Ultrasound Basics

Question 1

Describe the difference between hyperechoic and hypo/anechoic, and provide an example.

Answer 1

hyperechoic materials = appear bright on screen (bone)

hypo/anechoic materials = appear dark on screen (fluid)

Question 2

Describe how ultrasound images are generated.

Answer 2

An electric current is run through a piezoelectric material in the transducer.

Ultrasound waves propagate through tissue and reflect back to the transducer.

The transducer interprets these waves and creates an image on the screen.

Question 3

What are the three different probe types?

Answer 3

1. phased array (cardiac)
2. linear (vascular)
3. curvilinear (abdominal)

Question 4

Name the probes types in order of highest to lowest frequency.

Answer 4

linear (highest) > curvilinear > phased array (lowest)

Question 5

Describe the four movements of the probe.

Answer 5

slide, sweep, rotate, heel/toe

Question 6

What is refraction / edge artifact?

Answer 6

beams are bent away from the sides of a fluid-filled structure with echogenic walls, resulting in a dark shadow extending from the edges of the structure

Question 7

What is acoustic shadow artifact?

Answer 7

beams do not penetrate dense structures such as bone and create a shadow behind the tissue in far field

Question 8

What is enhancement artifact?

Answer 8

fluid filled structures do not impede ultrasound beams, and the tissue in far field reflect more energy, resulting in them appearing brighter than adjacent tissue

Question 9

What is mirror artifact?

Answer 9

structures near field to highly reflective structures can be mirrored in far field

Question 10

What is scatter?

Answer 10

beams scatter when hitting gas, resulting in uninterpretable images

Question 11

What is M-mode?

Answer 11

Measures movement along a vertical line (from near field to far field) on the ultrasound screen and graphs this over time.

Question 12

What is attenuation?

Answer 12

The degradation of the energy of the ultrasound beam as it passes through tissue. Higher density tissues cause more attenuation.

Question 13

What is B-mode?

Answer 13

Also known as greyscale. Almost all POCUS scanning is done in this mode. The image is created by reflected sound waves returning to the probe.

Question 14

What is resolution?

Answer 14

The degree to which ultrasound waves are able to distinguish whether adjacent structures are separate, rather than being one large object.

Question 15

Which setting should you adjust to improve axial resolution?

Answer 15

frequency of the probe

Question 16

Which setting should be adjusted to improve lateral resolution?

Answer 16

moving the location of focus