MR imaging of mediastinal lymph nodes: Evaluation using a superparamagnetic contrast agent

The purpose of this study was to determine whether Intravenous injection of a magnetic resonance (MR) contrast agent, ultrasmall superparamagnetic iro n oxide (ferumoxtran-10), can be useful in characterizing lymph nodes in pa tients with lung cancer. Twelve patients with known or suspected lung cance r were studied. Pre- and postcontrast injection of ferumoxtran-10 MR scans of the chest were obtained. Analysis of the signal intensities and bronchos copic fine needle aspiration of a single node were performed in each patien t. Six of 12 patients had a final diagnosis of lung cancer. T1-weighted ima ges were best for localizing mediastinal lymph nodes. Signal intensity chan ges before and after contrast were best visualized on T2-weighted and gradi ent-echo images. All four patients with lung cancer who had nodes positive for malignancy at biopsy had no change in signal intensity of the nodes on T2 images. The signal intensity decreased in the remaining two patients, an d the nodes were benign. Of the eight patients with benign disease, five ha d no change in signal intensity of the nodes. Therefore the sensitivity for tumor involvement of the nodes is 100%, but the specificity is only 37.5%. Ferumoxtran-10 is a contrast agent that can alter the signal intensity of lymph nodes. Lack of signal change may be due to malignant or inflammatory change. Studies in a larger population of lung cancer patients may help to characterize the utility of this agent further. (C) 2000 Wiley-Liss, Inc.