Dynamic studies of brain tumors by the use of digital fluoroscopy

By the use of an expanded X-ray video chain and contrast medium injection, brain tumors can be set off against cerebral tissue. Based on a theoretical model, such weak contrasts behind a strongly absorbing bony structure can be visualized with a nontomographic procedure by massive noise reduction and specialized subtraction technique using an X-ray system optimized to iodine contrasts. During a period of examination, four image series are taken and stored. Dynamic studies concerning redistribution of contrast medium in the intravasal and extravasal spaces of brain tissue and tumor tissue are obtained by the subtraction of stored images. Visualization of the blood flow dynamics has helped to improve internal tumor differentiation and to demarcate the lesion better, especially from a brain edema. As in fluoroscopy, the X-ray tube is operated at a low current so that the skin dose at the radiation entry port amounts to less than 0.4 R for an image series. How practicable this method is in complementing computed tomography is demonstrated by studies of two patients (from a total of 20 patients examined) with a glioblastoma and a third-degree astrocytoma.