US Flashcards
S3Q4
US: Intro
what based on what, origin, history (2)
in PT (4)
- cross imaging based on sound waves reflected off tissues
- origin in sonar
- 1940-1950: breast tissue lump
- 1980: MSK
PT
- biofeedback
- visualize stabilizing muscles of low back
- muscle morphology, function during activity
US: Intro
pulser - what + freq, how/when
US transducer - 1->1->1, array of crystals (2)
scan converter & monitor - purpose (2), colors (2)
PULSER
- produces electrical energy waves (2-15 MHz)
- delivers waves during frequency then silence in between
- sound waves are emitted at 1% of the time then received by transducer during 99%
US TRANSDUCER
- convert pulser’s electrical into sound waves -> go to tissues -> receive tissue’s reflected waves & convert back to electrical
- crystals: MSK (linear = longitudinal & same narrow as transducer), pelvic & abdominal US (curved = allow widening so deeper structures are imaged larger than superficial)
SCAN CONVERTER & MONITOR
- analog to digital, amplifies signal
- has 256 shades of gray, doppler gives color
US: Intro
doppler US - purpose (1=3), power doppler (3), velocity of vessels are measured based on (2), color doppler (1=3) + velocity colors
- measure blood flow in arteries & veins
- dx constriction, stenosis
- aid in operations needed to avoid or identify vessels (dry needling, US-guided injections)
power doppler
- visualize small vessels, inflammation, synovial proliferation
velocity of vessels
- vessels going to transducer = faster waves
- away from transducer = slower receive waves
color doppler
- visualize overall flow in area = presence, direction, circulation anomaly
- high velocity = red, low = blue
US: Tissues
absorption - 1=1->1=1, purpose
reflection - acoustic what, what, factor (4)
ABSORPTION
- intermolecular friction converts mechanical energy of US into heat = absorption
- responsible for attenuation
REFLECTION
- when sound is transmitted between 2 tissues that have varying acoustic impedance (resistance to sound waves) = reflection of waves
factors
- echogenicity: degree to which tissue reflects sound waves
- difference in impedance
- smoothness of reflective surface
- angle of reflection: further from perpendicular = less reflection back to transducer
US: Tissues
refraction - what, implication (2), factor (2)
scattering - if what then =1=1
REFRACTION
- change in direction as waves travel
- lead to changed quality d/t loss of reflected energy
factors
- difference in acoustic impedance
- angle of incidence: further from perpendicular = more refraction
SCATTERING
- if reflecting tissue surface is uneven = less energy return = less accurate localization
US: Tissues
echogenicity (3)
viewing US image - scanning planes (2=2)
ECHOGENICITY
- hyperechoic: reflect much energy = brighter image
- hypoechoic
- anechoic: no energy = no image
SCANNING PLANES
- longitudinal sonogram = sagittal slice of tendon
- transverse sonogram = axial slice of tendon
US: Pros & Cons
pros (6.
limits - penetrate (3), obese (2)
CLINICAL USES
- cost effective, high resolution, comparable to MRI, portable
- can modify image while imaging
- no known hazards
- can image beyond orthogonal planes
- can image c orthopedic hardware
- can follow structure (eg. peripheral nerve)
LIMITS
- can’t penetrate bone, intraarticular ligaments, air (lungs = superimpose)
- obese: less quality since difficult to find focal length & loss of acoustic energy
US: Pros & Cons - vs. MRI
muscle (2), tendons (3), ligaments (2), cysts & bursa (2)
- muscle: architecture, can do resistance during
- tendons: fiber structure, degenerative, longitudinal tear
- ligaments: fiber structure, can do stress test
- cyst & bursa: debris & septations are not seen in MRI
US: Tissues - Normal/Abnormal
cortical bone (3)
tendons & ligament (2) (3.3)
muscle (2) (2.1)
cortical bone
- normal: hyperechoic, smooth, continuous
tendons & ligaments
- normal: hyperechoic, distinct fiber pattern
- strain: disrupted fiber pattern, thickening, hypoechoic (hematoma & inflammation)
- rupture: disrupted structure, separated tendon ends, hypoechoic
muscle
- normal: hypoechoic, has parallel bands
- strain: disrupted bands, hypoechoic
- rupture: retraction of muscle
US: Tissues - Normal/Abnormal
bursa (1) (1)
hyaline (2) (1)
nerve (2) (2)
cyst (1) (2)
bursa
- normal: thin hypoechoic line
- abnormal: thick
hyaline
- normal: hypoechoic, next to cortex
- abnormal: inhomogenous thickening
nerve
- normal: hyperechoic, relative to muscle
- abnormal: flatten, swelling prox to compression
cyst
- normal: anechoic
- abnormal: septations, debris
