Prospective Evaluation of CEUS-URM in Axillary Lymph Nodes with Diffuse Cortical Thickening in Breast Cancer Patients.

Background

Conventional axillary ultrasound (US) is least reliable in lymph nodes with diffusely thickened cortex. We evaluated whether contrast-enhanced ultrasound with ultra-resolution microvascular imaging (CEUS-URM) improves discrimination of metastatic nodes in this subgroup. Materials and methods: This was a prospective single-center study of patients with histologically confirmed breast cancer; one index (most suspicious) node per patient (unit of analysis = index node). Two separately recruited consecutive cohorts were analyzed: a US-only cohort (n = 181; diffuse-thickening subgroup with histology, n = 52) and a subsequent CEUS-URM cohort (n = 42; 15 metastatic). Surgical histopathology (SLNB/ALND) was the reference standard. A CEUS-URM score was built from data-driven, Youden-optimized cut-offs (URM vessel count ≥8; DV mean density ≥ 13.05) and internally validated by bootstrap with optimism correction. As the cohorts were separate, the US-versus-CEUS comparison is cross-cohort and exploratory.

Results

Within the diagnostically challenging subgroup of lymph nodes with diffusely thickened cortex, conventional axillary US alone demonstrated limited discriminatory performance for metastatic involvement (AUC 0.43). CEUS-derived quantitative parameters significantly improved diagnostic accuracy, with the best individual parameter achieving an AUC of 0.68. A simple CEUS score combining hypervascular vessel count and vascular density provided the highest diagnostic performance (AUC 0.81, 95% CI 0.68-0.92). At a low threshold, the CEUS score showed high sensitivity (93%), suitable for screening and exclusion of nodal metastases, while at a higher threshold it achieved high specificity (96%), allowing reliable confirmation of metastatic disease.

Conclusions

In this exploratory study, a simple CEUS-URM score improved discrimination of diffusely thickened axillary nodes and may serve as an adjunct to conventional US. The findings are preliminary-derived and tested in the same small cohort-and require external, within-patient paired validation.