Magnetic resonance lymphography of profundus lymph nodes with liposomal gadolinium-diethylenetriamine pentaacetic acid

Lymphography, especially imaging of profundus lymph nodes, is a useful tool for diagnosis of cancer metastases in lymph nodes. However, positive enhan cement agents for magnetic resonance lymphography (MRL) have not been avail able, since the positive imaging agents so far introduced are low-molecular -weight materials that are not trapped in lymph nodes. For the purpose of i mproved positive enhanced MRL, we employed liposomes as carriers of a posit ive enhancer, gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). Mag netic resonance (MR) imaging was performed after subcutaneous injection of Gd-liposomes into the hind feet of rabbits which had reactive enlarged retr operitoneal lymph nodes. As a result, not only popliteal but also profundus retroperitoneal lymph nodes were positively enhanced by Gd-liposomes, espe cially after 20 min massage of the injected sites. Gd-Liposomes containing dipalmitoylphosphatidylglycerol were more effective than Gd-liposomes conta ining palmityl-D-glucuronide, a type of long-circulating liposomes, suggest ing that liposomal accumulation in lymph node is, at least partly, mediated by the trapping of liposomes by macrophages, These data show that liposome s modified with cd-DTPA are effective for positive enhancement of both regi onal and profundus lymph nodes in MR lymphography.