Imaging in Lameness Flashcards
What are indications for Diagnostic imaging?
- Acute or chronic lameness
- Skeletal or joint pain
- Fracture confirmation/characterisation
- Swelling centred on bones/joints
- Monitoring/screening for inherited musculoskeletal disease
- Metabolic bone disease
- Evaluation of systemic disease
What are different diagnostic imaging techniques?
- Radiographs
- Ultrasound
- CT + MRI
- Scintigraphy
What are limitations of radiography?
- Oblique projections can create apparent artefactual lesions
- Poor soft tissue contrast resolution
- Geometric distortion if structure at edge of collimated area + not parallel to film
- Need 2 projections 90o to each other so that you don’t miss anything
What is serial radiography?
- Monitor progression of disease
- Useful if diagnosis is uncertain
What are rontgen signs?
- Number
- Size
- Shape
- Location
- Opacity
What are specific assessments in musculoskeletal cases?
- Soft tissues = swelling / loss
- Bones =
-Alignment, shape, length
-Periosteal reaction / cortical lysis / defects
-Endosteal / medullary changes
-Physes (growth plates) - Joints =
-Swelling / effusion
-Subchondral bone
-Periarticular changes
What can cause reduced size in soft tissues?
- Atrophy (focal) =
-lameness
-neurogenic
-fibrosis/scarring - Weight loss (general)
What can cause increased size in soft tissue?
- Focal =
-Trauma
-Abscess / seroma
-Granuloma
-Neoplasia - Diffuse =
-Oedema
-Cellulitis / vasculitis
-Diffuse neoplasia
What is the anatomy of long bone?
- Out to in =
-Periosteum
-cortex
-Endosteum
-Medulla - Epiphysis - right next to joint
- Diaphysis = shaft
- Metaphysis = near growth plate
What can cause reduced opacity in bone?
- Artefactual - if overexposed
- Nutrition
- Neoplasia
- Osteomyelitis
What can cause generalised bone loss?
- Nutritional = 2o Hyperparathyroidisim
What can cause localised bone loss?
- Neoplasia
- Osteomyelitis
With joints what should be assessed?
- Soft tissue swelling
- Joint ‘space’ width
- Subchondral bone opacity
- Osteophyte / enthesophytes
- Periarticular mineralisation
What may joint effusion not be distinguishable from? What is the exception?
- Joint effusion + Periarticular swelling may look similar
- Stifle joint - surrounded by fat = contrast = easier to identify a joint effusion of the stifle
Why can’t cartilage be seen on radiograph?
- Same opacity as muscle / soft tissue
What can cause subchondral bone changes (defects)?
- Osteochondrosis
- Aseptic necrosis (femoral head)
- Septic arthritis
- Erosive arthritis (carpus/tarsus)
- Soft tissue neoplasia
- Trauma (avulsions)
- Osseous cyst like lesions
- (Osteoarthritis only if very severe)
What are mineralised bodies around joints?
- Sesamoids
- Accessory centres of ossification
- Incidental? - tendinopathies
- Pathological - osteochondral fragments
What are differential diagnosis for radiographic signs? (VITAMIND)
- Vascular
- Infectious/Immune-mediated
- Traumatic, toxic
- Anomalous
- Metabolic
- Idiopathic
- Neoplastic, nutritional
- Degenerative/Drug induced
Where is osteochondrosis more likely to be seen?
1.Caudal aspect humeral head
2.Medial part humeral condyle
3.Lateral femoral condyle
4.Medial trochlear ridge talus
Where are osteosarcomas likely to be seen?
1.Proximal humerus
2.Distal radius/ulna
3.Distal femur
4.Proximal tibia
- Towards knee away from the elbow
What are benefits of ultrasound?
- Muscles, tendons, ligaments well visualised
- Bone surface seen
- used for shoulders + Tarsus (calcaneal tendon) often
What area of bone do primary tumours tend to arise from?
- Metaphyseal area - osteosarc
- Usually monostotic - one bone
What tumours near joints can damage bones?
- Synovial cell tumour
- Histiocytic sarcoma
