1. Correct Answer: B. A structure will reflect the ultrasound beam only once

Rationale: Reverberation artifacts are created when the ultrasound beam bounces multiple times between two highly reflective surfaces during the listening phase, before returning to the transducer. This violates the assumption that the ultrasound has returned to the transducer after only a single reflection from the structure. Because the ultrasound beam bounces between two strong reflectors during the listening phase, the reverberation artifact lies distal to the imaged structure and often violates anatomic boundaries. When the distance between the two reflectors is small, the artifact will appear as closely approximated lines (or stepladder), creating a “ring-down” or “comet-tail” artifact.

1. Bertrand PB, Levine RA, Isselbacher EM, Vandervoort PM. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis. J Am Soc Echocardiogr. 2016;29(5):381-391.

2. Le HT, Hangiandreou N, Timmerman R, et al. Imaging artifacts in echocardiography. Anesth Analg. 2016;122(3):633-646.

2. Correct Answer: C. Near-field artifact

Rationale: Structures in the near field are sometimes obscured by high-amplitude oscillations by the transducer itself, causing near-field artifacts. These are often seen in structures that are close to the transducer, such as the pulmonary arteries or descending aorta. True pulmonary embolus moves with cardiac motion and will show a lack of color with color flow Doppler. With the addition of color flow Doppler on a near-field artifact, the color will encompass the entire pulmonary artery, without filling defects. In the patient scenario, this patient is coming to the operating room for coronary artery bypass grafting, without evidence of right heart strain or hypoxemia. This helps us to identify from the stem that this is an artifact. Contrast the image in the stem from the image in Figure 16.16 which is a pulmonary embolus. This image shows a discrete mass and filling defect in the right pulmonary artery.

1. Bertrand PB, Levine RA, Isselbacher EM, Vandervoort PM. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis. J Am Soc Echocardiogr. 2016;29(5):381-391.

3. Correct Answer: D. Pulses are propagated uniformly by all tissues

Rationale: The prosthetic aortic valve in Figure 16.3 acts as a strong reflector preventing ultrasound wave propagation beyond the valve. This creates an artifact called acoustic shadowing. Acoustic shadowing violates the assumption that pulses are propagated uniformly by all tissues. In this case, the prosthetic valve attenuates the pulse distal to the valve.

1. Bertrand PB, Levine RA, Isselbacher EM, Vandervoort PM. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis. J Am Soc Echocardiogr. 2016;29(5):381-391.

2. Le HT, Hangiandreou N, Timmerman R, et al. Imaging artifacts in echocardiography. Anesth Analg. 2016;122(3):633-646.

4. Correct Answer: D. Eustachian valve

Rationale: The Eustachian valve is an embryologic remnant that can be seen as a prominent crescent-shaped tissue at the posterior aspect of the inferior vena cava. In fetal life, it directed blood flow across the fossa ovalis. In this view (Figure 16.4), the Eustachian valve separates the inferior vena cava (above) from the coronary sinus (below). A Chiari network is a remnant of the right valve of the sinus venosus and appears as a filamentous structure in the right atrium. The crista terminalis is a ridge of myocardium at the junction of the right atrium and superior vena cava.

1. Silvestry FE, Cohen MS, Armsby LB, et al. Guidelines for the echocardiographic assessment of atrial septal defect and patent foramen ovale: from the American Society of Echocardiography and Society for Cardiac Angiography and Interventions. J Am Soc Echocardiogr. 2015;28(8):910-958.

5. Correct Answer: B. Spectral Doppler mirroring

Rationale: The duplication of the Doppler spectrum above and below the baseline represents spectral Doppler mirroring. This mirroring is caused by cross-talk, which is erroneous signal transfer when the echo exceeds the operating range of the circuit and results in the appearance of velocities on both sides of the baseline; or by directional ambiguity, which is when the Doppler angle is near 90°. The signal is typically more intense on one side of the baseline compared to the other side. Reducing the Doppler gain in the case of cross-talk will help to resolve the spectral Doppler mirroring, while changing the image such that the Doppler beam intersects close to 0° is helpful in directional ambiguity.

1. Le HT, Hangiandreou N, Timmerman R, et al. Imaging artifacts in echocardiography. Anesth Analg. 2016;122(3):633-646.

6. Correct Answer: A. Echoes return to the transducer after a single reflection

Rationale: In Figure 16.6, the ultrasound reaches the descending aorta before reaching a strong reflector. The strong reflector then creates a mirror image of the descending aorta inferior to the actual aorta. Mirror images occur because the ultrasound pulse reaches a smooth strong reflector (mirror), which directs the beam to the second reflector (in this case, the descending aorta). The beam then bounces from the target to the mirror-like surface on its return to the probe.

1. Bertrand PB, Levine RA, Isselbacher EM, Vandervoort PM. Fact or artifact in two-dimensional echocardiography: avoiding misdiagnosis and missed diagnosis. J Am Soc Echocardiogr. 2016:29(5):381-391.

2. Le HT, Hangiandreou N, Timmerman R, et al. Imaging artifacts in echocardiography. Anesth Analg. 2016;122(3):633-646.

7. Correct Answer: C. Side-lobe artifact

Rationale: The main ultrasound beam emits the most energy, while small portions of ultrasound energy emitted in “side-lobes” of the main ultrasound beam are often dissipated in the tissue. However, when this side-lobe energy is reflected by a strong reflector in its path, these reflections are interpreted by the scanner as originating from the central/main ultrasound beam. Numerous side-lobe artifacts can be generated as the transducer scans by sweeping in a radial direction, often merging the side-lobe images, producing a linear arc-like artifact. In the ascending aorta, side-lobe artifacts from highly reflective aortic sinotubular junctions could be mistaken for aortic dissection flaps. Because the patient in the scenario is being imaged for elective mitral repair, without a history of hypertension or connective tissue disorder, and is asymptomatic, Figure 16.7 represents a side-lobe artifact. Imaging in alternative planes and the addition of color flow Doppler can help to distinguish a side-lobe artifact from true pathology.