ARDMS Sonography Principles and Instrumentation SPI Exam Practice Test

Answer : D

Comprehensive and Detailed Explanation From Exact Extract:

Spatial compounding acquires multiple frames from different angles and combines them into a single image. This technique reduces the appearance of artifacts such as shadowing and speckle noise, resulting in a smoother, more uniform image.

According to sonography instrumentation reference:

''Spatial compounding reduces artifacts like posterior shadowing and speckle by averaging data from multiple insonation angles.''

Therefore, the correct answer is D: Decreases shadowing.

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Answer : B

Comprehensive and Detailed Explanation From Exact Extract:

Axial resolution depends on spatial pulse length (SPL), which is determined by the number of cycles per pulse. Fewer cycles per pulse shorten the SPL, thereby improving axial resolution and allowing better separation of closely spaced structures along the beam axis.

According to sonography instrumentation reference:

''Axial resolution improves with fewer cycles per pulse, which decreases the spatial pulse length and allows better discrimination of structures along the beam path.''

Therefore, the correct answer is B: Reducing the number of cycles per pulse.

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Answer : D

Comprehensive and Detailed Explanation From Exact Extract:

Axial resolution improves with shorter spatial pulse length, which is directly related to higher frequency. At shallow depths (such as 2 cm), higher frequency can be used effectively since attenuation is minimal.

Principles and Instrumentation state:

'Axial resolution improves with increasing frequency due to shorter wavelength and pulse length.'

Turning off spatial compounding (A) affects speckle reduction.

Harmonics (B) help with resolution but primarily lateral contrast.

Gain (C) affects brightness, not resolution directly.

Therefore, the correct answer is D: Increase frequency.

Answer : A

When a reflector (such as red blood cells) is moving toward the sound source, the frequency of the reflected sound waves increases. This phenomenon is known as the Doppler effect. The frequency shift occurs because the motion of the reflector compresses the sound waves, leading to a higher frequency than the emitted frequency. This increased frequency is what the Doppler ultrasound system detects and uses to calculate the velocity of the moving reflector.

ARDMS Sonography Principles and Instrumentation guidelines

Hoskins, P. R., Thrush, A., Martin, K., & Whittingham, T. A. (2010). Diagnostic Ultrasound: Physics and Equipment.

Answer : D

Enhancement artifact occurs when an anechoic (or low-attenuation) structure, such as a cyst or fluid-filled structure, allows the ultrasound beam to pass through it with minimal attenuation. As a result, the tissues located distal to this anechoic structure appear brighter (increased echo amplitude) on the ultrasound image because the sound waves are less attenuated by the anechoic structure, leading to higher intensity echoes returning from the distal tissue. This increased brightness beyond the anechoic area is known as enhancement. Reference:

ARDMS Sonography Principles and Instrumentation guidelines

Kremkau, F. W. (2015). Diagnostic Ultrasound: Principles and Instruments. Elsevier.

Answer : C

Color Doppler imaging is most effective when the angle between the ultrasound beam and the flow of blood is small.

At an angle of 88 degrees, the flow of blood is nearly perpendicular to the ultrasound beam.

When the angle is close to 90 degrees, the Doppler shift (frequency change) approaches zero, resulting in little to no color being visualized on the Doppler image.

Thus, to obtain a color signal, the angle should be optimized to be as close to 0 degrees as possible, with 60 degrees being the practical limit for accurate Doppler measurements. Reference:

ARDMS Sonography Principles and Instrumentation guidelines on Doppler angle and its effect on Doppler imaging.

Answer : B

When the depth of imaging is increased, the time it takes for the ultrasound pulses to travel to and from the deeper structures also increases, which can reduce the frame rate. To maintain the same frame rate, one effective adjustment is to decrease the image width. Narrowing the image width reduces the number of scan lines required to create each frame, allowing the system to maintain a higher frame rate despite the increased depth.

ARDMS Sonography Principles and Instrumentation guidelines

Kremkau, F. W. (2015). Diagnostic Ultrasound: Principles and Instruments.