[Tumor imaging with conventional X-ray using a new artificial blood substitute (perfluoroctylbromide emulsion, FOB)]

A new artificial blood substitute, FOB, which has been shown to be a good solvent for oxygen, contains a Bromine atom within its molecule. FOB is taken up in tumor macrophages and the Bromine shows opacity on X-ray film by absorbance of X-rays. In this study, tumor imaging possibilities were studied using conventional roentgenograms, on mice bearing transplanted Ehrlich ascites tumors on the right leg and which were given a 1-ml injection of 50 w/v % FOB. The results obtained follows: Solid Ehrlich tumors were imaged clearly wih injected FOB. X-ray films showed persisting homogeneous tumor staining, and irregular linear and plaque opacities. Larger tumors (more than 5,000 mm3 in volume) were imaged less clearly than smaller ones (about 1,000 mm3 in volume), because of superimposition of X-ray absorbance of the FOB taken up and of the larger tumor mass itself. The patterns of FOB taken up into the transplanted tumor were different according to various tumor growth time. Tumor imaging effect was enhanced by double time injection of 1 ml FOB. Histological features of Ehrlich tumors injected with FOB showed that FOB was phagocytosed by macrophages in the tumor tissue. The radiosensitization effect of FOB has already been reported by us. These results suggested that FOB acts not only as a sensitizer in radiation therapy, but also as a tumor imaging agent for diagnosis of the localization of malignancy in radiotherapeutic planning.