Ultrasound

Question 0

Ultra sound is a mechanical, longitudinal wave with a frequency that

Answer 0

Exceeds the upper limit of human hearing

20000 Hz

Question 1

Sound is a mechanical, ______ wave that travels in a _____. It requires a ____ through which to travel

Answer 1

Longitudinal wave
Straight line
Medium

Question 2

How many Hz (oscillations/second) is medical ultrasound? What about the transducers for UGRA?

Answer 2

2 to 16 MHz

4-13 MHz

Question 3

Ultrasound is produced by passing an alternating electrical current through a

Answer 3

Piezoelectrical crystal

Question 4

Ultrasound relies on ______ to image the body and diagnose and identify different structures in the body. They oscillate back and forth to produce a series of

Answer 4

High frequency sounds

Compressions and refractions

Question 5

Why are high frequencies used for scanning areas of the body close to the surface? Frequencies generally range between

Answer 5

Higher frequencies have shorter wavelengths that are absorbed easily so not as penetrating
1-50 MHz

Question 6

How does the resolution of the image produced by a lower frequency transducer compare to that of a higher frequency?

Answer 6

Lower resolution but can penetrate deeper (longer wavelengths)

Question 7

What is the formulas for velocity?

Answer 7

V = frequency x wavelength
Velocity = speed of wave
Frequency = oscillations per second
Wavelength = distance between two compressions or refractions

Question 8

What is the difference between a compression and refraction?

Answer 8

Particles in compressions are close together and there is high pressure. Refractions have particles that are far apart with low pressure

Question 9

What are the components of an ultrasound transducer?

Answer 9

Metal outer casing
Backing block
Plastic nose
Electrodes that apply an alternating potential difference
Piezoelectric crystal
Acoustic insulator
Power cable

Question 10

Running an alternating current through the piezoelectric crystal causes it to _____ depending on the voltage running through it. The ultrasound is produced when the crystal vibrates at ______. This conversion of electrical to mechanical energy is known as the

Answer 10

Grow and shrink
Vibrates at high speed
Piezoelectric effect

Question 11

When the ultrasound produced from the transducer hits the object under investigation, it bounces back off and hits the piezoelectric crystal, causing

Answer 11

The reverse effect to happen

Mechanical energy is converted back into electrical

Question 12

What interactions does ultrasound have with tissue?

Answer 12

Reflection
Refraction
Transmission
Attenuation

Question 13

Targets for UGRA are based on _____ and

Answer 13

Reflection

Impedance - tendency of a medium to conduct ultrasound

Question 14

When a sound travels through an object and contacts an adjacent object with a different impedance, a _____ is formed. At the interfaces between objects with different impedances, _____ occurs. Greater reflections are formed from ____ difference in acoustic impedance.

Answer 14

Demarcation
Reflection
Greater

Question 15

The ultrasound image is formed from

Answer 15

Reflected echoes

Question 16

Objects that are highly reflective are displayed as

Answer 16

White or hyper echoic

Examples include facial planes, bones, and some nerves, tendons, diaphragm

Question 17

Objects that are weakly reflected are

Answer 17

Darker or hypo echoic

Examples include muscle, fat, and some nerves

Question 18

How do blood vessels appear on the ultrasound?

Answer 18

Anechoic and black

Question 19

What is the fundamental clinical challenge in UGRA? Give an example?

Answer 19

Many neural structures lie in close proximity to one another with similar acoustic impedances so making a positive identification is challenging since the structures appear similar.
An example of this is distinguishing tendon from nerve in the distal arm or leg

Question 20

Why is cardiac imaging much easier?

Answer 20

Clear demarcation between blood filled chambers (black) on myocardium (whiter)

Question 21

The loss of ultrasound wave energy as it travels through tissue is known as _____. Lower frequency waves will _____ in comparison to a higher frequency wave.

Answer 21

Attenuation

Attenuate less

Question 22

The deeper the wave travel in the body, the weaker it becomes (attenuation) by three processes:

Answer 22

Reflection
Absorption
Refraction

Question 23

Balanced gain settings are important to obtaining adequate images.

Answer 23

Ok.

Question 24

Most solid organs on the ultrasound are? What about thick fluid?

Answer 24

Gray, weaker reflections

Thick fluid is iso echoic

Question 25

What structure a have no reflections?

Answer 25

Fluid within cysts, urine, blood

They are black dots, hypo echoic

Question 26

What determines how far the ultrasound waves travel?

Answer 26

FREQUENCY if the transducer

Attenuation is directly related to frequency

Question 27

The ultrasound beam comes out as a ____ that is ____ thick. The depth displayed is _____. The image produced is

Answer 27

Slice
1 mm thick
2D - tomographic slice that assumes no thickness

Question 28

The ultimate goal of the ultrasound is to make

Answer 28

Like tissues look the same and unlike tissues look different.

This is some tautology shit right here.

Question 29

Regional anesthesiologist prefer to use which axis to image nerves and blood vessels? Why?

Answer 29

Short axis

Simultaneous view of the anterior/posterior and lateral/medial perspective

Question 30

A short axis view can become long when the transducer is turned ____. Which perspective is lost in the long acid view?

Answer 30

90 degrees either direction

Lateral/medial perspective is lost

Question 31

Ten steps of peripheral UGRA are to

Answer 31

1 visualize key landmark structures
2 identify the nerves or plexus on short axis imaging
3 confirm normal anatomy or recognize variations
4 plan for safest and most effective needle approach
5 use aseptic needle insertion technique
6 follow the needle under real time visualization toward the target
7 consider a secondary confirmation technique such as nerve stimulation
8 when needle tip is assumed to be in correct position, inject small volume of test solution
9 make necessary needle adjustments to obtain optimal peri neural spread of local anesthesia
10 maintain traditional safety guidelines

Question 32

What is the PART maneuver in the ASRA recommended scanning techniques?

Answer 32

PRESSURE - varying degrees of pressure on the skin
ALIGNMENT - sliding movement to define lengthwise course of the nerve
ROTATION - in clockwise or counter to optimize the image
TILTING - in both directions to maximize angle of incidence

Question 33

All those pictures

Answer 33

Just look at it

Question 34

Different approaches to ultrasounds…?

Answer 34

Supra clavicle lateral to medial approach
Supra clavicular medial to lateral in plane approach
Interscalene block
Infraclavicular block
Auxiliary block
Femoral block
Subgluteal approach of sciatic nerve
Popliteal fossa sciatic nerve block