title: Simulation of MR angiography imaging for validation of cerebral arteries segmentation algorithms.
abstract: OBJECTIVE
  Accurate vessel segmentation of magnetic resonance angiography (MRA) images is essential for computer-aided diagnosis of cerebrovascular diseases such as stenosis or aneurysm. The ability of a segmentation algorithm to correctly reproduce the geometry of the arterial system should be expressed quantitatively and observer-independently to ensure objectivism of the evaluation.
  
  
  METHODS
  This paper introduces a methodology for validating vessel segmentation algorithms using a custom-designed MRA simulation framework. For this purpose, a realistic reference model of an intracranial arterial tree was developed based on a real Time-of-Flight (TOF) MRA data set. With this specific geometry blood flow was simulated and a series of TOF images was synthesized using various acquisition protocol parameters and signal-to-noise ratios. The synthesized arterial tree was then reconstructed using a level-set segmentation algorithm available in the Vascular Modeling Toolkit (VMTK). Moreover, to present versatile application of the proposed methodology, validation was also performed for two alternative techniques: a multi-scale vessel enhancement filter and the Chan-Vese variant of the level-set-based approach, as implemented in the Insight Segmentation and Registration Toolkit (ITK). The segmentation results were compared against the reference model.
  
  
  RESULTS
  The accuracy in determining the vessels centerline courses was very high for each tested segmentation algorithm (mean error rate = 5.6% if using VMTK). However, the estimated radii exhibited deviations from ground truth values with mean error rates ranging from 7% up to 79%, depending on the vessel size, image acquisition and segmentation method.
  
  
  CONCLUSIONS
  We demonstrated the practical application of the designed MRA simulator as a reliable tool for quantitative validation of MRA image processing algorithms that provides objective, reproducible results and is observer independent.
authors.affiliation: Institute of Electronics, Lodz University of Technology, Lodz, Poland. Electronic address: aklepaczko@p.lodz.pl.
authors.forename: Artur
authors.initials: A
authors.lastname: Klepaczko
authors.affiliation: Institute of Electronics, Lodz University of Technology, Lodz, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Szczypiński
authors.affiliation: Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Deistung
authors.affiliation: Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University, Jena, Germany; Michael Stifel Center for Data-driven and Simulation Science Jena, Friedrich Schiller University, Jena, Germany; Abbe School of Photonics, Friedrich Schiller University, Jena, Germany; Center of Medical Optics and Photonics, Friedrich Schiller University, Jena, Germany.
authors.forename: Jürgen R
authors.initials: JR
authors.lastname: Reichenbach
authors.affiliation: Institute of Electronics, Lodz University of Technology, Lodz, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Materka
mesh_terms: D000465:Algorithms; D002536:Cerebral Arteries / Q000000981:diagnostic imaging*; D006801:Humans; D018810:Magnetic Resonance Angiography
keywords: Cerebral vasculature modeling; MR angiography; MRI simulation; Quantitative validation; Vessel segmentation