Ultrasound Elastography for Differentiating Benign from Malignant Cervical Lymphadenopathy: Comparison with B-Mode and Color Doppler Findings

Abstract

Introduction: Elastography is a new technique that aim to assess tissue hardness non-invasively. Recently, it has been used for differentiating benign from malignant lymphadenopathy. Aim: To evaluate the sensitivity and specificity of elastography for differentiating benign from malignant cervical lymphadenopathy and to compare its findings with B-mode and color doppler findings. Materials and Methods: The present study was conducted on 50 patients with cervical lymphadenopathy. In each patient, even if multiple enlarged lymph nodes were found, only one lymph node was sampled which was most suspicious for malignancy. This selection was based on size of the lymph node and other B-mode sonography characteristics. B-mode and color doppler findings were recorded. In addition to this, strain elastography was done and five elastography patterns were defined: high elasticity (soft): pattern I represented no or very small hard area while spectrum pattern V presented where almost whole of lymph node showed hard pattern on strain elastography. Patterns II and III represented hard areas 45% respectively while pattern IV represented peripheral hard area with central soft area (due to central necrosis). Patterns I and II were considered benign. Patterns III, IV and V were considered to represent malignant lymph nodes. Additionally, a cine loop of elastography was acquired for calculation of strain ratio using adjacent muscle as reference. A cut-off value of less then two (<2) of strain ratio was used to define benign lymph nodes and more then or equal to two (≥2) was used to define malignant lymph nodes. Final diagnosis of benign versus malignant lymph node was based upon other relevant investigations like Fine Needle Aspiration Cytology (FNAC)/biopsy findings and/or clinical follow-up after three months. Statistical analysis was done using StatPac version 4.0 (StatPac, Inc., Bloomington, MN). Chi-square test was used to compare various B-mode and color doppler parameters, elastography patterns and strain ratio between benign and malignant groups. Results: Of all the B-mode parameters, only lymph node border and hilum showed more than 70% accuracy for correctly differentiating benign from malignant lymph nodes while color doppler showed 82% accuracy for the same. Elastography pattern and strain ratio achieved 90% and 94% accuracy for correctly differentiating benign from malignant lymph nodes. Conclusion: Elastography pattern and strain ratio are useful in addition to B-mode and color doppler ultrasound for evaluation of cervical lymph nodes.

Keywords

• elasticity
• lymph node
• sonography
• strain ratio