Fig. 3

Images in a 56-year-old female patient with a benign lymph node (LN). (a) Conventional B-mode US shows an LN (8 × 5 mm) with a clear margin and regular shape and indistinct cortex-medulla boundary. (b) High-frame-rate contrast-enhanced ultrasound examination: The area indicated by the white arrow denotes the LN location. The left image shows the initial seconds (at 9–10 s) after the contrast agent enters the LN, with contrast bubbles visible both peripherally and centrally. The right image shows a few seconds later (at10-11 s), with contrast bubbles rapidly filling the LN, presenting a mixed contrast pattern for the entire LN. (c) High-frame-rate contrast-enhanced ultrasound combined with contrast vector imaging (CVI) examination: The colored arrows within the yellow box represent the direction and trajectory of the movement of bubbles automatically tracked by CVI technology. The left image shows the initial seconds (at 9–10 s) after contrast injection, with contrast bubbles concentrated on one side and arrows indicating microbubble movement towards the periphery. The right image shows a few seconds later (at10-11 s), with a large number of contrast bubbles moving from the center to the periphery, arrows pointing towards the periphery and showing a lymphatic gate-like change and presenting a centrifugal contrast pattern. Pathological examination revealed inflammatory changes in the LN