What is DSA?

DSA stands for Digital Subtraction Angiography. What an awkward name it is! Its production is tortuous and contains a lot of profound knowledge.

Since the emergence of surgery, people have been exploring many problems, one of which is to find out how the arteries and blood vessels of the human body are distributed.

Therefore, after Roentgen discovered X-rays on1October 8, 1895, 165438, and soon after, someone made an arteriographic study of the hand on the corpse. The method is to inject contrast agent into the artery of the hand, and then take an X-ray, so that you can see the distribution of arterial blood vessels.

By 1923, someone made an angiography on the human body for the first time. In 1930s, with the development of cardiac X-ray angiography, arteriography can even be performed through lumbar puncture. Doctors constantly improve the method of arterial intubation, which makes arteriography widely used.

However, no matter how to improve it, some shortcomings of traditional X-ray photography always affect the quality of examination, and there are two major problems that have been puzzling the medical community.

First, arteriography needs to cut the skin and then insert a catheter from the artery. This is an "invasive" method, which has certain damage and pain to the patient. This imaging method is easy to cause many complications.

Secondly, when the body is thick, there are many bones and muscles, and the structure is complex, muscles, bones and organs often overlap with each other, and the X-rays taken by them block the blood vessels to be seen, which blurs the blood vessel image and affects the accuracy of diagnosis.

In order to find a simple, safe and clearer angiography method for patients, medical scientists have been studying and exploring. People imagine that if the background images (such as muscles and bones) overlapping with blood vessels can be removed, wouldn't that solve the problem? This is the original intention of subtraction.

From the idea to the final realization, many people have made efforts!

As early as the 1930s, some people referred to some methods of photo studios at that time and put forward the method of negative film subtraction, that is, the method of eliminating the background by overlapping positive and negative films. In 1960s, analog electronic subtraction reappeared. However, all of them have not been popularized because of complicated operation and poor photo quality. It was not until 1980s that digital subtraction technology appeared with the development of computer technology and its application in medicine.

Now, let's see what kind of investigation method this is, which broadens our horizons and what kind of realm it is.

Digital subtraction angiography, also known as digital radiography. This is a new angiography method, which combines the digital ability of computer with traditional X-ray photography and fluoroscopy equipment.

The procedure of this examination method is: before angiography, take an X-ray film of the examination site, which is called a mask image. Then inject a small amount of contrast agent from vein, and then take an angiogram X-ray in the same place. This is called imaging. After that, the two images pass through the X-ray camera enhancement system, and the formed image video signal is converted into a digital signal, which is stored in the corresponding mask image memory and contrast memory, and then input into the subtracter for subtraction, so that a clear blood vessel image marked by contrast agent can be obtained. After a series of complicated processes such as contrast, enhancement and analog conversion, this blood vessel image is clearly displayed on the TV screen. These images can also be imported into videos, tapes and movies for archiving. In this way, the comparison before and after treatment is very convenient.

As soon as digital subtraction angiography came out, it occupied an advantage with its many advantages. This method is simple, rapid and safe, with little pain for patients and no need for hospitalization. More importantly, it eliminates overlapping images unrelated to blood vessels, makes the preserved blood vessel images very clear, and greatly improves the accuracy of diagnosis. Using this method, the correct diagnosis rate of vascular stenosis and atherosclerosis can reach 97%, which is one of the best methods to evaluate vascular occlusive diseases at present.

Not only that, this technology can also guide doctors to carry out endovascular angioplasty, which can be used not only for general blood vessels, but also for coronary arteries of the heart.

Alex Burris of new york Central Medical University was the first person to perform intravascular surgery with digital subtraction angiography. He is a good observer and thinker. In 1970s, when he was an intern surgeon in Israel, he was inspired by the use of drip irrigation by farmers in the desert. He designed a very thin catheter. Under the guidance of digital subtraction angiography, he directly inserted the catheter into the blood vessel from outside the body (of course, all this was done under strict disinfection), dropped a small amount of strong adhesive, cut off the blood vessel of the tumor, treated the tumor and repaired the broken blood vessel.

Later, on his basis, someone attached a "laser knife" to the endoscope head with the aid of DSA technology and fiber-optic endoscope, and went directly into the blood vessel for surgery to remove intravascular lesions or dilate blood vessels. Of course, they can also perform operations on cerebral vessels, which makes it much easier to perform operations that were needed in the past.

From the expansion of the application scope of DSA technology, we see the role of "association" as a way of thinking in innovation.