Shear Wave Elastography in Head and Neck Lymph Node Assessment: Image Quality and Diagnostic Impact Compared with B-Mode and Doppler Ultrasonography

Abstract

The aim of this study was to assess the diagnostic performance of shear wave elastography (SWE) in comparison to B-mode and Doppler ultrasonography in differentiating benign from malignant head and neck lymph nodes (HNLNs). Sixty-two HNLNs from 56 patients were prospectively examined using B-mode, Doppler and SWE. The standard of reference was histopathology or cytology and follow-up. Qualitative malignant criteria (hilum infiltration, cortical hypo-echogenicity, irregular margins, abnormal vessels) were assessed on a five-point scale. Four quantitative parameters were obtained: long axis length, short axis length, short axis/long axis ratio, resistive index and maximum shear elasticity modulus (μmax). Diagnostic performance was analyzed with special emphasis on the sub-centimeter HNLN subgroup. Thirty HNLNs were malignant (48%). μmax intra-observer reproducibility was 0.899 (0.728 in sub-centimeter subgroup). Malignant HNLNs were stiffer (μmax = 72.4 ± 59.0 kPa) compared with benign nodes (μmax = 23.3 ± 25.3 kPa) (p < 0.001). Among the quantitative criteria, μmax had the highest diagnostic accuracy (area under the curve = 0.903 ± 0.042), especially in the sub-centimeter subgroup (area under the curve = 0.929 ± 0.045; p < 0.001) in which the area under the curve was significantly higher compared with the other quantitative criteria (p < 0.05). The additional use of SWE combined with B-mode tended to improve diagnostic accuracy (p > 0.05). SWE is a promising reproducible quantitative tool with which to predict malignant HNLNs, especially sub-centimeter nodes.

Keywords: Cervical lymph nodes; Diagnosis; Head and neck diseases; Shear wave elastography; Ultrasound.