Abstract: PURPOSE: To investigate the characteristics of metastatic and reactively hyperplastic lymph nodes in interstitial magnetic resonance lymphography enhanced by dextran-DTPA-Gd. METHODS: Twelve New Zealand white rabbits were divided into 2 groups at random：reactive hyperplasia group and tumor group. 0.2 mL dextran-DTPA-Gd was injected into the bilateral submucosa of the tongue in 12 New Zealand rabbits. Then the MR images by using 3-D enhancement magnetic resonance lymphography at 5, 15, 30, 45, 60 mins and 4, 24 h after injection were obtained. The signal intensities after enhancing were measured to calculate the enhanced rates (E%) of lymph nodes at the same time and the signal enhancing rates-time curve was drawn. The images were analyzed with pathological results.The data were analysed using SPSS17.0 software package. RESULTS: The signal of the tumor group reached a peak after 45 min with E% of 289% and the signal of reactive hyperplasia group reached a peak after 30 min with E% of 367%. The difference of enhancing rates between the metastatic lymph nodes and reactively hyperplastic lymph nodes was significant at the same time (P<0.05). In tumor group, 24 lymph nodes were diagnosed as metastatic lymph nodes by IMRLG with 2 false positivity; while 91.67% (22/24) metastatic lymph nodes were confirmed by pathological diagnosis. In the reactive hyperplasia group,5 lymph nodes were misdiagnosed as metastatic lymph nodes by IMRLG and the false-positive rate was 18.5% (5/27). CONCLUSIONS: IMRLG enhanced by dextran-DTPA-Gd could effectively detect metastatic and reactively hyperplastic cervical lymph nodes.

Key words: Metastatic lymph nodes, Reactively hyperplastic lymph nodes, Magnetic resonance imaging, Lymphography, Gadolinium