The role of MRI scanning in the diagnosis of cervical lymphadenopathy.

In a blind, prospective trial, 42 patients undergoing 51 cervical lymph node dissections for head and neck malignancies were investigated by a preoperative MRI scan. Histological examination of the dissection specimens recorded the distribution, size, percentage of neoplastic involvement and any extra-capsular spread of the sampled nodes. The MRI correctly diagnosed all 17 positive nodes (sensitivity 100%). However it could not differentiate between enlarged reactive and malignant nodes, so there was a significant false positive rate (specificity 53%). Routine use of MRI scans will allow an unnecessary neck dissection to be avoided in a patient with a clinically negative neck who also has a negative MRI scan.