Evaluation of efficient chemoembolization mixtures by magnetic resonance imaging therapy monitoring: an experimental study on the VX2 tumor in the rabbit liver.

To find effective chemoembolization mixtures, we tested combinations of carboplatin with the embolizates Spherex and Gelfoam in comparison to a therapy with NaCl-solution, a treatment with the cytostatic drug only, and a therapy with each of the embolizates alone. The experiments were carried out using as a model the VX2 tumor in the liver of male chinchilla rabbits (five for each group). Carboplatin was revealed by the 3-(4,5-dimethylthiazole-2)-yl-2,5-diphenyltetrazolium bromide test to be a potent cytostatic drug for VX2 rabbit tumor cells. We used magnetic resonance imaging to examine the tumor volume and signal intensity enhancement up to 15 min after Gd-DTPA administration within the tumor and liver before and after the different therapies. These parameters allowed us to evaluate tumor growth and vitality as well as liver injury for the different therapy types. The results found by magnetic resonance imaging corresponded very well to those obtained by histological analysis of the tumors. The chemoembolization therapies were significantly more efficient than the other therapies, as indicated by the reduction of signal intensity enhancement after contrast agent administration within the tumor and by the histologically determined necrotic fraction after therapy. In addition, we found a significant decrease of the tumor volume and no significant live injury for a therapy with Carboplat and Gelfoam.