Artefacts, mimics & look-alikes
Reverberation, side lobes, attenuation and near-field clutter — and the normal structures that masquerade as thrombus, tumour or dissection.
Numbers to remember
- A real structure is seen in two views and moves with the surrounding anatomy; an artefact often does not [17,173]
- Reverberations sit at multiples of the distance from a strong reflector [173]
Questions echo must answer
- Is this finding real?Two views, consistent motion, plausible anatomy, colour flow behaviour [17].
- What produced the artefact?A strong reflector (prosthesis, lead, calcium, catheter), poor window, gain or depth settings.
- Is it a normal structure?[176]
Acquisition protocol
- Change the window and angleAn artefact moves with the transducer, anatomy does not.
- Change depth, focus, gain and harmonics
- M-modeShows whether a line moves independently of the walls (dissection flap vs reverberation) [173].
- ContrastFills the cavity around a real thrombus and through an artefact.
Diagnosis & severity
| Artefact | Mechanism | Typical place |
|---|---|---|
| Reverberation | Sound bouncing between strong reflectors | Behind prostheses, leads, calcified aorta |
| Side lobe / beam width | Off-axis echoes placed in the beam | Near prosthetic rings, aortic root |
| Attenuation / shadowing | Strong reflector blocks the beam | Behind calcium and mechanical valves |
| Near-field clutter | Strong echoes close to the transducer | LV apex — "pseudo-thrombus" |
| Mirror image | Strong specular reflector | Duplicated structures |
Thresholds that change management
- When an important finding (thrombus, flap, vegetation) cannot be confirmed in a second view, say so and recommend contrast, TOE, CT or CMR rather than reporting it as present [140,173].
Pitfalls & mimics
- Apical clutter called thrombus.
- Aortic reverberation called dissection [173].
- Chiari network called vegetation.
- Hiatus hernia called a left atrial mass.
- Dilated coronary sinus called a pericardial effusion [176].