Diagnostic imaging of lame horse

Question 1

Intrathecal analgesia

Answer 1

Joints, bursae, tendon sheaths

Question 2

Blocks are not

Answer 2

Lasers

-may need to image adjacent structures

Question 3

If you can localize lameness

Answer 3

Bone scan
Neurologic
-Neuro exam
-Cranial and/or cervical imaging

Question 4

Radiography indications

Answer 4

1. Lame
2. Trauma
3. Infection
4. Screening
5. Eval healing

Question 5

Radiography pros

Answer 5

1. Technically simple
2. Inexpensive
3. Portable

Question 6

Radiography cons

Answer 6

1. Ionizing radiation
2. Limited by anatomical thickness
3. Limited contrast resolution: limited for soft tissue eval

Question 7

Portable machine settings

Answer 7

10-30 mA; 70-90 kVp

• Skull
• C spine
• Up to stifle/shoulder

Question 8

Marker always

Answer 8

Dorsal or

Lateral

Question 9

Myelography indication

Answer 9

Spinal cord compression DDX

• CVM (Wobblers)
• Trauma

Question 10

Arthrography/Bursography Indicationts

Answer 10

1. Determine communication with a wound
2. Eval adjacent structures
   - ligaments
   - joint capsule
   - tendons
   - cartilage

Question 11

Fistulography indications

Answer 11

1. Determine extent of wound and structures involved
2. Look for source of draining tract
   - FB, sequestrum

Question 12

Ultrasound indications

Answer 12

1. Ush second diagnostic step after rads
2. Suspected soft tissue injury
   - heat, swelling, pain on palpation tendons and ligaments
3. Trauma
   - limited by SC gas, best with intact skin
4. Guidance for intrathecal or intralesional injection

Question 13

Ultrasound Pros

Answer 13

1. Portable
2. Relatively inexpensive
3. No radiation
4. Good soft tissue eval
5. Great for serial eval-healing/progression

Question 14

Ultrasound cons

Answer 14

1. VERY user dependent
2. Limited Osseous eval
3. Limited depth of penetration

Question 15

Ultrasound procedure

Answer 15

1. Always image in two planes: long and transverse
2. Contralateral limb for comparison
3. Consistent labeling
   - Zones
   - Distance from point of hock or accessory carpal bone
   * Proximal to left, LF: lateral to left, RF: medial to left

Question 16

High frequency transducer

Answer 16

best resolution, less penetration

Question 17

Low frequency transducer

Answer 17

deeper penetration but poorer resolution

Question 18

7-12 MHz probe

Answer 18

Penetrates 5-7 cm

Question 19

5 MHz probe

Answer 19

Penetrates about 12-14 cm

Question 20

2-3 MHz probe

Answer 20

Penetrates 20-30 cm

Question 21

Depth knob

Answer 21

• Determines field of view

- Limited by frequency range of transducer

Question 22

Focal zone knob

Answer 22

• Point of greatest resolution of sound beam

- Change every time you change depth

Question 23

Gain knob

Answer 23

• Amplifies returning echoes

- TGC allows you to adjust gain by region

Question 24

Image interpretation

Answer 24

1. Size
2. Shape
3. Echogenicity
4. Margins
5. Fiber pattern

Question 25

Hyperechoic

Answer 25

Bright - Scar tissue - Mineralization

Question 26

Hypoechoic

Answer 26

Dark - Fiber disruption - Diffuse edema vs core lesion

Question 27

Nuclear scintigraphy

Answer 27

``` Binds to osteoblast act Vascular phase Soft tissue phase Bone phase *Images displayed as if looking at the horse *Sensitive, not specific ```

Question 28

Nuclear scintigraphy indications

Answer 28

1. Subtle/multiple limb lameness 2. Poor performance/unlocalized lameness 3. Assess hard to access areas 4. Whole body scan 5. Assess tissue viability

Question 29

MRI indications

Answer 29

1. Most complete eval-gold standard 2. No abnormalities on rads or US 3. Patient not responding to empirical tx 4. Early intervention needed - confirmation septic arthritis/osteomyelitis - +/- IV contrast

Question 30

MRI Pros

Answer 30

1. Gold standard for MSK 2. Excellent soft tissue contrast resolution - great anatomical detail 3. Sensitive for bone signal - bone edema/hemorrhage/necrosis

Question 31

MRI Cons

Answer 31

1. Expensive 2. Limited availability 3. Extremely limited by anatomy 4. General anesthesia 5. Specific targeted exam 6. Expertise req'd for interpretation

Question 32

MRI: the more detailed blocking pattern equals

Answer 32

More accurate MRI

Question 33

MRI High field (1-3T)

Answer 33

1. Mild lameness/subtle injury suspected 2. Joint dz is a major DDX 3. Lameness localizes to proximal to foot 4. Most amount of info

Question 34

MRI low field standing ( < 1 T)

Answer 34

1. Anesthesia contraindicated, not worth it 2. More severe injury suspected 3. Lameness reliably located to foot 4. Serial recheck exams

Question 35

CT indications

Answer 35

1. Characterize osseous injury 2. Surgical planning-fx repair/osseous debridement 3. Assess vascularity 4. Limited info about articular cartilage 5. Guidance FNA, BX

Question 36

CT Pros

Answer 36

1. Exam quick - less recumbency/anesthesia - can go directly to sx/tx 2. Less expensive than MRI - exam and anesthesia time

Question 37

CT Cons

Answer 37

1. Ionizing radiation 2. Anesthesia 3. Less soft tissue detail than MRI 4. Limited by anatomy - no shoulders/pelvis/thorax/abdomen/axial skeleton in adults