The clinical stakes are considerable. During stent-assisted treatment, a catheter is inserted through the femoral artery in the groin or the radial artery in the wrist and navigated through tortuous, branching vessels deep inside the brain. The stent must then be positioned so that its ends rest in straight sections of the vessel, providing stable anchoring while fully covering the aneurysm orifice. Misjudging the geometry can lead to stent migration, arterial occlusion, vessel damage, or stroke. Stent selection itself is a delicate balancing act: the device must match the diameter and length of the parent artery, accommodate the curvature of the vascular path, and leave adequate landing zones on both sides of the aneurysm neck. Traditional planning based on CT angiography, MR angiography, or digital subtraction angiography flattens this complex three-dimensional puzzle onto two dimensions, forcing clinicians to reconstruct the anatomy mentally at the very moment when errors matter most.

The Krakow team, led by Wojciech Chmiel together with Piotr Szwed, Joanna Kwiecień, Michał Turek and colleagues, built their platform around a workflow engine that automates the entire chain of image processing. Starting from volumetric medical images in NIfTI format, the system performs vessel segmentation using threshold-based binarization techniques such as Otsu’s method, cleans the resulting point clouds with the DBSCAN clustering algorithm to strip away outliers, and then computes the vessel’s medial axis, the invisible central spine along which a stent naturally wants to sit. The centerline extraction is particularly elegant: a distance-based potential field is evaluated for every interior point of the vessel, with the lowest potential values forming a valley along the vessel’s core, and the Dijkstra shortest-path algorithm then traces the optimal route between two operator-selected endpoints. Because the raw path follows a voxel grid and emerges as a staircase curve, a Savitzky-Golay filter smooths it into a anatomically plausible centerline without erasing genuine high-frequency curvature.

Once the centerline is established, the system computes a radial profile at each point, casting 120 rays spaced three degrees apart in a plane orthogonal to the axis and measuring the distance to the vessel wall along each one. These profiles act as a geometric fingerprint of the artery, allowing the software to pinpoint aneurysm necks and bifurcations with remarkable fidelity. At a spatial resolution of 0.05 millimeters per voxel, the smoothed profiles capture subtle variations in lumen diameter that would be invisible on a standard angiographic display. The operator then marks an attraction region on the centerline, a deliberately generous zone within which the stent simulation will unfold, and the processed mesh is exported to a format compatible with Microsoft’s HoloLens headset, complete with correctly oriented surface normal vectors that are essential for realistic shading and depth perception in stereoscopic rendering.

The heart of the system is its stent expansion simulation, which the authors describe as a computationally efficient, slice-based geometric approximation rather than a full biomechanical model. The stent is represented as a sequence of planar cross-sectional slices connected into a tubular triangular mesh. Each slice is iteratively expanded using cylindrical transformations, and when the expanding ring encounters the vessel wall, contact points freeze in place while the remaining points continue to move outward, deforming the ring to conform to the arterial geometry. These contact points are called support points, and the final slice border is interpolated through them using cubic splines. The researchers implemented four interaction modes, from rigid slice with rigid vessel to fully flexible combinations, and chose the flexible slice, rigid vessel configuration as the default because cerebral arteries do not dilate significantly during stent deployment. Restoring forces between neighboring mesh nodes smooth the vessel surface and prevent expansion artifacts, and stopping criteria based on slice asymmetry and area stagnation freeze slices that can no longer expand meaningfully.

What makes this approach genuinely practical for the operating room is speed. Full finite element simulations of stent deployment, while physically rigorous, are far too slow for real-time interaction. The Krakow team’s geometric approximation produces plausible, collision-aware stent configurations in seconds, generating what they call a solution space: a discrete set of candidate stent positions from which the clinician can select the configuration that best matches a specific device’s nominal diameter and foreshortening behavior. The system can even test microcatheter navigability, using rigid slice expansion to determine whether catheters with outer diameters between roughly 0.5 and 0.93 millimeters can physically pass through a given vascular segment. If slices freeze along the path, that signals a passage too tight for the chosen device, an early warning that could redirect the entire treatment strategy before the patient is ever on the table.

The augmented reality layer is where the system becomes genuinely striking. Through the HoloLens application, the operator sees a magnified, stereoscopic rendering of the patient’s vessel floating in the operating room, with semi-transparent stent models that can be picked from a virtual panel, moved into the artery, rotated, and snapped into alignment along the centerline, all through hand gestures detected by the headset’s cameras. Because touching a keyboard or mouse in a sterile surgical environment is impractical, the gesture subsystem was built on the Mixed Reality Toolkit 2 API and works even while the operator wears rubber surgical gloves. Perhaps most remarkably, the vessel model is scaled and calibrated so that the clinician can literally walk inside the rendered artery, inspecting the stent surface and its apposition to the vessel wall from the inside, an perspective no flat screen can provide.

Meeting the HoloLens’s demanding performance constraints required serious engineering discipline. The headset refreshes at 60 to 72 frames per second, leaving a render budget of under 16.6 milliseconds per frame to avoid inducing motion sickness, and stereoscopic rendering doubles the workload by requiring separate viewports for each eye. The team kept active geometry below 150,000 polygons per frame, minimized draw calls through batching, employed mobile-optimized shaders, and used Single-Pass Instanced Rendering to process both eye viewports in a single GPU execution. Late Stage Reprojection dynamically adjusts each frame’s focal point just before display, compensating for head-tracking latency and preventing parallax errors between the virtual models and the physical environment. These optimizations ensure that the immersive experience remains stable and comfortable even during prolonged planning sessions.

Beyond its intraoperative role, the platform doubles as a training and education tool. Every action, parameter choice, and correction made by a specialist during a workflow is recorded in a procedure repository, creating an audit trail that can be replayed for educational purposes or, subject to appropriate governance, used to train future artificial intelligence algorithms. This human-in-the-loop feedback cycle connects clinical expertise directly to algorithm development, addressing a well-known weakness in medical AI: the scarcity of large, expertly annotated datasets. The system’s workflow architecture is deliberately modular, meaning that today’s reference implementations of segmentation and simulation can be swapped for more advanced methods, including deep-learning approaches, without rebuilding the user interface or retraining clinicians on a new platform.

The authors are candid about limitations. The geometric stent simulation has not yet been quantitatively validated against benchtop deployment experiments, manufacturer data, or full finite element models, and it should not be regarded as more physically accurate than rigorous biomechanical approaches. Its advantages lie elsewhere: interactive speed, direct integration with the augmented reality workflow, and the ability to explore many candidate configurations in the time a single FEM run would take. Augmented reality headsets also impose inherent constraints on field of view and graphical resolution, though the team argues that vision-based tracking and semi-transparent rendering preserve sufficient localization precision even at high magnification. Looking forward, the researchers envision AI algorithms automating critical stages of image processing and generating comprehensive libraries of interventional scenarios. For now, the system stands as a compelling demonstration that 3D imaging, fast simulation, and immersive visualization can converge into a single tool that may make one of neurosurgery’s most delicate procedures measurably safer, more precise, and easier to teach.

Subject of Research: Augmented reality and 3D imaging support for stent-assisted treatment of cerebral aneurysms

Article Title: A Visual Support System for Stent-Assisted Treatment of Cerebral Aneurysms Using 3D Imaging and Augmented Reality

Article References: Chmiel, W., Szwed, P., Kwiecień, J., Turek, M., Jȩdrusik, S., Pałka, D., Waśniewski, M., Kadłuczka, P., Gumiela, D., & Zeja, A. (2026). A Visual Support System for Stent-Assisted Treatment of Cerebral Aneurysms Using 3D Imaging and Augmented Reality. Neuroinformatics, 24(4), Article 65. https://doi.org/10.1007/s12021-026-09812-2

Image Credits: AI Generated

DOI: 10.1007/s12021-026-09812-2

Keywords: cerebral aneurysm, augmented reality, stent-assisted coiling, 3D imaging, medical simulation, HoloLens, neurointerventional surgery, vessel segmentation, medial axis, workflow engine, digital health, Neuroinformatics

The novel coil procedure was led by David Santiago-Dieppa, MD, a cerebrovascular and endovascular neurosurgeon at UC San Diego Health and associate professor of neurological surgery at the University of California San Diego School of Medicine. According to Santiago-Dieppa, chronic subdural hematoma is an increasingly common condition in neurosurgical practice, and patients stand to benefit from minimally invasive approaches that can reduce the need for repeat operations. The first patient treated with the new coil technology at UC San Diego Health is recovering well, an encouraging early signal as clinicians continue to evaluate the device’s potential. He emphasized that advances in both coil-based and liquid embolization technologies are giving physicians more options to tailor treatment to each patient’s anatomy and clinical needs, with the ultimate goal of more consistently treating the source of these brain bleeds and improving outcomes.

Chronic subdural hematoma develops when blood collects between the brain and its outermost covering, the dura mater, often following a minor head injury that may have seemed trivial at the time. Because the bleeding accumulates slowly over days or weeks, symptoms such as headaches, confusion, memory problems, gait difficulties, and drowsiness can emerge gradually and are sometimes mistaken for normal aging or dementia. The condition is becoming steadily more common for two converging reasons: the population is growing older, and a rising number of people take blood-thinning medications such as anticoagulants and antiplatelet drugs, which impair the body’s ability to stop even small bleeds. That demographic and pharmacological trajectory is what drives the projection that chronic subdural hematoma may top the list of adult cranial neurosurgical conditions within the decade.

For much of modern neurosurgical history, the standard treatment was surgical drainage, in which a surgeon drills one or more small holes in the skull to evacuate the accumulated blood. While often effective, surgery carries risks for elderly patients and, crucially, does not address the underlying vascular source that can allow fluid and blood to reaccumulate. Recurrence rates after drainage alone have historically been a persistent clinical challenge, forcing a subset of patients back to the operating room for repeat procedures that compound their risk and prolong recovery.

In recent years, a minimally invasive alternative called middle meningeal artery embolization has transformed the treatment landscape. The middle meningeal artery, or MMA, is a branch of the external carotid artery that supplies the dura mater and is intimately involved in the formation and persistence of chronic subdural hematomas. During embolization, physicians navigate a tiny microcatheter through the vasculature, typically from an access point in the groin or wrist, until it reaches the MMA. They then deploy an embolic material to block the artery, cutting off the blood supply that feeds the bleed and helping prevent it from returning. Rather than replacing surgery in every case, embolization is often combined with drainage or used in select patients as a stand-alone strategy, and studies have shown it can reduce the likelihood that patients will need additional procedures while potentially improving long-term outcomes.

As MMA embolization has gained widespread adoption, device developers have raced to improve how physicians seal the target artery. Two broad technological philosophies have emerged. Coil-based approaches use specialized metallic coils to mechanically obstruct blood flow within the vessel, while liquid embolic materials are designed to flow with the bloodstream and penetrate smaller vessel branches farther from the treatment site, occluding a more diffuse vascular network. Each strategy has trade-offs related to vessel anatomy, procedural control, and the completeness of closure. The newly introduced coil technology adopted at UC San Diego Health is engineered to help physicians shut down the artery more completely and efficiently than previous generations of embolization coils. Its flexible design allows delivery through small and tortuous blood vessels, and it can treat a longer section of the artery than earlier coils, potentially reducing the number of devices and steps required in a given procedure.

Santiago-Dieppa’s role in the technology extended beyond the operating room. Drawing on extensive experience performing MMA embolization procedures, he provided clinical insights during the device’s development phase, helping shape a tool intended to improve procedural efficiency and the quality of artery closure. That clinician-inventor feedback loop, in which frontline operators inform device design before and after regulatory approval, has become an increasingly important pathway for translating neurovascular innovations into routine practice. It also reflects a broader trend in which academic medical centers serve simultaneously as early adopters, evaluators, and co-developers of emerging technologies.

UC San Diego Health’s leadership in this field is not limited to device adoption. Researchers in the Department of Neurological Surgery at UC San Diego School of Medicine developed the Patency After Coil Embolization, or PACE, scoring system, a standardized method for measuring how completely blood flow through the middle meningeal artery has been eliminated after treatment. The system gives clinicians and researchers a common language for grading technical success, and early research suggests that more complete closure of the artery may be linked to better resolution of the brain bleed over time. By quantifying the degree of occlusion achieved with different devices and techniques, tools like the PACE score help determine which patients benefit most from which embolization strategy, moving the field toward evidence-based personalization.

The institution has also been deeply involved in the clinical trial infrastructure supporting liquid embolic agents. J. Scott Pannell, MD, director of neurointerventional surgery, endovascular neurosurgeon, and neurointerventional radiologist at UC San Diego Health, and professor of neurological surgery and radiology at UC San Diego School of Medicine, served as a site investigator for the EMBOLISE clinical trial, which evaluated the addition of MMA embolization to standard treatment for chronic subdural hematoma. Evidence from that national trial and others supported the recent FDA approval of a liquid embolic for this indication, and Pannell’s involvement helped bring new embolization techniques and clinical research opportunities to patients in San Diego. He noted that the growing body of evidence supporting MMA embolization has fundamentally changed how physicians approach the condition, and that liquid embolic technologies offer a primary option that may allow more complete treatment in select patients. In his view, participation in trials such as EMBOLISE has been critical to understanding how these therapies can improve patient outcomes.

The convergence of these developments, from next-generation coils to approved liquid embolics and standardized occlusion scoring, points toward a future in which chronic subdural hematoma treatment becomes more predictable, effective, and accessible for the growing number of patients diagnosed each year. Physicians can now select among mechanical and liquid occlusion strategies based on vascular anatomy, the extent of dural supply, and patient-specific risk factors, rather than relying on a one-size-fits-all surgical approach. UC San Diego Health, nationally recognized for its treatment of complex brain, spine, and cerebrovascular disorders and ranked among the nation’s best in neurology and neurosurgery in the 2026-2027 U.S. News Best Hospitals rankings, continues to advance this evolution through research, clinical trials, and multidisciplinary care for conditions ranging from stroke and aneurysms to traumatic brain injury. As the population ages and anticoagulant use rises, the ability to treat the vascular source of chronic brain bleeds through a catheter rather than a craniotomy may prove to be one of the most consequential shifts in neurosurgery this decade.

Subject of Research: Minimally invasive middle meningeal artery embolization technologies for chronic subdural hematoma

Article Title: First health system on West Coast to use new brain bleed technologies

Article References: First health system on West Coast to use new brain bleed technologies. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: chronic subdural hematoma, middle meningeal artery embolization, neurosurgery, embolization coils, liquid embolic, UC San Diego Health, EMBOLISE trial, PACE score, minimally invasive procedures, brain bleed, neurointerventional surgery, aging population