Ultrasound elastography as an adjuvant to conventional ultrasound in the preoperative assessment of axillary lymph nodes in suspected breast cancer: a pilot study

Introduction

NICE guidelines recommend conventional ultrasound (CU) of the axilla as preliminary staging in patients with breast cancer. However, up to one-third of nodes showing normal morphology are metastatic on surgical histology [1]. Ultrasound elastography (UE) uses received radiofrequency data to produce an elastogram depicting tissue stiffness. UE has been researched in the breast but there are no published data regarding UE of the axilla.

Methods

Fifty women attending the breast unit as symptomatic GP referrals with breast lesions sonographically suspicious of breast cancer underwent UE of the axilla simultaneously with routine CU examination. Elastograms were visually scored, strain measurements calculated and nodal perimeter and area measurements recorded. UE was compared with CU with histology as the reference standard.

Results

Twenty-nine nodes were histologically normal, 21 were metastatic. Normal nodes were indistinguishable from surrounding tissue on UE. Using cut-off points for biopsy selected for the study, sensitivity was 90% for UE visual scoring, 100% for strain scoring and 76% for CU. Specificities were 86%, 48% and 78% respectively. ROC analysis yielded AUC values of 0.9 for UE visual scoring, 0.86 for strain scoring and 0.82 for CU. There was no significant difference between any area and perimeter measurements.

Conclusions

UE can demonstrate axillary lymph nodes and differentiate benign from malignant nodes. UE visual scoring shows greatest promise in improving yield without excessive benign biopsies.