8. CBCT Flashcards
CBCT acquisition
raw data volume (group of sequential images)
In order to mitigate this problem, engineers have designed algorithms to break through this and generate ____ and 2D renditions with slices that are ____-1mm thick
3D
0.5
i-CAT: earlier units advertised
- ____
CATScan
3D anatomy
Some of the algorithms
• Pixels and voxels
○ Pixels: ____ building blocks
○ Voxels: ____ building blocks of 3D MRI, 3D CT
We have to think in planes
• Different directions that we will be viewing 3D objects (our patient)
• ____ plane is not a fixed unit, it moves
• Axial plane will go ____ and south
○ Most of conventional views is ____ to nose
• Coronal is not highlighted on this image but that is anterior to posterior (ventral to
dorsal)
Image not included: • Just using the skull • Sagittal plane: divides left and right • Axial: North south • Coronal: anterior and posterior
2D 3D sagittal north toes
Axial CT bone/soft tissue windows
SOFT TISSUE WINDOW:
Bone just seems ____ (mitigates the bone), cannot see this but we see detail in soft tissue and vasculature
Two axial views of the head
• Can tell where we are
• Bone view to capture ____ and mandible to
coincide
opacified
maxilla
CBCT maximum intensity projections
Mollifies some of soft tissue and bone reads a little - combines it all so we get a really intense rather dull image but we can see a lot of ____ in this frontal view and sagittal view
• Mid-sagittal - plane film done in ____
• Can see earrings, impacted teeth with open bite anteriorly
• Good for ____ workup but not as useful for other tings
anatomy
orthodontics
orthodontic
Panoramic display
Conventional panoramic:
• Non-cone beam panoramic is about ____mm thick
• This is only ____mm - one slice pulled out and we punched in algorithm for panoramic display. That
makes it look like a pano
• Even though it is very thin, we can equate it to conventional panoramic
• Get external acoustic meatus in base of skull if lucky
• TMJ is only 1mm near brain when injecting into glenoid fossa - be careful with anesthetics
• Orbits is not well defined
• Sinuses will be ____ - air
○ Notice differences:
• Left sinus is full volume, full contour filled with air
• Right maxillary sinus - bottom right is opacified - soft tissue probably from respiratory epithelium because bone it does not have well defined boney structures visible (maybe sinus infection
REMEMBER: when reading cone beams, this is only ____ SLICE in “ream of 500 sheets”
• Pointed out lucency in mandible: remember some of mandible will be ____ screen or in front, same with coronoid process
○ Should not panic that there is a big tumor there - must go through every single slice
20 2 black one behind
Sagittal slice
Bone view:
• Can see maxillary sinus: the slice that has been pulled out has been to right of nose to see maxillary sinus
○ Without bone on outside border tells us it is ____ and not bone
○ Could be soft tissue or mucous in epithelium
○ Appears ____
See missing pieces:
• Base of skull
• Mandible
• THIS IS ONLY ____ SLICE!
soft tissue
benign
one
Coronal slice
FRONTAL VIEW:
• Molar with MD or MB root - hard to tell if molar or premolar
• Inferior aspect of right maxillary sinus occupied by same ____ non-bony lesion just within compartment itself
• Can’t really see intra-ocular musculature of eye
• Cannot see sphenoid because we are anterior near molar region
• Some thickening of turbinate’s - maybe some ____ problems
Frontal sinus also looks congested
lesion
sinus
Axial slice
Toes to nose
• Right side, we captured some of lesion means that we are low enough to make it seem that
entire sinus is occupied by benign lesion where as left side is pretty much open
• Part of ramus - not equal so patients head may have been ____
○ Can see pterygoid plates - level above maxillary arch form of
• Mastoid process
tilted
Inf alveolar nerve passing through the third molar bifurcation area
Colorized image
• Can help us identify whether ____ is between two roots
• Agenesis of 20, could be residual primary 2nd molar without succedaneous tooth
• Algorithm in computer to make us highlight things and colorize things to show the patient
root
Superimposition of 2 CBCT scans
Another way is to use different software in vivo
• Take a couple of positions of patient and superimpose them in varying modalities depending on which algorithm to utilize
• Closed condyle and open condyle (can do double exposure of films)
○ Can tell you physiology and movement of mandible in glenoid fossa
○ ____ slice
Shows in this case we are a couple mm thick near brain case
2D
Commercial third party softward
Get trial software when you can so you are sure it is consistent and repeatable results, gives you ____ results that you want before breaking the bank
quality
Airway evaluation
In surgery and oral medicine do airway evaluation:
• ____ and special airway evaluations from which we can do appliances or surgically move jaw forward to open airway a bit
• All digital and can be used in multiple ways
volumetric
Coronal section & 3D reconstructed
Sometimes we have ability to treat ____ cases
• LEFT: left ramus and a little bit of zygomatic arch (little dot)
○ On right, ramus shows fracture so condylar head is leaning medial into glenoid fossa space
• RIGHT: 3D reconstruction shows condylar head is fractured off
trauma
Incidental findings on CBCT
\_\_\_\_ Mucosal polyps \_\_\_\_ Bony abnormalities \_\_\_\_ Nasal septal deviations \_\_\_\_ And more
- Benign or malignant findings can be found in these radiographs - whether intraoral, panoramic, cone beam
- We already saw maybe epithelial changes in one sinus = mucous retention cysts
- Bony abnormalities
- Impactions of teeth
- TMJ - condylar fracture seen before
mucous retention cysts
soft tissue calcifications
TMJ findings
impactions of teeth
Panoramic image
REGULAR NON-CONE BEAM PANORAMIC
• ____ of different layers within the image itself
○ ____mm or more thick on conventional panoramic compared to 1mm for CBCT
• Periphery of maxilla and mandible looks ok
• Coronoid process looks ok
• Floor of sinus looks ok
• Younger patient
Look at wisdom teeth - maybe actually very younger because very underdeveloped
LOOKING MORE CAREFULLY: unerupted premolar within mass of uniformly opaque bony tissue in maxillary right that may have orthodontically moved 6 and 4 (hard to tell)
• Is this 5, supernumerary tooth?
superimposition
20
Maxillary sinus: sagittal view
Followed up with CT
• Sagittal or lateral view - plane is far enough out to capture molars
• Rather uniformly opacified but very expansive type of bony lesion = ____ (not soft tissue)
○ How do you know that?
• If you look at density of tissue it compares to normal bone density of every where else
○ May also have another impacted something posteriorly Sinus appears intact
mineralization
Midline clefts of cervical vertebrae: axial view and 3D recon
Now C1 C2 area - toes to nose
• Ramus and pterygoid plates
• Above all root tips of molars, still into lesion and you can see irregularity of some areas that are not ____ (radiolucent) in sinus
○ Root of impacted tooth straight down root canal - 1 and 16
○ Not eroding the bone which is probably benign like fibrous osseous lesion (like fibro
dysplasia)
Looking down in dorsal arch of C1, there is a developmental defect - not fused together
• Incidental finding! Should be ____!
«_space;reconstructed this - gap between two plates between dorsum of vertebral body with odontoid process
his is anterior - pre-maxilla embryologically
• If you have cleft, you have____
calcified
closed
C1
Another case
• First thing that hits us is a lot of teeth
• Thick, superimposed tissue
• Younger patient with unerupted teeth - well under 10 years of age due to 2nd molars
• Elevated, unmoved teeth
• Where arrow is pointing - typically follow outline of mandible from sigmoid to
mandible
• Inverted tear drops are ____
• Spine
• Hyoid
Something is causing teeth to not be erupting! (where arrow is)
• Something is ____ passage
pterygomaxillary
blocking
Lateral view:
• Clivus of base of skull with C1
• Tongue
• Canal is ____ that is developmental - canal goes into ….LISTEN
s-shaped
