154 - Imaging of the Musculoskeletal System Flashcards
Names describing how light or dark an object will be on an X-ray
Radiolucent or radio-opaque
Metaphysis
Wide part at the end of a long bone
Elevations on bone
EG greater tuberosity
Difference in epiphyses between young children and adults
Much more obvious on an X-ray from a young child
Apperance of residue of growth plate
A narrow, white scar (under an X-ray - white=more dense)
Nutrient foramen appearance on an X-ray
Can look like a fracture
Symphesis pubis
Fibrous joint with a cartilaginous structure in between bones.
Type of joint of suture in skull
Fibrous joint. Hard to see on an X-ray, more often seen on a CT
Example of a fibrocartilaginous joint
Pubic symphesis
What forms labra in joints?
Fibrocartilage
Subcondylar bone
Bone beneath hyaline (articular) cartilage in a synovial joint.
Slightly thickened bone.
Features of more-complex joints
More than one compartment, can have menisci (EG: elbow hinge joint)
How to look at an X-ray film 1 2 3 4 5 6 7 8 9
- Identity
- 2 views or more (projections. Often look at 2, which are perpendicular to one another)
- Alignment
- Joint surfaces and joint
- Trabecular bone and lines
- Bone outline
- Soft tissues
- Growth plates
- Invisible structures (structures that aren’t seen, EG articular cartilage, fluid)
Hidden structures in a shoulder X ray
Rotator cuff tendons, bursae
Ways to image musculoskeletal system 1 2 3 4 5
- Plain radiograph
- CT
- MRI
- Ultrasound
- Nuclear Scintigraphy
T1, T2 patterns of relaxation
In an MRI.
Align protons with magnetic field to 90 degrees of what they were initially.
These protons can then go back to relaxed state in two ways: T1 or T2 relaxation
Field strengths of MRI machines
0.3 to 7 Tesla magnets.
Three fundamental tissue properties on MRI
1) Proton density
2) T1 constant (spin-lattice)
3) T2 (spin-spin)
Can weight images to T1 or T2
Features of T1 weighted images 1 2 3 4 5 6
- Fluid – dark
- Fat – bright
- Muscle – intermediate
- Spinal cord - intermediate
- Cortical bone – very dark
- Flowing blood - dark
Features of T2 weighted images 1 2 3 4 5 6
- Fluid – bright
- Fat – intermediate to bright
- Muscle – intermediate
- Spinal cord - intermediate
- Cortical bone – very dark
- Flowing blood - dark
Main difference between T1- and T2-weighted images
Fluid is dark on T1 and bright on T2
Appearance of bone marrow on MRI
Fat in marrow makes centre of bones look lighter.
More fatty marrow in epiphyseal areas of bone.
Common way to view bones on MRI
Fat-suppressed T2-weighted image. Fat is normally too bright, drowns out fluid imaging.
What are plain films good for? 1 2 3 4 5 6 7
- Good overview of bones and joints
- Good for alignment
- Some flexibility in positioning eg standing views
- Less contrast/spatial resolution than CT
- Radiation, but less than CT
- Cheap and quick
- Readily available
Advantages of MRI 1 2 3 4 5
- Good spatial and contrast resolution
- Good for soft tissue and bone marrow
- Good for inside joints
- Cross-sectional imaging
- Imaging in multiple planes
Disadvantages of MRI 1 2 3 4 5
- Availability variable
- Limited functional information
- Contraindications – pacemaker, cochlear implant, some aneurysm clips.
- More expensive
- Long scans times (~ 20 minutes for a joint)
Advantages and disadvantages of CT
1
2
3
1) Good bone detail (especially complex joints and fractures)
2) More expensive than plain film
3) More radiation than plain film
