Ultrasound Flashcards
(36 cards)
Uses of ultrasound:
- extension of physical exam
- diagnostic studies
- guiding needles or instruments for procedures
How does ultrasound detect structure?
- echolocation using sound waves.
- no radiation involved.
What creates sound waves in the transducer of an ultrasound machine?
- a piezoelectric crystal that vibrates
What must always be used and placed in between the transducer and the body surface?
- gel
- helps sound waves travel more cleanly through the body
The two qualities of transducers that influence their use:
- frequency emitted
- shape
What frequencies have higher resolution on ultrasound, high or low?
high frequencies (at cost of low penetration)
What are the differences between using high and low frequencies in US?
- high frequencies have higher resolution with lower penetration
- low frequencies have lower resolution with deeper penetration
Linear transducer characteristics and use:
- Higher frequency (10-18MHZ)
- Rectangular image
- Musculoskeletal and soft tissue
- Superficial
Curvilinear transducer characteristics and use:
- Low frequency (1-5MHZ)
- Wide, convex image
- Abdomen
- Deep structures
Sector transducer characteristics and use:
- Low Frequency
- Wide, sector image (pie slice)
- Helps guide beam through windows such as ribs.
- Cardiac.
What transducer would you use for superficial and musculoskeletal structures?
linear
What transducer would you use for deep structures and the abdomen?
curvilinear (convex)
What transducer would you use for the heart?
sector
Hypoechoic:
weaker or low echo
i.e. muscle
Hyperechoic:
bright echo
i.e. bone
Anechoic:
no echo or blackness
i.e. fluid
Isoechoic:
equal echogenicity between 2 structures
The three US modes:
- brightness (B) mode
- doppler mode
- power doppler mode
Doppler mode:
- evaluates cardiovascular structures (arteries and veins)
- COLOR
- red = toward transducer
- blue = away from transducer
Power doppler mode:
- 5X more sensitive than doppler
- detects low blood flow
- one directional
- used for tumors and tendon evaluation
What ultrasound mode would you use to detect blood flow in tendons and/or tumors?
power doppler mode
The four things sound waves can do in tissue:
- reflect (back to transducer)
- refract
- scatter
- attenuate (lose energy)
Attenuation in the setting of US:
- the sound beam (echo) loses energy as tissue absorbs sound.
- lower frequency waves travel further and are less attenuated.
Do high or low frequency sound beams demonstrate less attenuation?
- low; so use low for deeper structures
