Diagnostic value of double subtraction technique

Modern angiography demands frequent use of subtraction techniques. The subtraction tenchnique has proved to bea valuable adjacent in angiography where the initial study is inconclusive because of bone structures overlappingand obscuring the contast filled vessels. This is especially true when the contast medium in the vessle ofintereset is dilute or the overlapping bone is under penetrated. In our depart, we use a Franklin rapid filmchanger for all cardiac and abdominal angiographic studies. The double subraction techniques are applied to thevertebral, cardiac and celiac angiography and obtained good results demonstrating enhanced vessel shadows and fineabnormal tumor vessels. We used Kodak RP/SU X-Omat and Fuji subtraction film which is a single emulsion film. Thefirst, second idapositive and final subtraction films are exposed under 30 watt bright bulb, at 180 cm distance,for 3 seconds. The exposed Kodak and Fuji films are routinely processed in Kodak RP-X-O mat processor.