Superparamagnetic iron oxide-enhanced MR imaging of head and neck lymph nodes.

PURPOSE: To compare findings on superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) images of the head and neck with those from resected lymph node specimens and to determine the effect of such imaging on surgical planning in patients with histopathologically proved squamous cell carcinoma of the head and neck.
MATERIALS AND METHODS: Thirty patients underwent MR imaging with nonenhanced and SPIO-enhanced (2.6 mg Fe/kg intravenously) T1-weighted (500/15 [repetition time msec/echo time msec]) and T2-weighted (1,900/80) spin-echo and T2-weighted gradient-echo (GRE) (500/15, 15 degrees flip angle) sequences. Signal intensity decrease was measured, and visual analysis was performed. Surgical plans were modified, if necessary, according to MR findings. Histopathologic and MR findings were compared.
RESULTS: Histopathologic evaluation of 1,029 lymph nodes revealed 69 were metastatic. MR imaging enabled detection of 59 metastases. Regarding lymph node levels, MR diagnosis was correct in 26 of 27 patients who underwent surgery: Only one metastasis was localized in level II with MR imaging, whereas histopathologic evaluation placed it at level III. Extent of surgery was changed in seven patients. SPIO-enhanced T2-weighted GRE was the best sequence for differentiating between benign and malignant lymph nodes.
CONCLUSION: SPIO-enhanced MR imaging has an important effect on planning the extent of surgery. On a patient basis, SPIO-enhanced MR images compared well with resected specimens.