Efficacy of acoustic radiation force impulse elastography in differentiation of benign and malignant lymph nodes

Abstract

Aims and Objectives: Aim of this study was to assess the clinical usefulness of Acoustic Radiation Force Impulse (ARFI) elastography imaging in differentiating benign and malignant/metastatic superficial nodes. Methods and Materials: ARFI elastography (Siemens Medical Solutions, Mountain View, CA) using Virtual touch Tissue Imaging (VTI) technique was performed and Shear wave velocity (m/sec) was measured in 85 patients (mean age, 49 years; range, 16–72 years) with 126 lymph nodes (96 axillary, 21 cervical and 9 inguinal nodes) which were biopsied and histo-pathologically correlated. Results: Of 126 nodes, 71 were benign (64 reactive and 7 koch's) and 55 were malignant (40 metastases and 15 lymphoma). The mean ARFI value of malignant nodes ±SD (4.42 ± 2.60) were significantly higher than the benign nodes (1.76 ± 0.44), with P <0.001. With the use of Receiver Operating Characteristic (ROC) curve, the cut off SWV was estimated to be 2.45m/s with sensitivity of 83.6%, specificity of 91%, and accuracy of 93.7 % while the conventional US based short axis diameter (SAD) measurement with cut off value of 10mm, showed the sensitivity of 62 %, specificity of 87% and accuracy of 87%. Conclusion: Acoustic radiation force impulse elastography is feasible for superficial lymph nodes and provides quantitative elasticity measurements, which may complement B-mode ultrasound and potentially improve the differentiation of benign and malignant/metastatic lymph nodes.

Keywords

• acoustic radiation force impulse elastography
• benign
• lymph nodes
• malignant
• shear wave
• ultrasound