Digital analysis and quantitative assessment of computed tomography for non-surgical treatments of brain tumors

It is difficult to exclude subjective impressions in the evaluation of the therapeutic effects of irradiation and chemotherapy on brain tumors, even in the CT image, which is much more useful than other, conventional methods of neuroradiological examinations. Using the system computer of EMI-1010, a series of new programs were developed for the digital analysis of CT images in order to make possible more objective and quantitative assessment of these non-surgical treatments. Among various therapeutic effects on the CT data, a reduction of the mass effect lowers the average CT-Numbers with a dilatation of cisterns and ventricles, on the contrary an improvement in the perifocal edema increases the average CT-No. of the region, however the changes in CT-No. of the tumor itself may be variable. The separate evaluation of these factors, therefore, gives more information about the results of the treatment than a simple analysis of the histogram of the region. Circumscribed tumors are fairly well evaluated with our programs for the statistic analysis of the volume and the CT-weight of tumors and the degree of contrast enhancement using histogram and subtraction scans. For the digital analysis of the ventricular system, the subarachnoid space, perifocal edema, and irregularly shaped infiltrative tumors, our programs for the character-image print-out and edge correction for the partial-volume effect of skull and air are much more useful than CRT display for data extraction and geographic-pattern recognition. (author)