AMI-227-enhanced MR lymphography: usefulness for differentiating reactive from tumor-bearing lymph nodes.

Abstract

To determine the value of magnetic resonance (MR) lymphography enhanced with AMI-227, a superparamagnetic reticuloendothelial-system-specific contrast agent, to distinguish normal and reactive from tumor-bearing lymph nodes. Mature male Copenhagen rats were inoculated with cell suspensions of R3327-MATLyLu rat prostate carcinoma (n = 16) or Complete Freund Adjuvant (n = 15) to generate ipsilateral popliteal lymph node metastases or lymphadenitis. At 12-14 days after inoculation, T1- and T2-weighted MR images of bilateral popliteal areas were obtained before and 24 hours after administration of AMI-227 (dose, 30 mumol Fe/kg). The contralateral popliteal nodes served as controls. Contrast-to-noise ratios (C/Ns) between the nodes and adjacent muscle were calculated in pre- and postcontrast images. Subsequently, bilateral popliteal nodes were excised. AMI-227 resulted in decreased C/N in reactive nodes (T1-weighted, -186% +/- 90% [standard deviation]; T2-weighted, -205% +/- 96%) and normal nodes (n = 7) (T1-weighted, -306% +/- 82; T2-weighted, -350% +/- 96). C/N remained unchanged or increased (T1-weighted, 88% +/- 92; T2-weighted, 306% +/- 256) (P < .05). Differences in AMI-227 uptake at MR imaging may help differentiate tumor-bearing from nontumor-bearing nodes.