Characterization of Tumor Vasculature to Specify Cancer Therapy

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The aim of this project is to establish the effect of abnormal constitution of tumor vascularure on dynamic flow/volume relation and subsequent metabolic state. In this connection, we have investigated following four themes.1) A battery of clinical examination such as angiography, dynamic contrast enhanced CT and radionuclide estudies using flow tracer as well as tumorseeking agents were done, in patients with malignant tumor. Data of these examinations revealed decreased tendeney of flow/volume relation in the tumor with increasing its size and with tumor sequestration of the radiotracer.2) Since heat accumulation within tumor due to the decreased flow/volume ratio might be plausible, in the hyperthermia therapy using RF capacitive heating, we validated this assumption using simulated dynamic phantom study.3) In order to establish the rational scheme for cancer control such as thermotherapy, imaging of this perfusion status with highly precision seems to be necessary. So, an attempt to image diffusion or microcirculation were successfuly accomplished using MR imaging modality.4) The lowered tendeney of perfusion status in the malignant tumor with increasing size was proved to cause anerobic energy production as evidence by the 31-P-MR Spectroscopy.5) In conclusion, anatomical derangement of the tumor vasculature causes metabolic change through decreased efficiency of the perfusion status (flow/volume relation). Thus adequate means for perfusion imaging such as diffusion imaging may play a key role to establish an adequate strategy for the cancer control.