Observations of blue-stripe artefacts in 2D SWE not reported in guidelines and their influence on diagnostic accuracy-A technical note.

Two-dimensional shear wave elastography is a clinically established technique used to detect and stage liver fibrosis. It generates a real-time elastogram map, which visually displays tissue stiffness and assists in assessing the severity of liver fibrosis. The elastogram map serves as a graphical depiction of how stiff or soft the liver tissue is, providing valuable information for diagnosis. However, artefacts can appear in elastogram maps. In this work, we report on "blue-stripe" artefacts that can appear in elastogram maps without being indicated as a technical error by the system and that are not mentioned in guidelines. To the best of our knowledge, this type of artefact has not been described in the literature and may inadvertently be included in measurements, potentially leading to inaccurate results. We describe 4 cases in which a blue-stripe artefact was present on liver 2-dimensional shear wave elastography elastograms and compare these measurements with artefact-free 2-dimensional shear wave elastography acquisitions and magnetic resonance elastography. In all 4 cases, 2-dimensional shear wave elastography values obtained in the presence of the blue-stripe artefact were lower than the corresponding artefact-free 2-dimensional shear wave elastography values and lower than expected from magnetic-resonance-elastography-based fibrosis assessment, creating a risk of underestimating advanced fibrosis. These cases highlight the importance of real-time recognition of blue-stripe artefacts during liver stiffness assessment. Excluding artefact-affected acquisitions may improve measurement reliability and help avoid false low-stiffness values in routine clinical practice.