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ANAT2012 > Muscle L5/6: Musculoskeletal Imaging > Flashcards

Muscle L5/6: Musculoskeletal Imaging Flashcards

1
Q

What are the 4 reasons for using imaging for MS conditions?

A
  1. Make an accurate tissue diagnosis
    • e.g. acute fracture … not always appropriate (e.g. low back pain, knee pain)
    • MRI in 2 different positions- give inaccurate conditions
  2. Rule out other pathology (red flags)
    • e.g. tumour
    • Refer to GP who would refer for appropriate imaging
  3. Determine prognosis or to track a disease
    • e.g. osteoarthritis
    • Can have a look @ what stage
  4. Indications for surgical intervention
    • e.g. ACL rupture MRI; can pick up clinically (with subjective& physical)
    • end-stage osteoarthritis x-ray (pain that can’t manage- knee replacement)
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2
Q

What are the 3 concepts of APA (Choosing widely)?

A
  1. Don’t request imaging for patients with non-specific lower back pai and no indicators of a serious cause for lower back pain
  2. Don’t request imaging on the cervical spine in trauma patients, unless indicated by a validated decision rule
  3. Don’t request imaging for acute ankle traumas unless indicated by the Ottawa Ankle Rules (localized bone tenderness or inability to weight bear as defined in the rules)
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3
Q

What are the 5 principles for using imaging for MS conditions?

A
  1. understand imaging results
    • what radiologists send back
  2. only order imaging that will influence management
    • ongoing pain to clear fracture (eg. talus)
  3. explain the imaging to the patient
  4. provide relevant clinical findings on the referral form
    • don’t have to refer to GP, can refer straight to radiologist
    • Need to say “suspected..etc”
    • Eg. “suspected PFJ OA- add skyline view imaging”
  5. work with radiographers & radiologists
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4
Q

Radiography: How does it work?

A
  • X-rays (electromagnetic radiation) in a fan beam are directed from a fixed tube through the body region of interest
  • X-rays are absorbed, scattered or transmitted through different tissues at different rates
  • Transmitted and scattered x-rays are detected by a detector device
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5
Q

X-rays (electromagnetic radiation) in a fan beam are directed from a _____ through the body region of interest

A

fixed tube

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6
Q

X-rays are _______, _______or ______through different tissues at different rates

A

absorbed; scattered; transmitted

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7
Q

Transmitted and scattered x-rays are detected by a _______.

A

detector device

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8
Q

Radiography: What tissues are imaged?

A
  • Tissues containing calcium (e.g. bone) absorb more x-rays than soft tissue …produces high contrast on detector - appears brighter/white
  • Bone – fractures, alignment, joint spacing, tumours, etc.
  • Eg. calcification in tendon (will show up) Spacing – OA component (wear down)
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9
Q

Radiography: What are 2 advantages?

A
  1. Cheap and fast
    • No appointment needed
    • $50 (depends on area)
  2. Widely available
    • Can be mobile
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10
Q

Radiography: What are 3 disadvantages?

A
  1. Uses ionizing radiation (low to medium dose)
  2. Cant differentiate soft tissue
    • Only see bone (implying)
  3. 2D image of a 3D structure
    • Can’t see rotation
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11
Q

Radiography: What are 2 contraindications?

A
  1. Pregnancy
  2. Breastfeeding
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12
Q

Radiography: When would radiography be used?

A
  • Bony injury
    • Eg. fracture; hairline; dislocation
  • Good entry/starting point
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13
Q

Radiography: What are the 3 different types of x-ray view?

A
  1. Anteriorposterior
  2. Lateral
  3. Skyline
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14
Q

Radiography: Grade 0 of OA

A

No OA

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15
Q

Radiography: Grade 1 of OA

A

possible osteophytic lipping, doubtful JSN

Early OA

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16
Q

Radiography: Grade 2 of OA

A

definite osteophytes, possible JSN

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17
Q

Radiography: Grade 3 of OA

A

moderate multiple osteophytes, definite JSN, some sclerosis, possible bone contour deformity

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18
Q

Radiography: Grade 4 of OA

A

large osteophytes, marked JSN, severe sclerosis, definite bony contour deformity

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19
Q

CT scanning: How does it work?

A

Computerised x-ray procedure X-ray tube and detector rotate around the patient Narrow beam of x-rays is aimed at the target region and rotated quickly around the body Produces signals that are processed to generate crosssectional images

  • can be viewed as slices
  • reconstructed to produce 3D image = clear images (used for surgery)
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20
Q

CT scanning: What tissues are imaged?

A

Bone – fractures in small bones, anatomically complex regions

21
Q

CT scanning: What are 4 advantages?

A
  1. Relatively cheap; fast; widely available
  2. Higher resolution than x-ray
  3. Defines bone detail and detects calcification better than MRI
  4. 3D data- geometrically accurate
22
Q

CT scanning: What are 3 disadvantages?

A
  1. Using ionizing radiation (medium to high dose)
  2. Lower soft tissue contrast (vs. MRI)
  3. Often requires contrasts- risk Substance injected (intra-venous)
23
Q

CT scanning: What are 3 contraindications?

A
  1. Pregnancy
  2. Breastfeeding
  3. Children
24
Q

CT scanning: When would CT scanning be used?

A
  • Complex fracture (small, difficult to see)
  • Can’t be picked up on x-ray
  • Complex orthopedic surgery
25
Q

Bone scan: How does it work?

A

Scintigraphy

Intravenous administration of radioisotope (bisphosphonate) –> binds to hydroxyapatite at sites of osteogenesis (active bone formation)

Scan performed with gamma camera – detects gamma radiation emitted from radioisotopes

  • 2D image (frontal plane; anterior or posterior)
  • 3D image (single photon emission CT [SPECT]) – detectors rotate around body
26
Q

Bone scan: What tissues are imaged?

A

Bone- stress fractures, tumour, etc.

Black areas= osteogenesis

27
Q

Bone scan: What are 2 advantages?

A
  1. can be combined with CT – anatomy & function
  2. may detect earlier stages of bony injury
28
Q

Bone scan: What are 4 disadvantages?

A
  1. relatively high radiation dose
  2. low resolution images (show uptake)
  3. slow (long period to keep still)
  4. reasonably expensive
29
Q

Bone scan: What are 2 contraindications?

A
  1. pregnancy
  2. breastfeeding
30
Q

Bone scan: When would bone scanning be used?

A

Osteogenesis occur- bone healing should have occurred

31
Q

Ultrasound: How does it work?

A

Sound waves (1-18MHz) are produced by a piezoelectric transducer

Waves travel through the body tissues

  • partially reflected anywhere there are acoustic impedence changes in the body (e.g. interface between different tissues)
  • some reflections returned to transducer, sound waves converted to electrical pulses, transformed into digital image (time, strength of echo)

Need coupling gel between transducer and skin (water-based)

32
Q

Ultrasound: What tissues are imaged?

A

Ligaments, tendons, muscle, nerves – not bone (bone = black void)

33
Q

Ultrasound: What are 5 advantages?

A
  1. Cheap; fast; widely available; portable
  2. Able to image soft tissue; high resolution
  3. Can perform dynamic imaging (real-time)
  4. Can interact with patient to correlate symptoms & findings
  5. Safe (no ionizing radiation)
34
Q

Ultrasound: What are 3 disadvantages?

A
  1. Small field of view; can can some image distortion
  2. Unable to penetrate bone & air
    • Enough gel
  3. Image quality depends on skill of operator
35
Q

Ultrasound: What are the contraindications?

A

N/A

36
Q

Ultrasound: When should ultrasound be used?

A
  • Hypoechoic region thickening: not penetrating completely
  • Neovessels: body’s healing effect
37
Q

MRI: How does it work?

A
  • Magnets produce a strong magnetic field (3.0T) that forces the protons in water molecules in the body to align with that field
  • Radiofrequency current is then pulsed through the body – stimulates the protons, which spin out of equilibrium against the pull of the magnetic field
  • When the radiofrequency current is turned off, MRI sensors detect the energy released when the protons realign with the magnetic field
  • Different tissues have different times for proton realignment, and different amounts of energy release – appear different on MR image
  • Signal detected by coil close to target body region
38
Q

MRI: What tissues are imaged?

A

All tissue

Can see everything (bone and tissue)

39
Q

MRI: What are the 4 common MRI sequences?

A
  1. T-1 weighted
  2. Proton density- weighted
  3. T2-weighted
  4. STIR
40
Q

MRI: What is a T1-weighted MRI?

A
  • sharp anatomical detail
  • shows bone marrow
  • good for meniscal pathology
  • lacks sensitivity to detect soft tissue injury

fat = bright

muscle = intermediate

water, tendons, fibrocartilage = dark

41
Q

MRI: What is a proton density- weighted MRI?

A

• good for menisci and ligaments

fat = bright / intermediate

water = intermediate

calcium, tendons, fibrocartilage = dark

42
Q

MRI: What is a T2-weighted MRI?

A
  • highly sensitive for most soft tissue injuries, especially tendons (or muscular)
  • Abnormal tendons have high signal intensity (bright) – contrasts with the black of normal tendon

water = bright

fat = intermediate

muscle, hyaline cartilage, fibrocartilage = dark

43
Q

MRI: What is a STIR MRI?

A
  • highlights excess water which may occur due to bone stress, bone marrow oedema, joint fluid and soft tissue pathology
  • use for bone stress injuries or subtle fractures not detectable on x-ray better than T weighted

water = very bright

fat, muscle menisci = dark

44
Q

MRI: What are 3 advantages?

A
  1. Excellent soft tissue contrast; geometrically accurate
  2. Non-invasive; no ionizing radiation
  3. Can scan in any plane; 3D image capability
45
Q

MRI: What are 3 disadvantages?

A
  1. Bone resolution not as clear as CT
  2. Expensive; slow (keep still); low availability
    • 10 mins- no movement at all
  3. Not-weighted bearing imaging (at present)
46
Q

MRI: What are 3 contraindications?

A
  1. Any implanted metal
    • Eg. placemaker, aneurysm clip
  2. Claustrophobia
    • Small tunnel
  3. It’s a really, really big magnet
    • Has to be declared MRI safe
47
Q

MRI: When would MRI be used?

A

Any structures- if other imaging options don’t fix (make sure to weight up time and cost)

48
Q

SUMMARY for x-ray, CT, bone scan, ultrasound, MRI

A

x-ray: bone CT: more bone detail (trabeculae) Bone scan: Osteogenesis (bony activity) Ultrasound: Soft tissue tendon, ligaments, muscle, nerves, not bone MRI: Everything can order multiple sequences (eg. STIR &T-1/T-2 weighted)

ANAT2012 (31 decks)

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