LEC 22 - Equine Radiology Intro Flashcards
When is ultrasound used in horse imaging of legs?
Therapy - joint injections
What is the MRI the best for looking at?
The hoof, or soft tissue damage
When is radiology used in a lameness case?
Once lameness is localized to a specific region. most useful for bones and joints.
How much change in bone must be present before you can see it on x-ray?
40% at least. Which is why there is a latent period with stress fractures.
What can be seen in legs when you use contrast for radiographs?
Soft tissue and synovial structures. Can see if there is a leak in the bursa.
What type of view is MOST important when taking radiographs?
Orthogonal views. at right angles, Oblique views as well.
What does the radiological view describe?
Point of entrance to point of exit of x-ray beam
What are the four major radiographic views taken?
Lateral-medial, Dorso-plantar, DLPMO, and DMPLO
With orthogonal views how much of the bone can be seen?
~ 50% of their surface
How do you make an orthogonal view look at 100% of the bones surface?
Take oblique views at a 45 degree angle to the dorsal aspect of the limb.
Where should the marker always be placed on a radiograph?
Lateral side of the limb
What is a ultrasonography?
2D multi-planar imaging technique based on passage of sound waves and principles of sound-tissue interaction
What is U/S a primary modality for?
Soft tissue structure (but also used to determine bone remodeling and ligamentous insertion sites on the bone)
What functional assessments can you get out of U/S?
Doppler and elastography for tendons and ligaments
What does U/S doppler tell you?
Blood flow
What does an elastography tell you?
Tissue strain
What compound is important for MRI’s to make an image?
Hydrogen
How does an MRI produce an image?
Exciting hydrogen nuclei at a specific radiofrequency within magnetic field. Then it detects the energy released by the nuclei as they relax.
How are MRI’s carried out on a horse?
Standing or under general anesthesia
What is MRI the gold standard for?
Seeing soft tissue structures within the hoof
What pathologies is MRI really good at finding?
Occult fractures, articular cartilage damage, and subchondral bone remodeling
If you see a brightness or increased amount of white on an U/S of a joint what could it mean?
Fluid signal - edema or inflammation
Why is CT better then radiographs?
No superimposition
What is CT good for?
Pre-operative planning for fracture repair or molar extraction. Can make a 3D recoonstruction of the image.
How does a nuclear scintigraphy work?
Radionucleotide coupled with diphosphate carrier injected IV. Thought to bind to exposed hydroxyapatite crystals in areas of bone remodeling or soft tissue mineralization. Emit gamma radiation.
What three phases can be used for nuclear scintigraphy?
Vascular, soft tissue, and bone
When is vascular N/S taken?
Immediately after injection
When is soft tissue N/S taken?
30 to 60 minutes after injection, have to pick a region and shoot there only because it leaves soft tissue so quickly.
When is bone N/S taken?
~ 90 minutes after injection
When is a N/S bone scan most likely done?
Obscure lameness or multiple limb lameness. When a radiograph shows no issues but horse is obviously lame.
What state does the horse have to be in for N/S?
Standing sedation (don’t want patient to move)
What is important to know about the N/S technique when it comes to safety?
The drug is metabolized in the kidney so urine will be contaminated with radiation. Will need to be in a special stall for about 24 to 36 hours.
What can thermography be used for?
Detect inflammation or vascular damage of the limbs
What can effect a thermograph reading?
Environmental temperature, air flow, length of horse hair, previous bandaging, etc.
