SPI Mock Exam Verified Solutions
How does increasing transmit power affect patient safety?
✔️✔️Increasing transmit power boosts image brightness and penetration but also raises patient
exposure, so it’s used carefully to maintain safe levels.
What is the role of frequency in determining axial resolution?
✔️✔️Higher frequencies produce shorter wavelengths, which improve axial resolution by allowing
finer detail along the ultrasound beam’s path.
Explain how spatial pulse length influences axial resolution.
✔️✔️Shorter spatial pulse length improves axial resolution, enabling the ultrasound system to
distinguish between closely spaced structures.
What causes enhancement artifact, and how does it appear?
✔️✔️Enhancement occurs when sound travels through a low-attenuation structure, such as fluid,
resulting in a brighter area behind it.
What is the purpose of frequency compounding in ultrasound imaging?
✔️✔️Frequency compounding combines multiple frequencies to reduce noise and enhance tissue
boundaries, creating a clearer image.
Describe how power Doppler differs from color Doppler.
✔️✔️Power Doppler displays the intensity of blood flow, regardless of direction, making it more
sensitive to low-flow areas but without directional information.
How does the sound wave’s angle of incidence affect reflection?
✔️✔️A perpendicular angle of incidence produces maximum reflection, while an oblique angle can
reduce the intensity of returning echoes.
, Explain the term “artifact” in ultrasound and give an example.
✔️✔️An artifact is an error or distortion in the ultrasound image; for example, reverberation artifact
shows multiple, repeated echoes from strong reflectors.
What is the purpose of a phased array transducer?
✔️✔️A phased array transducer electronically steers and focuses the ultrasound beam, ideal for
imaging structures like the heart with limited probe movement.
How does frame averaging affect temporal resolution?
✔️✔️Frame averaging reduces temporal resolution by smoothing out the image, as it takes longer to
average multiple frames before display.
Why is a low-frequency transducer preferable for deep tissue imaging?
✔️✔️Low-frequency transducers provide deeper penetration with less resolution loss, making them
suitable for imaging structures further from the surface.
Describe the impact of sound wave absorption on tissue heating.
✔️✔️Absorption converts sound energy into heat, causing tissue warming, which is monitored
through thermal index settings to prevent overheating.
How does aliasing affect spectral Doppler imaging?
✔️✔️Aliasing shows as a wraparound of Doppler signals, making it appear that flow is reversing
direction; adjusting PRF can help reduce this.
What does the Nyquist limit represent in Doppler ultrasound?
✔️✔️The Nyquist limit is the maximum detectable Doppler shift frequency before aliasing occurs,
equal to half the PRF.
What is axial resolution, and why is it typically superior to lateral resolution?
✔️✔️Axial resolution, dependent on pulse length, is often better because pulses are naturally shorter
than the width of the ultrasound beam.
How does increasing transmit power affect patient safety?
✔️✔️Increasing transmit power boosts image brightness and penetration but also raises patient
exposure, so it’s used carefully to maintain safe levels.
What is the role of frequency in determining axial resolution?
✔️✔️Higher frequencies produce shorter wavelengths, which improve axial resolution by allowing
finer detail along the ultrasound beam’s path.
Explain how spatial pulse length influences axial resolution.
✔️✔️Shorter spatial pulse length improves axial resolution, enabling the ultrasound system to
distinguish between closely spaced structures.
What causes enhancement artifact, and how does it appear?
✔️✔️Enhancement occurs when sound travels through a low-attenuation structure, such as fluid,
resulting in a brighter area behind it.
What is the purpose of frequency compounding in ultrasound imaging?
✔️✔️Frequency compounding combines multiple frequencies to reduce noise and enhance tissue
boundaries, creating a clearer image.
Describe how power Doppler differs from color Doppler.
✔️✔️Power Doppler displays the intensity of blood flow, regardless of direction, making it more
sensitive to low-flow areas but without directional information.
How does the sound wave’s angle of incidence affect reflection?
✔️✔️A perpendicular angle of incidence produces maximum reflection, while an oblique angle can
reduce the intensity of returning echoes.
, Explain the term “artifact” in ultrasound and give an example.
✔️✔️An artifact is an error or distortion in the ultrasound image; for example, reverberation artifact
shows multiple, repeated echoes from strong reflectors.
What is the purpose of a phased array transducer?
✔️✔️A phased array transducer electronically steers and focuses the ultrasound beam, ideal for
imaging structures like the heart with limited probe movement.
How does frame averaging affect temporal resolution?
✔️✔️Frame averaging reduces temporal resolution by smoothing out the image, as it takes longer to
average multiple frames before display.
Why is a low-frequency transducer preferable for deep tissue imaging?
✔️✔️Low-frequency transducers provide deeper penetration with less resolution loss, making them
suitable for imaging structures further from the surface.
Describe the impact of sound wave absorption on tissue heating.
✔️✔️Absorption converts sound energy into heat, causing tissue warming, which is monitored
through thermal index settings to prevent overheating.
How does aliasing affect spectral Doppler imaging?
✔️✔️Aliasing shows as a wraparound of Doppler signals, making it appear that flow is reversing
direction; adjusting PRF can help reduce this.
What does the Nyquist limit represent in Doppler ultrasound?
✔️✔️The Nyquist limit is the maximum detectable Doppler shift frequency before aliasing occurs,
equal to half the PRF.
What is axial resolution, and why is it typically superior to lateral resolution?
✔️✔️Axial resolution, dependent on pulse length, is often better because pulses are naturally shorter
than the width of the ultrasound beam.
