Imaging Flashcards
What is the differences in what x-ray; CT and MRI are able to see anatomically?
x-rays only show bony outlines; CT shows bone outlines in more detail and some soft tissue structures; MRI shows bone outlines in less detail but shows all soft tissue structures
How should consecutive vertebrae appear in contrast to each other?
have similar size
When is a CT used to image spinal trauma?
when x-ray shows # but more detail is required or wonder if there are more# or if x-ray is noram but there is a high clinical suspicion of #
What is the function of ligaments in the spine?
ligaments tether vertebrae together and are responsible for spinal stability
How can you know if there are intact ligaments on x-ray and CT if they cannot be seen?
seeing normal vertbral alignments implies this
How do normal and damaged ligaments appear on MRI?
normal appear black whereas if damaged they appear white
When would MRI be used to image spinal traume?
if a pt has neuro which isnt explained by x-ray or CT
What might be seen on x-ray and CT with a bone tumour of the spine?
bone destruction; vertebral collapse (pathological #); bone sclerosis
What may be seen on MRI in a bony tumour?
early- bone marrow infiltration
late- extradural mass and spinal cord compression
What is the only mode of imaging that adequately shows the spinal cord?
MRI
What can cause spinal cord disease?
trauma; demyelination; tumour; ischaemia
What type of pattern of joints affected is seen in OA
asymmetrical
What joints are infected in primary OA?
weight bearing or active joints- spine, hip, knee, thumb base , DIP
what is secondary OA?
when unexpected joints are affected by OA because there is overuse, previous injury or previous arthritis
Why is there sclerosis of subchondral bone in OA?
increased subchondral bone cellulairty and vascularity which excites bone turnover leading to sclerosis
What leads to osteophyte formation?
increased vascularity stimulates the periosteum to increase the joint SA to share the load
What results in joint deformity in OA?
weakened bone caves in
What is the distribution of affecgted joints in RA?
symmetrical- MCP;MTP; IP; wrists; hips; knees; hsoulders; atlanto-axial
What causes soft tissue swelling in RA?
synovial prolferation and reactive joint effusion
What else is seen on x-ray in RA?
periarticular osteoporosis; destroyed bone-marginal erosions
what destroys the bone in RA?
inflammatory pannus- inflamed thicked synovium
What are the hallmark lesions of RA?
marginal erosions
What causes joint subluxation and deformity in RA?
the bones become eroded and shorter which makes the ligaments and capsules lax and inflam also softens the ligamnets which stretch further leading ot increased subluxation and joint deformity
Why might ankylosis be seen in RA?
if the eroded bones become exposed to each otehr and then fuse