Purpose:To determine the accuracy of ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI) for nodal staging in patients with head and neck cancer.
Materials and Methods:Twenty patients with carcinomas of the upper aerodigestive tract were prospectively enrolled. MRI was performed before and 24 -36 hours after intravenous infusion of an USPIO agent, ferumoxtran-10 (Sinerem; Guerbet, France; and Combidex; Advanced Magnetics) at a dose of 2.6 mg Fe/kg using T2-weighted spin-echo and gradient-echo sequences. Surgery was performed the same day or the day after the ferumoxtran-10 -enhanced MR examination. Based on MRI, selected nodes were surgically removed and directly correlated with pathology using hematoxylin-eosin (H&E) and Perls stainings.Results: A total of 63 nodes were studied; 36 were nonmetastatic, 25 metastatic, and two inflammatory. Ferumoxtran-10 -enhanced MRI allowed diagnosis of 24 metastatic and 30 nonmetastatic nodes, yielding a sensitivity of 96%, a specificity of 78.9%, a positive predictive value of 75%, and a negative predictive value of 96.8%, compared to 64%, 78.9%, 66.6%, and 76.9%, respectively, for nonenhanced MRI. Accuracy of ferumoxtran-10 -enhanced MRI was 85.7%. The gradient-echo T2-weighted sequence was the most accurate to detect signal loss in nonmetastatic nodes.Conclusion: USPIO-enhanced MRI is useful for nodal staging of patients with head and neck cancers. CROSS-SECTIONAL IMAGING plays an important role in the study of patients with head and neck squamous cell carcinomas, allowing detection of lymph nodes (LN) missed by physical examination, or demonstrating invasion of structures such as the skull base or the carotid arteries (1,2). Using these imaging modalities, the criteria for diagnosing metastatic nodes is mainly dimensional. Measurements include the minimum transaxial diameter, the maximum transaxial diameter or a ratio between the maximum longitudinal and the maximum axial diameters (3-7). Other parameters, such as morphological criteria or the pattern of enhancement, are regarded as less important in this setting. Nodal metastases in the head and neck are frequently smaller than 10 mm, sometimes even under 5 mm in diameter, a fact that accounts for the unsatisfactory performance of the current imaging techniques (8,9).MRI can be improved when using contrast agents suited for intravenous MR lymphography, such as the new ultrasmall superparamagnetic iron oxide (USPIO) particles, which are taken up by cells of the reticuloendothelial system of nonmetastatic LN (10 -15). As it has been shown in previous studies, iron oxide deposition leads to a decrease in the signal intensity (SI) in nonmetastatic nodes due to the T2 shortening effects, whereas metastatic nodes, devoid of macrophages, will not undergo SI changes when using T2-weighted sequences (11). The clinical use of this contrast agent is still under evaluation on phase III clinical trials (15)(16)(17)(18)(19)(20). Reports show promising results, with sensitivity and specificity value...