
Bone or detail algorithm with a ___-____cm dfov
Film same as coronal
Reconstruct axial images into _____
Scout 90 degree azimuth ( lateral) from chin thru mid brain
1-2 mm slices from inferior mastoids thru petrous ridges
Slices angled parallel to oml
Bone or detail algorithm with a 14-20 cm dfov
Film same as coronal
Reconstruct axial images into coronal
Mallelus
Hammer like structure in ear
Pituitary and sella turcica scan done with ?
Iv contrast and without delayed due to blood brain barrier
Infendibulum
Pituitary gland hangs on it and connects to hypothalamus
Coronal position best sees ____ and ______
Pituitary
Sella turcica
Pituitary gland sits on_____
Sella turcica
Pituitary and sella turcica coronal protocol
Scout 90 degree azimuth ( lateral) from______thru ______
_____mm slices from posterior sella turcica thru the anterior sella turcica
Slices angled perpendicular to ____
Bone or detail algorithm with a ___-___cm dfov
Film in both and soft tissue windows
Scout 90 degree azimuth ( lateral) from posterior skull base thru frontal bone
1 mm slices from posterior sella turcica thru the anterior sella turcica
Slices angled perpendicular to oml
Bone or detail algorithm with a 10-14 cm dfov
Film in both and soft tissue windows
Pituitary and sella turcica protocol axial
Scout 90 degree azimuth ( lateral) from ____thru ___
1mm slices from ____ sella thru ____ sella
Slices angled parallel to _____
Film as coronal
Reconstruct axial images into _____image
Scout 90 degree azimuth ( lateral) from chin thru mid brain
1mm slices from inferior sella thru superior sella
Slices angled parallel to oml
Film as coronal
Reconstruct axial images into coronal
Ct scan soft tissue neck non contrast
Parotid calculi ( gland - salivary gland)
Ct scan soft tissue neck with contrast(6)
Lymphadenopathy Tumors Abcess Vascular pathology Tracheal stenosis or fracture Trauma
Ct scan soft tissue neck positioning
Head first Supine Head jewelry removed Remove dental work Head placed into immobilization cradle Cushion under legs Shield Patient centered midcoronal and midsagital with positioning lasers Patient closes eyes with laser
Soft tissue neck protocol
Scout 90 degree azimuth (lateral) from____to midbrain approx___mm
___-____mm slices _______ to _____
____ mm slices for ct angiography of carotid arteries
Usually no gantry angulation but may be angled ______ to neck
Standard or soft algorithm with a ___-____cm
Display field of view ( neck size)
Scout 90 degree azimuth (lateral) fromT-2 to midbrain approx 350mm
1-3 mm slices superior base of tongue to lung apices
1mm slices for ct angiography of carotid arteries
Usually no gantry angulation but may be angled parallel to neck
Standard or soft algorithm with a 20-25 cm
Display field of view ( neck size)
Soft tissue neck scanning procedure
Inject ___-___ cc of iodinated contrast material with a ___-___second scan delay ___-___sec delay for carotid
Instruct patient not ____ during exam
Evaluate vocal cord motility instruct to phonate the letter ______while scanning
Reconstruct with bone algorithm for trauma- can see ______
Film soft tissue ___-___ window width and ___-___window level and _____ww and ___wl for bone when trauma is suspected
Air windows of ____ww and ____wl may helpful evaluate tracheal leaks
Inject 60-120 cc of iodinated contrast material with a 60-65 second scan delay 10-15 sec delay for carotid
Instruct patient not swallow during exam
Evaluate vocal cord motility instruct to phonate the letter āeā while scanning
Reconstruct with bone algorithm for trauma- can see free air
Film soft tissue 90-120 window width and 0-50 window level and 2500 ww and 500wl for bone when trauma is suspected
Air windows of 1500ww and -500 wl may helpful evaluate tracheal leaks
Parotid
Largest salivary gland
External carotid artery
Blood supply face
Internal carotid artery
Blood supply brain
Epiglottis
Flap over esophagus
Sternocleidomastoid muscle
Rotates head to opposite side and flexion of neck
Parotid gland
Secretes saliva through parotid duct into mouth to facilitate mastification and swallowing
Sublingual gland
Smallest salivary gland
Veins vs artery
Veins more outside
Veins larger
Ct angiography of carotids and circle of Willis
Clinical indication (7)
Aneurysm Stenosis Trauma Dissection Atherosclerosis Vascular malformations Subarachnoid hemorrhage
Ct carotids and circle Willis positioning
Head first Supine Head jewelry removed Remove dental work Head placed into immobilization cradle Cushion under legs Shield Patient centered midcoronal and midsagital with positioning lasers Patient closes eyes with laser
Cta carotid protocol
Scout 90 degree azimuth ( lateral) from ______to _____
_-_mm slices from aortic arch to temporal region
Usually no gantry angulation but may be angled _____to neck
Standard or soft algorithm with a ___-___cm display filed of view (dfov)
Inject ___-___cc iodinated contrast material at __-___cc/sec with ___-___sec scan delay. Optional use of test bolus 20 cc injection at level of ____or manual start scan bolus timing software to avoid venous contamination
Faster injection brighter image will look. Need larger needle lumen
Instruct not swallow during exam
Reconstruct overlapping slices
Post process with maximum intensity projection ( mip) Volume rendered(vr), multiplanner reconstruction( mpr)
Scout 90 degree azimuth ( lateral) from aortic arch to midbrain
1-2 mm slices from aortic arch to temporal region
Usually no gantry angulation but may be angled parallel to neck
Standard or soft algorithm with a 15-20 cm display filed of view (dfov)
Inject 90-120cc iodinated contrast material at 3-5 cc/sec with 12-20 sec scan delay. Optional use of test bolus 20 cc injection at level of c6 or manual start scan bolus timing software to avoid venous contamination
Faster injection brighter image will look. Need larger needle lumen
Instruct not swallow during exam
Reconstruct overlapping slices
Post process with maximum intensity projection ( mip) Volume rendered(vr), multiplanner reconstruction( mpr)
Cta circle of willis (cow) protcol
Scout 90 degree azimuth ( lateral) from ___-thru _____
___mm slices from foremen magnum to _____ or thru ___
no gantry angulation
Brain algorithm with a ___-___cm display field of view
Inject ___-___cc iodinated contrast material at ___-___cc/sec with _____sec scan delay. Optional use of test bolus ___cc injection at level of circle of Willis or manual start scan bolus timing software to avoid
venous contamination
_____injection brighter image will look. Need ____ needle lumen
Instruct not ______during exam
Reconstruct overlapping slices( take away _____and ____if just wanna see carotids
Post process with maximum intensity projection ( mip) Volume rendered(vr), multiplanner reconstruction( mpr)
Scout 90 degree azimuth ( lateral) from t2-thru skull apex
1mm slices from foremen magnum to skull apex or thru mid brain
no gantry angulation
Brain algorithm with a 20-25 cm display field of view
Inject 90-120cc iodinated contrast material at 3-5 cc/sec with 12-20 sec scan delay. Optional use of test bolus 20 cc injection at level of circle of Willis or manual start scan bolus timing software to avoid
venous contamination
Faster injection brighter image will look. Need larger needle lumen
Instruct not swallow during exam
Reconstruct overlapping slices( take away skin/ bone if just wanna see carotids
Post process with maximum intensity projection ( mip) Volume rendered(vr), multiplanner reconstruction( mpr)
Anterior cerebral artery
Blood supply midline to portions of frontal lobe and superior medial parietal lobes
Anterior communicating artery
Connects left and right anterior cerebral arteries
Middle cerebral arteries
One three major arteries supplying blood cerebellum. Supplies blood also to anterior temporal lobes and insular cortices
Posterior communicating artery
Connects between posterior the cerebral artery and internal artery
Posterior cerebral artery
Supply oxygen blood supply to posterior portion of brain
