title: Measurement with microscopic MRI and simulation of flow in different aneurysm models.
abstract: OBJECTIVE
  The impact and the development of aneurysms depend to a significant degree on the exchange of liquid between the regular vessel and the pathological extension. A better understanding of this process will lead to improved prediction capabilities. The aim of the current study was to investigate fluid-exchange in aneurysm models of different complexities by combining microscopic magnetic resonance measurements with numerical simulations. In order to evaluate the accuracy and applicability of these methods, the fluid-exchange process between the unaltered vessel lumen and the aneurysm phantoms was analyzed quantitatively using high spatial resolution.
  
  
  METHODS
  Magnetic resonance flow imaging was used to visualize fluid-exchange in two different models produced with a 3D printer. One model of an aneurysm was based on histological findings. The flow distribution in the different models was measured on a microscopic scale using time of flight magnetic resonance imaging. The whole experiment was simulated using fast graphics processing unit-based numerical simulations. The obtained simulation results were compared qualitatively and quantitatively with the magnetic resonance imaging measurements, taking into account flow and spin-lattice relaxation.
  
  
  RESULTS
  The results of both presented methods compared well for the used aneurysm models and the chosen flow distributions. The results from the fluid-exchange analysis showed comparable characteristics concerning measurement and simulation. Similar symmetry behavior was observed. Based on these results, the amount of fluid-exchange was calculated. Depending on the geometry of the models, 7% to 45% of the liquid was exchanged per second.
  
  
  CONCLUSIONS
  The result of the numerical simulations coincides well with the experimentally determined velocity field. The rate of fluid-exchange between vessel and aneurysm was well-predicted. Hence, the results obtained by simulation could be validated by the experiment. The observed deviations can be caused by the noise in the measurement and by the limited resolution of the simulation. The resulting differences are small enough to allow reliable predictions of the flow distribution in vessels with stents and for pulsed blood flow.
authors.affiliation: Experimental Physics III, TU Dortmund University, Otto-Hahn-Street 4, Dortmund 44227, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Edelhoff
authors.affiliation: Computer Science VII, TU Dortmund University, Otto-Hahn-Street 16, Dortmund 44227, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Walczak
authors.affiliation: Experimental Physics III, TU Dortmund University, Otto-Hahn-Street 4, Dortmund 44227, Germany.
authors.forename: Frauke
authors.initials: F
authors.lastname: Frank
authors.affiliation: Experimental Physics III, TU Dortmund University, Otto-Hahn-Street 4, Dortmund 44227, Germany.
authors.forename: Marvin
authors.initials: M
authors.lastname: Heil
authors.affiliation: Institute for Pathology, Ruhr Universität Bochum, Bürkle-de-la-Camp-Platz 1, Bochum 44789, Germany.
authors.forename: Inge
authors.initials: I
authors.lastname: Schmitz
authors.affiliation: Computer Science VII, TU Dortmund University, Otto-Hahn-Street 16, Dortmund 44227, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Weichert
authors.affiliation: Experimental Physics III, TU Dortmund University, Otto-Hahn-Street 4, Dortmund 44227, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Suter
mesh_terms: D000783:Aneurysm / Q000503:physiopathology*; D001775:Blood Circulation; D008279:Magnetic Resonance Imaging; D008954:Models, Biological