The Role of Ultrasound Elastography in Evaluation for Axillary Lymph Nodes of Patients with Breast Cancer

Abstract Background: Axillary lymph node status is the most reliable prognostic indicator for disease recurrence and patient survival in breast cancer. Axillary ultrasound is an important mean for detecting metastatic LNs, being non-invasive, avail-able & cheap. Aim of Study: To investigate the role of strain elastography combined with conventional ultrasound in the diagnosis of axillary lymph nodes in patients with breast cancer. Patients and Methods: 24 patients diagnosed with breast cancer with enlarged axillary lymph node were included in this study over the course of six months, they were examined bu B mode ultrasound and ultrasound elastography. Finally, findings of B-mode US and elastography were compared with pathological results (reference standard). ROC analysis was constructed to obtain best cutoff values for B-mode criteria, alasticity score and strain ratio. Results: Elastography score and strain ratio had a higher specifcity (83.3% vs. 33.3%) and a lower sensitivity (88.9% vs. 100%) than gray-scale ultrasonography. Of all the 6 benign axillary lymph nodes analysed in the present study, 2 were determined to be metastatic by gray-scale ultrasonography, while these diagnoses were corrected by RTE. As regards the semi-quantitative assessment; strain ratio, in our study there was a significant increase in mean strain ratio in the malignant nodes (1-8.3) than the benign ones (0.7-3.4) (p=0.005), with the best cutoff value 2.5 which yielded sensitivity of 88.89, specificity of 83.33,accuracy of 90%, PPV 94.1%, NPV 71.4%. Conclusion: Ultrasound elastography by its qualitative (elasticity score) and quantitative (strain ratio) evaluation has proved to useful in differentiation between benign and malig-nant nodes as a complementary to conventional ultrasound. Using elasticity score/strain ratio; 11 out of 18 pathologically proved malignant nodes, were diagnosed as malignant, 5 out of 6 benign nodes were diagnosed as benign.