Ultrasound

Question 1

What are the 4 types of ultrasound?

Answer 1

1. A-mode
2. B-mode
3. M-mode
4. doppler

Question 2

what is A-mode ultrasound?

Answer 2

“sonar”- measures how far the echo has travelled and how loud the echo is when it gets back
*cannot determine what object looks like though

Question 3

What is B-mode ultrasound?

Answer 3

“brightness mode”- can recognize size and shape of object

*uses a linear array of transducers

Question 4

what is M-mode?

Answer 4

“motion picture”- like B mode, but can image fetal movements, heart pumping

Question 5

how is doppler used as US?

Answer 5

measures blood flow using doppler physics

Question 6

MSK transducers located in the probe produce the sound at what frequency?

Answer 6

at 7.5-12 Mhz - pulsed at 20 microsecond intervals

Question 7

what is the function of a transducer?

Answer 7

generates impulse and receives back the reflected sound wave to produce an image

Question 8

what does the term attenuation mean?

Answer 8

the deeper the signal travels into the tissue, the more it is absorbed, and the weaker the signal that is reflected back from the tissue

Question 9

how deep does a 7.5 transducer penetrate?

Answer 9

7cm

Question 10

what is a hyperechoic signal? what color does it appear on US?

Answer 10

the more dense the target tissue, the more echo/signal that is reflected back to produce an image
(will appear bright or white on US- ex. bone)

Question 11

what color does bone appear on ultrasound?

Answer 11

white

Question 12

what is a hypoechoic signal? what color does it appear on the US?

Answer 12

soft structures absorb more US and appear hypoechoic (gray) or anechoic (black)

Question 13

Name the hyperechoic structures.

Answer 13

bone, tendon, ligament, fascia

Question 14

Name the hypoechoic structures.

Answer 14

muscle, articular cartilage, fat

Question 15

Name the hyperechoic structure that is striated.

Answer 15

tendon

fascia is non-striated

Question 16

Name the hypoechoic structure that is striated.

Answer 16

muscle

Question 17

Name the anechoic structures.

Answer 17

water( fluid) and air

*nerve is also black due to presence of water

Question 18

what is the near zone?

Answer 18

(area nearest to the transducer ) the region of sound beam in which teh beam diameter decreases as the distance from the transducer increases

Question 19

what is the far zone?

Answer 19

(area furthest from transducer) the region of sound beam in which the beam diameter increases as the distance from the transducer increases

Question 20

Name this technique that enhances scanning: US images obtained from multiple view angles combined into a single compounded image to improve tissue plane definition

Answer 20

spatial compounding

Question 21

what is the function of tissue harmonic imaging?

Answer 21

eliminates all the extraneous echos to assist in evaluating deep structures and improves joint and tendon surface visibility

Question 22

Name this technique: increases/ dec. signal strength of returning echo

Answer 22

time gain compensation

Question 23

what is the relationship btwn transducer frequency and image resolution?

Answer 23

higher frequency transducers provide better image resolution (but penetrate less)

Question 24

Name the characteristics of high frequency transducers.

Answer 24

-improved resolution
-decreased depth of penetration
-used on superficial structures
(Ex. foot and ankle btwn 7.5-12 Mhz)

Question 25

Name the characteristics of low frequency transducers.

Answer 25

-dec. resolution
-full depth of penetration
-best for abdominal and pelvic imaging
(Ex. 1-6Mhz)

Question 26

what is write zoom?

Answer 26

a close-up photo of a small part of a larger scene to increase image quality BUT, there is little info about the surrounding structures

Question 27

what is read zoom?

Answer 27

like taking a photo of a distant scene and then examining parts w/ a magnifying glas
*details are enlarged but imperfections are obvious

Question 28

how does focusing work?

Answer 28

shortening the near field and the focal zone works to increase divergence of the beam in the far field

Question 29

what artifact occurs when the beam is not directly perpendicular to tissues being examined?

Answer 29

anisotrophy

*instead of looking hyperechoic, the structure becomes more hypoechoic

Question 30

List the naturally-occuring artifacts that may occur during US that may decrease quality of image.

Answer 30

1. anisotropy
2. shadowing
3. posterior acoustic enhancement
4. posterior reverberation

Question 31

what artifact occurs when US beam is reflected, resorbed, or refracted from bone or calcified object?

Answer 31

shadowing

*structure will show a false anechoic area extending deep from the involved interface

Question 32

what artifact occurs during imaging of fluid and deep to the fluid collection, the soft tissue appears relatively hyperechoic?

Answer 32

posterior acoustic enhancement

Question 33

what artifact occurs when imaging a smooth and flat object (i.e. metal foreign body or bone surface) and the beam reflects back and forth between the surface and transducer producing a series of linear reflective echoes that extend deep to the structure?

Answer 33

posterior reverberation

Question 34

Name the techniques that improve the quality of US image.

Answer 34

read zoom
write zoom
spatial compounding 
tissue harmonic imaging
time gain compensation