Radiology Flashcards
signs suggesting OA
asymmetrical joint involvement
weight bearing/active joints
what is seen on an x-ray in OA
Loss of joint space
Osteophytes
Subchondral cysts
Subchondral sclerosis
what causes a loss of joint space in OA
asymmetric cartilage wear
weakened bones caves
what causes subchondral sclerosis in OA
increased subchondral bone cellularity and vascularity excites bone turnover
what causes subchondral cysts in OA
synovial fluid dissects into bone
what causes osteophyte formation in OA
periosteal stimulation
signs suggesting RA
symmetrical joint involvement
affects synovial joints
commonly - MCP, MTP, PIP, C1/2 (atlantoaxial joint), wrist/hip/knee/shoulder
what joint in the hands are not affected by RA
DIP
radiographic features of RA
LESS Lost of joint space (joint subluxation) Erosions (Destruction of bone at joint margins) Soft tissue swelling Soft bones (osteopenia)
what causes soft tissue in RA
synovial proliferation and reactive joint effusion
what cause periarticular osteoporosis in RA
Hyperaemia causing bone demineralisation resulting
what causes destruction of bone in RA
inflammatory pannus
what causes joint subluxation/deformity
capsular and ligamentous softening
what fuses in RA
Exposed eroded bone ends may fuse (ankylosis)
features of seronegative arthritis
Sacroiliac joint and spine involvement
Ill-defined periarticular bone formation
Tendency to joint ankylosis
psoriatic arthritis joint distribution
small joints of hands and feet
DIP joints, IP joint great toe
AS joint distribution
scattered lower limb large joints
reactive arthritis distribution
scattered lower limb large joints
lower limb entheses
why are x-rays not often used to diagnose arthritis
can only see late stage damage
should be prevented
other lab tests first line
how can increased vascularity around joints be seen
isotope bone scan
what can a Doppler US show in arthritis
Thickening of synovium and increased blood flow
what do each Ix show
x-ray - bone but no soft tissues
CT - bone in more detail and some soft tissue
MRI - bone in less detail and all soft tissues
which vertebra has no body and what is it called
C1
Atlas
when is 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 tether vertebrae together are are responsible for spinal stability
intervertebral ligaments
are ligaments seen on x-ray or CT
no
but seeing normal alignment on test test implies intact ligaments and a stable spine
how do ligaments appear on MRI
normal - black
damaged - 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, such as:
acute prolapsed intervertebral disc
epidural haematoma
spinal cord damage
pathogenesis of intervertebral disc disease
- discs dehydrated as a prelude to disease
- disc material herniates through disc lining into spinal canal
- press on spinal nerve
- sciatica
what imaging is used for intervertebral disc disease
CT and MRI
MRI is best showing early disc dehydration preceding herniation
what Ix is used to see spinal cord
MRI
principles of imagine
- Clinical features are there to help you
- One view is rarely enough
- Fracture appearance is variable
- Always assess bony alignment
- Check for soft tissue abnormality
- Children can sustain a unique set of injuries
- Don’t switch off after finding one abnormality
- Only dense foreign bodies are shown by x-rays
features of Hx/Ex that help guide x-ray interpretation
- MOI
- site of bone tenderness
- presence of deformity
- patient age
** views for cervical spine
AP
Lateral
Odontoid peg
** views for scaphoid
AP
Lateral
Two obliques
what are avulsion fracture mimics
sesamoid bone
accessory ossification centres
old non-united fracture
what is the posterior fat pad sign
elbow effusion most commonly caused by trauma
displaced fat pad visible posterior to distal humerus