Basic Ultrasound Priniciples

Question 1

Transverse Plane

Answer 1

Surface Orientation:

• anterior
• posterior
• right (medial/lateral)
• left (medial/lateral

Question 2

Answer 2

transverse plane

Question 3

Longitudinal Plane

Answer 3

Surface Orientation:

• anterior
• posterior
• superior
• inferior
• saggital divides body into UNEQUAL right and left sections

Question 4

Answer 4

Longitudinal plane

Question 5

Transverse vs Longitudinal Visual

Answer 5

Question 6

Transducer Orientation

Answer 6

• scan lines come out transducer to form a plane or slice
• the image is then displayed on the screen
• for proper orientation the INDICATOR must match the SCREEN orientation

Question 7

When is screen orientation usually opposite?

Answer 7

• echocardiography

Question 8

Answer 8

Transverse, Off-Axis

Question 9

Answer 9

Longitudinal, In-Axis

Question 10

3 Primary Ways to Use US for Needle Guidance

Answer 10

1) In axis, in plane (long of anatomy, needle in plane)
2) Off axis, off plane (trans of anatomy, needle out of plane) used for PICC lines and PIVs
3) Off axis, in plane (trans of anatomy, needle in plane) most popular for regional anesthesia and blocks.

Question 11

Answer 11

In axis, in plane

Question 12

Answer 12

off axis, off plane

Question 13

Answer 13

off axis, in plane (how you will hit a nerve)

Question 14

echogenic

Answer 14

having echoes, white

Question 15

anechoic/sonolucent

Answer 15

without echoes, black

Question 16

hyperechoic

Answer 16

having more echoes when compared to adjacent structure

Question 17

hypoechoic

Answer 17

having less echoes when compared to adjacent structure

Question 18

isoechoic

Answer 18

having the same echogenicity as adjacent structure

Question 19

Sonographic Terminology Visual

Answer 19

Question 20

What does fluid look like on US?

Answer 20

Question 21

Acoustic Shadow

Answer 21

• when structures deep to an object are missing, not displayed
• due to high attenuation of US by dense structures, stones, or bone

Question 22

Pulse-Echo Technique

Answer 22

• US sent into body
• reflects off structures
• returns to transducer
• computer processes reflections into image

Question 23

Pulsed Ultrasound

Answer 23

• each pulse produces one line of information
• the instrument assumes:
• the US went straight through the body
• reflected off different structures
• reflections traveled straight back to the transducer
• this path only happened once

Question 24

Scan Lines

Answer 24

• display reflections of varying intensities based on the intensity of the returning echo and in locations corresponding to the direction the beam was sent out and depth of reflectors
• beam is moved through body in sweeping action producing real-time

Question 25

Sound Waves

Answer 25

- carry energy - mechanical: must have a medium to travel through - cannot travel in a vaccuum - medium has dramatic effect on wa e - not electromagnetic waves (x-ray, light)

Question 26

Longitudinal Waves

Answer 26

- particle motion is parallel to wave direction

Question 27

Frequency

Answer 27

of cycles per second, measured in Hertz (Hz) - audilble is 20 - 20,000 Hz - Ultrasound is \>20,000 Hz

Question 28

Diagnostic Range

Answer 28

- 2-15 Megahertz (millions of cycles per sec)

Question 29

Attenuation vs Resolution

Answer 29

_High Freq_: better resolution (image detail), more attenuation (absorption of sound energy - doesn't penetrate as well) _Low Freq_: poorer resolution, less attenuation (penetrates better but resolution is poor ie: bass coming through neighbor's wall) ***use highest freq possible that allows for adequate penetration***

Question 30

Reflections

Answer 30

- occur when there is a change in the impedance of the medium - 2 types: specular vs non-specular (diffuse, scatter) - everything grey/white is a reflection

Question 31

Specular Reflectors

Answer 31

- create the most artifact, especially when imaged at an obliqued angle. **You should image them perpendicular.** - examples: diaphragm, gallbladder wall, gallstone, liver/kidney, vessel wall, fetal femur, **vessel walls, nerves, etc.**

Question 32

Anisotrophy

Answer 32

- variation of US interaction w fibrillar tissues, resulting in artifact (missing structures) when imaged other than 90 degrees - 5 degree change can cause artifact

Question 33

Depth Based on Speed and Time

Answer 33

- instrument determines depth of reflectors by: - assuming propagation speed/velocity of 1540 m/s (1.54 mm/sec) - determining the round trip time of echo - depth mm = 1.55 mm/us x time us

Question 34

reverberation

Answer 34

- US beam makes the path more than once - extra echoes on the image that do not represent true anatomy - causes mirror image so ***know your anatomy!***

Question 35

Piezoelectric Crystal Transducer

Answer 35

- converts electral energy into ultrasound and vice versa - lead zirconate titanate (PZT) man made - fragile

Question 36

Types of Transducers

Answer 36

- different types for different exams: vectors, liner, transvaginal, transrectal, endoscopic, etc - different freqs for different imaging ie: high freq = better resolution, less penetration low freq = poorer resolution, more penetration

Question 37

Sound is a \_\_\_\_\_, ______ wave.

Answer 37

Sound is a _mechanical_, _longitudinal_ wave.

Question 38

2 Properties of Sound:

Answer 38

1) frequency 2) attenuation