Philipp Berg

Philipp Berg
Otto-von-Guericke-Universität Magdeburg | OvGU · Institute of Fluid Dynamics and Thermodynamics (ISUT)

Priv.-Doz. Dr.-Ing. habil.

About

114
Publications
23,513
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1,307
Citations
Citations since 2017
77 Research Items
1148 Citations
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2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250

Publications

Publications (114)
Article
Background and purpose: A variety of approaches exists where numerical methods that underlie numerous assumptions are used in order to predict rupture in intracranial aneurysms. Since many hemodynamic parameters have been derived from these computations but no persistent explanation for rupture has been found, the acceptance of CFD among physician...
Article
Although flow-diverting devices are promising treatment options for intracranial aneurysms, jailed side branches might occlude leading to insufficient blood supply. Especially differences in the local stent strut compression may have a drastic influence on subsequent endothelialization. To investigate the outcome of different treatment scenarios, o...
Article
Full-text available
PurposeCircumferential enhancement on MR vessel wall imaging has been proposed as a biomarker of a higher risk of rupture in intracranial aneurysms. Focal enhancement is frequently encountered in unruptured aneurysms, but its implication for risk stratification and patient management remains unclear. This study investigates the association of focal...
Article
Computational blood flow modeling in intracranial aneurysms (IAs) has enormous potential for the assessment of highly resolved hemodynamics and derived wall stresses. This results in an improved knowledge in important research fields, such as rupture risk assessment and treatment optimization. However, due to the requirement of assumptions and simp...
Article
Full-text available
Purpose Advanced morphology analysis and image-based hemodynamic simulations are increasingly used to assess the rupture risk of intracranial aneurysms (IAs). However, the accuracy of those results strongly depends on the quality of the vessel wall segmentation. Methods To evaluate state-of-the-art segmentation approaches, the Multiple Aneurysms A...
Article
Full-text available
Objectives Assessing the risk associated with unruptured intracranial aneurysms (IAs) is essential in clinical decision making. Several geometric risk parameters have been proposed for this purpose. However, performance of these parameters has been inconsistent. This study evaluates the performance and robustness of geometric risk parameters on two...
Article
Full-text available
For hemodynamic simulations of intracranial aneurysms boundary conditions (BC) are required. In most cases, these are not patient-specific and thus do not reflect the real flow conditions in the patient. This study investigates the influence of patient-specific inflow BC on intra-aneurysmal hemodynamics. The focus lies on gender and age variations...
Article
Background and objective: Contrary to flows in small intracranial vessels, many blood flow configurations such as those found in aortic vessels and aneurysms involve larger Reynolds numbers and, therefore, transitional or turbulent conditions. Dealing with such systems require both robust and efficient numerical methods. Methods: We assess here...
Preprint
Background and objective: Contrary to flows in small intracranial vessels, many blood flow configurations such as those found in aortic vessels and aneurysms involve larger Reynolds numbers and, therefore, transitional or turbulent conditions. Dealing with such systems require both robust and efficient numerical methods. Methods: We assess here the...
Article
Full-text available
Background: Flow-diverting stents are increasingly used for the minimally-invasive treatment of intracranial aneurysms. However, a correct positioning of such devices can be challenging due to varying vessel diameters as well as the complex anatomy of the neurovasculature. As a consequence, unsuccessful treatment outcomes are increasingly reported...
Article
Full-text available
Four-dimensional (4D) flow MRI allows quantifying flow in blood vessels–non invasively and in vivo. The clinical use of 4D flow MRI in small vessels, however, is hampered by long examination times and limited spatial resolution. Compressed SENSE (CS-SENSE) is a technique that can accelerate 4D flow dramatically. Here, we investigated the effect of...
Article
Full-text available
Numerous studies assess intracranial aneurysm rupture risk based on morphological and hemodynamic parameter analysis in addition to clinical information such as aneurysm localization, age, and sex. However, intracranial aneurysms mostly occur with a saccular shape located either lateral to the parent artery or at a bifurcation. In contrast, fusifor...
Article
Full-text available
Purpose The treatment of intracranial arteriovenous malformations (AVM) is challenging due to their complex anatomy. For this vessel pathology, arteries are directly linked to veins without a capillary bed in between. For endovascular treatment, embolization is carried out, where the arteries that supply the AVM are consecutively blocked. A virtual...
Article
Full-text available
Although popliteal artery aneurysms (PAAs) are the most frequent aneurysms in the lower peripheral arteries, research has not covered the potential of blood flow analysis of these pathologies yet. We therefore present a pilot study for the image-based hemodynamic evaluation of patient-specific PAAs. To ensure a large vascular domain with similar bo...
Article
Full-text available
Intracranial aneurysms (IA) is not-uncommon pathology of cerebral vessels. Vessel wall magnetic resonance imaging can visualize the vascular walls of IAs. In some aneurysms, the wall-adjacent and a luminal hyperintense signal was detected. The signal was attributed to the inflammation and specific hemodynamic features of aneurysms. But, up to now,...
Article
Full-text available
Intracranial aneurysms at the anterior communicating artery (AcomA) are associated with a higher rupture risk and a more challenging therapy since they are supplied with blood from both sides of the anterior vasculature. Since the standard imaging modality, i.e. digital subtraction angiography, involves the contrast agent injection into a single ce...
Article
Full-text available
Purpose Intracranial aneurysm (IA) wall enhancement on post-contrast vessel wall magnetic resonance imaging (VW-MRI) is assumed to be a biomarker for vessel wall inflammation and aneurysm instability. However, the exact factors contributing to enhancement are not yet clarified. This study investigates the relationship between luminal enhancement an...
Conference Paper
Introduction/Purpose The discrimination between hemodynamically stable and unstable intracranial aneurysms remains challenging. Recent studies reveal the potential existence of intra-aneurysmal velocity fluctuations, which appear at high frequency. Since these flow disturbances might promote the vessel wall remodeling process, indications regarding...
Conference Paper
Introduction/Purpose Interventional treatment of arteriovenous malformations (AVMs) using liquid embolics is challenging especially in larger AVMs with multiple feeding arteries. Premature occlusion of the draining vein(s) may lead to fatal AVM rupture and sequential occlusion of different feeding arteries is associated with the risks of incomplete...
Conference Paper
Introduction/Purpose Counseling of patients harboring unruptured intracranial aneurysms (UIAs) has remained challenging despite the availability of several risk scores assessing the aneurysm rupture risk for individual patients. However, besides aneurysm size and simple morphological features no advanced hemodynamic or geometric factors have been u...
Conference Paper
Introduction/Purpose Blebs of intracranial aneurysms are clear bulges or outpouchings of the aneurysms wall. Since irregularly shaped aneurysms, i.e. aneurysms with lobulated shapes including one or multiple blebs are associated with a higher rupture risk, bleb occurrence is important for aneurysm treatment planning. Hence, an automatic computer-ba...
Article
Background: High-resolution vessel wall imaging plays an increasingly important role in assessing the risk of aneurysm rupture. Objective: To introduce an approach toward the validation of the wall enhancement as a direct surrogate parameter for aneurysm stability. Methods: A total of 19 patients harboring 22 incidental intracranial aneurysms...
Article
Full-text available
Intracranial aneurysm treatment based on blood flow reduction with braided flow diverters (FDs) has become highly relevant. However, FDs have several limitations, e.g., sudden torsional collapse, variable porosity, and possible side branch occlusions. Thin‐film FD stents can overcome these limitations by offering high design freedom to produce pati...
Conference Paper
Full-text available
Rupture risk assessment is a key to devise patient-specific treatment plans of cerebral aneurysms. To understand and predict the development of aneurysms and other vascular diseases over time, both hemodynamic flow patterns and their effect on the vessel surface need to be analyzed. Flow structures close to the vessel wall often correlate directly...
Article
Full-text available
Purpose For the status evaluation of intracranial aneurysms (IAs), morphological and hemodynamic parameters can provide valuable information. For their extraction, a separation of the aneurysm sac from its parent vessel is required that yields the neck curve and the ostium. However, manual and subjective neck curve and ostium definitions might lead...
Presentation
Objective - High resolution vessel wall imaging plays an increasingly important role in assessing the risk of aneurysm rupture. We aim to introduce an approach towards the validation of the wall enhancement as a direct surrogate parameter for aneurysm stability. Methods - 19 patients harboring 22 incidental, intracranial aneurysms were enrolled in...
Poster
Objective - For rupture risk assessment of intracranial aneurysms, a multitude of approaches have been postulated. However, the amount of potential predictive factors is not applicable in clinical practice and they are rejected in favor of the more practical PHASES Score. For the subgroup of multiple intracranial aneurysms (MIA), the PHASES Score m...
Article
Full-text available
Purpose For the evaluation and rupture risk assessment of intracranial aneurysms, clinical, morphological and hemodynamic parameters are analyzed. The reliability of intracranial hemodynamic simulations strongly depends on the underlying models. Due to the missing information about the intracranial vessel wall, the patient-specific wall thickness i...
Article
Full-text available
Background: Vessel-wall enhancement (VWE) on black-blood MRI (BB MRI) has been proposed as an imaging marker for a higher risk of rupture and associated with wall inflammation. Whether VWE is causally linked to inflammation or rather induced by flow phenomena has been a subject of debate. Purpose: To study the effects of slow flow, spatial resol...
Article
The lattice Boltzmann method (LBM) has recently emerged as an efficient alternative to classical Navier-Stokes solvers. This is particularly true for hemodynamics in complex geometries. However, in its most basic formulation, i.e. with the so-called single relaxation time (SRT) collision operator, it has been observed to have a limited stability do...
Chapter
Full-text available
This work aims at a deep learning-based prediction of wall shear stresses (WSS) for intracranial aneurysms. Based on real patient cases, we created artificial surface models of bifurcation aneurysms. After simulation and WSS extraction, these models were used for training a deep neural network. The trained neural network for 3D mesh segmentation wa...
Chapter
Arteriovenous malformations in the brain are abnormal connections between cerebral arteries and veins without the capillary system. They might rupture with fatal consequences. Their treatment is highly patient-specific and includes careful analysis of the vessels' configuration. We present an application that visualizes the blood flow after differe...
Preprint
Full-text available
The lattice Boltzmann method (LBM) has recently emerged as an efficient alternative to classical Navier-Stokes solvers. This is particularly true for hemodynamics in complex geometries. However, in its most basic formulation, {i.e.} with the so-called single relaxation time (SRT) collision operator, it has been observed to have a limited stability...
Article
Full-text available
Purpose: Flow models of intracranial aneurysms (IAs) can be used to test new and existing endovascular treatments with flow modulation devices (FMDs). Additionally, 4D flow magnetic resonance imaging (MRI) offers the ability to measure hemodynamics. This way, the effect of FMDs can be determined noninvasively and compared to patient data. Here, we...
Article
Full-text available
Introduction A multitude of approaches have been postulated for assessing the risk of intracranial aneurysm rupture. However, the amount of potential predictive factors is not applicable in clinical practice and they are rejected in favor of the more practical PHASES score. For the subgroup of multiple intracranial aneurysms (MIAs), the PHASES scor...
Article
Background and Objective: Time resolved three-dimensional phase contrast magnetic resonance imaging (4D-Flow MRI) has been used to non-invasively measure blood velocities in the human vascular system. However, issues such as low spatio-temporal resolution, acquisition noise, velocity aliasing, and phase-offset artifacts have hampered its clinical a...
Article
Full-text available
Incisional hernia repair makes use of prosthetic meshes to re-establish a biomechanically stable abdominal wall. Mesh sizing and fixation have been found to be essential for the clinical outcome. Comparative CT images a) under rest versus b) under Valsalva maneuver (exhalation against closed airways) provide useful information for hernia characteri...
Conference Paper
Full-text available
Background In vitro vascular models for brain aneurysms and acute stroke have been used for training, simulation and research purpose. However, the use of realistic in vitro models for arteriovenous malformation (AVM) have not been reported. Current in vitro AVM models analyzing the efficacy of embolic materials or flow conditions are limited due t...
Article
BACKGROUND Current in vitro models for human brain arteriovenous malformation (AVM) analyzing the efficacy of embolic materials or flow conditions are limited by a lack of realistic anatomic features of complex AVM nidus. The purpose of this study is to evaluate a newly developed in vitro AVM model for embolic material testing, preclinical training...
Conference Paper
Introduction: 3D printed human vascular in vitro models of aneurysms and acute stroke have been utilized for training, simulation and device development. However, there are no realistic in vitro arteriovenous malformation (AVM) models. Current experimental models analyzing the efficacy of embolic materials or flow conditions are limited by their si...
Article
Introduction: 3D printed human vascular in vitro models of aneurysms and acute stroke have been utilized for training, simulation and device development. However, there are no realistic in vitro arteriovenous malformation (AVM) models. Current experimental models analyzing the efficacy of embolic materials or flow conditions are limited by their si...
Article
Purpose Image-based hemodynamic simulations have great potential for precise blood flow predictions in intracranial aneurysms. Due to model assumptions and simplifications with respect to boundary conditions, clinical acceptance remains limited. Methods Within this study, we analyzed the influence of outflow-splitting approaches on multiple aneury...
Article
Full-text available
Background: The use of flow-diverters for non-saccular cerebral posterior circulation aneurysms requires complex deployment techniques and is associated with high mortality and morbidity. Therefore, further studies are required to clarify the effect of stenting on post-treatment hemodynamics in such aneurysms. In this study, we evaluated flow alte...
Article
Background: Stent-assisted coiling has become an important treatment option for intracranial aneurysms. However, studies have shown that this procedure can lead to the deformation of the local vasculature. Its effect on intra-aneurysmal hemodynamics still remains unclear. Methods: Pre- and post-interventional image data of three representative m...
Article
Full-text available
Background Image-based blood flow simulations have been increasingly applied to investigate intracranial aneurysm (IA) hemodynamics. However, the acceptance among physicians remains limited due to the high variability in the underlying assumptions and quality of results. Methods To evaluate the vessel segmentation as one of the most important sour...
Article
Purpose Assessing the rupture probability of intracranial aneurysms (IAs) remains challenging. Therefore, hemodynamic simulations are increasingly applied toward supporting physicians during treatment planning. However, due to several assumptions, the clinical acceptance of these methods remains limited. Methods To provide an overview of state-of-...
Article
Full-text available
Background Geometric parameters have been proposed for prediction of cerebral aneurysm rupture risk. Predicting the rupture risk for incidentally detected unruptured aneurysms could help clinicians in their treatment decision. However, assessment of geometric parameters depends on several factors, including the spatial resolution of the imaging mod...
Article
BACKGROUND: Flow diverter stents have become a useful tool for treatment of complex intracranial aneurysms. A serious complication is incomplete wall apposition after flow diverter placement. The aim of this study was to present a comprehensive investigation of hemodynamic changes induced by incomplete expansion of a flow diverter. METHODS: A case...
Article
Full-text available
Purpose Image-based computational fluid dynamics (CFD) is widely used to predict intracranial aneurysm wall shear stress (WSS), particularly with the goal of improving rupture risk assessment. Nevertheless, concern has been expressed over the variability of predicted WSS and inconsistent associations with rupture. Previous challenges, and studies f...
Article
Full-text available
Computational Fluid Dynamics studies try to support physicians during therapy planning of intracranial aneurysms. However, multiple assumptions (e.g. rigid vessel walls) are required leading to a sparse acceptance of numerical approaches within the medical community. This study incorporates multiple fluid-structural simulations for an intracranial...
Article
Full-text available
PurposeMorphological parameters of intracranial aneurysms (IAs) are well established for rupture risk assessment. However, a manual measurement is error-prone, not reproducible and cumbersome. For an automatic extraction of morphological parameters, a 3D neck curve reconstruction approach to delineate the aneurysm from the parent vessel is required...
Article
This paper presents a framework to explore multi-field data of aneurysms occurring at intracranial and cardiac arteries by using statistical graphics. The rupture of an aneurysm is often a fatal scenario, whereas during treatment serious complications for the patient can occur. Whether an aneurysm ruptures or whether a treatment is successful depen...
Article
Image-based hemodynamic simulations to assess the rupture risk or improve the treatment planning of intracranial aneurysms have become popular recently. However, due to strong modeling assumptions and limitations, the acceptance of numerical approaches remains limited. Therefore, validation using experimental methods is mandatory. In this study, a...
Conference Paper
Three-dimensional shape analysis and imagebased hemodynamic simulations are widely used to assess the individual rupture risk of intracranial aneurysms. However, the quality of those results highly depends on pre-simulative working steps including image reconstruction and segmentation. Within this study, three patient-specific aneurysms were recons...
Article
Endovascular treatment of intracranial aneurysms using flow-diverting devices has revolutionized the treatment of large and complex lesions due to its minimally invasive nature and potential clinical outcomes. However, incomplete or delayed occlusion and persistent intracranial aneurysm growth are still an issue for up to one-third of the patients....
Article
Rupture risk assessment is a key to devise patient-specific treatment plans of cerebral aneurysms. To understand and predictthe development of aneurysms and other vascular diseases over time, both hemodynamic flow patterns and their effect on thevessel surface need to be analyzed. Flow structures close to the vessel wall often correlate directly wi...
Article
Full-text available
Cerebral aneurysms are a major risk factor for intracranial bleeding with devastating consequences for the patient. One recently established treatment is the implantation of flow-diverters (FD). Methods to predict their treatment success before or directly after implantation are not well investigated yet. The aim of this work was to quantitatively...
Data
MRI velocity measurement protocol. (PDF)
Chapter
With increasing computational resources, more and more engineering methods are applied to medical-related problems in order to support physicians. One prominent example is the development of virtual stent deployment techniques for cardio-vascular diseases that allow a numerical reproduction of treatment scenarios at no risk for the individual patie...
Preprint
Cerebral aneurysms are a major risk factor for intracranial bleeding with devastating consequences for the patient. One recently established treatment is the implantation of flow diverters (FD). Methods to predict their treatment success before or directly after implantation are not well investigated yet. The aim of this work was to quantitatively...