[Changes in 31P-MR spectroscopy in murine experimental tumor (SCC VII) after irradiation].

Changes in the phosphate metabolism of transplanted squamous cell carcinoma VII (SCC VII) tumor were studied after irradiation using in vivo 31P-magnetic resonance spectroscopy (MRS). The results were as follows. 1) Phosphocreatine (PCr), gamma-,alpha- and beta-ATP, inorganic phosphate (Pi), phosphomonoester (PME) and phosphodiester (PDE) were detected in 31P-MR spectroscopy of SCC VII solid tumor. 2) 31P-MRS parameters, including PCr, beta-ATP, PCr/Pi, beta-ATP, beta-ATP/Pi and pH, increased after irradiation, then decreased with tumor regrowth. 3) Pi, PME and PDE decreased transiently after irradiation, and thereafter increased gradually. 4) PCr/Pi showed the most remarkable increase (p < 0.05) of all parameters following irradiation. Therefore, it may be employed as a therapeutic index in radiation therapy. Because PCr/Pi decreased again after irradiation prior to regrowth of tumor, it may be used to predict tumor regrowth. From these results, it was suggested that 31P-MRS was useful for monitoring the effects of radiation therapy, and regrowth after irradiation.

[Primary leiomyosarcoma of the pancreas].

Primary leiomyosarcoma of the pancreas is a very rare malignant tumor, with only 12 cases reported. A case of primary pancreatic leiomyosarcoma in a 55 year-old female with diabetes mellitus is described. US and CT demonstrated tumor masses in the head and tail of the pancreas. By angiography, abundant tumor vessels corresponding to the pancreatic tumor masses were revealed in the pancreas. The patient underwent surgical resection of the tumor in the tail of the pancreas, and then, microscopically it was diagnosed as leiomyosarcoma. The tumor in the head of the pancreas was not resected on account of the presence of diabetes mellitus and the possibility of poor prognosis. Macroscopically, it seemed to be the same as the tumor in the pancreatic tail. By operative findings, there was invasion from the pancreatic head to the duodenum and there was nothing to justify suspicion of the extra-ductal growing type of primary leiomyosarcoma of the duodenum. There were no metastases noted at the time.

[Experience of air-CT cisternography].

Ten patients were examined with air-CT cisternography. Two acoustic neurinomas protruding into the cistern were visualized as filling defects in the air. Air-CT cisternography identified the 2 tumors with a sensitivity rate of 100%. This retrospective study is aimed to assess the diagnostic efficacy of Air-CT in relation to MRI, enhanced CT and other radiographic studies.

[Minimal effective dose of perfluorochemical emulsion as a radiosensitizer].

Perfluorochemical emulsion can dissolve large amount of oxygen, carry it into tissues, and consequently enhance the response of hypoxic tumor cells to radiation. Previously we reported on the radiosensitizing effect of perfluorochemical emulsion. In the present study, the minimal effective dose of Fluosol-DA Saline 20% (FDAS), one of preparations of perfluorochemical emulsion, was determined. Mice bearing Lewis lung carcinoma in their thighs were injected in single i.v. of FDAS (1.25-20 ml/kg) and were allowed to breath carbogen (95% O2 + 5% CO2) for 30 min. before and during irradiation (15 Gy). The effect of FDAS was measured by the growth delay of the treated tumor. Administration of FDAS at over 5 ml/kg together with carbogen breathing significantly (p less than 0.01) enhanced the tumor growth delay as compared with treatment of carbogen breathing without FDAS. There was a significant difference (p less than 0.05) in the radiosensitizing effect between injection of FDAS at 5 ml/kg and 20 ml/kg, while there were not significant differences between injection of FDAS at 5 ml/kg and 10 ml/kg, or 10 ml/kg and 20 ml/kg, respectively. These results indicate that the minimal effective dose of FDAS is 5 ml/kg, which could be applied to clinical fractionated irradiation therapy as a standard FDAS-dose.

[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.

[Radiosensitization by oxygen in Ehrlich tumor receiving artificial blood substitute (FOB 20%)].

To enhance tissue PO2 of radioresistant hypoxic cells of tumor, artificial blood substitute (FOB) was applied, because it is excellent solvent for oxygen and allows the blood circulation system to recover and consequently increase the oxygen supply from blood to the tissue. When trasplanted Ehrlich tumor of mice on thigh grew about 1,000 mm3 in volume, those were divided into three groups, group 1: 60Co gamma-ray irradiation alone, group 2: irradiation under breathing oxygen, and group 3: irradiation under breathing oxygen after exchange transfusion with FOB. The radiosensitization of FOB was studied by comparing with the OER values of three groups for 50% TGD time, 50% SD time, and 50% and 75% TCP. The OER values of 50% TGD time, 5, 10 and 50% SD time 10 of oxygen group were 1.46, 1.29, and 1.22, respectively, and oxygen effect was observed in this group. Those values of FOB group were 2.02, 1.56, and 1.56, respectively and oxygen effect of FOB group was greater than those of oxygen effect of FOB group was greater than those of oxygen group. Animals receiving FOB were apparently radiosensitized by oxygen against animals breathing oxygen at small doses irradiation effect (50% TGD time, and 50% SD time). The OER values of 50% and 75% TCP at 30 days and 90 days after irradiation of oxygen group were about 1.5 (1.46-1.61) and these of FOB group about 1.3 (1.15-1.38). Radiosensitization by oxygen of animals receiving FOB was not clearly recognized against animals breathing oxygen in TCP effect at high dose irradiation. These results indicate that radioresistant hypoxic cells of tumor receiving artificial blood substitute (FOB) increase the sensitivity of 60Co gamma-ray irradiation, especially at small dose irradiation.