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RAD512 > MRI MSK 1 > Flashcards

MRI MSK 1 Flashcards

1
Q

Why is MRI good for MSK?

A
  • Great detail
  • Very sensitive to disease and trauma
  • joints don’t move
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2
Q

What are the common sequences for MSK MR?

A

T1 : SE, FSE/TSE
T2 : FSE/TSE
PD: FSE/TSE
Fat saturation : (STIR, fatsat, Dixon) (T1, T2 or PD)
Volume scans - isotopic

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3
Q

What changes may you see in a T1 weighted Joint?

A

Synovial fluid
Blood products
Effusion
Reactive changes

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4
Q

What are the technical factors of T1 weighted images?

A

~ fluid demonstrates as low signal
~ inherently high SNR
~ can use smaller FOV
~ higher matrix resolution
~ ideally true spin echo contrast

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5
Q

What is T1 good for looking at MSK?

A

Trabeculae patterns
Good contrast between bone and soft tissue

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6
Q

What are the technical factors of T2 weighted images?

A
  • fluid demonstrated as high signal
  • demonstrates pathology well
  • Higher SNR
  • FSE/TSE used for T2 or PD weighting usually t1 in MSK imaging
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7
Q

What are the methods of fat saturation? And how do they achieve this?

A

STIR and chemical fat sat

STIR = (Short T1 inversion recovery) suppressed by time inversion sequence

Chemical FS = fat suppression by radio frequency, pulse centred on fat peak.

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8
Q

Why is it needed to suppress fat?

A

To suppress the signal from medullary fat
To demonstrate choncral cartilage defects
To demonstrate oedema/ bone bruising (as high signal).

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9
Q

Why is MRI useful in the pelvis?

A

Ruling out occult fractures - NOF, pubic rami, sacrum etc
Tendon injuries, bursitis, or, neoplasms, infection

Often after inconclusive X-ray

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10
Q

What is the common sequence for an MSK pelvis?

A

Coronal / axial T1 and STIR

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11
Q

What is involved with an ankle MRI?

A

Chimney dedicated coil - foot an ankle

Foot and leg at 90 degreees

Limited rotation for joint

Use immobilisation pads

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12
Q

What is the sagittal positioning for an ankle MRI?
Why do we use sagittal?

A

Sagittal perpendicular to joint
Better demonstration of ligaments
Cover laterally to demonstrate ligaments
Use coronal to ensure perpendicular to tibia.

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13
Q

What is the coronal positioning for an ankle MRI?

A

Coronal - perpendicular to talus through the malleoli

Cover front to back to include Achilles and anterior tendons

Use sagittal scan to ensure perpendicular to tibia

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14
Q

What is the positioning or an axial ankle MRI?

A

Axial - perpendicular to tibia parallel to talus joint

Use sag and cor to plan slices

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15
Q

What does the axial PD fat sat demonstrate around the tendons or ligaments?

A

High signal in pathology

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16
Q

What does oCD stand for?

A

Osteochondritis dissecans

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17
Q

What causes OCD?

A

Original inversion injury
- Compressor force
- Bone is less elastic than cartilage
- Bone fracture without Chondral fracture
- Healing dependent on overlying cartilage (stages 1-4)

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18
Q

Where and who does oCD mainly affect?

A

Elbow and knee

Men more than women Moore in adolescence

19
Q

What are the problems associated with osteochondral defects form an inversion injury?

A

Can be hard to clinically diagnose

May become necrotic

Can develop into a loose body

20
Q

What are the goals of imaging for Osteochondral defects?

A

To detect, localise and classify prior to treatment

21
Q

What is stage 1 OCD?

A

Compression fracture

22
Q

What is stage 2 OCD?

A

Partially avulsed

23
Q

What is stage 3 OCD?

A

Avulsed but un-displaced

Cortical fragments separated by intermediate signal intensity, material from the concave, bony defect beneath it .

24
Q

What is stage 4 OCD?

A

Displaced osteochondral fragment - crater develops beneath thee fragment

25
Q

What is involved with scanning the Achilles tendon?

A

The ankle coil, extremity coil, head coil or torso coil may be used

Positioning : neutral position in plantar flexion, otherwise gaps due to rupture maybe missed.

26
Q

Where is the insertion of the Achilles tendon?

A

High into the calf muscle

The water shed is 2-4 cm above the insertion

27
Q

What are the clinical indications for shoulder MRI?

A
  • Pain
  • Restricted movement
  • Recurrent dislocations
28
Q

What is the positioning for shoulder MRI?

A

Pt supine
Shoulder externally rotated - extends tendon to assist in detecting pathology

Avoid hand over abdo - keep hand still

Immobilised strap arm down

Shoulder off centre for optimism fat sat

29
Q

What is the planning positioning for shoulder MRI?

A

Axial positioning

Cover from AC joint to sub glenoid labrum

4mm slice and 1mm gap

Used as a localiser for coronal and sag obliques

30
Q

What is the planning for coronal obl for shoulder MRI?

A

Coverage of joint capsule

3mm slice and 1 mm gap

Perpendicular to glenoid

31
Q

What are the sequences for MRI shoulder? And what are their benefits?

A

T1 SE - Coronal obl
= Excellent, anatomical view of the muscles and ligaments of the shoulder
= Effusion and pathology demonstrated as low signal .

T1 SE - sag obl
= used to assess the degree of impingement of the supraspinatous muscle by the AC joint
= Demonstrates bone, bruising

32
Q

What is the planning for Saggital obl MRI shoulder?

A

3mm slice and 1 mm gap
Parallel with glenoid
Perpendicular to coronal

33
Q

What is the clinical presentation of rotator cuff tear?

A
  • painful movement in all directions
  • restriction on abduction and flexion
  • acute pain
  • history of trauma or overuse
  • problems with ADL
34
Q

What is impingement syndrome in the shoulder?

A
  • degeneration of tendon
  • Swelling - impingement against the chromium and coracoacromial ligament
  • Spur formation
  • Supraspinous, eventually tears
35
Q

What is a bank art lesion?

A

Avulsion of labrum From anterior Glenoid - diagnosed when fluid separates labour from glenoid

36
Q

What are MR arthrograms?
What are they used to detect?

A

Arthrography gives additional detail if intra-articular structures
Useful for clarification of inconclusive findings on a standard MRI

Better detection and assessment of :
- Small, loose bodies
- Cartilage flaps
- Glenoid labour tears
- Better assessment of the undersurface of the rotator cuff ( a frequent site of partial tears)

37
Q

What is the positioning for a wrist MRI?

A

Dedicated coil

Better with pt prone (superman position) however supine with wrist by side can also be done (my need wide bore)

Uncomfortable position - superman

38
Q

What is the positioning for a wrist MRI?

A

Neutral position - aligned long access of radius with central metacarpal axis

Incorrect positioning can result in pseudo instability of capitolunate angle on the sagittal.

39
Q

What are the sequences used for wrist MRI?

A

~ T1 - anatomy
~ Fatsat (STIR if metallic artefact) - bone oedema /fractures
~ T2* - cartilage / ligaments / TFCC
~
axial useful for tendons and ligaments in cross section

40
Q

What does TFCC stand for?

A

Triangular fibrocartilage complex

41
Q

Where it’s the TFCC?

A

In the wrist Between the ulna and carpal bones

42
Q

What are the technical consideration for wrist imaging?

A

High spatial resolution

  • high matrices
  • thin slices
  • interleaving
43
Q

What are the common places of scaphoid fractures?

A

70% - occur at the waist
20% occur at the proximal pole

Non-union fractures may result in AVN

RAD512 (26 decks)

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