Interstitial magnetic resonance lymphography using a polymeric t1 contrast agent: initial experience with Gadomer-17

RATIONALE AND OBJECTIVES: The detection of lymph node metastases is an important step in tumor staging and is significant for therapy planning. Lymph node-specific contrast agents can raise the sensitivity and specificity of modern diagnostic methods. This study investigated the suitability of the dendritic contrast agent Gadomer-17 in magnetic resonance (MR) lymph node imaging and compared three different dosages in such an application. METHODS: Doses of 1.0, 2.5, and 10.0 micromol Gd/kg body weight were interstitially injected into the hind legs of dogs; the signal intensities of two successive lymph node groups (inguinal and iliacal) were then recorded up to 120 minutes after injection. RESULTS: Gadomer-17 induced a strong increase in signal intensity of the examined lymph node groups. At 15 minutes postinjection, the enhancement increased by 120% to 680%, depending on the dose. The maximum enhancement was 450% to 960% at 60 to 90 minutes postinjection. Doses of 2.5 and 10.0 micromol Gd/kg showed comparable results; even the lowest dose (1.0 micromol Gd/kg) enhanced the contrast of the inguinal lymph nodes in 4 of 5 animals and the iliacal lymph nodes in three of five animals. Therefore, the minimum effective dose of Gadomer-17 in this study was approximately 2.5 micromol Gd/kg. CONCLUSION: This study revealed the excellent suitability of the dendritic contrast agent Gadomer-17 for MR imaging of the lymphatic system (lymph nodes and lymph vessels).