Ultrasonography

Question 1

Ultrasound is used for

Answer 1

Used to image soft tissues
Cannot image through bone or gas
Can provide anatomical and functional information of organs that are simply gray shapes on radiographs

Question 2

Why does ultrasound not have the same risks as radiography

Answer 2

Since ultrasound involves sound waves, it is not believed to have the same risks as radiography
The waves involve mechanical energy, not electromagnetic

Question 3

How does ultrasound work

Answer 3

A beam of high frequency sound waves is sent into a patient
Interacts with different organs and tissues where they primarily are absorbed or reflected
If they are reflected, they are sent back to the ultrasound (u/s) machine
Computer in u/s machine interprets the returning soundwaves and displays a gray-scale image on the monitor

Question 4

Patient prep for ultrasound

Answer 4

Patient may need to be shaved depending on
Areas being imaged
Patient haircoat
Examination being performed
Patient may require fasting
Patient may require sedation

Question 5

Echocardiography is

Answer 5

The use of ultrasound in the investigation of the heart and great vessels and the diagnosis of cardiovascular lesions
Echo or Echoes: what the soundwaves are called in ultrasonography or echocardiography

Question 6

Attenuation is and contributing factors

Answer 6

Reduction in the intensity of sound waves reflected back to transducer
Factors that contribute:
Absorption of some of the sound waves or their strength
Scatter of some of the sound waves in directions other than back to transducer
Reflection back to the transducer

Question 7

Echogenicity is

Answer 7

Appearance of tissues on u/s based on ability to reflect sound waves
Refers to brightness of tissues

Question 8

Hyperchoic is

Answer 8

Tissues that reflect basically all u/s waves back to transducer (higher intensity)
Include bone and air
Appear very white or light

Question 9

Hypoechoic is

Answer 9

Tissues that reflect only some of the u/s waves back to transducer (lower intensity)
Some waves continue to penetrate deeper to be reflected back by other tissues
Appear as varying shades of gray

Question 10

Isoechoic

Answer 10

Two structures that have relatively similar echogenicity toward each other

Question 11

Anechoic

Answer 11

Tissues lacking internal echoes (no intensity)
Includes fluids
Appear black on screen

Question 12

The transducer consists of

Answer 12

Consists of one or more piezoelectric crystals that convert electrical signals into mechanical signals and then back into electrical signals for processing by a computer

Question 13

Basic principles of ultrasound

Answer 13

u/s uses high frequency soundwaves to generate an image
Frequencies used in diagnostic imaging
2.5-13 MHz

Question 14

2.5-3.5 MHz used on ultrasound on

Answer 14

LA- heart and abdomen

Question 15

5.0 MHz used on

Answer 15

LA – heart, abdomen, thorax (lung), reproduction
SA – abdomen and heart (large dogs)

Question 16

7.5-13MHz used on ultrasound when

Answer 16

LA - tendons, ligaments, eye, superficial structures
SA – abdomen, heart, eye, superficial structures

Question 17

How does ultrasound work

Answer 17

Short burst of current applied to crystal causing it to vibrate at high frequency
Crystal deforms and emits sound waves
Transducer placed in contact with patient and soundwaves travel through patient
Within tissues, sound waves are either absorbed
Soundwaves eventually reflected back to transducer where they interact with crystal again and are converted back to electric signals

Question 18

What do the different densities look like in ultrasound

Answer 18

Bone = 100% reflection
Air = scattering of sound waves causing 99% reflection
Soft tissue = reflects small amounts of sound waves but allows others to pass through to deeper tissues
Fluid = 100% transmission of sound waves to deeper tissues

Question 19

Types of ultrasound

Answer 19

B-Mode
M-Mode
Doppler

Question 20

B-mode ultrasound is

Answer 20

‘Brightness’ mode
Real time ultrasound
Commonly recognized images produced by ultrasound
2-dimensional display of returning echoes
Amplitude of returning echo is converted to the brightness of a dot on the display
Brighter the dot = stronger the returning echo
Location of dot on display corresponds to location of echo reflector

Question 21

What does the image look like on b-mode

Answer 21

Single, frozen static image (static B-mode)
Many frames can be acquired and displayed within one second (real time B-mode)
In real-time imaging, each frame is refreshed when next echo pulse sweeps across the tissue cross-section
30-60 pictures/second
Allows evaluation of moving structures

Question 22

M-mode ultrasound is

Answer 22

‘Motion’ mode
1-dimensional view of depth vs time

Question 23

M-mode and echocardiography

Answer 23

Single scan line selected from the B-mode image
Displays cardiac structures moving over time
Vertical axis – depth of structure from transducer
Horizontal axis – time

Question 24

Why use M-mode ultrasound

Answer 24

Used to obtain cardiac measurements
Cardiac chamber
Wall thickness
Used to evaluate valve and wall motion

Question 25

How does doppler work

Answer 25

Not really a separate type of ultrasound, but more an application of ultrasound properties
Based on Doppler principle of changing frequency of sound related to direction of sound (echo) source

Question 26

What does doppler detect

Answer 26

When applied to blood flow can detect:
Velocity
Direction
Flow pattern

Question 27

Two types of doppler

Answer 27

Spectral
Color-flow (CFD)

Question 28

Spectral doppler is

Answer 28

Wave form display of blood velocity and direction
Displayed over time
Above baseline = towards transducer
Below baseline = away from transducer

Question 29

Color flow doppler is

Answer 29

Color display superimposed over a 2D image
Usual color display
BART
Blue = Away
Red = Towards
Turbulence = mosaic/mixture of colors

Question 30

Artifacts in ultrasound

Answer 30

Ultrasound is riddled with them!
Occur as structures that are either:
Not real
Missing
Improperly located
Improper brightness, shape or size
Knowledge of artifacts is important
Make proper analysis
Some helpful, others not
Many artifacts occur because of computer confusion

Question 31

Uses of ultrasound in vet med

Answer 31

Abdominal
Cardiac
Eye
Musculoskeletal
Non-cardiac thoracic
Reproductive
Biopsies
Foreign bodies/radiolucent objects

Question 32

When is ultrasound contraindicated

Answer 32

Extremely gas-filled structures
To determine function of organ
Except for the heart