Ultrasound (Exam I) Flashcards
Ultrasound is defined as sound with a frequency greater than ___________ hz (the human hearing limit).
What range do ultrasound devices operate at?
- 20,000 hz
- 2 - 18 megahertz
What type of ultrasound probe provides the best resolution in exchange for poor penetration?
What frequency is seen with this probe?
- Linear
- High frequency
What type of ultrasound probe provides the decent resolution and decent penetration?
- Curvilinear
What type of ultrasound probe provides the best penetration in exchange for poor resolution?
What frequency is seen with this probe?
- Phased
- Low frequency
What aspect of the ultrasound probe converts electricity into sound?
- Piezoelectric elements
Is the output from the ultrasound probe constant? Why or why not?
- No because a “listening” period is needed for returning signals.
What tissue allows for the quickest sound conduction?
What then would have the slowest conduction speed?
- Bone
- Air
What zone is indicated by 1 in the figure below?
What is it’s importance?
- Fresnel Zone (near field)
- Decent lateral resolution in this region
What zone is indicated by 2 in the figure below?
What is it’s importance?
- Fraunhofer Zone (far field)
- Poor lateral resolution in this region
What zone is indicated by 3 in the figure below?
What is it’s importance?
- Focal Zone (ultrasound is narrowest and beam intensity is greatest here.)
- Best lateral resolution in this region
What is impedance?
What has the greatest impedance?
The least?
- The resistance to ultrasound propagation as it moves through a medium.
- Greatest impedance = bone
- Least impedance = air
What is ultrasound reflection?
- Reflection of ultrasound waves back to the probe
What has the highest reflection property?
What tissue is highest?
- Air
- Bone has highest reflection
What is mirror artifact?
- Artifact where tissue is mirrored on the other side of a structure (diaphragm/liver example)
What is refraction?
- Occurs when ultrasound strikes two tissues with different impedance values.
What is edge artifact?
- Artifact occurring at the edges of smooth or rounded structures creating a shadow at structures edge.
What is ultrasound attenuation?
What probe would be most affected by attenuation?
- Loss of amplitude & intensity the deeper ultrasound waves penetrate. (due to absorption, refraction, & reflection)
- Linear probe (due to higher frequency)
What is ultrasound absorption?
- Occurs as ultrasound wave travels through a medium losing energy.
What is Anechoic? What is an example?
- Structures that appear black due to having no internal echoes.
- Ex. Blood vessels, bladder, cysts, etc.
What is hypoechoic? What are tissue examples?
- Structures that appear darker than surrounding tissue.
-seen in increased density tissues
- Ex. kidney compared to spleen.
What is hyperechoic? What are tissue examples?
- Structures that are brighter than the surrounding tissue.
-lower density tissue
Ex. Fatty tumors & bone
What type of artifact is noted in the picture below?
- Shadowing (occurs from bone reflecting back most ultrasound waves, and the rest attenuating quickly).
What type of artifact is noted in the picture below?
Posterior Acoustic Enhancement
-increased brightness on posterior due to passing through low attenuation coefficent
(occurs from passing through low impedance tissue).
What does M-mode do in the ultrasound machine?
What is it useful for?
- Gives a motion over time display.
- Lung sliding, fetal heart rate, etc.
What color would the doppler appear based on the picture evaluating the radial artery below?
- Red (blood moving towards doppler)
What color would the doppler appear based on the picture evaluating the radial artery below?
- Blue (blood moving away from doppler)
When getting a pulse-wave doppler (PWD) how should the probe be positioned?
- Parallel with the direction of flow. (perpendicular will cause flattening of the waveform)
What doppler technique is depicted below?
- Sliding (movement along long axis)
What doppler technique is depicted below?
- Sweeping (movement along short axis)
What doppler technique is depicted below?
- Tilting/Fanning (tilting along short axis)
What doppler technique is depicted below?
Rocking/Heeling (tilting along long axis)
What doppler technique is utilized to change between a short and long axis view?
- Rotating
Is an out-of-plane or in-plane view depicted below?
- Out-of-plane
Is an out-of-plane or in-plane view depicted below?
- In-plane
