Conventional contrast-enhanced ultrasound (CEUS) versus side-by-side CEUS in the assessment of difficult liver lesions

Purpose: Hepatic lesions located at segments IVa and VIII have always been considered difficult to assess with ultrasound and even more difficult when they are small. The purpose of our work is to assess the role of side-by-side CEUS versus conventional CEUS in the diagnosis of difficult focal liver lesions.

Methods and materials: A homogeneous group of 72 consecutive non-angiomatous focal liver lesions (liver segments IV and VIII, diameter range 14 to 30mm) was divided into two random subgroups and assessed with conventional (a single dynamic image on the screen, 31 lesions) and side-by-side CEUS (two simultaneous images – with and without contrast setting – on the screen, 41 lesions). Two sonographers with the same experience in liver ultrasound evaluated both groups each blindly, assessing the contrast images during both arterial and late phases, trying to highlight the differences between lesions smaller (40 cases) or bigger (32 cases) than 20mm.

Results: Side-by-side CEUS allowed to assess the arterial phase in 16/17 lesions >20mm and in 22/24 <20mm and the late phase in all lesions. On the other hand, conventional CEUS gave the same outcome in 6/15 lesions >20mm and in 3/16 <20mm and the late phase in 9/15 lesions >20mm and in 9/16 <20mm. The difference is statistically significant (p<0.01) both for the arterial and late phases.

Conclusions: The comparison of conventional and side-by-side CEUS indicates the superiority of the latter when assessing difficult liver lesions and must always be preferred when available.