Digital subtraction angiography.

DSA is a promising method for improving the results of cerebrovascular angiography. Experience suggests that VI-DSA will have a more limited application than was originally expected. It is a low-risk, cost-efficient technique for serial and postoperative studies and for screening outpatients who may have occlusive extracranial lesions that have not been detected by noninvasive tests; however, false-negative results may be obtained. AI-DSA provides far more accurate and reliable results than VI-DSA and has the potential for increasing the flexibility, efficiency, and safety of angiography, in comparison with conventional techniques.