# Intraoperative Ex Vivo Shear-Wave Elastography of Sentinel Lymph Nodes in Endometrial Cancer and Other Gynaecological Malignancies

## TL;DR

This study explores using shear-wave elastography to quickly assess lymph node status during gynaecological cancer surgery, but finds it insufficient on its own.

## Contribution

The study evaluates the feasibility and limitations of ex vivo shear-wave elastography for intraoperative lymph node assessment in gynaecological cancers.

## Key findings

- Ex vivo shear-wave elastography is fast, safe, and technically feasible for intraoperative use.
- Tissue stiffness measured by elastography does not reliably distinguish tumour-free from metastatic lymph nodes.
- Future improvements may require combining elastography with advanced imaging and computational methods.

## Abstract

Accurate assessment of lymph node involvement during surgery is essential for optimal management of gynaecological cancers. Conventional intraoperative evaluation methods are reliable but time-consuming and not universally available, which can limit real-time surgical decision-making. This study was undertaken to investigate whether Shear-wave Elastography can provide immediate information on lymph node status after removal, without affecting routine pathological examination. The study aimed to determine the ability of this approach to distinguish tumour-free from metastatic lymph nodes across different gynaecological malignancies. The results demonstrate that, while the method is fast, safe, and technically feasible, tissue stiffness alone does not reliably identify nodal metastases. These findings inform the research community that future progress will likely depend on combining elastography with advanced imaging analysis and computational methods to enhance intraoperative lymph node evaluation.

Background: Accurate intraoperative assessment of sentinel lymph node (SLN) status is critical for staging and guiding surgical management in gynaecological malignancies. Frozen-section histopathology remains the gold standard, but it is time-consuming and resource-intensive. Shear-wave elastography (SWE) quantifies tissue stiffness in real time and may offer a rapid alternative. Methods: In this prospective single-centre study, 63 women (median age 62 years) undergoing primary surgery with sentinel lymph node biopsy (SLNB) for endometrial, cervical, vulvar, or early ovarian carcinoma were enrolled. A total of 172 SLNs were excised, submerged in coupling gel, and scanned ex vivo using a 9 MHz linear probe. Results: A total of 172 SLNs underwent SWE (mean 2.7 nodes/patient). Endometrial primaries accounted for 58% of nodes, mostly retrieved by robotic-assisted surgery (71.8%). Node dimensions were significantly larger in malignant lesions for sonographic (long-axis: 13.02 ± 3.31 mm vs. 10.80 ± 3.28 mm; p = 0.002) and pathological long-axis measurements (11.45 ± 2.83 mm vs. 9.75 ± 2.61 mm; p = 0.004). Mean SWE velocities were similar between groups (1.381 ± 0.307 vs. 1.343 ± 0.236 m/s; p = 0.541). Histopathology identified metastases in 18% of SLNs, comprising macrometastases (7%), micrometastases (5%), and isolated tumour cells (6%). Conclusions: Although ex vivo SWE is rapid, reproducible, and integrates seamlessly into the sterile field, stiffness measurements alone lack sufficient discriminatory power for SLN staging in gynaecological cancers. Future research should focus on three-dimensional SWE, advanced radiomic analyses, and machine-learning algorithms to improve the detection of low-volume metastatic disease.