Post-vascular phase of contrast-enhanced ultrasound with perfluorobutane for preoperative evaluation of axillary lymph node status in early-stage breast cancer.

Abstract

Purpose: To investigate the feasibility of post-vascular phase imaging on contrast-enhanced ultrasound (CEUS) with perfluorobutane for diagnosing axillary lymph node metastasis (ALNM) and prediction of metastatic burden in early-stage breast cancer.

Material and methods: The prospective study enrolled patients with early-stage invasive breast cancer and non-palpable axillary lymph node (ALN) from November 2022 to June 2023. All participants of the entire cohort were scheduled for both conventional ultrasound (US) and CEUS with perfluorobutane examination immediately followed by US-guided core-needle biopsy basing on the guidance of CEUS result. The main features of US, vascular phase imaging, and post-vascular phase imaging were selected according to comparison between positive and negative ALNM using the Chi-square or Fisher exact test, of which diagnostic performance of different combinations on ALNM was calculated and compared for determining optimal diagnostic criteria. As for burden analysis, the predictive power of number of lymph nodes with post-vascular defect for metastatic burden was also estimated among surgery cohort who underwent axillary surgery without neoadjuvant chemotherapy.

Results: A total of 146 female patients (median age, 51 [42-58] years) with 146 target ALNs (median size, 16 [13-21] mm; 82 positive ALNM and 64 negative ALNM) were enrolled in the entire cohort. The post-vascular phase finding "post-vascular defect" had an AUC of 0.92 (95% CI 0.86, 0.97) and sensitivity of 99% (95% CI 93%, 100%) with a negative predictive value of 98% (95% CI 90%, 100%) for the diagnosis of positive ALNM. Overall, the post-vascular phase finding performed better than that of US (AUC, 0.77, 95% CI 0.69, 0.85, P < 0.001) and vascular phase findings (AUC, 0.85, 95% CI 0.78, 0.91, P < 0.001). As for burden analysis among surgery cohort with 89 patients, the number of lymph nodes with post-vascular defect was highly predictive of metastatic burden, with AUC of 0.90 (95% CI 0.82, 0.97) for predicting disease-free axilla and AUC of 0.75 (95% CI 0.60, 0.89) for discriminating between low and heavy metastatic burden.

Conclusion: Post-vascular phase imaging on CEUS with perfluorobutane demonstrated good performance for preoperatively assessing the ALN status in patients with early-stage invasive breast cancer. Chinese Clinical Trial Registry No. ChiCTR2400080297.