DSA画像における記録系の基礎的および臨床的検討

抄録

Digital Subtraction Angiography (DSA) digtizes conventional X-ray images produced by the image intensifier TV system, and shows analogue vascular images on the monitor simultaneously. This modality is more sensitive to a contrast medium than the conventional angiography and can visualize vessels filled with a low concentration of a contrast medium very clearly. About two years has passed since the Philips DSA unit (DVI-1) was installed in Osaka University Hospital. During this period, about 600 cases were examined using the DSA. Factors that influenced the quality of the DSA imagies were divided into three categories as follows. 1) X-ray system (x-ray dose, tube voltage) 2) Display and recording system (film, multiformat camera) 3) Clinical problems (e.g., patients movement during X-ray exposure) We studied the relation between these factors and quality of the DSA images in this report. The most adequate X-ray dose was about 2,500 μR and tube voltage was 60 to 80 kVp. The result of evaluation of the film was that the film with wide latitude gave goodimages, because the specificity of the images could be changed by adjusting the brightness and contrast of the multiformat camera to get the best image. The multiformat camera that we used in this report could not give satisfactory imagies and should be designed fit to the specificity of the DSA images. Misregistration was mostly caused by patient movement, in many cases ; the movement was caused because of an inadequate explanation of the DSA examination to the patients. However, the current DSA system is limited because of the temporal subtraction method. One of the solutions for the misregistration is to decrease the patient's heat sensation by using a contrast medium having a low osmotic pressure. The contrast medium having a low osmotic pressure seems to be warking well. The other way is to use the dual energy subtraction method to decrease the misregistration. This system will become popular in the future. We discussed the major problems and some solutions for the DSA images by using our clinical experience.