GEPARD – Vessel Wall Simulation and Visualization for Patient-Specific Blood Flow Prediction for Intracranial Aneurysm Modeling

• Applicants: Privatdozent Philipp Berg, Ph.D.; Professorin Dr.-Ing. Sylvia Saalfeld
• Subject Area: Fluid Mechanics
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 399581926

• Final Report Year: 2023

Final Report Abstract

Intracranial aneurysms (IAs) can lead to severe disability or rapid death in case of rupture. Consequently, computer-aided methods are used to predict the individual risk of rupture and to support the patient-specific therapy planning of treating physicians. However, due to current angiographic diagnostics, only the individual lumen of IAs is usually considered, whereas rupture often depends significantly on inflammatory processes in the vessel wall. Therefore, it is necessary to extend existing computer-based evaluation approaches. Within this research project, the integration of neurovascular walls and surrounding information is being performed so that clinically relevant conclusions can be drawn with regard to this complex pathology. This includes the extension of the flow domain by an elastic and deformable vessel wall as well as an analysis of the surrounding extravascular space. For this purpose, segmentation methods were developed, which allow the extraction of a larger vascular domain and are adapted specifically to flow simulations, e.g., by integrating flow splitting analyses and other methods for the determination of boundary conditions. In addition, individual vessel wall layers and various histological components of the intracranial aneurysm wall could be successfully analyzed. Since this information is insufficiently available with conventional imaging modalities such as computed tomographic angiography, MR angiography, and 3D digital subtraction angiography, new experimental imaging modalities (e.g., optical coherence tomography, 7T-MR angiography) and sophisticated histological analyses (including various staining techniques) were used. The resulting (partly unique) multimodal images were combined by means of novel registration procedures and adapted for advanced fluid-structure simulations. Finally, a detailed analysis of the influences regarding the different segmentation, simulation and evaluation steps was performed. During the project, international scientific competitions and expert surveys were held (MATCH, VICTORIA) and these steps were systematically evaluated on patient-specific geometries to quantify their hemodynamical impact. Thus, the project provides new insights into the intracranial aneurysm wall and its influence on intra-aneurysmal hemodynamics as well as a valuable assessment of these additional factors for clinically relevant rupture risk analysis of IAs.

Publications

• 3DRA Reconstruction of Intracranial Aneurysms – How does Voxel Size Influences Morphologic and Hemodynamic Parameters. 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 1327-1330. IEEE.
  Berg, Philipp; Radtke, Livia; Vos, Samuel; Serowy, Steffen; Janiga, Gabor; Preim, Berhard; Beuing, Oliver & Saalfeld, Sylvia
  
• Advanced blood flow filtering for the rupture risk assessment of intracranial aneurysms, In: 8th World Congress of Biomechanics, Dublin, Ireland, 2018
  Berg, P., Behrendt, B., Saalfeld, S., Janiga, G. & Beuing, O.
  
• CFD Validation of intracranial aneurysm flow: Impact of light sheet thickness on PIV results, In: The 17th International Conference on Fluid Flow Technologies, Budapest, Hungary, 1-6, 2018
  Roloff, C., Berg, P., Beyrau, F. & Thévenin, D.
  
• Fluid-structure interaction in intracranial vessel walls: The role of patient-specific wall thickness. Current Directions in Biomedical Engineering, 4(1), 587-590.
  Voß, Samuel; Saalfeld, Sylvia; Hoffmann, Thomas; Beuing, Oliver; Janiga, Gábor & Berg, Philipp
  
• Multiple Aneurysms AnaTomy Challenge 2018 (MATCH) – State-of-the-art segmentation and hemodynamic simulation, In: 53. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., Frankfurt, Germany, 2018
  Berg, P., Saalfeld, S., Janiga, G. & Beuing, O.
  
• Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH): Phase I: Segmentation. Cardiovascular Engineering and Technology, 9(4), 565-581.
  Berg, Philipp; Voß, Samuel; Saalfeld, Sylvia; Janiga, Gábor; Bergersen, Aslak W.; Valen-Sendstad, Kristian; Bruening, Jan; Goubergrits, Leonid; Spuler, Andreas; Cancelliere, Nicole M.; Steinman, David A.; Pereira, Vitor M.; Chiu, Tin Lok; Tsang, Anderson Chun On; Chung, Bong Jae; Cebral, Juan R.; Cito, Salvatore; Pallarès, Jordi; Copelli, Gabriele ... & Beuing, Oliver
  
• Rupture sStatus classification of intracranial aneurysms using morphological parameters, In: 31st IEEE International Symposium on Computer-Based Medical Systems, Karlstad, Sweden, pp. 1-6, 2018
  Niemann, U., Berg, P., Niemann, A., Beuing, O., Preim, B., Spiliopoulou, M. & Saalfeld, S.
  
• Validation of intracranial neurysm flow: standard PIV vs. stereoscopic PIV vs. tomographic PIV vs. phase-contrast MRI vs. CFD. In: Interdisciplinary Cerebrovascular Symposium (ICS), Magdeburg, Germany, 2018
  Roloff, C., Stucht, D., Janiga, G., Beuing, O. & Berg, P.
  
• A review on the reliability of hemodynamic modeling in intracranial aneurysms: why computational fluid dynamics alone cannot solve the equation. Neurosurgical Focus, 47(1), E15.
  Berg, Philipp; Saalfeld, Sylvia; Voß, Samuel; Beuing, Oliver & Janiga, Gábor
  
• Association of low flow conditions and histologic signs of inflammation in intracranial aneurysms with focal enhancement on MR vessel wall imaging, In: 15th Congress of the World Federation of Interventional and Therapeutics Neuroradiology, Naples, Italy, 2019
  Berg, P., Saalfeld, S., Flüh, C. & Larsen, N.
  
• Combining high-resolution vessel wall imaging with image-based flow evaluation in unruptured middle cerebral aneurysms, In: 54. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., Frankfurt, Germany, 2019
  Berg, P., Larsen, N., Flüh, C., Voß, S. & Saalfeld, S.
  
• Evolutionary pathlines for blood flow exploration in eerebral aneurysms, In: Eurographics Workshop on Visual Computing for Biology and Medicine, Brno, Czech Republic, pp. 1-11, 2019
  Behrendt, B., Engelke, W., Berg, P., Beuing, O., Preim, B., Hotz, I. & Saalfeld, S.
  
• Flow-splitting-based computation of outlet boundary conditions for improved cerebrovascular simulation in multiple intracranial aneurysms. International Journal of Computer Assisted Radiology and Surgery, 14(10), 1805-1813.
  Saalfeld, Sylvia; Voß, Samuel; Beuing, Oliver; Preim, Bernhard & Berg, Philipp
  
• Hemodynamic Modeling in Intracranial Aneurysms - Why Simulations Alone Cannot Solve the Equation, In: The 46th European Society for Artificial Organs Congress, Hannover, Germany, 2019
  Berg, P.
  
• Interactive exploration of a 3D intracranial aneurysm wall model extracted from histologic slices. International Journal of Computer Assisted Radiology and Surgery, 15(1), 99-107.
  Niemann, Annika; Weigand, Simon; Hoffmann, Thomas; Skalej, Martin; Tulamo, Riikka; Preim, Bernhard & Saalfeld, Sylvia
  
• Local flow analysis in unruptured middle cerebral artery aneurysms with vessel wall enhancement, In: 6th International Conference on Computational and Mathematical Biomedical Engineering, Sendai, Japan, 558-561, 2019
  Berg, P., Saalfeld, S., Behrendt, B. & Larsen, N.
  
• Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH): uncertainty quantification of geometric rupture risk parameters. BioMedical Engineering OnLine, 18(1).
  Goubergrits, Leonid; Hellmeier, Florian; Bruening, Jan; Spuler, Andreas; Hege, Hans-Christian; Voss, Samuel; Janiga, Gábor; Saalfeld, Sylvia; Beuing, Oliver & Berg, Philipp
  
• Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH)—Phase Ib: Effect of morphology on hemodynamics. PLOS ONE, 14(5), e0216813.
  Voß, Samuel; Beuing, Oliver; Janiga, Gábor & Berg, Philipp
  
• Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH)—phase II: rupture risk assessment. International Journal of Computer Assisted Radiology and Surgery, 14(10), 1795-1804.
  Berg, Philipp; Voß, Samuel; Janiga, Gábor; Saalfeld, Sylvia; Bergersen, Aslak W.; Valen-Sendstad, Kristian; Bruening, Jan; Goubergrits, Leonid; Spuler, Andreas; Chiu, Tin Lok; Tsang, Anderson Chun On; Copelli, Gabriele; Csippa, Benjamin; Paál, György; Závodszky, Gábor; Detmer, Felicitas J.; Chung, Bong J.; Cebral, Juan R.; Fujimura, Soichiro ... & Beuing, Oliver
  
• Rupture risk assessment based on clinical, morphological and hemodynamic parameters in patients with multiple aneurysms, In: Jahrestagung der Deutschen Gesellschaft für Neurochirurgie, Würzburg, Germany, 2019
  Swiatek, V.M, Neyazi, B., Saalfeld, S., Berg, P., Beuing, O., Voß, S., Maslehaty, H., Stein, K.P., Skalej, M & Sandalciolgu, I.E.
  
• Verification and validation of merging patient-specific computational fluid dynamics and 4D-flow MRI, In: 27th International Society for Magnetic Resonance in Medicine Meeting, Montréal, Canada, 2019
  Miller, A.M., Bakhshinejad, A., Firoozabad, M.F., Baghaei, A., Sacho, R., Koch, K.M. Roloff, C., Berg, P. & D’Souza, R.M.
  
• VICTORIA - Virtual neck Curve and True Ostium Reconstruction of Intracranial Aneurysms, In: 15th Congress of the World Federation of Interventional and Therapeutics Neuroradiology, Naples, Italy, 2019
  Voß, S., Saalfeld, S., Beuing, O. & Berg, P.
  
• Computer-support for intracranial aneurysms.
  Saalfeld, S.
  
• Deep learning segmentation for 3D intracranial aneurysm models, In: 55. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., Frankfurt, Germany, 2020
  Niemann, A., Schneider, L., Neyazi, B., Beuing, O., Berg, P., Saalfeld, S. & Larsen, N.
  
• Fokales Wand-Enhancement in intrakraniellen Aneurysmen ist assoziiert mit lokalen hämodynamischen low flow-Verhältnissen und Wandinflammation, In: 101st German X-Ray Congress, Virtual, 2020
  Larsen, N., Flüh, C., Saalfeld, S., Voß, S., Hille, G., Jansen, O. & Berg, P.
  
• Investigation of black blood MRI signal enhancement in a patient-specific aneurysm model, In: Annual Meeting of the International Society for Magnetic Resonance in Medicine, Virtual conference, pp. 1-6, 2020
  Pravdivtseva, M., Hoffman, C., Rivera-Rivera, L., Medero, R., Bodart, L., Roldan-Alzate, A., Speidel, M., Mistretta, C., Strother, C., Johnson, K., Wieben, O., Jansen, O., Larsen, N., Berg. P., Peschke, E. & Hövener, J.
  
• Multimodal validation of focal enhancement in intracranial aneurysms as a surrogate marker for aneurysm instability. Neuroradiology, 62(12), 1627-1635.
  Larsen, Naomi; Flüh, Charlotte; Saalfeld, Sylvia; Voß, Samuel; Hille, Georg; Trick, David; Wodarg, Fritz; Synowitz, Michael; Jansen, Olav & Berg, Philipp
  
• Multimodal validation of focal enhancement in intracranial aneurysms as an imaging marker of a higher risk of rupture, In: 55. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., Frankfurt, Germany, 2020
  Larsen, N., Saalfeld, S., Flüh, C., Voß, S., Hille, G., Pravdivtseva, M. & Berg, P.
  
• Rupture risk assessment for multiple intracranial aneurysms: why there is no need for dozens of clinical, morphological and hemodynamic parameters. Therapeutic Advances in Neurological Disorders, 13.
  Neyazi, Belal; Swiatek, Vanessa M.; Skalej, Martin; Beuing, Oliver; Stein, Klaus-Peter; Hattingen, Jörg; Preim, Bernhard; Berg, Philipp; Saalfeld, Sylvia & Sandalcioglu, I. Erol
  
• Shrinking tube mesh: combined mesh generation and smoothing for pathologic vessels. Current Directions in Biomedical Engineering, 6(1).
  Niemann, Annika; Preim, Bernhard & Saalfeld, Sylvia
  
• VICTORIA - Virtual neck Curve and True Ostium Reconstruction of Intracranial Aneurysms, In: Computer Assisted Radiology and Surgery, Munich, Germany, 2020
  Saalfeld, S., Berg, P., Behrendt, B., Voß, S., Beuing, O., Neyazi, B. & Preim, B.
  
• VICTORIA. Informatik aktuell, 209-214. Springer Fachmedien Wiesbaden.
  Behrendt, Benjamin; Voss, Samuel; Beuing, Oliver; Preim, Bernhard; Berg, Philipp & Saalfeld, Sylvia
  
• Wall enhancement segmentation for intracranial aneurysm. Current Directions in Biomedical Engineering, 6(1).
  Niemann, Annika; Larsen, Naomi; Preim, Bernhard & Saalfeld, Sylvia
  
• Advanced flow-splitting for image-based hemodynamic simulations in neurovascular diseases, In: The 46th European Society for Artificial Organs Congress, Virtual, 2021
  Korte, J., Gaidzik, F., Weiß, T., Saalfeld, S. & Berg, P.
  
• Aneurysm Wall Enhancement Is Associated With Decreased Intrasaccular IL-10 and Morphological Features of Instability. Neurosurgery, 89(4), 664-671.
  Swiatek, Vanessa M.; Neyazi, Belal; Roa, Jorge A.; Zanaty, Mario; Samaniego, Edgar A.; Ishii, Daizo; Lu, Yongjun; Sandalcioglu, I. Erol; Saalfeld, Sylvia; Berg, Philipp & Hasan, David M.
  
• Assoziation von Kontrastmittelanreicherung in der Wand von intrakraniellen Aneurysmen mit einer verminderten intraaneurysmatischen Konzentration von IL-10 und morphologischen Instabilitätsparametern, In: Jahrestagung der Deutschen Gesellschaft für Neurochirurgie, Virtual, Germany, 2021
  Swiatek, V., Neyazi, B., Roa, J., Zanaty, M., Samaniego, E., Ishii, D., Lu, Y., Sandalcioglu, I.E., Saalfeld, S., Berg, P. & Hasan, D.
  
• Complex wall modeling for hemodynamic simulations of intracranial aneurysms based on histologic images. International Journal of Computer Assisted Radiology and Surgery, 16(4), 597–607.
  Niemann, Annika; Voß, Samuel; Tulamo, Riikka; Weigand, Simon; Preim, Bernhard; Berg, Philipp & Saalfeld, Sylvia
  
• Correlations between black blood MRI and hemodynamics in intracranial aneurysms, In: 5. Image-Guided Interventions Conference, Magdeburg, Germany, 2021
  Korte, J., Marsh, L., Gaidzik, F., Pravdivtseva M., Larsen, N. & Berg, P.
  
• Definition and extraction of 2D shape indices of intracranial aneurysm necks for rupture risk assessment. International Journal of Computer Assisted Radiology and Surgery, 16(11), 1977-1984.
  Mittenentzwei, Sarah; Beuing, Oliver; Neyazi, Belal; Sandalcioglu, I. Erol; Larsen, Naomi; Preim, Bernhard & Saalfeld, Sylvia
  
• Discrimination between stable and unstable intracranial aneurysms using image-based blood flow simulations, In: Annual Meeting of the Society of NeuroInterventional Surgery, Colorado Springs, USA, 2021
  Behme, D., Voß, S., Thormann, M.J.C., Mpotsaris, A., Saalfeld, S., Janiga, G. & Berg, P.
  
• Facial Feature Removal for Anonymization of Neurological Image Data. Current Directions in Biomedical Engineering, 7(1), 130-134.
  Gießler, Fina; Thormann, Maximilian; Preim, Bernhard; Behme, Daniel & Saalfeld, Sylvia
  
• Focal enhancement in intracranial aneurysms – effects of local hemodynamics on black blood MRI signals, In: Summer Biomechanics, Bioengineering, and Biotransport Conference, Virtual, 2021
  Gaidzik, F., Pravdivtseva, M.S., Korte, J., Larsen, N., Saalfeld, S., Janiga, G. & Berg, P.
  
• Hemodynamics of anterior communicating artery aneurysms using combined imaging of the anterior circulation. Current Directions in Biomedical Engineering, 7(2), 887-890.
  Saalfeld, Sylvia; Behme, Daniel; Almizel, Mahmoud & Berg, Philipp
  
• Identifikation stabiler und instabiler intrakranieller Aneurysmen mittels bildbasierter Blutflusssimulation, In: 56. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., Kassel, Germany, 2021
  Behme, D., Voß, S., Korte, J., Thormann, M., Mpotsaris, A., Saalfeld, S., Janiga, G. & Berg, P.
  
• Luminal enhancement in intracranial aneurysms: fact or feature?—A quantitative multimodal flow analysis. International Journal of Computer Assisted Radiology and Surgery, 16(11), 1999-2008.
  Gaidzik, Franziska; Pravdivtseva, Mariya; Larsen, Naomi; Jansen, Olav; Hövener, Jan-Bernd & Berg, Philipp
  
• MedmeshCNN - Enabling meshcnn for medical surface models. Computer Methods and Programs in Biomedicine, 210, 106372.
  Schneider, Lisa; Niemann, Annika; Beuing, Oliver; Preim, Bernhard & Saalfeld, Sylvia
  
• Multimodale Modellierung intravaskulärer Hämodynamik am Beispiel zerebraler Aneurysmen.
  Berg, P.
  
• Structured reporting of aneurysm rupture risk utilizing geometric and hemodynamic analysis (STARR) - a sophisticated approach towards patient counseling, In: Annual Meeting of the Society of NeuroInterventional Surgery, Colorado Springs, USA, 2021
  Behme, D., Reinitz, I., Beuing, O., Thormann, M.J.C., Neyazi, B., Sandalcioglu, I.E., Mpotsaris, A., Preim, B., Berg, P. & Saalfeld, S.
  
• Strukturiertes Reporting geometrischer und hämodynamischer Aneurysmaeigenschaften zur Stratifikation des Rupturrisikos, In: 56. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., Kassel, Germany, 2021
  Behme, D., Reinitz, I., Beuing, O., Thormann, M., Neyazi, B., Sandalcioglu, E., Mpotsaris, A., Preim, B., Berg, P. & Saalfeld, S.
  
• Tissue segmentation in histologic images of intracranial aneurysm wall. Interdisciplinary Neurosurgery, 26, 101307.
  Niemann, Annika; Talagini, Anitha; Kandapagari, Pavan; Preim, Bernhard & Saalfeld, Sylvia
  
• Towards automated intracranial aneurysmal bleb detection, In: Annual Meeting of the Society of NeuroInterventional Surgery, Colorado Springs, USA, 2021
  Behme, D., Langolf, L., Thormann, M.J.C., Mpotsaris, A., Preim, B., Berg, P. & Saalfeld, S.
  
• Towards Deep Learning-based Wall Shear Stress Prediction for Intracranial Aneurysms. Informatik aktuell, 105-110. Springer Fachmedien Wiesbaden.
  Niemann, Annika; Schneider, Lisa; Preim, Bernhard; Voß, Samuel; Berg, Philipp & Saalfeld, Sylvia
  
• VICTORIA: VIrtual neck Curve and True Ostium Reconstruction of Intracranial Aneurysms. Cardiovascular Engineering and Technology, 12(4), 454-465.
  Berg, Philipp; Behrendt, Benjamin; Voß, Samuel; Beuing, Oliver; Neyazi, Belal; Sandalcioglu, Ibrahim Erol; Preim, Bernhard & Saalfeld, Sylvia
  
• Virtual embolization for treatment support of intracranial AVMs using an interactive desktop and VR application. International Journal of Computer Assisted Radiology and Surgery, 16(12), 2119-2127.
  Sprengel, Ulrike; Saalfeld, Patrick; Stahl, Janneck; Mittenentzwei, Sarah; Drittel, Moritz; Behrendt, Benjamin; Kaneko, Naoki; Behme, Daniel; Berg, Philipp; Preim, Bernhard & Saalfeld, Sylvia
  
• Visual exploration of intracranial aneurysm blood flow adapted to the clinical researcher, In: 23rd EuroVis conference, Virtual, Zurich, Switzerland, pp. 1-5, 2021
  Behrendt, B., Engelke, W., Berg, P., Beuing, O., Hotz, I., Preim, B. & Saalfeld, S.
  
• BB MRI for monitoring aneurysm treatment – a new biomarker?, In: 57. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., Kassel, Germany, 2022
  Pravdivtseva, M.S., Toraman, H., Korte, J., Gaidzik, F., Berg, P., Bautz, L., Wodarg, F., Hövener, J.-B., Jansen, O. & Larsen, N.
  
• Can black blood MRI predict hemodynamics in intracranial aneurysms? - An analysis of in-vitro signal intensity and CFD, In: The 18th International Conference on Fluid Flow Technologies, Budapest, Hungary, pp. 246-251, 2022
  Korte, J., Marsh, L., Pravdivtseva, M., Gaidzig, F., Larsen, N., Janiga, G. & Berg, P.
  
• Centerline and blockstructure for fast structured mesh generation. Current Directions in Biomedical Engineering, 8(1), 13-16.
  Niemann, Annika; Janiga, Gabor; Preim, Bernhard; Behme, Daniel & Saalfeld, Sylvia
  
• Fusiform vs. saccular intracranial aneurysms: Image-based blood flow simulations can help to understand formation and treatment effects, In: Summer Biomechanics, Bioengineering, and Biotransport Conference, Cambridge, Maryland, USA, 2022
  Korte, J., Marsh, L., Saalfeld, S., Stahl, J., Behme, D. & Berg, P.
  
• Geometric deep learning for aneuryms diagnosis, In: 7th International Conference on Computational and Mathematical Biomedical Engineering, Milano, Italy, pp. 1-4, 2022
  Niemann, A., Mandal, A., Kutty, L., Sudhi, V., Preim, B., Berg, P. & Saalfeld, S.
  
• Geometric uncertainty in intracranial aneurysm rupture status discrimination: a two-site retrospective study. BMJ Open, 12(11), e063051.
  Hellmeier, Florian; Brüning, Jan; Berg, Philipp; Saalfeld, Sylvia; Spuler, Andreas; Sandalcioglu, Ibrahim Erol; Beuing, Oliver; Larsen, Naomi; Schaller, Jens & Goubergrits, Leonid
  
• Multimodal analysis of intracranial aneurysm walls.
  Niemann, A.
  
• Predicting Aneurysm Rupture with Deep Learning on 3D Models, In: Bildverarbeitung für die Medizin, Heidelberg, Germany, pp. 315–320, 2022
  Niemann, A., Preim, B., Beuing, O. & Saalfeld, S.
  
• Uncertainty quantification of hemodynamic parameters for cerebral aneurysm rupture risk assessment, In: Virtual Physiological Human Conference (VPH), Porto, Portugal, 2022
  Schlief, A., Brüning, J., Voß, S., Berg, P. & Goubergrits, L.
  
• Unsicherheit in der hämodynamischen Charakterisierung intrakranieller Aneurysmen.
  Voß, S.
  
• Deep learning-based semantic vessel graph extraction for intracranial aneurysm rupture risk management. International Journal of Computer Assisted Radiology and Surgery.
  Niemann, Annika; Behme, Daniel; Larsen, Naomi; Preim, Bernhard & Saalfeld, Sylvia
  
• Multimodal exploration of the intracranial aneurysm wall. International Journal of Computer Assisted Radiology and Surgery, 18(12), 2243-2252.
  Niemann, Annika; Tulamo, Riikka; Netti, Eliisa; Preim, Bernhard; Berg, Philipp; Cebral, Juan; Robertson, Anne & Saalfeld, Sylvia