Interstitial Magnetic Resonance Lymphography Using Gadolinium-Ethoxybenzyl-Diethylenetriamine Pentaacetic Acid in Rabbits With Lymph Node Metastasis

Abstract

To investigate the dose dependency of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for interstitial magnetic resonance (MR) lymphography and the detection of lymph node metastasis in rabbits. Eighteen VX2 tumor-bearing rabbits were subjected to MR lymphography using clinical MRI equipment. The enhancement of popliteal lymph nodes was studied in these rabbits before and at 2.5 to 10 minutes after the subcutaneous administration of 4, 8, or 17 micromol Gd/kg of Gd-EOB-DTPA in TSE and 3D-FLASH (n = 6). Signal-to-noise ratio and contrast-to-noise ratio were statistically compared between each group by the Tukey test. After MR imaging, the popliteal lymph nodes were removed, and sections were prepared for microscopic examination. In the histologic findings, all metastases (3-12 mm) in the popliteal lymph nodes were detected by 3D-FLASH images. Gd-EOB-DTPA-enhanced T1WI showed a hypointense region for metastasis and a hyperintense region for nontumor regions, although the lymph nodes containing metastasis were detected as a hyperintense region by conventional PDWI and T2WI. Signal enhancement of the nontumor regions and contrast between the nontumor regions and metastasis showed dose dependency and reached a plateau at 8 micromol Gd/kg on T1WI (signal-to-noise ratio: 13.9 +/- 1.6; contrast-to-noise ratio: -12.7 +/- 1.7). This study showed that interstitial MR lymphography with Gd-EOB-DTPA can detect metastasis and that the optimal dose in rabbits is 8 micromol Gd/kg as a subcutaneous application.