Long-lasting microbubble-enhanced super-resolution ultrasound imaging unveils lymphatic activity in lymph node.

Rationale: As the central regulatory hub localized at the interfaces between the blood and lymphatic vascular system, lymph nodes play a pivotal role in maintaining immune homeostasis and coordinating responses to disease. Systematic evaluation of lymph node functional status holds significant clinical value. However, there are currently no established non-invasive imaging biomarkers capable of reliably evaluating lymph node activity. Methods: This study developed a novel lipid-based long-lasting microbubble contrast agent (SuperVue-MB) integrated with three-dimensional super-resolution ultrasound (SRUS) imaging to achieve multiparametric hemodynamic visualization of blood vessels within lymph nodes. Results: Experimental validation demonstrated strong correlations between SRUS-derived vascular parameters and established reference standards (r = 0.86, p < 0.01), including micro-CT angiography and histopathological markers, confirming the reliability and accuracy of the technique. Furthermore, this study introduces a new vascular subtyping strategy that systematically correlates these hemodynamic patterns with immune functional states. Specifically, the density and number of microbubble tracks associated with key vascular subtypes, exhibiting significant positive correlations with lymphatic vessel density (r = 0.91, p < 0.01). Conclusions: This study offers a promising noninvasive approach for evaluating immune activation within lymph nodes, while establishing a novel paradigm for surveillance of sentinel lymph node metastasis and immunotherapy response monitoring.