ARDMS Updated SPI Exam Questions and Answers by sunny

Comprehensive and Detailed Explanation From Exact Extract:

Mechanical Index (MI) is proportional to the peak negative pressure and inversely proportional to the square root of frequency. Lowering output power directly decreases the peak pressure, thus reducing MI.

Principles and Instrumentation state:

"Mechanical index decreases with lower output power, reducing the risk of mechanical bioeffects such as cavitation."

Lowering frequency (A) increases MI.

Tissue harmonics (B) improves image quality but does not reduce MI directly.

Increasing gain (D) affects displayed brightness, not acoustic power.

Therefore, the correct answer is C: Decreasing output power.

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Comprehensive and Detailed Explanation From Exact Extract:

Damping reduces the number of cycles per pulse, shortening pulse duration and spatial pulse length, which directly improves axial resolution.

Principles and Instrumentation:

"Axial resolution improves with shorter spatial pulse length, achieved by damping, which limits ringing of the transducer."

Lateral resolution (A) depends on beam width.

Contrast resolution (B) relates to dynamic range.

Temporal resolution (C) is tied to frame rate.

Therefore, the correct answer is D: Axial.

Comprehensive and Detailed Explanation From Exact Extract:

Overall gain amplifies the strength of all returning echoes equally, regardless of depth. It does not affect the transmitted pulse or selectively compensate for attenuation; it simply amplifies received signals uniformly.

According to sonography instrumentation reference:

“Overall gain controls the amplification of all returning echoes across the entire image, increasing brightness uniformly at all depths.”

Therefore, the correct answer is B: Amplification of signals from all depths.

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In a variance mode color map, the upper right side typically indicates higher velocity and turbulent flow with a positive Doppler shift. Variance mode maps are designed to display not only the mean velocity and direction of blood flow but also the presence of turbulence. The color green is often used in the upper right quadrant to represent areas of turbulence with positive Doppler shifts, which occur when the blood flow is moving towards the transducer at higher velocities and with increased chaotic motion.References:

ARDMS Sonography Principles and Instrumentation guidelines

"Diagnostic Ultrasound: Physics and Equipment" by Peter Hoskins, Kevin Martin, Abigail Thrush