Exam 3 Flashcards
(18 cards)
Lecture 37
SA Skull lecture with cases (37)
Know the limitations of radiographic evaluation of the skull.
Know how to tell MR images from CT images and recall the different CT windows and meaning of CT numbers.
Presented in lecture 30-CT windowing
Know how to make and name the standard radiographic projections of the skull.
Know the required images for assessing the nasal cavity
Be familiar with naming and interpreting oblique radiographic projections
Understand the indications and advantages of using CT vs. radiography for the skull.
Understand the problems and trends with differentiating between infection and neoplasia on skull radiographs.
Be familiar with the case material presented in lecture to the extent you can recognize the radiographic changes when given a case study.
Know how the brain appears on T1, T2 w images. See
What are some of the reasons why skull radiographs are a challenge?
Compare radiographs to CT
- Lack of anesthesia
CT
-Great for nasal cavity
-Superior for HBC and nasal tumor
How many projections and which ones are best?
Lateral and VD
Head superimposition
-Jaw drops and rotates, so need something underneath it, like a sponge
-Hard palate needs to be parallel to cassette
VD view with open mouth why?
-So that we can see nasal cavity
-Money view: “open mouth, ventral 20 degrees rostral caudal” the beam is aimed 20 degrees parallel to plate
Frontal view to look at the sinuses, use for HBC, nasal cases
-Beam parallel to dorsum of nose
Case 1 3 year old DSH
-Views are ok
-Rostral to caudal: shows opaque, should have more air
-One side of the nasal cavity is more radiopaque
-Does not seem to be any bone loss
-Cribiform plate, the upside down V
-DX unilateral nasal opacity
Findings
-Rhinitis
-It could have been a tumor, but difficult to tell if slow growing
Compare Rhinitis vs. Neoplasia
Rhinitis
-Little or no osseous destruction
-Focal ST opacity
-Lack of sinus involvement
Neoplasia
-Almost always destruction surrounding of the bones
-ST opacity entire ipsilateral nasal cavity
-Sinus involvement
There is overlap between rhinitis and neoplasia
Fluid Opacity/Soft tissue
-Opacity in cats in frontal sinus, obstruction, mucus build up
3 yr old dog with chronic rhinorrhea
-Concave lysis (little bitty holes)
-Pucntate lysis
-Vohmer bone
-Conchal destruction and inflammatory mass
DX: destructive rhinitis from Aspergillus spp. **Difficult to distinguish from neoplasia.
-Aspergilloma
6 yr old Lab with serosanguinous nasal discharge
Findings
-Really common not to make radiographs right away, usually treat with antibacterial and when they don’t get better then you know maybe neoplasia or fungal.
CT bone window
-Ethmoidal bone gone due to tumor
-Marked destruction of maxillary plates
-Dx can be wrong. Depending on age is the most accurate guess about whether it is or not neoplasia
Nasal tumors
-Chondrosarcoma: usually in the turbinate bones, calcified.
Two cases with calvarial masses
-10 yr old with skull mass
-Old collie history of draining tract: foreign body (stick embbeded right next to skull) osteomyelitis
Bones only do two things, get sick or lose or get sick and gain bone
Cat with nasolaryngeal issues
-Mass inside and outside the angle of the mandible, gotta look for it
-No air in the nasopharynx, probably not fluid, it is a mass though same opacity
CT NP polyps
-Nasopharynx
-Rhinitis and sinusitis going on
9 yr old swollen painfuful
-Craniomadibular osteopathy: thick skull thick jaw
-They get better, but can interfere with mastication
One of the most common dental disease
-Lysis around the tooth
-Periapical abscess
-Lamina dura is gone and the periodontal space is too wide
Left is dorsal Ventral is right
Dental radiography slide 42
-Rt bulla, has something in it, can be soft tissue, fluid
-HU = 45-50
-Bone window: bone looks thinner, digital artifact.
-Soft tissue: bone looks wider
How do you compare T2 vs. T1.
T2: is CSF is bright
T1: if CSF is dark
Lecture 38
Lateromedial projection
-No angle involved
-Beam going from lateral to medial
-Talus ridges superimposed perfectly
-LM
Dorsoplantar projection
-DP
-Calcaneus
-Talar ridges
-Beam enters and exiting plantarly
Obliques
Dorsolateral plantaromedial oblique
-Going in dorsal and lateral and exiting medial and plantar
-Picks dorsal medial edge and plantar lateral edge, tangent
Dorsomedial plantarolateral oblique
-Picks Dorsal lateral edge
-Plantar medial edge
DLPM = Dorsomedial, Plantarolateral
CT of the digits
-Mainly to look at fractures, complex
-Usually take right to surgery bc already anesthetized
Nuclear Imaging
-Radioactive compound emits gamma rays
-Picture of a hot tooth, alveolar perialveolar abscesses, bone turnover, osteoclasts.
MR Imaging
-Can see soft tissue even better than bones
-Carpal ligaments, some blood vessels, SDFT, DDFT.
Ultrasound
-Tendon, ligaments, large joints
-Require extensive knowledge base
- There is no reference with ultrasound you are just looking at a little tiny window.
-Most lesions are hypoechoic, edema, necrosis, are dark in an ultrasound
Lecture 39
6 yr old QH bilateral heel pain and forelimb lameness…
-Presumptive Dx: Navicular syndrome
“Money view” = upright pedal. Dorsoproximal-palmarodistal
-80 degrees best
-Other options, 90 degrees, 45, 65.
Second most important view = Navicular skyline
-Palmaroproximal-palmarodistal oblique
-Foot back
-Picks off flexor cortex and medullary cavity
