154 - Imaging of the Musculoskeletal System

Question 1

Names describing how light or dark an object will be on an X-ray

Answer 1

Radiolucent or radio-opaque

Question 2

Metaphysis

Answer 2

Wide part at the end of a long bone

Question 3

Elevations on bone

Answer 3

EG greater tuberosity

Question 4

Difference in epiphyses between young children and adults

Answer 4

Much more obvious on an X-ray from a young child

Question 5

Apperance of residue of growth plate

Answer 5

A narrow, white scar (under an X-ray - white=more dense)

Question 6

Nutrient foramen appearance on an X-ray

Answer 6

Can look like a fracture

Question 7

Symphesis pubis

Answer 7

Fibrous joint with a cartilaginous structure in between bones.

Question 8

Type of joint of suture in skull

Answer 8

Fibrous joint. Hard to see on an X-ray, more often seen on a CT

Question 9

Example of a fibrocartilaginous joint

Answer 9

Pubic symphesis

Question 10

What forms labra in joints?

Answer 10

Fibrocartilage

Question 11

Subcondylar bone

Answer 11

Bone beneath hyaline (articular) cartilage in a synovial joint.
Slightly thickened bone.

Question 12

Features of more-complex joints

Answer 12

More than one compartment, can have menisci (EG: elbow hinge joint)

Question 13

How to look at an X-ray film
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Answer 13

• 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)

Question 14

Hidden structures in a shoulder X ray

Answer 14

Rotator cuff tendons, bursae

Question 15

Ways to image musculoskeletal system 
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Answer 15

• Plain radiograph
• CT
• MRI
• Ultrasound
• Nuclear Scintigraphy

Question 16

T1, T2 patterns of relaxation

Answer 16

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

Question 17

Field strengths of MRI machines

Answer 17

0.3 to 7 Tesla magnets.

Question 18

Three fundamental tissue properties on MRI

Answer 18

1) Proton density
2) T1 constant (spin-lattice)
3) T2 (spin-spin)
Can weight images to T1 or T2

Question 19

Features of T1 weighted images
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Answer 19

• Fluid – dark
• Fat – bright
• Muscle – intermediate
• Spinal cord - intermediate
• Cortical bone – very dark
• Flowing blood - dark

Question 20

Features of T2 weighted images
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Answer 20

• Fluid – bright
• Fat – intermediate to bright
• Muscle – intermediate
• Spinal cord - intermediate
• Cortical bone – very dark
• Flowing blood - dark

Question 21

Main difference between T1- and T2-weighted images

Answer 21

Fluid is dark on T1 and bright on T2

Question 22

Appearance of bone marrow on MRI

Answer 22

Fat in marrow makes centre of bones look lighter.

More fatty marrow in epiphyseal areas of bone.

Question 23

Common way to view bones on MRI

Answer 23

Fat-suppressed T2-weighted image. Fat is normally too bright, drowns out fluid imaging.

Question 24

What are plain films good for?
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Answer 24

• 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

Question 25

Advantages of MRI
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Answer 25

• Good spatial and contrast resolution
• Good for soft tissue and bone marrow
• Good for inside joints
• Cross-sectional imaging
• Imaging in multiple planes

Question 26

Disadvantages of MRI
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Answer 26

• Availability variable
• Limited functional information
• Contraindications – pacemaker, cochlear implant, some aneurysm clips.
• More expensive
• Long scans times (~ 20 minutes for a joint)

Question 27

Advantages and disadvantages of CT
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Answer 27

1) Good bone detail (especially complex joints and fractures)
2) More expensive than plain film
3) More radiation than plain film