Image processing and quantitative assessment in computer tomography for non-surgical treatment of brain tumours

Using the EMI computer tomographic (CT) system, EMI-1010, a series of new programmes were developed for the digital analysis of the CT images in order to make a more objective and quantitative assessment possible of two non-surgical methods of treatment of brain tumours such as irradiation and chemotherapy. Amongst the various therapeutic effects demonstrable from the Ct data, a reduction of the mass effect was found to lower the average CT number, with a dilatation of the cisterns and ventricles. In contrast, an improvement in the amount of perifocal oedema increased the average CT number of the region, however the changes in CT number of the tumour 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 tumours are fairly well evaluated with our programme for the statistical analysis of the volume and the CT weight of tumours and the degree of contrast enhancement using histograms and subtraction scans. For the digital analysis of the ventricular system, the subarachnoid space, perifocal oedema, and irregularly shaped infiltrating tumours, our programmes for the character-image print-out and edge correction for the partial-volume effect of skull and air are much more useful than the CRT display for data extraction and geographic-pattern recognition.