Principles of Imaging/Radiology Flashcards
what are the most common types of arthritis?
rheumatoid arthritis
osteoarthritis
what joints are usually affected in OA?
weight bearing joints as due to wear and tear (spine, hip, knee, thumb base)
often asymmetrical
what are the radiological features of OA?
asymmetrical loss of joint space subchondral sclerosis subchondral cysts osteophyte formation gross joint deformity
what causes subchondral sclerosis in OA?
increased subchondral bone cellularity and vascularity excited bone turnover
what causes osteophytes formation?
periosteal formation
describe joint involvement in RA?
only affects synovial joints symmetrical commonly - MCP, MTP - PIP - wrists, hips, knees, shoulders - C1/C2 DIP sparing
what happens in the synovium in RA?
increased proliferation and vascularisation in synovium
what are the radiographic features of RA?
soft tissue swelling periarticular osteoporosis (darkening of bone on X ray due to loss of bone density) destruction of joint margin by inflammatory pannus (later throughout the joint)
what causes soft tissue swelling in RA?
synovial proliferation and reactive joint effusion
what causes osteoporosis in RA?
hyperaemia causes bone demineralisation
how can deformity occur in RA?
capsular and ligamentous softening allow joint subluxation and deformity
what can happen to eroded bone in RA?
eroded bone ends may fuse (ankylosis)
what are the common characteristics of sero-negative arthritis?
sacro-iliac joint and spine involvement
ill defined periarticular bone formation
tendency to joint ankylosis
describe new bone formation in RA vs OA?
RA = more fuzzy and ill defined
why are fractures more unstable in RA?
bc all bones and ligaments etc are ossified so no soft tissue to stabilise the fracture
name 3 types of sero-negative arthritis?
psoriatic arhtitis
ankylosing spondylitis
reiter’s syndrome (reactive arthritis)
what are the shared features of each sero-negative arthritis?
sacroiliac joint and spine involvement
ill defined periarticular bone formation
tendency to joint ankylosis
what do radiographic features indicate in arthritis?
indicate that bone and joint damage that has already occurred, therefore patients might have missed the opportunity to have their disease modified
what early features of arthritis can be shown by other imaging tests and may indicate that its not too late to modify the disease?
increased joint vascularity inflamed synovium bone marrow oedema subtle early bone erosion - e.g bone scan, doppler US, MRI, MR
what can be seen on imaging of the spine?
bones ligaments IV discs Spinal cord and nerves blood vessels
what is the most detailed imaging?
X ray = bone outline
CT = detailed bone outline and some soft tissues
MRI = bone outline, bone marrow, discs, ligaments, spinal cord and nerves (all soft tissue)
describe normal curvature of the spine
smooth
loss of normal alignment spells trouble
what are the common features of all vertebrae from C3-L5?
vertebral body posterior arch containing - 2 pedicles - 2 laminae - 1 spinous process - 2 transverse processes
where is the neural foramen in vertebrae?
lies inferior to the pedicle
what forms the facet joints?
articular processes project superiorly and inferiorly between the pedicles and laminae forming the facet joints with adjacent vertebrae
how can adjacent vertebrae indicate a problem?
consecutive vertebrae usually have similar size
variation can indicate problem
describe C1
no vertebral body
anterior and posterior arch united by two large lateral masses
describe C2
has an odontoid process which projects superiorly into C1 forming a joint with its anterior arch
what is the best imaging to use for spinal fracture?
CT
when is a CT used in spinal trauma?
if X ray shows fracture but more detail needed
if X ray normal but high clinical suspicion of fracture
what provides stability to the spinal column?
surrounding ligaments
how can you image spinal ligaments?
only MRI
but seeing normal alignment of the vertebrae on X ray or CT implies intact ligaments and a stable spine and vice versa
what do normal/damaged ligaments look like on MRI?
normal = black
damaged = light
gap in black line shows where tear is in the ligament
when is MRI used in spinal trauma?
to get detail of spinal ligaments
in patients with neurological deficit which is not explained by X ray or CT
what soft tissue injuries can cause a neurological deficit?
acute prolapsed IV disc
epidural haematoma
spinal cord damage
what does a bony tumour look like on X ray and CT?
bone destruction
vertebral collapse
bone sclerosis
what does a bony tumour look like on MRI?
early = bone marrow infiltration late = extradural mass and spinal cord compression
what do bone metastases look like on MRI?
dark spots within the bone
how are IV discs imaged?
discs are invisible on X rays (may show some disc space narrowing but correlates poorly with sciatica symptoms)
CT and MRI can show discs but MRI is best as it shows earlier disc dehydration
how is the spinal cord imaged?
invisible on X ray and only poorly shown by CT
only adequately shown by MRI
what can cause spinal cord disease?
trauma
demyelination
tumour
ischaemia
describe the disease distribution in psoriatic arthritis
small joints of hands and feet
DIP joints
IP joint of big toe
describe the disease distribution of ankylosing spondylitis
scattered lower limb large joints
describe the disease distribution of reiters syndrome
scattered lower limb large joints
lower limb entheses
