[Experimental studies on evaluation of the effects of radiotherapy and chemotherapy in urogenital tumors using 31P-magnetic resonance spectroscopy].

The effects of local irradiation and intraperitoneal injection of cisplatinum (CDDP) and VP-16 were examined in the sequential 31P magnetic resonance spectroscopy (MRS) in testicular cancer (TC-1) and bladder tumor (BT-8) of human origin, serially transplanted in nude mice. In the early phase of tumor growth, high-energy phosphate metabolites such as phosphocreatinine (PCr), adenosine triphosphate (ATP) and phosphomonoester (PME) were detected in both grafted tumors. However, the relative value of inorganic phosphate (Pi) to PCr increased with the growth of the tumor. Irradiation had the most pronounced effect to inhibit growth, followed by CDDP in both strains. However, growth inhibition was not observed in the VP-16 group. The effect of irradiation on the tumor histology was severely expressed in the nucleus and cytoplasm on the 4th to 7th day. The high PCr/Pi ratio during 2 to 14 days after irradiation suggested reoxygenation in the tumors with a high hypoxic cell fraction. In the CDDP and VP-16 groups, without histological change, the changes of PCr and Pi were milder than that in the irradiation group. Thus the spectroscopic analysis is presumably expected to give us an earlier and more accurate information on the tumor than the conventional parameters.