SPI PRACTICE QUESTIONS ALL ANSWERS CORRECT
What is the purpose of axial resolution in ultrasound?
✔️✔️Axial resolution allows for the distinction between two structures along the direction of the
sound beam, determined by pulse length and frequency.
How does acoustic enhancement appear on an ultrasound image?
✔️✔️Acoustic enhancement appears as increased brightness behind fluid-filled structures, as fluids
cause minimal attenuation of sound waves.
What is the primary factor that affects the speed of sound in a medium?
✔️✔️The speed of sound depends on the medium’s density and stiffness, with denser and stiffer
materials transmitting sound faster.
Explain the term “thermal index” in ultrasound safety.
✔️✔️Thermal index estimates the potential for tissue heating during an ultrasound, guiding safe use,
especially during prolonged scans.
How does a lower frequency impact tissue penetration?
✔️✔️Lower frequencies penetrate tissues more deeply but offer less detailed resolution, useful for
imaging deeper structures like the abdomen.
What causes comet tail artifacts in ultrasound?
✔️✔️Comet tail artifacts occur when sound waves reverberate within a small, highly reflective
structure, creating a series of bright, closely spaced lines.
Describe how lateral resolution changes with distance from the transducer.
✔️✔️Lateral resolution decreases as the distance from the transducer increases due to the natural
widening of the sound beam in the far field.
,How does spatial resolution differ from temporal resolution in ultrasound?
✔️✔️Spatial resolution relates to image detail, while temporal resolution indicates the ability to track
movement over time, dependent on frame rate.
What is the function of the matching layer on a transducer?
✔️✔️The matching layer reduces impedance mismatch between the transducer and skin, improving
sound transmission and image quality.
What does reverberation artifact look like on an ultrasound image?
✔️✔️Reverberation appears as multiple, equally spaced echoes resulting from sound waves reflecting
back and forth between two interfaces.
How does pulse duration impact both resolution and signal strength?
✔️✔️A shorter pulse duration improves resolution but reduces signal strength, while a longer pulse
duration increases strength at the expense of resolution.
What is the main cause of the mirror image artifact?
✔️✔️Mirror image artifacts occur when sound waves reflect off strong interfaces, creating a
duplicated image on the other side of the interface.
Why is frame rate important in Doppler ultrasound?
✔️✔️Frame rate is critical in Doppler ultrasound to accurately capture fast-moving blood flow, as
lower frame rates can miss rapid changes.
How does increasing the dynamic range affect the ultrasound image?
✔️✔️Increasing dynamic range displays a broader range of echo intensities, reducing contrast but
providing more detail in areas with subtle differences.
Explain the purpose of spectral Doppler in ultrasound imaging.
✔️✔️Spectral Doppler displays blood flow velocities graphically, helping assess flow patterns and
potential abnormalities within vessels.
, What is the effect of the Nyquist limit in Doppler ultrasound?
✔️✔️The Nyquist limit represents the maximum measurable Doppler frequency shift; exceeding this
limit results in aliasing.
How does focusing improve ultrasound image quality?
✔️✔️Focusing narrows the ultrasound beam at a specific depth, enhancing lateral resolution and
improving image sharpness at the focal point.
What is the role of “frequency compounding” in ultrasound imaging?
✔️✔️Frequency compounding uses multiple frequencies to generate images, reducing noise and
improving tissue differentiation.
Why are high-frequency transducers used in musculoskeletal ultrasound?
✔️✔️High-frequency transducers provide superior resolution, necessary for visualizing small and
superficial structures like tendons and muscles.
Describe what happens when ultrasound encounters an anechoic structure.
✔️✔️Anechoic structures do not reflect sound, appearing as black areas on the image, often
indicating fluid-filled spaces like cysts or blood vessels.
How does absorption contribute to attenuation in ultrasound?
✔️✔️Absorption is the conversion of sound energy into heat, reducing the sound wave’s strength as it
penetrates tissue, contributing to attenuation.
What is beam steering, and why is it useful in ultrasound?
✔️✔️Beam steering electronically directs the ultrasound beam without moving the transducer, useful
for obtaining multiple angles and avoiding artifacts.
How does the presence of gas affect ultrasound imaging?
What is the purpose of axial resolution in ultrasound?
✔️✔️Axial resolution allows for the distinction between two structures along the direction of the
sound beam, determined by pulse length and frequency.
How does acoustic enhancement appear on an ultrasound image?
✔️✔️Acoustic enhancement appears as increased brightness behind fluid-filled structures, as fluids
cause minimal attenuation of sound waves.
What is the primary factor that affects the speed of sound in a medium?
✔️✔️The speed of sound depends on the medium’s density and stiffness, with denser and stiffer
materials transmitting sound faster.
Explain the term “thermal index” in ultrasound safety.
✔️✔️Thermal index estimates the potential for tissue heating during an ultrasound, guiding safe use,
especially during prolonged scans.
How does a lower frequency impact tissue penetration?
✔️✔️Lower frequencies penetrate tissues more deeply but offer less detailed resolution, useful for
imaging deeper structures like the abdomen.
What causes comet tail artifacts in ultrasound?
✔️✔️Comet tail artifacts occur when sound waves reverberate within a small, highly reflective
structure, creating a series of bright, closely spaced lines.
Describe how lateral resolution changes with distance from the transducer.
✔️✔️Lateral resolution decreases as the distance from the transducer increases due to the natural
widening of the sound beam in the far field.
,How does spatial resolution differ from temporal resolution in ultrasound?
✔️✔️Spatial resolution relates to image detail, while temporal resolution indicates the ability to track
movement over time, dependent on frame rate.
What is the function of the matching layer on a transducer?
✔️✔️The matching layer reduces impedance mismatch between the transducer and skin, improving
sound transmission and image quality.
What does reverberation artifact look like on an ultrasound image?
✔️✔️Reverberation appears as multiple, equally spaced echoes resulting from sound waves reflecting
back and forth between two interfaces.
How does pulse duration impact both resolution and signal strength?
✔️✔️A shorter pulse duration improves resolution but reduces signal strength, while a longer pulse
duration increases strength at the expense of resolution.
What is the main cause of the mirror image artifact?
✔️✔️Mirror image artifacts occur when sound waves reflect off strong interfaces, creating a
duplicated image on the other side of the interface.
Why is frame rate important in Doppler ultrasound?
✔️✔️Frame rate is critical in Doppler ultrasound to accurately capture fast-moving blood flow, as
lower frame rates can miss rapid changes.
How does increasing the dynamic range affect the ultrasound image?
✔️✔️Increasing dynamic range displays a broader range of echo intensities, reducing contrast but
providing more detail in areas with subtle differences.
Explain the purpose of spectral Doppler in ultrasound imaging.
✔️✔️Spectral Doppler displays blood flow velocities graphically, helping assess flow patterns and
potential abnormalities within vessels.
, What is the effect of the Nyquist limit in Doppler ultrasound?
✔️✔️The Nyquist limit represents the maximum measurable Doppler frequency shift; exceeding this
limit results in aliasing.
How does focusing improve ultrasound image quality?
✔️✔️Focusing narrows the ultrasound beam at a specific depth, enhancing lateral resolution and
improving image sharpness at the focal point.
What is the role of “frequency compounding” in ultrasound imaging?
✔️✔️Frequency compounding uses multiple frequencies to generate images, reducing noise and
improving tissue differentiation.
Why are high-frequency transducers used in musculoskeletal ultrasound?
✔️✔️High-frequency transducers provide superior resolution, necessary for visualizing small and
superficial structures like tendons and muscles.
Describe what happens when ultrasound encounters an anechoic structure.
✔️✔️Anechoic structures do not reflect sound, appearing as black areas on the image, often
indicating fluid-filled spaces like cysts or blood vessels.
How does absorption contribute to attenuation in ultrasound?
✔️✔️Absorption is the conversion of sound energy into heat, reducing the sound wave’s strength as it
penetrates tissue, contributing to attenuation.
What is beam steering, and why is it useful in ultrasound?
✔️✔️Beam steering electronically directs the ultrasound beam without moving the transducer, useful
for obtaining multiple angles and avoiding artifacts.
How does the presence of gas affect ultrasound imaging?
