Exam 1 Ultrasound

Question 1

Ultrasound is defined as sound with a frequency above _________ Hz.

What is the frequency range for human hearing?

Answer 1

20,000 Hz

20 to 20000 Hz

Question 2

Describe a Linear Probe

Answer 2

High Frequency
Great Resolution
Poor Penetration

Ideal for imaging vessels, muscles, tendons, breast, and thyroid. Anything just below the surface of the skin.

Question 3

Describe a Curved/ Curvilinear Probe

Answer 3

Medium to Low Frequency
Wider and deeper field of view, sacrifice resolution.

Ideal for OB/Pelvic exams.

Question 4

Describe a Phased Array Probe

Answer 4

Medium to Low Frequency
Deeper image, sacrifice resolution

A smaller footprint allows easier imaging between rib spaces, perfect for cardiac scanning, and can be used for the abdomen as well.

Question 5

What piece of item in the ultrasound probe will convert electricity to sound?

Answer 5

The piezoelectric element will vibrate and produce sound waves that will send sound waves to the body.

Don’t drop the probe

Question 6

What is the relationship between frequency and wavelengths?

Answer 6

Inverse relationship

High Frequency = Short Wavelength
High Resolution, Superficial Image

Low Frequency = Long Wavelength
Low Resolution, Deep Image

Question 7

The maximum height of the wave is called the __________.

Answer 7

Amplitude (dB)
(as described as the max particle displacement dB)

Question 8

___________ is the speed at which the wave propagates through a medium.

Answer 8

Velocity (m/s)

Vibrations will move through solids a lot faster than air

Question 9

Why is there a delay in imaging with an ultrasound?

Answer 9

Sound waves are produced in pulses that are spaced apart. We need to allow time for echoes to be reflected back to the transducer and processed before emitting a new pulse.

Move slowly and scan

Question 10

What is the relationship between stiffness and speed?

What is the relationship between density and speed?

Answer 10

Proportional.
Increase stiffness, Increase Speed

Inverse relationship.
Increase density, Decrease speed

Because mediums within the body have varying density and stiffness, the propagation speed of sound will change between different mediums.

Question 11

Which type of ultrasound uses a beam sweep?

Answer 11

Linear Transducer
Curvilinear Transducer

Beam sweep refers to the waves working down the transducer and receiving echoes to produce an image

Question 12

Which type of ultrasound does not use a beam sweep?

Answer 12

Phase Array

The Piezoelectric elements are packed near the center of the transducer and produce a focus beam that originates from the center

Question 13

What is the Fraunhofer Zone?

Answer 13

Far field, area distal to the focal point.

Beam is diverging, poor image quality.
Higher frequency, less divergence in far field.

Lateral resolution is greatly reduced.

Question 14

What is the Freshnel Zone?

Answer 14

Near field, area proximal to the focal point.

Beam diameter is same as transducer.

Higher frequency = longer near field zone.

Lateral resolution is good.

Question 15

What is the resistance to ultrasound?

Answer 15

Impedance (density x propagation speed of sound)

Increase tissue density, increase impedance.

High impedance, high reflection. (bone)

Question 16

This image is showing good _______.

Answer 16

Reflection

Reflection occurs when sound strikes the interface of two mediums with significant impedance values

Question 17

Why do we use ultrasound jelly?

Answer 17

Sound waves are unable to penetrate/travel through the air, the gel is used to reduce the air between the patient and the transducer which reduces the impedance and reflection to allow a clear image to be produced.

Question 18

A reflection coefficient of 0 corresponds to _________ reflection.

Answer 18

No reflection, total transmission.

Question 19

What causes mirror artifacts?

Answer 19

Mirror image artifacts occur when the transmitted pulse and returning echo reflect off of a highly reflective interface (diaphragm) and change direction before returning to the transducer.

Question 20

What is going on here?

What kind of artifacts will this lead to?

How do you mitigate this?

Answer 20

Refraction

Edge artifacts

Tilt the probe to reduce refraction.

Question 21

What are these?

Answer 21

Attenuation and Absorption

Attenuation is when sound waves travel through tissue, the intensity and amplitude decrease.

Absorption occurs when soundwaves loses energy as it travels through a medium.

Question 22

Refers to the ability to reflect or transmit ultrasound waves in the context of surrounding tissues

Answer 22

Echogenicity

Question 23

What is anechoic?

Answer 23

Anechoicrefers to structures that appear black, meaning that there are no internal echoes.

Think fluid-filled vessels, bladder, gallbladder

Question 24

What is hypoechoic?

Answer 24

Hypoechoicstructures appear darker than surrounding structures; gives off fewer echoes. Often seen in tissues with increased density such as fibrous masses. Can also be used to describe the appearance of one organ in relation to another.

The kidney (outlined in blue) is hypoechoic to the adjacent splenic tissue

Question 25

What is hyperechoic?

Answer 25

It is used to describe structures that appear brighter than surrounding structures; these structures give off more echoes.  This can be seen in structures with lower density than the surrounding structures allowing for increased propagation speeds.

Question 26

What is isoechoic

Answer 26

Isoechoic is used to describe a structure that gives off similar echoes relative to another structure in the same image.  *In this image of the kidney/liver interface the kidney (outlined in blue) is isoechoic to the adjacent liver tissue.*

Question 27

What is shadowing?

Answer 27

Occurs when sound waves encounter a structure that has a very high attenuation coefficient (such as bone or solids).  We know that the vast majority of the sound waves that strike solids are reflected back to the transducer, but the remaining sound waves attenuate very quickly causing a shadow. *Radius (highlighted in blue) demonstrates shadowing deep to a dense reflector.  The sound is unable to continue through the bone causing a black appearance void of echoes*

Question 28

What is posterior acoustic enhancements?

Answer 28

Opposite of shadowing. It occurs when sound waves pass through a structure with a very low attenuation coefficient (fluid filled structures). Because sound passes through fluid filled structures exceptionally well, there is an increase in the brightness of posterior echoes. *Bladder demonstrates posterior acoustic enhancement (highlighted in blue) deep to the bladder*

Question 29

What is reverberation?

Answer 29

Reverberation occurs in the presence of highly reflective surfaces (usually a hardware like a needle). This causes the image to record and display multiple evenly spaced echoes on the screen which are not real.

Question 30

What is gain?

Answer 30

Gain is the contrast. High gain brighter, low gain darker.

Question 31

What is 2D or B-mode?

Answer 31

Standard grayscale mode. The "B" stands for brightness. This mode of ultrasound imaging provides structural information using different shades of gray in a 2D (two dimensional) image. *Here is the view of the liver*

Question 32

What is M-mode?

Answer 32

Motion mode imaging to look at things that are moving (lung).

Question 33

For color doppler mode what does red indicate what does blue indicate?

Answer 33

Color red, indicating blood flow toward the transducer. Color blood, blood flow away from transducer. *The red color does not signify the vessel is arterial.*

Question 34

What is the movement called?

Answer 34

Sliding Moving the transducer along its long axis.

Question 35

What is the movement called?

Answer 35

Sweeping Moving the transducer along its short axis.

Question 36

What is the movement called?

Answer 36

Tilting or Fanning While maintaining a fixed position on the body, the transducer is moved along its short axis to change the angle of incidence < 90°.

Question 37

What is the movement called?

Answer 37

Rocking or Heeling While maintaining a fixed position on the body, pressure is applied to one side of the transducer to move in the long axis and reduce the incident angle < 90°.

Question 38

What is the movement called?

Answer 38

Rotating Turning the transducer in a clockwise or counterclockwise direction over a fixed point on the body to change between a short and long-axis view.

Question 39

An interscalene block will most likely cause what syndrome?

Answer 39

Horner Syndrome

Question 40

What view is this?

Answer 40

Long axis

Question 41

What technique is this?

Answer 41

Out-of-plane technique: a needle is inserted perpendicular to the imaging plane, resulting in only a "slice" of the needle being visible on the screen (tip or shaft), where the needle tip can be visualized approaching the target of interest by sequentially tracking the needle during its insertion. *Out-of-plane vascular access. A short axis view of a peripheral vein model demonstrating the needle tip as a hyperechoic point immediately above the vein.*

Question 42

What technique is this?

Answer 42

In-plane probe positioning: A needle is inserted parallel to the imaging plane.  *A long axis view of a peripheral vein model demonstrating the entire needle as a hyperechoic line above and cannulating the vein.*

Question 43

What view is this?

Answer 43

Short axis

Question 44

What are the focal zone and focal point?

Answer 44

The focal point is where the US beam is the narrowest and beam intensity is the greatest. The focal zone is the area around the focal point. Lateral resolution is best within the focal zone.