Digital subtraction angiography, or DSA, is a fluoroscopic imaging technique that produces highly detailed images of blood vessels by injecting contrast dye through a catheter and digitally removing the background structures to isolate the vessels. While DSA is an invasive procedure requiring arterial or venous puncture, it remains the gold standard against which non-invasive vascular imaging methods, including Doppler ultrasound, are measured. Understanding DSA is important for sonography students because ultrasound criteria for grading vascular stenosis, such as the velocity thresholds used in carotid ultrasound, were originally validated against DSA measurements. In modern practice, DSA is increasingly reserved for cases where ultrasound and other non-invasive imaging are inconclusive or when intervention is planned.
Sonography Term