Evaluation of Axillary Lymph Nodes by Diffusion-Weighted MRI Using Ultrasmall Superparamagnetic Iron Oxide in Patients With Breast Cancer: Initial Clinical Experience

Purpose: To investigate the diagnostic performance and clinical feasibility of diffusion-weighted magnetic resonance imaging (MRI) using ultrasmall superparamagnetic iron oxide (USPIO) in the evaluation of axillary lymph nodes (ALNs) in patients with breast cancer. Materials and Methods: Sixteen patients with known breast cancer underwent 1.5 T MRI. Axial diffusion-weighted images (DWIs) and conventional T1- and T2*-weighted images (CIs) were acquired before and 24-36 hours after intravenous administration of USPIO. Detection of ALNs was evaluated on DWIs in comparison with CIs. The apparent diffusion coefficient values (ADCvs) of the nonmetastatic and metastatic nodes in precontrast DWIs were determined. The diagnostic performance of DWI using USPIO was compared with that of CIs using USPIO with pathological correlation. Results: Out of a total of 286 ALNs, 216/286 (76%) nodes were detected on DWIs and 238/286 (83%) on CIs. The differences in the ADCvs between metastatic and nonmetastatic nodes were not significant (P = 0.06). Sensitivity of CIs and DWIs using USPIO were respectively 70% and 83%, specificity 98% and 98%, and overall accuracy 93% and 95%. Conclusion: Although the detection on DWIs of ALNs in patients with breast cancer was inferior compared to CIs, the sensitivity and accuracy of DWIs using USPIO were superior in the diagnosis of ALNs metastasis.