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Brain angiography with AI

Annette Birkhold | Siemens Inventors of the Year | Newcomer

An arteriovenous malformation (AVM) is a vascular disease of irregularly connected arteries and veins, which disrupts blood flow and oxygen circulation. In the affected area of the body, the arteries and veins don’t branch out into fine capillaries as they do in healthy people; instead, they grow together in a complex vascular tangle. AVMs can occur throughout the body, but they’re especially medically challenging in the brain. “Such a malformation in the brain can be the cause of various neurological deficits or even a cerebral hemorrhage. How dangerous it is in individual cases and how it’s best treated, however, depends on the exact anatomy of the vascular tangle. Sometimes drug therapy is possible, but sometimes surgery is necessary: for example, when the tanglecauses the blood pressure to rise so high locally that vessels can rupture,” explains Annette Birkhold, Inventor of the Year 2024 in the Newcomer category. “My invention supports the doctors' treating patients with detailed 3D and 4D images of arteries and veins. It can also be used in the diagnosis and treatment planning for AVM patients and for other vascular diseases.”

Glance into the brain

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Blood vessels can be examined by means of angiography. In an angiography of the brain, a catheter is first inserted into the inguinal artery and then under x-ray imaging is pushed up to the vessels in the neck. A contrast agent (or dye) is then injected into the bloodstream, filling the vessels and making the vessels visible under x-rays. Using an imaging procedure similar to CT but using an angiography system, a detailed three-dimensional image of the contrast-filled blood vessels is created.

“The anatomy of an AVM can be very complex. It can often only be visualized in its entirety if the contrast agent is injected at different points one after the other. And this is only possible with several angiographies,” Annette explains. “My method is used to synchronize the image data from several angiographies and merge them into one model.” This creates a detailed and comprehensive 3D representation of all the blood vessels involved in the AVM and a 4D video that shows how the contrast agent moves through the vessels over time.

Therapy support

These 4D images can support the treating physicians throughout the entire treatment planning and implementation process. During planning, it’s especially important for them to understand what’s happening in the center of the AVM, the nidus. “The 4D image makes it possible to focus on the time range when the contrast medium is passing through the nidus and block out everything that happens before or after,” Annette says. “This makes it clear which arteries are in front of the nidus and which veins are behind it.”

If endovascular therapy is needed – a minimally invasive procedure that involves closing the vessels of the nidus – the 4D image helps determine the route through the vessels to the nidus in advance. During the procedure when the catheter is again pushed to the target region and monitored using continuous 2D X-ray imaging, the 4D image can also be displayed and provide the surgeon with additional guidance.

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Estimating local blood pressure with simulation

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“This detailed model of the AVM, a digital twin, also offers the opportunity to provide more support using mathematical methods. “We’re working on models that use artificial intelligence and flow simulation to estimate the blood pressure in the vessels,” Annette says. “We will be able to provide even more information in the future about where dangerous vascular ruptures may occur in an AVM.”