Other: Imaging Flashcards
How can a bone scan be used to monitor arthritis activity?
Can show increased vascularity around joints which accompanies synovitis
What is an avulsion fracture?
Avulsion of soft tissue fragments cause fracture of the bone
How could you tell the difference between a 5th MT base fracture in an adolescent and the normal anatomical accessory ossification centre?
Ossification centre is longitudinal, 5th MT base fractures are transverse
Arrow = normal apophysis, arrowheads are other ossification centres
What is bone sclerosis?
Increased bone density
What is an impacted fracture?
Axial force through the bone impacts the two bone ends together, so the bone appears sclerotic
What does cortical involvement indicate when imaging a potential bone tumour?
Aggressive tumour and surgery should be considered before the tumour causes a pathological fracture
What causes the loss of joint space in osteoarthritis?
Aymmetric cartilage wear leads to asymmetric joint space reduction
What is the fabella?
Sesamoid within the lateral head of gastrocnemius, often visible posterior to the distal femur
What does Codman triangle indicate when imaging a potential bone tumour?
Periosteal reaction which suggests a more slow-growing tumour
Which joints are commonly affected in Reiter’s syndrome?
Scattered large lower limb joints, lower limb entheses
What is the mechanism of injury in a spiral fracture?
Occur due to torsional (twisting) forces
What causes subchondral cysts in osteoarthritis?
Synovial fluid dissects into bone, forming cysts
What might be mistaken for a fracture of the posterior calcaneus in a child?
Fragmented accessory ossification centre
How can US be used to monitor arthritis activity?
Colour Doppler US can show thickening of synovium and increased blood flow within it
Name the x-ray views used to image the cervical spine
AP, lateral, odontiod peg (mouth open)
What is the mechanism of injury in a comminuted fracture?
Generally a reflection of a higher energy injury (or poor bone quality)
What is the mechanism of injury in an oblique fracture?
Occur with a shearing force
What causes osteopenia in rheumatoid arthritis?
Hyperaemia causes bone demineralisation resulting in periarticular osteoporosis
What is a segmental fracture?
Very unstable fracture that occurs when the bone is fractured in two separate places
What are technetium bone scans useful for in imaging trauma?
Can be useful to detect stress fractures (e.g. hip, femur, tibia, fibula, 2nd metatarsal) as these may fail to show up on x-ray until hard callus begins to appear
If a bony ring e.g. pelvis is injured, what should you be looking for on x-ray?
Two or more disruptions (fractures/dislocations)
What is the best modality for imaging sciatica?
MRI - shows all disc prolapses, and even the preceeding disc dehydration
What causes subchondral sclerosis in osteoarthritis?
Increase in subchondral bone vascularity and cellularity drives new bone formation, leading to sclerosis of subchondral bone
What is the mechanism of injury in a transverse fracture?
Occur with pure bending force where the cortex on one side fails in compression and the cortex on the other side in tension
Rounded sesamoid bones always present on the medial and lateral plantar aspect of which digit of the foot?
1st metatarsal head
Which joints are commonly affected in ankylosing spondylitis?
Scattered large lower limb joints
What is the ostrigonum?
Accessory ossification centre commonly seen posterior to the tallus
What is the angulation of a fracture?
Describes the direction in which the distal fragment points towards, and the degree of this deformity
Why should you always check for joint involvement when imaging trauma?
If not reduced properly patient will be predisposed to OA of that joint
What is an x-ray used for in imaging trauma?
Can show fracture
What is an CT used for in imaging trauma?
Used when fracture shown on x-ray but more detail is needed, or if x-ray is normal but there is high clinical suspicion of fracture
What causes deformity in rheumatoid arthritis?
Erosion ‘shortens’ the bones, so the ligaments and capsule surrounding the joint becomes lax
Inflammation softens ligaments, which stretch further
Joint subluxation and deformity develop
Name the radiographic features of rheumatoid arthritis
Soft tissue swelling, osteopenia, erosion, deformity
What does a sunburst appearance indicate when imaging a potential bone tumour?
Periosteal reaction which suggests a more aggressive tumour
Is a poorly defined zone of transition on imaging of a bone tumour is suggestive of a benign or malignant tumour?
Malignant
How would you assess a potential acromioclavicular dislocation?
Assess bony alignment
What is a displaced fracture?
Bone ends are no longer in contact
How can MRI be used to monitor arthritis activity?
Can show periarticular bone marrow oedema - often precedes significant joint erosion/damage so provides early evidence of inflammatory joint disease
What causes erosion in rheumatoid arthritis?
Inflamed thickend synovium (pannus) destroys bone, initially at the joint margins (marginal erosion is the hallmark of RA)
With time bone erosion progresses, spreading across the joint
What causes the formation of osteophytes in osteoarthritis?
Periosteal stimulation
What is the rotation of a fracture?
Describes one type of fracture displacement where there has been a rotation of the distal fracture fragment in relation to the proximal portion
What is a posterior fat pad sign indicative of?
Elbow trauma
What causes soft tissue swelling in rheumatoid arthritis?
Synovial proliferation and reactive joint effusion
What is a comminuted fracture?
Fractures with 3 or more fragments
Which is the only modality to adequately show the spinal cord?
MRI
What is the translation of a fracture?
Describes the movement of fractured bones away from each other
Which joints are commonly affected in psoriatic arthritis?
Small joints of hands and feet (DIP joints, IP of great toe)
What is an MRI used for in imaging trauma?
Undisplaced fractures as shows bone marrow in detail, also can show soft tissue damage
Name the radiographic features of osteoarthritis
Loss of joint space, osteophytes, subchondral sclerosis, synovial cysts
Name the x-ray views used to image the scaphoid
AP, lateral, two obliques
