Ultrasound Imaging Flashcards
describe how USI works
- A current is applied to a crystal which causes oscillations at the base frequency which creates an ultrasound beam
- Beam applied through soft tissues
- Reflected beams received by crystals, causing charge
- from this data, image is contructed
where is the intensity greatest in an ultrasound beam?
center of beam
what is the focal zone?
narrowest zone along long axis of beam
list and describe the 2 scanning planes in USI
- longitudinal sonogram → long axis of transducer aligned to long axis of structure
- transverse sonogram → transducer applied across structure
the field of view in USI is the same as ______
long axis of transducer
define hyperechoic
“lots of echoes”
appear as light gray or white
hyperechoic masses are not as dense as hypoechoic ones are. They may contain air, fat, or fluid
define hypoechoic
“not many echoes”
appear as dark gray
hypoechoic masses are more dense or solid than usual
list tissue types that are normally hyperechoic
- cortical bone
- tendons and ligaments
- nerves
list tissue types that are normally hypoechoic
- muscle
- bursa
- hyaline cartilage
how would a tendon or ligament injury appear on USI
- strains → thickening, of mixed echogenicity, disrupted fiber pattern
- hypoechoic if inflammation or hematoma
- ruptures → disruption of fibrous bands; initially filled with hypoechoic hematoma, and separation of ends
describe how a muscle strain vs rupture my appear on USI
- strain → disruption of fibrous bands, hypoechoic hematoma in early stages
- rupture → retraction of muscle
describe how an abnormal bursa would look with USI
increased width of bursa
in later stages, hyperechoic thickening of bursa walls
describe how abnormal hyaline cartilage may look with USI
early changes display inhomogenous thickening
later irregularity and disruption
describe how a nerve compression may look with USI
flattening, swelling proximal to compression
describe how a cyst may look with USI
normally anechoic
abnormally → increased volume, thickened walls, separations, debris
how is blood velocity measured with Doppler US?
measured on the difference of:
- when moving toward the transducer, sound waves reflected off of blood cells arrive back at transducer faster
- when moving away from transducer, sound waves reflected off of blood cells arrive at transducer slower
what does doppler US provide information on?
- presence of blood flow
- direction of blood flow
- gross circulation abnormalities
how is blood flow through a narrowing foramen (stenosis) characterized with doppler US?
increased speed and turbulence
list several clinical indications and benefits of USI
- ID/Differentiation of MSK lesion
- Real-time assessment
- allows for dynamic testing (shoulder, subluxing ankle evertors, etc.)
- Biofeedback → RUSI
- Continuous monitoring of health conditions
- Doppler US
what is RUSI?
real-time ultrasound imaging
rehabilitative ultrasound imaging
Ex → LBP → RUSI can help you see activation of TrA or Multifidus
list several advantages of musculoskeletal ultrasound
- high-resolution soft tissue imaging
- ability to image in real-time
- facilitates dynamic examination of anatomic structures
- can interact with the pt while imaging
- minimally affected by metal artifact (ie, implants and hardware)
- ability to guide procedures (eg, aspirations, injections)
- enables rapid contralateral limb examination for comparison
- portable
- relatively inexpensive
- lacks radiation
- no known contraindications
list general advantages of ultrasound imaging relative to MRI
- low cost and portability
- no contraindications, orthopedic hardware not a problem
- ability to visualize structures not limited by orthogonal planes
- continuous modification of imaging based on findings
- palpation, stress, testing, and application of resistance while imaging
list advantages of USI over MRI
- Muscles → architecture, imaging while testing with resistance
- Tendons → fiber structure, degenerative changes, longitudinal tears
- Ligaments → fiber structure, ability to stress test while imaging
- Cysts and bursae → separation, debris not seen on MRI
list disadvantages of USI relative to MRI
- Joints; Intra-articular structures → limited ability to show joint surfaces and intra-articular surfaces
- Bones → can only show cortical outline of bone
- Scanning across lung fields → US does not cross air/tissue interfaces
list technical disadvantages of musculoskeletal US
- limited field of view
- incomplete evaluation of bones and joints
- limited penetration
list several examples of common clinical application of MSK USI
- Tendinopathies
- Muscle strains
- Front-line diagnostics for pt’s with shoulder pain
- assessment of superficial areas of joint (e.g posterior GH joint pathology)
- Post-op assessment
- joint stability w/dynamic stress testing
- peripheral nerve compression
- superficial disruption of bone cortices (eg rib frx)
- inflammatory arthropathies (eg. RA)
list several shoulder pathologies that USI can help diagnose
- rotator cuff and biceps tendon lesions
- swelling in bursae
- subacromial impingement (dynamic assessment)
