Equine Ultrasonography

Question 1

Transverse scan

Answer 1

• Superficial structures - SFDT
• Can assess margins of structures

Question 2

Answer 2

Transverse scan

Question 3

Longitudinal scan

Answer 3

• Superficial structures - fibre pattern

Question 4

Answer 4

Longitudinal scan

Question 5

Settings for deeper structures

Answer 5

• Inc depth, move focal zones, pos adjust TGC
• Suspensory ligament (SL), check ligament (ALDDFT)
• Transverse scan - relative echogenicity + size
• Longitudinal scan - deeper structures

Question 6

SL branches

Answer 6

• Focal zone(s) - need to be near field - v superficial structures
• Image insertion of branches on proximal sesamoid bones (PSBs)
• Rounded triangular appearance of transverse scan
• Longitudinal = smooth abaxial surface of PSBs as they insert

Question 7

Answer 7

Transverse scan

Question 8

Answer 8

Longitudinal scan - can assess fibre pattern

Question 9

Indicators of tendon + ligament injury

Answer 9

• Size (of tendon/ligament and/or lesion within it). Size can be measured in terms of cross-sectional area (CSA), and some ultrasound machines have a trace function so you can trace the outline of a lesion with the tracker ball, and the machine will calculate CSA for you
• Echogenicity (with lesions appearing hypoechoic)
• Fibre pattern alignment on longitudinal scan
• (Margin can also be also informative if you are looking at a lesion at the periphery of a tendon/ligament).

Question 10

Proximal aspect of palmar metacarpal region (transverse)

Answer 10

• SL, ALDDFT, DDFT, SDFT
• Proximal SL can be difficult to image and may be clearer
  without the standoff
• Sometimes muscle fibres within the PSL can mimic lesions, as they appear hypoechoic. It is important to compare with the contralateral limb, to determine what is normal for any given individual.
• Proximal suspensory desmitis is a common injury in horses, and is diagnosed by a combination of diagnostic analgesia, ultrasonography and radiography

Question 11

Mid palmar metacarpal region (transverse)

Answer 11

• SDFT becomes slightly falttened
• ALDDFT merges w/ DDFT by halfway down MCIII (zone 2B)
• Note the slight hypoechoic appearance of the DDFT at this point, *do not mistake this for a lesion. The SL splits into the medial and lateral branches at the junction of the distal 1/3 and proximal 2/3 of MCIII (zone 3A)

Question 12

Distal palmar metacarpal region (transverse)

Answer 12

• SDTF has a flattened appearance
• DDFT = flattened oval
• Manica flexoria found at around zone 3B. This structure comes off the SDFT
  and wraps around the DDFT, just below the level of the buttons of the splints. The distal extent of it is at the proximal sesamoid bones. It is difficult to see clearly on ultrasound when it is normal, but it is an important structure for you to be aware of, as MF tears are a commonly Dx causes of lameness (esp in cobs + ponies)

Question 13

Fetlock (transverse)

Answer 13

• Zone 3C
• Dx of palmar annular ligament issues e.g. PAL desmitis
• Normal thickness = 1 - 2 mm, should be < 5 mm if you measure from SDFT to skin

Question 14

Proximal palmar metacarpal region (longitudinal)

Answer 14

Question 15

Mid palmar metacarpal region (longitudinal)

Answer 15

Question 16

Distal palmar metacarpal region (longitudinal)

Answer 16

Question 17

MRI of carpus

Answer 17

Question 18

Answer 18

Question 19

Answer 19

Question 20

Answer 20

Question 21

Answer 21

Question 22

Answer 22

Swelling on palmaroproximal aspect of flexor tendons

Question 23

Answer 23

• Large area of reduced echogenicity within SDFT
• Dx = core lesion within SDFT

Question 24

Answer 24

• Area of reduced echogenicity within the proximal suspensory ligament w/ enlargement of the ligament + irregular margins
• Dx = proximal suspensory desmitis