Table 4 Imaging artefacts

Swirling

Description

Swirling of contrast, especially in the nearfield, is common, particularly when the LV is dilated and there is impaired function (Additional file 4: Video S4)

This results in poor endocardial border definition and poor appreciation of apical pathology like thrombus which may be overlooked

This is more often seen in LVO mode as the MI is higher which results in destruction of UCA

Solution

1. If available, use ‘Low MI’ imaging, the low MI will significantly minimise bubble destruction

2. Where low MI is not available, change the imaging mode from harmonic to fundamental (CGen to CPen) in the LVO mode. This will automatically reduce the MI but maintain optimal imaging

3. Consider moving focal point towards the apex which will reduce UCA destruction (with a near field focus, the beams in the near field become much narrower and will not overlap, reducing the energy each bubble is exposed to)

4. If swirling is observed throughout the LV, increase the rate and/or the volume/concentration of UCA injection

Attenuation

Description

Results from a high volume/concentration of microbubbles in the apex, causing a near-field backscatter and acoustic shadowing of far-field structures

Manifests as a dark shadow in the far-field, particularly at the base of the LV making delineation of the endocardial borders impossible (Additional file 5: Video S5)

Solution

1. Lower the dose of UCA (volume/concentration) being injected

2. Slow the rate of bolus injection or of continuous infusion

3. Brief application of high MI imaging or colour doppler will clear the excess microbubbles and rapidly resolve the artefact

4. Remember: an inexperienced echocardiographer might assume more contrast is required to overcome the shadow. However, the exact opposite is required

Blooming

Description

Often follows attenuation. Gives the appearance of contrast within the myocardium and could be mistaken for perfusion (but IS NOT perfusion)

With blooming artefact, contrast signals are spread beyond the tissue into neighbouring regions (Additional file 6: Video S6)

This results in poor delineation of endocardial borders and small thrombi can also go undetected

Solution

1. Reduce the dose of UCA (volume/concentration) and/or slow down the rate of bolus injection

2. A good technique is to stop injecting as soon as a streak of UCA is observed in the RV and if required inject more; giving too much too soon will result in blooming

3. If using a continuous infusion, reduce the rate of infusion

4. If blooming occurs during SE at peak stress, every attempt should be made to promptly destroy the microbubbles by briefly applying high MI imaging or colour doppler to clear excess microbubbles and reverse blooming

5. The key to avoid attenuation/blooming artifact is slow injection

Description

A series of events following the injection of a high concentration/volume, with apical blooming followed by basal attenuation and a gradual clearance of UCA allowing for better endocardial border definition at the apex and base (Additional file 7: Video S7)

Rib / papillary muscle artefacts

Description

Rib artefacts are seen in the lateral wall of the apical four-chamber view and result from adjacent ribs obstructing the transmission of ultrasound from the transducer in the lateral scan planes (Additional file 8: Video S8). This can similarly be seen in the apical four- and two-chamber views where the papillary muscles obstruct the transmission of ultrasound in the same way

Solution

1. Moving the probe footprint to adjust the image orientation will usually compensate for this artefact