Dynamic micro-magnetic resonance imaging of liver micrometastasis in mice with a novel liver macromolecular magnetic resonance contrast agent DAB-Am64-(1B4M-Gd)(64).

DAB-Am64-(1B4M-Gd)(64) is a newly synthesized macromolecular liver magnetic resonance imaging (MRI) contrast agent with a polypropylenimine diaminobutane (DAB) dendrimer conjugated with a bifunctional diethylenetriaminepentaacetic acid (DTPA) derivative for complexing Gd(III) atoms. The characteristics of DAB-Am64-(1B4M-Gd)(64), which quickly accumulated in the liver, have been reported recently. In the present study, the dynamic micro-MRI with DAB-Am64-(1B4M-Gd)(64) was obtained in the mouse liver metastasis model using colon carcinoma cells to evaluate the ability to visualize the micrometastatic tumors compared with that using Gd-DTPA. The dynamic micro-MRI with DAB-Am64-(1B4M-Gd)(64) was able to homogeneously enhance the normal liver parenchyma and visualize micrometastatic tumors of 0.3-mm diameter in the liver of the mice with better contrast than that with Gd-DTPA. In conclusion, DAB-Am64-(1B4M-Gd)(64) is a new liver MRI contrast agent potentially useful for diagnosis of micrometastasis in the liver.