Evaluating lymph node status with high-frequency ultrasound during breast conservation surgery

Abstract

High-frequency (20–80 MHz) ultrasound was used to evaluate 78 lymph nodes from 39 patients to identify metastatic breast cancer during breast conservation surgery. Point measurements were collected from resected lymph nodes in both through-transmission and pulse-echo modes using 50-MHz, 6.35-mm diameter, single-element transducers. Attenuation and peak density (the number of peaks and valleys in a specified frequency band) were calculated from the ultrasonic waveforms and power spectra, respectively. The two parameters were additionally combined to perform a multivariate analysis. Fisher’s exact test was used to determine the accuracy, sensitivity, and specificity of each parameter and the multivariate analysis for detecting malignant lymph nodes. The multivariate analysis showed the greatest statistical measures, with an 83.3% accuracy, 87.5% sensitivity, 82.9% specificity, and a p-value of 0.000078 (high statistical significance). The results demonstrate that high-frequency ultrasound provides very good...