Mixed Deck — All ARDMS SPI Topics Flashcards

The Doppler equation states that the Doppler shift is directly proportional to which of the following?

Answer: The transmitted frequency, flow velocity, and cosine of the Doppler angle

The Doppler shift (Δf) = 2 × f₀ × v × cos θ / c, meaning it is directly proportional to the transmitted frequency, flow velocity, and the cosine of the angle between the beam and flow direction.

Which QA measurement describes the shortest distance from the transducer face at which the system can display accurate image information?

Answer: Dead zone

The dead zone is the region immediately adjacent to the transducer face where the system cannot detect echoes due to the ring-down artifact from the transmitted pulse.

A resistive index (RI) value close to 1.0 in a renal artery waveform suggests:

Answer: Absent or reversed diastolic flow

An RI near 1.0 indicates minimal or absent end-diastolic flow, suggesting markedly elevated distal resistance.

The spatial pulse length (SPL) is determined by:

Answer: Number of cycles × wavelength

SPL = number of cycles per pulse × wavelength; shorter SPL (fewer cycles, shorter wavelength) means better axial resolution.

In a 1.5D array transducer compared to a standard 1D array, the key improvement is:

Answer: Limited electronic control in the elevation dimension to improve slice-thickness resolution

A 1.5D array adds a few rows of elements in the elevation direction, allowing limited electronic focusing to reduce slice-thickness artifacts compared to a fixed lens.

When the color Doppler gate is positioned at 90° to flow direction, the resulting color display will show:

Answer: No color signal

At 90° insonation angle the Doppler frequency shift is zero, so no color signal is generated.

Grating lobes in array transducers are caused by:

Answer: Constructive interference from equally spaced element spacing greater than half a wavelength

When element spacing exceeds half a wavelength, spatial aliasing causes grating lobes — additional beams fired at off-axis angles that can produce spurious echoes in the image.

A spectral Doppler waveform displaying a mirror image of the true waveform simultaneously on both sides of the baseline is most likely caused by:

Answer: Doppler gain set too high, causing cross-talk (ghosting) artifact

Cross-talk (ghosting or mirror image artifact) in spectral Doppler occurs when the Doppler gain is set too high, causing the waveform signal to bleed through to the opposite side of the baseline.

Which statement correctly describes range ambiguity artifact in PW Doppler?

Answer: It occurs when echoes from a previous pulse return after the next pulse has been transmitted, causing signals from two depths to be displayed simultaneously

Range ambiguity occurs when a high PRF is used and echoes from deep structures return after the next pulse is already transmitted, causing signals from multiple depths to be displayed as if from the gate location.

In diagnostic ultrasound, increasing the frequency of the transducer will:

Answer: Decrease penetration depth and increase axial resolution

Higher frequency shortens wavelength, improving axial resolution, but also increases attenuation, reducing penetration depth.

Which of the following is an ergonomic device built into sonographic equipment for the sonographer's musculoskeletal safety?

Answer: Monitor articulation

Monitor articulation allows sonographers to adjust the display screen's height, tilt, and swivel to their individual needs and scanning position. This ergonomic feature helps reduce neck, back, and eye strain by promoting a neutral posture during examinations. By minimizing physical discomfort and awkward positions, it directly contributes to musculoskeletal safety and helps prevent work-related injuries.

The wall filter (high-pass filter) in Doppler ultrasound is used primarily to:

Answer: Eliminate low-frequency signals from slow-moving vessel walls and tissue clutter

The wall filter removes low-frequency, high-amplitude Doppler signals produced by slow-moving vessel walls and surrounding tissues (clutter) so that weaker signals from blood flow can be displayed.

Side lobes in ultrasound transducers are most problematic because they:

Answer: Create artifact echoes that appear to originate from the main beam

Side lobes radiate energy off-axis; reflectors in their path produce echoes that the system incorrectly places along the main beam axis, creating artifacts.

The resonant frequency of a piezoelectric crystal is primarily determined by its:

Answer: Thickness

Resonant frequency is inversely proportional to crystal thickness: f = c / 2t, where c is the propagation speed within the crystal.

The depth of field (depth of focus) of an ultrasound beam refers to:

Answer: The range of depths over which lateral resolution remains acceptable

Depth of field describes the axial extent around the focal point where lateral resolution stays within an acceptable limit.

The spatial pulse length (SPL) is calculated as:

Answer: Number of cycles × wavelength

SPL = number of cycles × wavelength; shorter SPL yields better axial resolution.

Increasing the number of focal zones in a linear array will:

Answer: Improve lateral resolution throughout the image at the cost of frame rate

Multiple transmit focal zones improve lateral resolution over more depths but require multiple firings, reducing frame rate.

Which of the following best describes the concept of the Nyquist limit in pulsed-wave Doppler?

Answer: The maximum Doppler shift frequency that can be unambiguously detected, equal to one-half the PRF

The Nyquist limit is PRF/2; Doppler shifts exceeding this value cannot be correctly displayed and appear aliased (wrapped around the baseline).

In continuous wave (CW) Doppler, which limitation is NOT present in pulsed wave Doppler?

Answer: Range ambiguity (cannot localize signal depth)

CW Doppler uses simultaneous transmit and receive crystals and cannot determine the depth of origin of Doppler signals, causing range ambiguity.

A sonographer is optimizing a color Doppler image and notices that the color extends beyond the vessel walls into the surrounding stationary tissue. Which of the following adjustments should be made FIRST to correct this?

Answer: Decrease the color gain

When color appears in stationary tissue outside the vessel lumen, it is known as color bleed, blooming, or flash artifact. [13, 16] This is caused by the color gain being set too high, which over-amplifies the signal and noise. [7] The first and most appropriate action is to incrementally decrease the color gain until the color is confined within the vessel walls. [7, 13]