Articles - Distal limb Flashcards
What TE (echo time) for T2 FSE eliminates the effects of the Magic Angle in the collateral ligaments of the distal interphalangeal joint?
140ms
What TE (echo time) for T2 FSE is recommended to mitigate the Magic Angle effects of the collateral ligaments of the distal interphalangeal joint BUT still keep adequate contrast?
120ms
The advantage of a long TE (echo time) for T2 FSE is helpful due to the minimization of the magic angle… but what do you lose?
Reduces SNR and contrast
Thus you lose the ability to see small lesions
Also, fibrous scarring will typically be decreased in intensity and there for a high TE will lose the ability to see it. (only shows hyperintense on low TE)
Heterogeneous intensity in the collateral ligaments of the distal interphalangeal joint likely due to?
Difference in fiber orientation and density throughout the ligament structure.
Big difference between tendons which have a straight fiber orientation.
What layers does the less opaque layer of the hoof correlate with?
Stratum lamellatum - epidermis
Stratum retculare - dermis
Inter and intraobserver correlation for DR and MRI for assessment of the equine hoof was?
DR = 0.98 MRI = 0.99
Avg sole thickness?
~13mm
What ligament is the largest (cross sectional area) in a new born; suspensory, DDF or SDFT? When does this change?
Suspensory is the biggest.
This changes at the origin at 2months
This changes at the body at 5 months
At what age is the most change seen in the CSA (cross sectional area) in the DDF?
2-5 months
At what age is the most change seen in the CSA (cross sectional area) in the SDF?
10-15 months
Increased in palmar compact bone of the navicular was seen correlated with what lesions on MRI?
DDFT lesions
Collateral sesamoidean ligament lesions
Lesions of the navicular bone (medulla and prox compact bone)
Long toed horses had a high incidence of lesions involving what on MRI?
Spongiosa and proximal border of the navicular bone
Elongation of the navicular bone was associated with lesions on MRI?
Proximal and distal injuries of the navicular bone
Reduction in palmar angle and increased angle of the distal interphalangeal joint was associated with what lesions on MRI?
Collateral lig of the distal interphalangeal joint
Navicular spongiosa
Classification and regression trees (CARTs) can be to correlate radiographic findings with MRI at what percentage of accuracy?
> 80%
What does prodromal means?
Changes or signs before something happens
What percentage of parasagittal P1 fractures were prodromal changes noted in TB racing horses?
14%
Are parasagittal P1 fractures in TB racing horses monotomic or stress fractures?
BOTH
Since 14% show prodromal changes then 14% might be stress related.
What are the three classifications of parasagittal fractures of P1?
Short incomplete
Long incomplete
Complete
They are all articular
What is a short incomplete parasagittal fracture?
<30mm
What is a long incomplete parasagittal fracture?
> 30mm
Where are most prodromal changes seen in P1?
Dorsoproximal aspect of P1
- thickening of the proximal subchondral bone plate
When comparing CT to radiographs; which is better at finding the fracture? What is the intermodality agreement?
CT is better. Identified more fractures.
Intermodality agreement was 56%
When was intermodality agreement good when comparing CT and rads in distal limb fractures?
Which bone is involved
Localization within the bone
Did fractures become more complicated in P1 fractures in 120 TB racehorses?
Yes - their complete complexity could not be assessed on initial radiographs.
Is there seasonality to P1 fractures in TB racing horses?
Yes - only seen in 2-3 year olds
March - October
The seasonality of P1 fractures in TB racing horses likely correlates with what?
UK turf racing
What percentage of TB racing horses were in training when fractured their P1?
92%
Most common configuration of the P1 fractures is?
Long incomplete parasagittal
Fracture of P1 that coursed further distally past the middle third of the diaphysis usually turned which way?
Laterally.
Where did most delayed unions take place in P1 fractures?
proximal portion of the fracture
- suggest this is from prodromal changes
Articular comminution of proximal P1 fractures was?
20% - more common than previously thought.
The sensitivity for contrast enhanced CT finding DDFT lesions?
93%
What area of the DDFT had the lowest detection rate on contrast enhanced CT?
Immediately adjacent to the navicular bone
Does regional limb perfusion of gadolinium contrast cause good enhancement on MRI?
Yes
How much gadopentetate dimeglumine was administered in the regional limb perfusion for MRI evaluation? Was anything else mixed with it?
5ml
Yes - 5 ml of saline
What vein was used to MRI enhanced regional limb perfusion for injection of gadopentetate?
palmar/plantar digital vein
Where was the tourniquet placed in the MRI enhanced regional limb perfusion study?
Mid aspect of 3MC or 3MT
Where there lesion exclusively seen following contrast enhanced regional limb perfusion?
Yes - 12/144 lesions
Total of 92/144 lesions (64%) contrast enhanced
Short frontal plane fractures involving the dorsoproximal articular surface of P1 are likely on what side?
Medial - like 95%
Short frontal plane fractures involving the dorsoproximal articular surface of P1 are most common in what type of horse?
TB racing
Can short frontal plane fractures involving the dorsoproximal articular surface of P1 be bilateral?
Yes
What is the best views to use to see frontal plane fractures ivolving the dorsoproximal articular surface of P1?
Laterals
DLPMO - 70-80 degrees
The obliquity of the frontal plane fractures involving the dorsoproximal articular surface of P1 were described as?
Extending from proximal palmar/plantar to distal dorsal
Majority of short frontal plane fractures involving the dorsoproximal articular surface of P1 at seen in which feet?
Hind limbs
What is the half-life of 18F- sodium fluoride used in PET scan of the equine distal limb?
2 hours
Compare that with 6 hours of 99m Tc MDP
How long after 18F - Sodium fluoride was injected was the distal limb images obtained?
45min
Compare this to 2-3 hours in a bone scan
The effective dose for 18F-NaF (sodium fluoride) is increased or decreased when comparing to 99mTc MDP
50% reduction
Whats the primary advantage of PET vs scintigraphy?
Cross-sectional imaging
Higher spatial resolution
Adding additional palmarprox-palmarodistal obliques increases or decreases your specificity or sensitivity in finding cortical lesions in the navicular bone on radiographs?
Improves sensitivity
Decreases specificity
Also improves:
- Interobserver agreement
- Confidence
- Accuracy finding a lesion
- Accuracy in grading a lesions severity
Alternate angle that is suggested for additional palmarprox-palmarodistal obliques of the navicular bone are what?
Flatter angles = ~35-45 degrees
Regular angle is 55-65 degrees
What are the four layers of the hoof?
Stratum externum (tectorium) Stratum medium Stratum internum (lamellatum) Dermis parietis (corium)
Superficial layer of the hoof (more radiopaque layer) is made up of what layers?
Stratum externum (tectorium) Stratum medium
Deep layer of the hoof (more radiolucent layer) is made up of what layers?
Stratum internum
Dermis parietis
What percentage of the hoof is normal the superficial layer of the hoof (more radiopaque layer)?
65% - Mean
55-71% - range
Where do most of the laminitic changes occur in the hoof aka what layers?
Stratum internum (lamellatum) Dermis parietis (corium)
What is the threshold value for the absolute thickness of the dorsal hoof wall?
20mm
What type of needle is used in MRI guided injections?
Titanium - 16g
Injection success with MRI guidance into the DDFT was evaluated using gross pathology and MRI. What was the success rate in both?
70% proximal and 100% distal for the Gross
60% proximal and 70% distal in the MRI
What sequence was used in MRI guided DDFT injections?
T1
Was there a difference in accuracy in MRI guidance when injecting the medial or lateral lobes of the DDFT?
NO
What was the avg time it took for MRI guided injections of the DDFT?
6-17min
In MRI of navicular bursa adhesions they divided adhesions into three types… what were they?
Type 1: Discontinuity of the bursa fluid signal
Type 2: Bursa fluid was disrupted and an ill-defined tissue was present.
Type 3: Bursa fluid was disrupted and an well-defined tissue was present.
MRI for navicular bursa adhesions had a positive predictive value for each type of adhesion classification…what were they?
Type 1: 50%
Type 2: 67%
Type 3: 100%
Are other podotrochlear lesions common with navicular bursa adhesions? If so, what are they?
Yes Lesions were seen most commonly in the: #2 - DDFT #1 - Navicular bone Collateral sesamoidean ligaments distal sesamoidean impar lig.
How are adhesions made?
Erosions in the fibrocartilage of the navicular bone and fibrillation of the dorsal surface of the DDFT
What are the best sequences to evaluate the navicular bursa for adhesions?
PD
STIR
T2 was alright too
What sequence is terrible for looking at the navicular bursa for adhesions?
T1 (27% were seen)
Why might there be less adhesion noted at surgery than on MRI?
When you go in the bursa you are probably tearing some of the adhesion.
MRI also makes up shit due to volume avg
What views (dorsal, sagittal or transverse) should you use to evaluate the navicular bursa?
Sagittal and transverse
Dorsal is trach and only 21% of adhesions could be found.
What is the T ligament?
A piece of tissue in the proximal pouch of the navicular bursa connecting the DDFT and the collateral sesamoidean ligaments
Hypertrophy of this ligament can be seen
Do horses need to have joint swelling or be lame to have sagittal groove injuries of P1?
No
Most common P1 injuries noted in warmbloods on low field MRI?
Incomplete short mid-sagittal fractures
Osseous cyst-like lesions
Subchondral bone loss
Contusions
Injuries noted in the P1 sagittal grove consistent with acute or chronic injuries?
Chronic, from repetitive motion
80% had osteoarthritis
What does hyperintense signal on STIR mean?
Edema Hemorrhage Necrosis Fibrosis Degeneration Microdamage Bone remodeling
What percentage of warmbloods with sagittal groove injuries were still lame at time of follow-up MRI?
69%
What is the most common cause of septic arthritis in an adult horse?
Trauma - Penetrating wounds = most common source
Synovial injections
Post operative
Do all septic arthritis cases look similar?
No
What is the biggest factor that determines how septic arthritis will look on US?
Time from start of clinical signs to time of ultrasound
The majority of horse in the “Ultrasound of septic synovitis in horses” had what changes on radiographs?
None
Majority of horses have what changes on US when looking at septic arthritis?
Marked degree of effusion
Severe synovial thickening
Synovial fluid could be echogenic or anechoic
What radiopharmecutical is used in PET of the distal limb?
18F-Fluorodeoxyglucose (1.5-2.9 Mbq/kg)
Where was the highest uptake of 18F-FDG in the distal limb of the horse?
Coronary band
Where was the lowest uptake of 18F-FDG in the distal limb of the horse?
Bones and tendons
When did the horses in Spriet’s study on PET scan in anesthesized horse get to a level (2mRem/h) where they could be released?
8 hours vs 24 hours in scinitgraphy
What was the difference in image quality between 1.5 mBq/kg and 3.0 mBq/kg of 18F- FDG
Nothing… speaks to possible dose reduction
Where do most injuries occur when a horse experiences a solar foot penetration?
Distal border of the navicular bone
Facies flexoria
DDF was involved in all horses in the study (schiavo 2018)
Scintigraphic uptake at the fascies flexoria correlates well with what?
A lesion in the DDF, WHERE EVER its location.
Compact bone thickening at the fascies flexoria is a sign of podotrochlear syndrome?
NO. Erosion of the fascies flexoria may have correlation with navicular bursitis due to the correlation between erosions and synovial proliferation of the navicular bursa.
Can horses have a good outcome with solar penetrating wounds that involve the DDF but are not septic?
YES
Basically many other studied said involvement of the DDF was a death sentence.. This paper says that may not be the case if sepsis is not noted.
What is the “street nail” procedure?
Making a radical excision of the penetrating tract and resection or fenestration of the DDF
What is the best sequence for seeing solar penetrating wounds?
T2* - can pick up hemorrhage with good contrast
What is the best orientation for observing solar penetrating wounds?
Transverse plane
The most common limitation for finding solar penetrating wounds on MRI was what?
Motion artifact
When was the penetrating solar wound most likely to be visualized?
In the first 7 days.. this is statistically significant
What was the most common reactions to ultrasonographic contrast in horses was?
Increase in systolic pressure
Increase respiration rate
Is the venous system or the arterial system better for injecting ultrasonographic contrast in horses for visualization of the distal limb?
intra arterial
LATERAL PALMAR DIGITAL Arteries
What do horses have in their pulmonary vasculature that may make them more susceptible to ultrasonographic contrast?
Pulmonary intravascular macrophages
This is why a horses shock organ is the lungs
Besides better visualization what is another advantage in using the arterial system instead of the venous system when injecting ultrasonographic contrast in a horse’s distal limb?
Less dose need (10x less)
