Prof. Dr. med. Daniel Rüfenacht

Computational Aneurysm Phantom:
Its Potential for Use in Clinical Sciences, and the SwissNeuro-FoundationAneurysmDataBase: a Library Offering Shape-based Categorization

(Dienstag, 15.15 Uhr, Schinkelsaal)

Daniel Ruefenacht

Numerical assessment and simulation, as a "virtual reality" method for better disease understanding and planning endovascular treatment of aneurysms disease, has in recent years received increasing attention by engineering and by medical as well as by basic and by clinical scientists.

Intracranial aneurysm disease presents with a low, but risky incidence of hemorrhage (10/100'000/y) due to rupture, while there is a high prevalence of silent lesions (approx. 3000/100'000) that, today are increasingly found incidentally on regular brain imaging examinations. Once diagnosed, the incidental finding of an aneurysm leads to the difficult question of whether to treat or not a patient to prevent him from experiencing a risky aneurysm bleeding. With diagnosis based on imaging information, use of an image disease surrogate, a computational phantom, would be welcome and efficient in many ways. While the wall of an aneurysm is too thin to be directly visualized by imaging, the characterization of its biomechanical strength is a matter of indirect assessment. With all currently used medical imaging evaluation methods for aneurysms, able of providing flow-based and contrast-material enhanced visualization of the circulating blood, a digital 3D replica of the vascular lumen can be easily produced for more detailed analysis. Current concepts suggest that blood governs wall remodeling by multiple biological steps. The process starts with flow induced thrombus adhesion (atherothrombosis) to the wall, leading secondarily to the release of biological mediators of inflammation and ensuing destructive remodeling. Destructive wall remodeling jeopardizes the mechanical wall integrity (circumscribed softening and expansion of the aneurysm shape). These are the critical steps of the mechano-biological transduction chain in aneurysm disease as is understood today. Further illumination of the exact interconnection of these steps is a matter of continuous research, involving validation and computational biology studies, with the potential of further unraveling the secrets of this degenerative arterial disease in the interest of understanding and developing predictive capabilities to estimate the evolution potential of an incidental aneurysm and with the potential of simulating and designing flow modulating corrective endovascular measures.

Today, the computational aneurysm phantom has become the most promising instrument for characterizing reproducibly intracranial aneurysms, potentially allowing for predicting their evolution in an individual case and help prepare for flow correction measures using endovascular treatment methods involving devices such as special stents (flow diverters).

Further, shape analysis methods have become robust and reproducible and allow for personalized morphological description of a computational aneurysm phantom. To help building registries, this categorization service is offered at the SwissNeuroFoundation-AneurysmDataBase, where a library of cerebral aneurysm phantoms including phenomenological data is made available.

Prof. Dr. med. Daniel Rüfenacht
Center for Diagnostic and Interventional Radiology, Zurich