Second-order subtraction with simultaneous bilateral carotid, internal carotid injections.

Abstract

Second-order subtraction technic in conjunction with simultaneous bilateral carotid angiography has definite advantages in comparing subtle changes in expansive processes. Displacement of minor blood vessels or variations in circulation time can be better appreciated. During the capillary phase, the brain can be seen with contrast loading. History Second-order subtraction was described in 1961 by Ziedses des Plantes (1) in his monograph. Little interest in this technic has been expressed in the American literature (2, 3). Simultaneous injections of both carotid arteries have not been widely advocated (4, 5). The fear of subintimal injections into both carotid arteries with resultant sudden, near total, reduction in blood supply to the cerebral cortex reduces the attractiveness of the procedure. Amundsen et al. (6), Saltzman (7, 9), and Gryspeerdt (8) have made extensive use of the cross compression test to get opacification of the opposite internal carotid artery system with no adverse reactions. Amundsen, by employing a percutaneous catheter technic, reported a complication rate of less than 0.3 per cent in 971 consecutive carotid angiograms. It is his routine to compress the opposite carotid artery to compare both middle cerebral arteries on the anteroposterior projection. Material Between January and July 1965, 25 patients were subjected to bilateral carotid angiography with simultaneous injection into both internal carotid arteries. This was followed by use of the subtraction technic of the roentgenograms. The simultaneous bilateral angiograms have been so helpful that the method has now been established as part of our routine projections. No adverse reactions related to the simultaneous injections have been recorded. Technic A percutaneous catheter technic for carotid angiography has been used at UCLA since 1961. The details of this procedure have been published elsewhere (10). In general, a 1 mm (O.D.) catheter is passed percutaneously by a modified Seldinger technic into the low common carotid artery. Under fluoroscopic control the tip of the catheter is maneuvered into the internal carotid and advanced for a distance of 3–5 cm. Since the carotid bulb tends to act as an arterial pressure stabilizer, injections made distal to the bulb will cause a slight rise in intra-arterial pressure. This slight rise produced better filling of the internal carotid system without the overlapping of the external carotid vessels. With a catheter in the internal carotid artery, forceful hand injections of 6 cc of contrast material can be made without fear of extravasation or intramural injection. First-Order Subtraction Subtraction requires taking a roentgenogram immediately prior to serial angiography. This radiograph is called the base film and contains no injected contrast material. A photographic contact print or diapositive is made of this base film, reversing the image relationships from black to white and vice versa.