LEC 22 - Equine Radiology Intro

Question 1

When is ultrasound used in horse imaging of legs?

Answer 1

Therapy - joint injections

Question 2

What is the MRI the best for looking at?

Answer 2

The hoof, or soft tissue damage

Question 3

When is radiology used in a lameness case?

Answer 3

Once lameness is localized to a specific region. most useful for bones and joints.

Question 4

How much change in bone must be present before you can see it on x-ray?

Answer 4

40% at least. Which is why there is a latent period with stress fractures.

Question 5

What can be seen in legs when you use contrast for radiographs?

Answer 5

Soft tissue and synovial structures. Can see if there is a leak in the bursa.

Question 6

What type of view is MOST important when taking radiographs?

Answer 6

Orthogonal views. at right angles, Oblique views as well.

Question 7

What does the radiological view describe?

Answer 7

Point of entrance to point of exit of x-ray beam

Question 8

What are the four major radiographic views taken?

Answer 8

Lateral-medial, Dorso-plantar, DLPMO, and DMPLO

Question 9

With orthogonal views how much of the bone can be seen?

Answer 9

~ 50% of their surface

Question 10

How do you make an orthogonal view look at 100% of the bones surface?

Answer 10

Take oblique views at a 45 degree angle to the dorsal aspect of the limb.

Question 11

Where should the marker always be placed on a radiograph?

Answer 11

Lateral side of the limb

Question 12

What is a ultrasonography?

Answer 12

2D multi-planar imaging technique based on passage of sound waves and principles of sound-tissue interaction

Question 13

What is U/S a primary modality for?

Answer 13

Soft tissue structure (but also used to determine bone remodeling and ligamentous insertion sites on the bone)

Question 14

What functional assessments can you get out of U/S?

Answer 14

Doppler and elastography for tendons and ligaments

Question 15

What does U/S doppler tell you?

Answer 15

Blood flow

Question 16

What does an elastography tell you?

Answer 16

Tissue strain

Question 17

What compound is important for MRI’s to make an image?

Answer 17

Hydrogen

Question 18

How does an MRI produce an image?

Answer 18

Exciting hydrogen nuclei at a specific radiofrequency within magnetic field. Then it detects the energy released by the nuclei as they relax.

Question 19

How are MRI’s carried out on a horse?

Answer 19

Standing or under general anesthesia

Question 20

What is MRI the gold standard for?

Answer 20

Seeing soft tissue structures within the hoof

Question 21

What pathologies is MRI really good at finding?

Answer 21

Occult fractures, articular cartilage damage, and subchondral bone remodeling

Question 22

If you see a brightness or increased amount of white on an U/S of a joint what could it mean?

Answer 22

Fluid signal - edema or inflammation

Question 23

Why is CT better then radiographs?

Answer 23

No superimposition

Question 24

What is CT good for?

Answer 24

Pre-operative planning for fracture repair or molar extraction. Can make a 3D recoonstruction of the image.

Question 25

How does a nuclear scintigraphy work?

Answer 25

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.

Question 26

What three phases can be used for nuclear scintigraphy?

Answer 26

Vascular, soft tissue, and bone

Question 27

When is vascular N/S taken?

Answer 27

Immediately after injection

Question 28

When is soft tissue N/S taken?

Answer 28

30 to 60 minutes after injection, have to pick a region and shoot there only because it leaves soft tissue so quickly.

Question 29

When is bone N/S taken?

Answer 29

~ 90 minutes after injection

Question 30

When is a N/S bone scan most likely done?

Answer 30

Obscure lameness or multiple limb lameness. When a radiograph shows no issues but horse is obviously lame.

Question 31

What state does the horse have to be in for N/S?

Answer 31

Standing sedation (don’t want patient to move)

Question 32

What is important to know about the N/S technique when it comes to safety?

Answer 32

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.

Question 33

What can thermography be used for?

Answer 33

Detect inflammation or vascular damage of the limbs

Question 34

What can effect a thermograph reading?

Answer 34

Environmental temperature, air flow, length of horse hair, previous bandaging, etc.