Imaging Flashcards
what is the role of imaging in arthritis
make a diagnosis
monitor disease activity and response to treatment
what are the sero-negative arthrides
psoriatic arthritis, ankylosing spondylitis,
reiters syndrome
what is reiters syndrome
reactive arthritis
what is the disease distribution of OA
asymmetrical
affects weight bearing/ active joints
affects other joints where overuse, previous injury, previous arthritis
describe the radiographic features of OA
(Loss) asymmetrical cartilage wear which lead to asymmetric joint space reduction
(osteophytes) periosteal stimulation leads to marginal osteophyte formation
(sclerosis) increased subchondral bone cellularity and vascularity excites bone turnover leading to sclerosis of subchondral bone
(subchondral cysts) synovial fluid dissects into bone forming cysts
weakened bone caves in, resulting in joint deformity
what is the distribution of RA
usually symmetrical any synovial joint but: -MCP, MTP -PIP (not DIP) -wrists, hips, knees, shoulders -atlantoaxial joint (C1/2)- ligamentous instability and subluxation
sacroiliac joint and spine involvement
describe the radiographic features of RA
synovial proliferation and reactive joint effusion cause soft tissue swelling
hyperaemia (increased blood supply) causes bone demineralisation resulting in periarticular osteoporosis
inflammatory pannus destroys bone, initially at joint margins (as no hyaline cartilage to protect bone at margins) and then later throughout the joint
capsular and ligamentous softening allow joint subluxation and deformity
exposed eroded bone ends may fuse (ankylosis) (much more common in sero negative arthritis)
ill-defined periarticular bone formation (fuzzy)
what is the process of ankylosis
inflammation followed by ossification leading to fusion of the vertebrae
what distribution of is the psoriatic arthritis
small joints of hands and feet
DIP, MCP, PIP joints, IP joint great toe
what is the distribution of ankylosing spondylitis
scattered lower limb large joints
spine and sacroiliac joints
what is the distribution of reiters syndrome
scattered lower limb large joints
lower limb entheses (achilles and plantar fascia onto the calcaneous)
what are signs of early rheumatoid arthritis disease
increased joint vascularity
inflammed synovium
bone marrow oedema
subtle bone erosion
what can an isotrope bone scan show in arthritis
increased vascularity around joints accompanies synovitis and is shown on an isotope bone scan
what might ultrasound show in arthritis
thickening of synovium and increased blood flow within it can be demonstrated by colour doppler ultrasound
what can show bone marrow oedema
MRI
what does bone marrow oedema usually precede
significant joint erosion/ damage
what might an MRI showing radiocarpal erosions trigger
treatment to prevent worsening of disease
what does an x ray show
bone outlines
what does a CT show
bone outlines in more detail and some soft tissue structures (e.g. lumbar discs)
what do MRIs show
bone outlines in less detail but shows bone marrow, discs, ligaments and the spinal cord and nerves (all soft tissue structures)
what are the normal curves of the spine
cervical lordosis, thoracic kyphosis, lumbar lordosis
what are the shared components of the 3-7th cervical, 12 thoracic and 5 lumbar vertebrae
vertebral body posterior arch: -2 pedicles -2 laminae - 1 spinous process -2 transverse processes
what does the neutral foramen of the vertebrae lie inferior to
the pedicle
what do the articular processes do
project superiorly and inferiorly between the pedicles and laminae, forming the facet joints
are consecutive vertebrae the same size
yes
why is C1 different from the other vertebrae
have no vertebral body
anterior and posterior arches united by two large lateral masses which articulate with the occipital bone and C2
why is C2 different from the other vertebrae
has an ondontoid process which projects superiorly into C1 forming a joint with its anterior arch
when is a CT used to image spinal trauma
X ray shows # but more detail required, any more fractures present?
x ray normal but high clinical suspicion of #
what is responsible for spinal stability
intervertebral ligaments
what implies that intervertebral ligaments are intact on a CT or x ray
normal alignment of the vertebrae
what are the intervertebral ligaments
anterior and posterior longitudinal ligaments ligamentum flavum (runs between spinous processes)
what imaging shows ligaments directly
MRI
what do normal and damaged ligaments look like on MRI
normal ligaments black
damaged ligaments light
when is MRI used in spinal trauma
to provide detail of the spinal ligaments
in patients with neurological deficit which is not explained by x ray or CT, to show soft tissue abnormality
what might be seen in a bony tumour of the spine on x ray and CT
bone destruction (reduced bone density)
vertebral collapse (pathlogical #)
bone sclerosis (osteoblasts stimulated)
what are the unique MRI findings of a bony tumour of the spine
early- bone marrow infiltration
late- extradural mass and spinal chord compression
can you see inter-vertebral disc on x ray
no
what imaging shows discs and discs prolapse
CT and MRI (MRI best, shows early disc dehydration which precedes herniation)
what imaging shows the spinal chord
MRI (CT shows it poorly)
what are the 4 causes of spinal cord disease
trauma, demyelination, tumour, ischaemia
what imaging can appreciate normal vertebral anatomy
x rays
what imaging is the best for soft tissue disorders (disc prolapse, malignant cord compression and spinal cord disease)
MRI
how can you see the ondontoid peg via x ray
view from open mouth
how can the scaphoid bone be shown
via different views e.g. oblique planes
how might a fracture appear on a bone
lucency crossing a bone, cortical extension, spiral/ transverse, comminution, joint involvement, angulation, displacement, impaction, avulsion
what is an avulsion fracture
injury to bone where a tendon/ligament attaches- tendon/ ligament come off
how can you tell an avulsion fracture fragment of bone
has incomplete corticated contour
what can mimic an avulsion fracture fragment
sesamoid bones, accessory ossification centres, old united fractures
how do you check humero capitella allignment
should hit the medial of the capitella
what direction does the humeral head displace in an anterior shoulder dislocation
inferiorly and medially
when is the fat pad of the distal humerus abnormal
when it is posterior not anterior to the distal humerus
what is a buckle fracture or bowing
when immature bones are damaged but bend or bow unlike mature bones that snap and break
what is the weakest part of developing bone
physis (the lucency between the epiphysis and metaphysis) (physis can mimic fractures_
what is a salter harris fracture
fracture of the epiphysis or growth plate of a bone
why does a fractures in the radius/ ulnar usually mean an injury in the ulnar/ radius aswell
as they form a ring
can you see plastic or wood on x ray
no same density as soft tissue
what is seen on a colles fracture
dorsal angulation
supracondylar fractures are easily missed, what must you assess
humerocapitellar alignment, posterior fat pad, damage to brachial artery
what is the risk of a scaphoid fracture
AVN due to retrograde blood supply, lack of healing, early onset OA
what is a bennetts fracture
first metacarpal base, tendons pulling thumb distal cause displacement
what other imaging modality can overcome x rays problem with overlapping structures
CT- is cross sectional
what other imaging modality can overcome x rays inability to show some structures
CT- can show fractures irregardless on plane
what other imaging modality can overcome x rays difficulty to show undisplaced fractures
MRI- can show undisplaced fractures
what other imaging modality can overcome x rays inability to show soft tissue injury
ultrasound- superficial soft tissue
MRI- deep soft tissue
what do lower limb fractures often look like
impacted so look sclerotic
what complications can an intracapsular fracture (infront of trochanteric line) cause
interfere with blood supply to the femoral head, AVN
treated with haemarthroplasty
what are you at risk of with a femoral shaft fracture
blood loos and fat embolus
what is lipohaemarthrosis
blood and fat collecting int he suprapatellar recess- sign of intra articular fracture
what artery can be imposed in knee dislocation
popliteal
what movement causes a tibial plateau fracture
valgus force with foot planted
what imaging is good for assessing extensor mechanisms injuries
US
what injuries is MRI good at showing
meniscal tears, cruciate ligament tears, hyaline cartilage injuries, subtle fractures
what movements often cause ankle injuries
inversion or eversion
what is a lis franc injury
TMT joint injury- where one or more metatarsals are displaced from the tarsus
how do you asses TMT joint conjurity
1st and 2nd AP view
3rd to 5th oblique view
