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Radiology Of The Canine And Feline Skull - 1

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sihirlifil's version from 2017-11-03 18:55

Anatomy & Radiographic Techniques

Question Answer
Relevant anatomy (8)Maxilla/mandible
Teeth
Nasal cavity
Tympanic bullae
TMJ
Cranium
Orbita
Pharynx/larynx
Dolichocephalic =Long snout
Mesaticephalic =Medium snout
Brachycephalic =Short snout
Special thing about brachycephalicMost have no frontal sinus
Why is positioning so important when radiographing the skull?Visualize symmetry
Complex anatomy
WHat is necessary for positioning most projections?Heavy sedation or GA
Positioning aids, ties, sandbags
Use of metal markers to ID L & R (most structures bilateral)
What can be seen in the lateral view?Skull
Cranium
Frontal sinus
Nasal cavities (L & R superimposed)
Maxilla
Nasopharynx
Oropharynx
Hard & soft palate
Teeth
How is the patient positioned for lateral view?Lateral recumbency
Forelimbs extended caudally
Use foam wedge to support head, avoid axial rotation, keep nose parallel to cassette
Which view? Stars mean?
Lateral (normal skull)
White = ethmoid turbinates
Orange = nasal turbinates
Yellow = Frontal sinus
What can be seen on the VD/DV view?Skull
Cranium
Orbits
TMJs
Maxilla
Mandible
Nasal cavities
External ear canals
How is the patient positioned for VD/DV view?Patient in dorsal (VD) or sternal (DV) view
Center on lateral canthus of eye (arrows)
Include entire skull
Which view?
VD OR DV! (normal skull)
Can't tell without labels
Caveat for VD/DV viewMARKERS! structures are bilateral so need to tell which side is which
Label this shit (VD/DV view)
A: Maxilla (superimposed with mandible)
B: Nasal cavities
C: Bony nasal septum
D: Mandible
E: Orbits
F: Temporomandibular joints
G: Tympanic bullae (not ideal view)
H: External ear canals (superimpose with cranium)
I: Cranium
What can be seen with the VD Open-mouth projection of the maxilla?Maxilla
Nasal cavities
How is the patient positioned for the VD Open-mouth projection of the maxilla?Under GA, Dorsal recumbency
Mouth open, maxilla as parallel to cassette/tabletop as possible
Tie mandible, cull caudally
Collimage to show entire maxilla. Beam at 10-20* angle
Which view?
VD open-mouth of maxilla
Benefits of the VD open-mouth projection of the maxillaMandibles not superimposed
Fine bony structures of nasal & ethmoid turbinates visible
What can be seen on the DV intraoral view of the maxilla?Rostral maxilla
How is the patient positioned for the DV intraoral view of the maxilla?Sternal recumbency
Film & screen in oral cavity, corner of film/screen on midline (to visualize more caudal structures)
PLACE L/R MARKER!
Which view?
DV intraoral view of maxilla
What can be seen in the VD intraoral view of the mandible?Incisors
Canines
Rostral premolars
Mandibular symphysis
Rostral part of mandibular rami
How is the patient positioned for VD intraoral mandible?Dorsal recumbency
Forelimbs extended caudally, film screen in mouth
Center so entire rostral manible is included, collimate, place maker
Which view?
VD intraoral of mandible
What are the lateral oblique projections?L 30* Dorsal-R ventral oblique (or L-dors R-vent)
L 30* Ventral-R dorsal oblique (or R-vent L-dors)
L 20* Rostral- R caudal oblique (or R rost-L caudal) (tilted up lateral/sagittal oblique)
What is the point of lateral oblique projections?Project bilateral structrues e.g. tympanic bullae, TMJs, dental arcades, maxilla/mandible with minimal superimposition of corresponding contralateral side
Helpful to perform both sides at a similar angle for comparison
What can be seen on the 30* V-D oblique?Tympanic bullae
Not good for TMJ (joint too oblique)
How is the patient positioned for a 30* V-D oblique?Side of interest closest to the cassette (if want to see R bulla, pt in RLR, beam comes from L)
Lateral recumbency
Degree of obliquity depends on area of interest
Which view?
L30* V-R D oblique for R tympanic bulla
Lucent line = TM joint
L bulla superimposing with skull bones
What can be seen on the 20* Rostral-caudal oblique?TMJ joints better than lat oblique
How is the patient positioned for a 20* Rostral-caudal oblique?Patient lies on side of interest
Nose elevated by 10-30 degrees with triangular foam wedge
Take both sides for comparison
20* Rostral-caudal oblique: how are brachycephalics positioned?Require larger elevation (skulls are broader)
20* Rostral-caudal oblique: What happens to the TMJ joint?Elevation of nose shifts dependent TMJ into vertical position (parallel to x-ray beam), which means the joint space is seen more clearly
20* Rostral-caudal oblique: How is the TMJ projected?Dependent TMJ is cranial to non-dependent
20* Rostral-caudal oblique: patients with lock jaw should?Be radiographed with jaws both OPEN and CLOSED
Which view?
R 20* Rostral-L caudal oblique
R TMJ is rostral
Only the side of interest (rostral) is clearly visible (bulla partially superimposed on caudal, need to radiograph both sides!)
Head rests on cassette
What projections can be done with lateral oblique view?Tympanic bulla & TMJ
Maxilla
Mandible
How is the patient positioned for the lateral oblique view of the TMJ & tympanic bullae?Lateral recumbency, affected side down
TIp nose up, rotate cranium slightly so 'down' tympanic bulla & TMJ projected ventrally
PLACE MARKER (or 2), otherwise label 'down' structure with marker ventral to bulla/TMJ
Which view?
Lateral oblique for tymp bullae & TMJ
Arrows are pointing to?
(Lateral oblique TMJ & bullae, cat)
Orange = Tympanic bullae
Green = TMJ of affected side (down, projected ventrally)
Correct placement of markers prevents confusion!
How is the patient positioned for the lateral oblique view of the maxilla?Lateral recumbency, limbs extended caudally
Mouth opened with radiolucent decie e.g. PVC tube (can use mouth gag but metal opacity sucks)
Rotate patient 45* dorsally, support mandible with foam wedge. Visualized arcade is closest to cassette
Which view is this?
L lateral oblique projection of maxilla
Left arcade is closest to cassette, patient in LLR
Arrow pointing to?
L maxillary dental arcade (interest in maxillary teeth)
Dog radiographed in LLR with mouth open to minimize superimposition
Projection: R ventral-L dorsal oblique
How is the patient positioned for the lateral oblique view of the mandible?Lateral recumbency, forelegs extended caudally
Mouth open
Foam wedge behind cranium to rotate towards the table 20-30*
Metal markers dorsal and ventral to mandible to avoid confusion, label L & R manible rami
Which view is this?
Lateral oblique of mandible
LLR, left side projected ventral
What can be seen with the Open mouth rostrocaudal projection?Tympanic bullae! Minimal superimposition!
Dens axis
Axis/occiput
What do you have to keep in mind with the open mouth rostrocaudal projection?Avoid in animals with atlanto-axial instability
Place ET tube so it does not superimpose with the bullae, or extubate for this projection (be quick!)
How is the patient positioned for the Open mouth rostrocaudal view?Dorsal recumbency
Which views are these (and which species?)
Open mouth rostrocaudal projection
Left: dog
Right: cat
The only way view that allows you to see tympanic bulla in dogs?Open mouth rostrocaudal
To take the Open mouth rostrocaudal projection in a dog, how do you adjust positioning for different breeds?Angle between hard palate and vertical x-ray beam adjusted to project the tympanic bullae
The longer the nose, the more acute the angle
Which techniques are used to image the tympanic bullae in CATS?A: 10* ventro-caudodorsal oblique
B: Open mouth rostrocaudal
What can be seen in the Rostrocaudal frontal sinus view?Frontal sinus (see if involved in nasal disease)
How is the patient positioned for the rostrocaudal frontal sinus view?(Should do lateral view first to scout!)
Dorsal recumbency, legs extended caudally
Mouth closed, nose slightly caudal to vertical, center on dorsum of nose
Which view?
Rostrocaudal frontal sinus
How do you take a rostrocaudal frontal sinus view of a brachycephalic dog?IMPOSSIBLE TO ACHIEVE IN MANY BRACHYCEPHALIC BREEDS who do not have frontal sinus!
Check on lateral view to see if sinus present
Which views are used to see the pharynx & larynx?DV/VD
Lateral: head & neck moderately extended, forelimbs extended caudally
Which views? For what structures?
DV/VD & Lateral
Nasopharynx, oropharynx, laryngopharynx
What are the cartilages of the hyoid apparatus?
Stylohyoid
Epihyoid
Ceratohyoid
Basihyoid
Thyrohyoid
(@ = soft palate, N = nasopharynx, O = oropharynx, L = laryngopharynx)
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