Ultrasound Flashcards
US must be _______ by the tissue to have an effect
absorbed
US is preferentially absorbed by tissues with a higher ______ content
protein
What 5 tissues are going to have the best US absorption
- tendon
- ligament
- fascia
- joint capsule
- scar tissue
For tissue in combination, absorption of US depends on what 2 things?
- Half-value depth in each tissue component
2. Amount of reflection at tissue boundaries
___MHz is preferable for heating large soft tissue volumes if bone is deeply located
1
__MHz or low intensity _MHz is preferable where superficial bone is present
3;1
If using US on your hand, what Hz would you use?
3
If using US on your thigh, what Hz would you use
1
What are 2 categories of biophysical effects of US ?
- thermal
2. non-thermal
Proteins ____ as they absorb US energy
vibrate
The resulting ______ ______ of proteins vibrating from absorbing US causes heating, aka thermal US
molecular friction
The temp increase in thermal US depends on what 4 things?
- amount of energy applied
- frequency of sound wave
- type of tissue being insonated
- duration of treatment
There is a ___ and ____ dependent increase in tissue temp with thermal US
time; dose
3MHz heats significantly ____ than 1 MHz, but at a ______ depth
faster; shallower
Vigorous heating (__-__ deg C) for at least 5 mins may temporarily increase the extensibility of ____ ______, _____ , _____ and ______ ______ ; also causes vasodilation
40-45; joint capsules; ligaments; tendons; scar tissues
Vigorous heating will provoke a mild ______ reaction, which can be useful for tissue healing
inflammatory
Temps > ___ degrees C are destructive
45
What are 6 effects of mild heating?`
- reduce pain
- reduce muscle spasms
- promote healing
- alter nerve conduction
- vasodilation
- increase enzymatic activity
Soft-tissue bone interface heats substantially due to _____ impedance mismatch
acoustic
US is an effective way to heat near ____ or ____
joint; bone
______ has limited blood supply and cannot dissipate heat quickly
periosteum
To avoid overheating periosteum (which may lead to deep bone pain) always keep transducer head ______
moving
What 4 things is thermal US used for?
- pain relief
- decrease joint stiffness
- improve blood flow
- promote tissue healing
What are 4 mechanisms whereby non-thermal US may work?
- cavitation
- acoustic
- standing waves
- micromassage
_______ = formation of tiny gas bubbles in tissues as a result of US
cavitation
______ may be stable or unstable
cavitation
Unstable cavitation is _______, and unlikely to occur in mammalian tissue at therapeutic intensities
destructive
In stable cavitation, bubbles form, then ______, increasing and decreasing in volume.
oscillate
Stable bubbles may play a therapeutic role in _____ streaming
acoustic
_______ _______ = unidirectional, localized liquid flow occurring around stable bubbles and cell membranes during US current
acoustic streaming
Acoustic streaming causes _____ on cell membranes
stress
What are 3 effects of the stress caused on cell membranes with acoustic streaming?
- altered sodium permeability
- influx of calcium into cells
- diffusion of other ions and metabolites away from cell membranes
Acoustic streaming can accelerate ______ repair
tissue
______ _____ = US beam reflected from an interface between tissues with significantly different acoustic impedances, and incident and reflected waves superimpose to create peaks of high-intensity energy
standing waves
_________ _____ may cause cellular damage, impede flow of blood cells locally, or damage blood vessel endothelium causing clot formation or free radical formation
standing waves
How do you avoid making standing waves ?
always keep transducer head moving!!!
_________ is caused by waves of compression/rarefaction
micromassage
______ causes pressure difference between cell layers and at tissue boundaries
micromassage
_______ is thought to reduce edema
micromassage
5 non-thermal US effects?
- increased membrane permeability
- stimulation of protein synthesis
- degranulation of mast cell and histamine release
- increased transport of calcium across membrane
- stimulation of collagen synthesis
There is (min/mod/good) evidence that non-thermal US is beneficial for wound healing
good
non-thermal US can alter ____ _____ formation
scar tissue
US treatment activates _____ ______
tissue repair
Via what 3 mechanisms does US treatment activate tissue repair ?
- inflammation optimizer (when used at correct dose!)
- appears to accelerate inflammatory stage of tissue repair
- may promote resolution of chronic inflammation
US causes releaser of wound-healing factors - _____ from mast cells, ______ from platelets, probably by altering membrane permeability to calcium and other ions
histamine; serotonin
US appears to accelerate the inflammatory stage to make it as _______ as possible
efficient
LIPUS accelerates _____ healing by up to 40%
fracture
US encourages ____ to occur more rapidly, and then subside more quickly
edema
In the inflammation stage, use ___-____! Too much US is counterproductive
low-dose (still pro-inflammatory but increases tissue healing)
How does US effect proliferation and granulation tissue healing stage?
by affecting fibroblasts, endothelial cells and myofibroblasts
US increase collagen secretion from _______ (20-30%)
fibroblasts
US increases fibroblast proliferation, probably secondary to direct stimulation of _______
macrophages
During stage 2/3 of healing, higher dose is pro-inflammatory, but increases tissue healing! Too ____ US will be ineffective
little
US dose must be matched to _____ of healing!
phase
Total ______ of US is important in determining outcomes
energy
Deos total energy by itself ensure an effective treatment?
NO; also dependent on type of tissue/condition being treated and stage of healing
How can total energy per treatment be determined?
watts per cm^2 X applicator size (in cm^2) x time (in s)
6 determinants of energy in US?
- intensity
- continuous vs pulsed
- frequency of US
- size of area being treated
- duration of treatment
- total number of treatments
Most studies showing benefit in later stages of soft tissue injuries (> 4 weeks old) were using _____ doses of US
higher
US dose for acute injuries ?
LOW
US dose for chronic injuries?
HIGHER
After first stage of tissue healing, move _____ to higher energy per treatment
quickly
Very low dose intensity ?
0.1 W/cm^2
Low dose intensity ?
0.5 W/cm^2
Medium dose intensity?
1-1.2 W/cm^2
High does intensity?
> 1.5-2 W/cm^2
Total energy depends on what 2 things?`=
- intensity
2. duration of application
What is the usual time guidelines for treatment?
5-10 mins per treatment are a
What is the treatment area?
2xERA
If heating tissue, ~__ mins to raise skeletal muscle temp by 3.5 deg
11
Treatment frequency for for acute conditions ?
low dose, once per day
Treatment frequency for chronic conditions ?
high dose, alternate days
Dosage of US depends on what 4 things?
- nature of problem
- nature of tissue environment
- depth of tissue being treated
- size of treatment area
What are 3 treatment progression options?
- pulse ratio: 1:8 –> 1:1 –> continuous
- intensity - 0.25W/cm^2 –> 2.5 W/cm^2
- time (duration) - shorter –> longer
Clear evidence of benefit of LIPUS in management of ____-____ and ___-____ fractures
delayed - union; non - union
Some evidence that LIPUS may stimulate cartilage repair in mild to moderate ______
OA
How does LIPUS potentially stimulate cartilage repair in development of OA?
downregulates IL-1beta
