Nodal shape (S/L) and its combination with size for assessment of cervical lymphadenopathy: which cut-off should be used?

The short axis to long axis (S/L) ratio is commonly used to assess cervical lymphadenopathy; however, the cut-off value used has been limited to 0.5. The accuracy of the combination of S/L ratio and nodal size has not been documented previously. We evaluated 1143 normal cervical nodes from 95 healthy subjects, and 1441 nodes from 290 patients with proven cervical lymphadenopathy. The optimum cut-off value of the S/L ratio was determined in different regions of the neck: submental (0.5), submandibular (0.7), parotid (0.5), upper cervical (0.4), middle cervical (0.3) and posterior triangle (0.4). In the submandibular and parotid regions, the combination of the S/L ratio and short axis shows substantial improvement in diagnostic accuracy when compared to the S/L ratio alone.