PMC

(arrow) in apical 4-chamber view, mimicking apical thrombus. Moving images () show normal apical myocardial kinetics, and no relationship between clutter and myocardial motion.

(A) The theoretical genesis of a mirror artifact (animation in ). (B) Parasternal long axis image showing a mirror artefact below the pericardium-lung interface (red arrow), moving images in . Notice the mirror image of the posterior myocardial tissue (*), the posterior mitral leaflet (full arrowhead) and the anterior mitral leaflet (empty arrowhead). Comet-tail reverberations below the pericardium due to the strongly reflecting lung interface can be observed as well.

(A) The theoretical genesis of a refraction artifact. Ultrasound waves directed through a ‘lens’ are refracted towards the respective cardiac object and back, resulting in a duplicate of this object in the initial beam direction (animation in ). (B) Double image of the aorta (full arrowhead) in a subcostal short-axis image of the heart, due to refraction of the ultrasound beam at perihepatic fatty tissue (arrow). A Swann-Ganz catheter in the right ventricular outflow tract is doubled as well (empty arrowhead). Moving images in .

(1) Ultrasound waves obey the physical laws of reflection and refraction. The boundary of two tissues with different acoustic impedance acts as a specular reflector if significantly larger than the wavelength of the ultrasound waves. A portion of ultrasound wave energy will be reflected with reflection angle equal to the angle of incidence. Another portion will be transmitted with a reflection angle dependent on the magnitude of difference in acoustic impedance between both tissues.
(2) Ultrasound beam-forming is associated with small parts of ultrasound energy travelling off-axis in so-called side lobes or grating lobes.

(A–B) The theoretical genesis of a reverberation artifact (animation in ). The second reflector can either be the transducer itself (A) leading to a reverberation at twice the distance to the probe, or another strong reflector (B) located above the first reflector.
(C) Reverberation artifact in parasternal long-axis view mimicking a mass in the left atrium (arrowhead). Detailed analysis of the mass shows it is a reverberation of the calcified aortic annulus (arrow), with the mass presenting at exactly twice the distance from the transducer (). (D) Typical ‘step ladder’ of reverberations (full arrowheads) below a ‘multi-layered’ aortic calcification (arrow) acting as the first and second reflector (). Comet-tail reverberations below a strongly reflecting pericardium can be observed as well (empty arrowheads).

(A) Mechanical mitral valve prosthesis causing multiple reverberations and comet-tails below the prosthesis (arrow) as well as two acoustic shadowing regions below the prosthesis frame (*)(). (B) Acoustic shadowing (*) distal from an implanted MitraClip device (arrow). Notice the shadowing of the color flow signal as well, potentially leading to underestimation of residual mitral regurgitation post clip. (C) Pacemaker wire in right atrium (arrow) with linear comet-tail reverberation (arrowhead) below the wire and side lobe artifact extending in radial direction. (D) Defibrillator wire in right ventricle (arrow) with linear arc-like side lobe artifact crossing the anatomical borders (interventricular septum). Should not be misinterpreted as a dislocated (perforated) wire into the left ventricular cavity (). RA, right atrium; RV, right ventricle; LV, left ventricle;

(A) The lateral width and elevation width of the ultrasound beam respectively cause a decrease in lateral resolution and the occurrence of beam width artifacts. The blue squared object within the scanning plane is correctly identified in the center of the beam. However, due to the elevation width of the beam, the green circular object outside of the imaging plane is incorrectly positioned within the scanning plane. (B) Parasternal short-axis image of pulmonary arteries showing unexplained turbulent flow into the left pulmonary artery (LPA, arrow), without evidence of shunting or stenosis. (C) Tilting of the probe out of the scanning plane reveals massive mitral regurgitation into the left atrium picked up by the beam as if occurring in the pulmonary artery.
RA, right atrium; LA, left atrium; PA, pulmonary artery; RPA, right pulmonary artery; RVOT, right ventricular outflow tract; Ao, aorta

(A) The genesis of a side lobe artifact. While ‘interrogating’ the imaging plane in a radial direction, side lobe energy can encounter a strong reflector. Reflections of side lobe energy are interpreted as if originating from the direction in which the transducer is ‘looking’. Ultimately, this leads to a linear ‘arc-like’ artifact at both sides of the strong reflector (short animation in ). (B) Parasternal long axis view with linear side lobe artifact (arrow) in the aorta ascendens due to a calcified sinotubular junction (arrowhead). This artifact can sometime be misinterpreted as a dissection flap. (C) Parasternal long axis view of a healthy patient with strongly reflecting pericardium, causing a side lobe artifact in the left atrium (arrow). In moving images () comet-tail reverberations, acoustic shadowing, near field clutter and a mirror image of the mitral valve leaflets can be observed as well.

(A) Three-dimensional echocardiography of an Amplatzer Cardiac Plug after successful implantation in left atrial appendage. (B) Apical 5-chamber view in the same patient, with an Amplatzer Cardiac Plug in the correct position presenting as a figure-of-eight (). (C) Apical 3-chamber view (slightly off-axis) in a patient following left atrial appendage occlusion. (D) A patent foramen ovale (PFO) occluder device in a parasternal off-axis image of the interatrial septum in a patient a few years after PFO occlusion (). (Central image) Because of the epitrochoidal mesh geometry of the disc occluders, sound is reflected back to the probe only by the small segments of mesh with fibers orthogonal to the beam direction. These align in a figure-of-eight (as shown by the green lines on the figure). Adapted from Bertrand et al. with permission.
RA, right atrium; RV, right ventricle; LV, left ventricle; Ao, aorta;

(A) Reverberation artifact of mitral valve leaflet at exactly twice the distance from the probe, presenting as a wire in the left ventricular cavity (). (B) Mechanical aortic valve casting an acoustic shadow over the majority of the right ventricle (*) and a reverberation (comet-tail) to the side (arrowhead) (). (C) Transseptal guiding catheter during pulmonary vein isolation procedure presenting with a series of closely-spaced reverberations (arrowheads) due to reflections at the upper and lower side of the (hollow) catheter and one reverberation at twice the distance to the probe due to reflection at the transducer itself. (D) Mirror artifact (*) of the ascending aorta mimicking two parallel aortas. Notice the mirroring of the color flow in the mirror image as well, the mechanism being similar i.e. the assumption of wave propagation (). (E) Reverberation artifact in the left atrial appendage mimicking thrombus. Detailed analysis from multiple angles (F) and applying color flow imaging in the respective region confirms the presence of a reverberation from the warfarin ridge (*) rather than true thrombus (–). (G) Side lobe artifact (arrow) from a calcified sinotubular junction (arrowhead) extending in the ascending aorta () should not be misinterpreted as a dissection flap. (H) Similarly, a reverberation in the ascending aorta might be misinterpreted as being a dissection flap.
LA, left atrium; RA, right atrium; LV, left ventricle; Ao, aorta;