Prof. Dr. Ulf Teichgräber
Director of Radiology Department at the University Hospital of Jena
Thanks to a new, automatic injector and optimized imaging protocols, optimal results in peripheral angiography can be achieved using CO₂ as contrast medium.
CO₂ has been used as an intra-arterial contrast medium since the 1970s, as an alternative solution to the traditional iodinated contrast medium. As the technology continued to improve, CO₂ has evolved into a viable vascular imaging agent.
Although used initially to treat patients with renal failure or iodinated contrast allergy, the many unique properties of CO₂ yielded multiple advantages. It is now used in a multitude of scenarios, either alone or in combination with traditional contrast agents. It has been used with great success in both adults and children for more than three decades with only limited reportable complications. But still until now, it has only been possible to use CO₂ as a contrast medium in angiography by “manually injecting it.” This technique has significant issues: it is impossible to control the injection pressure, and there is a risk of air contamination. In addition, manually injecting CO₂ can be painful for the patient and therefore can result in poor image quality, especially in critical districts.
“If I give a colleague images with CO2 contrast and normal iodine contrast it will be difficult for them to figure out what contrast medium has been used.”
Prof. Dr. Ulf Teichgräber, Director of Radiology Department at the University Hospital of Jena, remembers: “We always tried to avoid CO₂, because of its technical limitations. In our daily business, it was rarely used, and only for patients with impaired kidney function.” But thanks to the automatic CO₂ injector and specially optimized imaging protocols in the Artis zeego angio system, optimal results in peripheral angiography can now be achieved using CO₂ as the contrast medium. Teichgräber takes care of many cases with CO₂ imaging: “Today we use it in 10 to 20 percent of our cases, and we are increasing that – because the image quality is good – and it’s also easy to use.”
“We were able to design and realize the first machine that allows users to set very fine and accurate pressure parameters for the injection.”
How to overcome the challenges in CO₂ imaging
There are still some challenges with this technology. First challenge: the position of the patient. Teichgräber explains: “The gas always goes up – that’s why the head of the patient has to point down to avoid gas embolism. This is still true for CO₂ imaging today. When you have a normal ceiling-mounted system, you have to move the table. And for safety reasons, you’re not really able to move the table. This is very uncomfortable for the operator as well as the patient.” But Teichgräber’s team found a solution: “We decided on Artis zeego. For one thing, the robot brings a big advantage: Once you’ve placed the patient head-down, you don’t have to move the table anymore. You just move the robotic C-arm wherever you want it to be. So you can cover nearly the entire body without moving the patient. That makes working with a robot a totally different experience.”
The second challenge was to convince the patient, because the CO₂ injection can be very painful. Teichgräber solved this challenge in Italy with the Angiodroid CO₂ injector: “I tested it and was very impressed. Now the image quality using CO₂ contrast is higher, because the very constant soft injection fills the vessels continuously and provides an even better flow. The result: Because the CO₂ doesn’t pour suddenly into the vessel, the pressure release is very soft. That means less pain for the patient and a really big improvement in image quality.”
The Angiodroid injector provides a constant CO2 injection adapted to the systolic blood pressure
Sebastiano Zannoli, CEO Angiodroid, on the new CO₂ injector generation:
What was your motivation to develop a new device for CO2 injection?
SEBASTIANO ZANNOLI: CO₂ angiography is not a new technique. We decided to invest for two reasons: First, the technical advances in X-ray systems have enabled significantly better image quality using CO₂ contrast. There is now an algorithm for optimally visualizing the bolus of gas. The second reason is the increase in diabetes in the general population. As this patient group increases, the market needs a machine that allows you to push a button and inject the CO₂ contrast medium, and not have to use iodine.
What is the basic technical principle behind your development?
SEBASTIANO ZANNOLI: It’s typically very difficult to inject a gas. When you inject a liquid, you only need to define the flow. But when you inject gas, you‘re also injecting under pressure. We were able to design and realize the first machine that allows users to set very fine and accurate pressure parameters for the injection. The result: The patient doesn’t feel pain. With our injector, you set your parameters and push a button – and the machine does everything else.
3 Facts about CO₂ Angiography
- CO₂ is less dense than iodinated contrast medium, and demands special acquisition protocols of the angiography system.
- CO₂ doesn’t cause allergic reactions, and there is no renal toxicity: Even patients with diabetes or compromised renal function can be treated.
- Costs are reduced in cases where CO₂ is used as contrast medium instead of conventional iodine contrast medium.