Preoperative esophageal cancer staging: magnetic resonance imaging of lymph node with ferumoxtran-10, an ultrasmall superparamagnetic iron oxide.

Background: Accurate detection of metastasis to lymph nodes is an essential component of the approach to treatment. The purpose of this study was to evaluate the utility of magnetic resonance imaging with ferumoxtran-10 in diagnosing lymph node metastasis in esophageal cancer.

Study Design: Sixteen patients with esophageal cancer who were scheduled for surgical lymph node dissection were enrolled. All patients underwent MRI scanning before and 24 hours after intravenous administration of ferumoxtran-10, an ultrasmall, superparamagnetic iron oxide. The presence or absence of metastasis was identified in lymph nodes by their enhancement patterns. Nonmalignant nodes contained macrophages that phagocytosed ferumoxtran-10. Metastatic nodes exhibited a decrease in phagocytic activity, and consequently showed little or no uptake of ferumoxtran-10. So we subdivided the enhancement patterns into the following three patterns: (A) node having an overall low signal intensity, (B) node having an area of high signal intensity, and (C) node having an overall high signal intensity. We identified that patterns (B) and (C) were metastatic patterns. The imaging results were compared with histopathologic findings.

Results: Of the 408 resected lymph nodes, imaging results of 133 nodes could be compared with histopathologic findings. Twenty-four lymph nodes had histopathologic metastases. Using our enhancement criteria, sensitivity was 100%, specificity was 95.4%, and accuracy was 96.2% for diagnosis of metastatic nodes.

Conclusions: Ferumoxtran-10 is useful for characterizing benign or malignant lymph nodes in esophageal cancer patients based on the defined enhancement criteria.