[Cerebral blood flow measured by Xenon enhanced CT in brain tumors]

In the management of malignant brain tumors, it is important to know the extent and viability of tumors. However, an ordinary CT scan with iodine enhancement has only a limited ability to distinguish the tumor from surrounding normal tissue. Since the blood flow in tumor tissue was found to be relatively high in a previous experimental report, we have investigated the blood flow in a tumor and the surrounding brain. The Xenon enhanced CT method has several advantages over the conventional isotope method and enables us to evaluate rCBF with the same resolving power as with the CT scan. We evaluated rCBF in 15 brain tumor cases and obtained the following results. Mean rCBF value of the tumor is a little lower than that of gray matter and higher than that of surrounding edema. Our Xe-CT method enables us to distinguish the demarcation between the tumor area and the surrounding edematous area and offers useful information for determining the extent of resection in surgery. Mean lambda value of the tumor which is not obtainable in vivo by radionuclide scanning, was 1.02 +/- 0.06 for gliomas and 0.72 +/- 0.09 for metastatic tumors. rCBF value and lambda value are important elements to know the uptake rate of anticancer drugs into the brain tumors. And to evaluate these value in each brain tumor is useful in the selection of chemotherapeutic agents.