title: Simulation of cerebral hemodynamics for preoperative risk assessment.
abstract: BACKGROUND
  An important part of the medical treatment of many cerebrovascular diseases is the occlusion of brain supplying arteries. Until now, the risk of this intervention can only be estimated by invasive diagnostics including the risk of cerebrovascular accidents.
  
  
  RESULTS
  As a supporting tool, a computer model of the circle of Willis was designed. The model is based upon linear differential equations describing electrotechnical circuits extended non-linearly. By these means, time continuous simulations of different states and the online observation of all calculated state variables such as blood pressure and blood flow in every modeled vessel became feasible. For individual simulations, model parameters were determined by MR-angiography and boundary values by simultaneous Duplex-measurements in both carotid and vertebral arteries. State variables generated by the model behaved physiologically and the reaction of individual cerebrovascular systems in critical situations could be investigated by special scenarios. Inaccuracies concerning the determination of model parameters and boundary values of the used differential equations are likely to be resolved in the near future through a more careful and technically improved determination of these values.
  
  
  CONCLUSIONS
  Computer models of subjects were created taking in account the individual anatomical and non-linear physical properties of real vascular systems supplying the brain. Thereby information could be obtained concerning the hemodynamic effects of an iatrogenic vascular occlusion.
authors.affiliation: Clinic for Neurology, University Hospital of Saarland, 66421 Homburg/Saar, Germany. florian.roessler@uniklinik-saarland.de
authors.forename: F C
authors.initials: FC
authors.lastname: Roessler
authors.forename: W
authors.initials: W
authors.lastname: Reith
authors.forename: G
authors.initials: G
authors.lastname: Siegel
mesh_terms: D001921:Brain / Q000098:blood supply / Q000502:physiology; D002339:Carotid Arteries / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D002536:Cerebral Arteries / Q000502:physiology / Q000601:surgery; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002561:Cerebrovascular Disorders / Q000503:physiopathology / Q000601:surgery; D002941:Circle of Willis / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D004621:Embolization, Therapeutic / Q000009:adverse effects* / Q000379:methods*; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D018810:Magnetic Resonance Angiography; D008954:Models, Biological; D017711:Nonlinear Dynamics; D011300:Preoperative Care / Q000379:methods*; D018570:Risk Assessment / Q000379:methods; D018616:Ultrasonography, Doppler, Duplex; D014711:Vertebral Artery / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery