[Demonstration of brain tumors using a computer-assisted x-ray image enhancement technic]

It is possible to distinguish cerebral tumours from brain tissue after the injection of contrast by using an x-ray-video chain. Weak contrast situated behind strongly absorbing bone can be demonstrated by a nontomographic method by reducing the noise level and by using a special subtraction technique designed for optimal iodine contrast. For this examination, four series of images are prepared and stored (one before the administration of contrast and three subsequently). Dynamic studies of the distribution of contrast in the intra- and extra-vascular spaces of brain and tumour are produced by subtracting the stored images. The demonstration of blood-flow dynamics improves the differentiation of the tumour and, in particular, makes it possible to distinguish the tumour from cerebral oedema. The current input into the x-ray tube is low and the skin dose on the entry side is less than 0.6R for each series. The usefulness of the method in complementing computer tomography for surgical and radiation treatment is illustrated from various types of tumour. Up to the present 35 patients have been examined by this method.