Deserno WMLLG et al. (2004) Urinary bladder cancer: preoperative nodal staging with ferumoxtran-10-enhanced MR imaging. Radiology 233: 449–456

In their recent study, Deserno et al. have shown that ferumoxtran-10-enhanced MRI is superior to nonenhanced MRI in detecting metastatic lymph nodes in patients with bladder cancer. Importantly, this method does not rely on nodal size or shape to distinguish between benign and malignant nodes.

Fifty-eight patients with bladder cancer underwent MRI before and 24–36 hours after intravenous injection of ferumoxtran-10 iron-oxide nanoparticles. Precontrast images were interpreted on the basis of node size; round nodes larger than 8 mm or oval nodes of axial diameter greater than 10 mm were defined as malignant. Postcontrast images were interpreted by comparing them with the precontrast images; benign nodes show a homogenous decrease in signal intensity due to the accumulation of iron oxide in the nodal macrophages, whereas metastatic nodes show either a heterogeneous decrease or no decrease in signal, since the normal macrophages are replaced with cancer cells.

By comparing the MRI results with histologic findings for 172 dissected nodes, the authors showed that the sensitivity of ferumoxtran-10–enhanced MRI was significantly better than that obtained using precontrast images alone (96% vs 76%, P <0.01) and that the negative predictive value was also significantly improved (98% vs 91%, P <0.01).

Noting that ferumoxtran-10–enhanced MRI could be used to identify metastases even in normal-sized nodes, the authors conclude that the technique allows superior preoperative nodal staging in patients with bladder cancer, compared with standard, nonenhanced MRI.