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Musculoskeletal Physiotherapy 2 > Week 10 > Flashcards

Week 10 Flashcards

1
Q

what is msk ultrasound imaging?

A

msk ultrasound imaging uses sound waves to produce pictures of muscles, tendons, ligaments and joints throughout the body, it is used to help diagnose sprains, strains, tears and other soft tissue conditions

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2
Q

US imaging

A

traditionally performed by diagnostic radiologists

increasingly available to physiotherapists and other medical practitioners with appropriate training
-aim to improve diagnosis/classification of msk disorders which, theoretically at least, should lead to improved clinical outcomes

post grad cert in msk imaging
research higher degree (masters/PHD)

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3
Q

US imaging history

A

derived from technology used in military and metallurgy applications

Began as science of navigation - first form was SONAR used on war ships WWII
- bounced sound waves off ocean floor and interpreted ‘echoes’

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4
Q

US imaging history

A

late 1940s scans performed as a new way to ‘image’ patient

  • subject immersed in water bath
  • produced single, static cross - sectional image
  • early images looked like seismograph output
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5
Q

US imaging - history

A

1950s-1960s used by doctors for

  • cardiac patients
  • –progressing rto
  • obstetrics gynaecology
  • abdominal application

1970s
-greyscale images depicting cross section of patient anatomy

1980s
-computer technology added to produce ‘modern ultrasound’ image

1990s
-addition of colour Doppler to black and white images

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6
Q

US imaging history - today

A

dynamic visual images that provide insight human body
continually evolving
- software to measure tissue elasticity
-3D and 4D imaging

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7
Q

US imaging history

A

physiotherapy applications began in 1980s
-direct visualisation of muscle size and activity

high portability + low cost +excellent resolution = useful tool

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8
Q

How does it work

A

scanner includes

  • hand held probe + central unit that displays image
  • probe commonly used are linear or curvilinear
  • you need to understand the machine settings
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9
Q

how does it work

A

Uses high frequency sound wave with short focused pulses to generate images
-no radiation

sound waves passes through body
-percentage is reflected back (normally 1%)

sound waves reflected back to probe by varying boundaries are recorded

  • each pulse produce a single line
  • single (greyscale) image = multitude of lines (can be >100)
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10
Q

What is wavelength

A

spatial period of wave

-distance over wave shape repeat

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11
Q

what is amplitude

A

measure of change over specific period

-peak & peak to peak

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12
Q

How does it work

A

Probe operates at specific frequencies

  • higher frequency = shorter wavelength - shorter pulses
  • – higher resolution of image but limited depth of vision
  • lower frequency = longer wavelength - longer pulses produced
  • –less absorption of US meaning lower resolution but allows vision of deeper structures

Depth of image demonstrated as scale of distance from probe

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13
Q

Linear probe

A

normal operational frequency >7.5 MHz

Produce high resolution images

rectangular images

approximate depth of vision =5cm

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14
Q

Curvilinear probe

A

normal operational frequency between 2-5 MHz

lower resolution images

fan shaped image

depth of vision up to 15cm

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15
Q

Doppler imaging

A

used to detect flow of blood
measure change in soundwave frequency reflected by moving structure
displayed as colour and pulsed Doppler

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16
Q

Doppler imaging cont

A

colour

  • added as colour to greyscale image
  • blue and red commonly used to represent flow towards and away from probe

pulsed
-displays spectrum of velocity vs time

17
Q

Terms relevant to US imaging

A

attenuation

  • weakening of sound wave passing through tissue due to parts being
  • absorbed
  • reflected
  • scattered
  • refracted
  • diffracted
18
Q

Terms relevant to US imaging

A

reflection

  • occurs at boundary of 2 materials creating acoustic impedance
  • determines echogenicity of tissue
  • –small impedance - weak echo (i.e. soft tissue)
  • –Large impedance = strong echo (i.e. bone)
19
Q

Typical tissue appearance

A

variation due to

  • different individuals
  • scanner quality, frequency
  • but mostly by amount and nature of tissue
  • echogenicity
  • -compared to normal/expected
  • -diseased states issues can be
  • —more echogenic (hyperechoic- brighter)
  • —less echogenic (hypoechoic - darker)
  • -compared to other tissue types
20
Q

Typical tissue appearance

A

skin

  • appears smooth bright
  • –highly reflecive, hyperechoic

fat
-can be bright or dark
subcutaneous - commonly dark with fine, bright septa throughout

fluid

  • normally black (anechoic)
  • absorbs less sound than surrounding soft tissue
  • –tissue deep to fluid can appear relatively bright
21
Q

Typical tissue appearance

A

muscle

  • dark in cross section
  • long section - internal structure visible due to reflective muscle fibres

tendons
-typically bright but affected by orientation relative to probe

22
Q

Typical tissue appearance

nerves & bone

A

Nerves
-peripheral - appear bright or dark depending on orientation
distinguished from tendons by following course through surrounding tissues

bone

  • surface appear as bright line
  • outer surface reflects sound so unable to see deeper
23
Q

US imaging uses

A

physio - biofeedback

diagnostic tool - to an extent (training)

24
Q

US imaging uses cont

A

it is important to consider that diagnostic US is a user dependant modality
- skill and experience of operator has considerable influence on outcome

radiologists are still the experts

if you plan to use diagnostic US, it is a skill that requires training and experience

  • consider courses, guidance, and mentoring, especially amongst those from radiology community
  • formal training is optimal for valid and reliable diagnosis
25
Q

US imaging in physiotherapy

A

imaging that can

  • enable clinician to view soft tissue
  • provide real time image
  • evaluate pathological changes
  • display muscle contractions
  • display movement of tendons and joints
26
Q

US imaging in physiotherapy

A

applications are wide ranging

  • biofeedback
  • –TrA retraining in LBP patients, multifidus
  • –pelvic floor
  • commonly used to aid diagnosis of more superficial joint/tissues pathology
  • -shoulder e.g. rotator cuff tears
  • -elbow, eg. common extensor tendinopathy
  • -hand/wrist, eg. ganglion, median nerve (CTS), flexor pollicis longus tendinopathy
  • -knee eg. collateral ligament sprain
  • -ankle eg. lateral ligament sprain
27
Q

US in diagnosis

A

Measurement of soft tissue strain and elasticity

  • elastographic capabilities demonstrating promise relation to idiopathic inflammatory myopathies (can be difficult to diagnose)
    • chronic muscle inflammation & weakness
  • – dermayositis, polymyositis, juvenile myositis
  • Elastograms - may be able to determine pre-symptomatic tendinopathy changes
  • -Achilles tendon- may show elasticity changes that indicate predisposition to future problems
28
Q

US in diagnosis cont

A

subacromial disorders

  • investigation of diagnostic accuracy of US for subacromial disorders
  • systematic review with meta analysis
  • statistical pooling where available

Strongly recommended US for patients
-where conservative management is not successful
-to rule in/out full thickness tears
to rule in partial thickness tears
-lesser extent - to diagnose tendinopathy, subacromial bursitis, calcifying tendonitis

29
Q

Ultrasound in diagnosis cont 2

A

carpal tunnel syndrome

  • history, PE, nerve conduction velocity studies
  • 12/5 MHz linear array transducer
  • Measurement of size of median nerve
  • -cross sectional area measured
  • Symptomatic patients - enlargement of median nerve noted at distal wrist crease
  • Proposed as
  • -reliable modality for imaging of wrist in CTS patient
  • -safe and well tolerated
30
Q

US in treatment

A

retraining of TrA and multifidus

  • real time US imaging feedback may enhance motor relearning for specific muscles
  • -interactive tool
  • -allows visualisation of contraction
  • -non-invasive, user friendly and quick application
  • But adjunct to clinical skills
  • *NB - disadvantages of limited field of view (deep muscles) ; movement observation not objective measure
31
Q

US in treatment

A

retaining TrA and multifidus

  • LBP pt
  • rehabilitative US imaging (RUSI) for thickness measurement of TrA and multifidus at rest and contracting
  • based on mean of 2 measures
  • -highly reliable for single examiner
  • -adequately reliable with different examiners

-can be used as effectively as MRI to measure contraction

32
Q

Pros of US I

A

useful - diagnostically and as biofeedback for muscle retraining

-advantages
-safe
non invasive
relatively accessible
portable
low cost
comparable diagnostic accuracy to more expensive technology
e.g. MRI in some situations
–and in varying patient positions

33
Q

Cons

A

disadvantages

  • difficult to interpret for the novice
  • training and repetition help
  • -a level of interpretive error remains for all viewers though
  • remember this
  • -increased likelihood of false positives or false negative compared to other tech e.g. MRI in some circumstances

Over reliance
-easily accessible ‘we’ll send you for an US to tell us what’s wrong’
But probably wrong to categorise this as a disadvantage of US - more a misapplication by the clinician

Musculoskeletal Physiotherapy 2 (10 decks)

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