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Senior - Emed 5 > 1 - Ultrasound Basics > Flashcards

1 - Ultrasound Basics Flashcards

(55 cards)

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1
Q

She said “make sure you read the book”

A

LOL

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2
Q

Simplest way to describe US?

A

Pulse-echo principle
- like sonar

The amount of elapsed time required for the “echo” to return subsequent to striking an object allows the relative distance to be calculated

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3
Q

What is piezoelectric effect?

A

Constant pulse of high frequency, longitudinal, mechanical sound waves that can be measured and used in calculations

Voltage -> crystals deformed -> pressure wave

Pressure wave -> crystals -> electric current -> machine translates into a pixel

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4
Q

What speed does US travel through the body? (Velocity)

A

1540m/s

No really she said it was important. I cannot for the life of me figure out why

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5
Q

What frequency is diagnostic US?

A

Between 2 and 15 million cycles/second

- 2 - 15 MHz

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6
Q

Amplitude?

A

Peak pressure of wave

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7
Q

Period

A

Time required to complete one cycle

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8
Q

Frequency

A

of times/second wave is repeated (MHz)

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9
Q

Pulse

A

Period when transducer generates US waves

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10
Q

Spatial pulse length

A

Length of each pulse (distance)

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11
Q

Velocity (propigation of speed)

A

Speed of wave 1540 m/s

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12
Q

Wave length

A

Distance the wave travels in a single cycle

- propagation speed/frequency

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13
Q

Transducer frequency effect on image?

A

High freq:

  • enhanced image quality
  • tissue penetration decreases

Low frequency:

  • lower image quality
  • better tissue penetration

Pic on 18

Its like explosives:
H freq: C4 (or any fancy one) is hot fast and creates a lot of damage in close
L Freq: Dynamite (esp in fertilizer w motor oil on it) will move huge amounts of dirt or objects a long ways with the pressure wave. slower more powerful wave

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14
Q

What is attenuation?

A

Progressive weakening of sound as it travels through a medium

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15
Q

Contributing factors for attenuation?

A

Medium density
Wavelength of sound
Number of interfaces encountered

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16
Q

`forms of attenuation?

A

Reflection
Refraction
Scattering
Absorption

Pic on slied 27

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17
Q

What type of tissue does US work best in?

A

With The least attenuation, through homogenous fluid-filled structures

  • why it works better to have a full bladder when looking at the uterus
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18
Q

Modes of US?

A 
B mode 
M mode
Doppler
- color - directionality
- power - strength of signal (low velocity flow)
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19
Q

B mode is?

A

Brightness mode

  • 2D tomographic slice
  • MC mode in ED
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20
Q

M-Mode?

A

Motion
- simultaneously display of 2D B mode and characteristic waveform

Slide 32

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21
Q

Doppler technology relies on?

A

Frequency shift that exists between transmitted and received doppler signal while anatomy (blood w/in vessel) is moving

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22
Q

Color doppler?

A

Pulse-echo principle that generates color images
- superimposed on 2D image

Blue : Away
Red : Toward

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23
Q

Power doppler?

Study These Flashcards
A

Based on amplitude or strength of the motion

Uses one continuous color (varies by shade)

Pics on 39-41

24
Q

What is power doppler good for?

Study These Flashcards
A

Better sensitivity for slow flow or low blood volume states :

  • ovarian torsion
  • testicular torsion
25
What is echogenicity?
Amplitude (brightness) of the signals reflected from a given structure compared to the amplitude of the signals from surrounding structures
26
Variations of echoic?
Hyperechoic - of increased amplitude than surrounding anatomy Hypoechoic - decreased amplitude Isoechoic - same echogenicty as surrounding tissue Anechoic - absence of echos (fluid filled structure looks black) Pics on 44
27
Types of image artifacts?
``` Shadowing (clean and dirty) Edge artifact Acoustic enhancement Reverberation artifact Mirror image artifact Side lobe artifact ```
28
Defintion of artifact?
Echo information that does not correspond to accurate anatomical information
29
Common causes of artifacts?
Something in the pt Attenuation or refraction Something outside pt Operator error
30
What causes acoustic shadows?
Sound encounters a highly reflective (high attenuation) surface
31
Types of shadows?
Clean shadows: ribs, gallstones and calcified structures Dirty shadows: acoustic mismatch of tissue - air interfaces (MCC bowel gas) Pic on 49
32
Edge artifact?
Stripes caused by the edge of a round object | - slide 50 and 51
33
Acoustic enhancement?
Low attenuation areas cause posterior acoustic enhancement A bright spot on the back side of fluid Pic on 52, 53
34
What is acoustic enhancement used for?
Confirm presence of fluid in an area - hemorrhage - joint effusion - tissue necrosis - abscess - spread of anesthetic
35
___ is the enemy of ultrasound
Gas - large differences in density scatter the acoustic energy and you cant see shit Pic on 56
36
How does reverbereation effect the image?
Sound bounces between 2 highly reflected objects - bright arcs displayed at equidistant intervals from the transducer Pic on 58, 59, 60
37
What causes mirroring?
Objects that appear on both sides of a strong reflector | - beam undergoes multiple reflections returns as a duplication of structures
38
Where are mirror artifacts common?
- diaphragm (hepatic structures) on both sides of it Pics on slides 63,64
39
Mirroring during a FAST?
During the FAST | - mirror artifact of liver or spleen above diaphragm helps r/o pleural effusion or hemothorax
40
Side lobes?
Sound at a weird angle causes a white line on the pics - the crystals dont just send out straight sounds they go out at angles too, usually these just go off into the goo and arent a problem. Sometimes though they hit something and return, confusing the machine - Slides 65 and 66
41
What is acoustic power?
Aka output power - amplitude of sound waves produced by the transducer - helps determine the brightness of the image
42
Greater acoustic power may?
Improve image quality - increased contrast But it can also heat up the tissue, causing damage
43
Acoustic power is related to?
Intensity of the US beam - amount of energy in a given area - determines the bioeffect of US
44
When using US the acoustic power should be?
ALARA As Low As Reasonably Achievable - lowest power setting necessary for the image
45
Gain?
Primary control to adjust brightness - changes brightness by adjusting the amplification of the electronic signals after the echoes have returned to the transducer Pic on 70
46
TGC?
Time gain compensation - adjust brightness of the image at different depths Pic on 73
47
Most frequently used button/knob on US machine?
Depth
48
Reasons to adjust depth?
1. Size of display, makes images smaller allowing more to show 2. Reduces the display frame rate
49
Zoom button
You guessed it, magnification | - resolution remains the same
50
Freeze?
Holds an image - dont worry though modern US machines have “live photos” so if you are a little off on timing you can scroll back a few sec “Live photos” are aka “cine loop”
51
How do you measure shit on an US?
The machine has electronic calipers
52
Dont want tons of transducers hanging around everywhere making you look like a late night infomercial?
General purpose transducers | - 2-4 MHz abdominal transducer than can be switched to 2, 3 or 4 MHz
53
Whats the deal with footprints?
Area that sounds goes through on its way to the pt Large footprint - better deep but confused by sound resistant barriers ( skin and ribs) Small footprint - smaller more directed beam that can go between structure but loose resolution in far fields Slide 81 has pics
54
Types of transducer array?
Linear - flat face - high freq Convex - curved - includes the trans vag Phased array - like linear but smaller and more precise - used for cardiology etc
55
I’m terrified of elevators
I’m going to start taking steps to avoid them.

Senior - Emed 5 (8 decks)

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