Despite all recent advances, the most important progress in neuroradiol ogy has been in our knowledge of the anatomy of the nervous system. DANDY'S injection of ventricles and cisterns with air, SICARD'S studies of the epidural and subarachoid space with lipiodol, MONIZ'S work on cerebral arteries and veins, and, more recently, DJINDJIAN'S and DI CHIRO'S investiga tions of spinal arteries, have modified, refined and expanded current knowl edge of anatomy of the central nervous system. As described by LINDGREN, "the neuroradiologist dissects the region of interest with x-rays like a surgeon...