Neck lymph nodes: Characterization with diffusion-weighted MRI

PurposeTo evaluate the role of diffusion-weighted imaging (DWI) in differentiating the various causes of enlarged neck lymph nodes.Materials and methodsThirty-four patients with enlarged neck lymph nodes clinically suggestive of malignancy underwent DWI with b values (0 and 1000). Apparent diffusion coefficient (ADC) maps are generated from DWI and ADC values were calculated for the enlarged lymph nodes and compared with histopathological results.ResultsThe patients were divided into nine patients with benign neck lymphadenopathy, 14 patients with metastasis from head and neck cancer and 11 patients with nodal lymphoma. The mean ADC of the benign neck lymph nodes (1.51 ± 0.36 × 10−3 mm2/s) was significantly higher than those of the metastatic (0.92 ± 0.13 × 10−3 mm2/s) and lymphomatous (0.74 ± 0.14 × 10−3 mm2/s) lymph nodes (p < 0.0001) and the mean ADC of the metastatic nodes was significantly higher than that of nodal lymphoma (p = 0.04). The mean ADC of well- and moderately differentiated metastasis (0.98 ± 0.14 × 10−3 mm2/s) was significantly higher than that of poorly differentiated metastasis (0.83 ± 0.06 × 10−3 mm2/s) (p = 0.03). The mean ADC of non-Hodgkin lymphoma (0.65 ± 0.06 × 10−3 mm2/s) was significantly lower than that of Hodgkin lymphoma (0.86 ± 0.11 × 10−3 mm2/s) (p = 0.004). The best threshold for differentiating malignant from benign lymph nodes was 1.15 × 10−3 mm2/s.ConclusionDWI is a non-invasive technique that can help in the identification of the cause of enlarged neck lymph nodes.