Real-time fluoroscopic digital subtraction.

For many years, conventional fluoroscopy has been used as a guide in angiography for catheter placement before filming an angiographic series and, as such , has certainly been adequate. With the advent and increased use of interventional radiology, particularly in neuroradiology, a highquality fluoroscopic image, free of obscuring bony anatomy, is desirable. Conventional fluoroscopy, regardless of the quality of the image, includes an image of the catheter, contrast material , embolic material (or balloon), and a real-time video display of bone and soft-tissue densities. Bony and soft-tissue detail , however, is extraneous and may be confusing , especially when imaging the face, skull , and associated bony anatomy. A desire to image in a subtraction mode for interventional purposes with all surrounding bone and soft tissues subtracted from the real-time video display (Berenstein A, personal communication) encouraged us to investigate the possibility of using our existing digital vascular equipment to provide us with this end result.