Magnetic resonance imaging in the assessment of cervical nodal metastasis in oral squamous cell carcinoma

OBJECTIVE: The accurate pre-operative assessment of cervical lymph nodes is a well recognized problem in the management of patients with oral squamous cell carcinoma. Imaging techniques have improved the accuracy of staging but cannot determine if nodal enlargement is due to reactive changes or malignant involvement. We assessed the diagnostic performance of magnetic resonance imaging (MRI) in detecting metastatic disease within the neck in oral cancer patients. MATERIALS AND METHODS: A retrospective study was performed on 58 patients treated for oral squamous cell carcinoma. All patients had pre-operative MR imaging including axial and coronal short tau inversion recovery (STIR) sequences and pre- and post-gadolinium axial T1 weighted sequences. Nineteen patients had bilateral neck dissections giving 77 sides of neck for study. MR images were reviewed for nodal involvement at each anatomical level within the neck and correlated with findings at histology. RESULTS: Twenty-seven of the 77 sides of neck contained histologically positive nodes (35.1%). MRI sensitivity was 66.7% and specificity 68%. There was a false-negative rate of 20.9% and false-positive rate of 47.1%. Some enlarged, histologically positive nodes were not detected by MRI. Furthermore, in five cases the only histological evidence of nodal malignancy was the presence of a micrometastasis (<3 mm tumour deposit). MRI detected two of these. CONCLUSION: MRI lacks sufficient sensitivity and specificity to replace elective neck dissection for both staging and prognostic purposes.