title: Vessel-based registration of an optical shape sensing catheter for MR navigation.
abstract: OBJECTIVE
  Magnetic resonance navigation (MRN), achieved with an upgraded MRI scanner, aims to guide therapeutic nanoparticles from their release in the hepatic vascular network to embolize highly vascularized liver tumors. Visualizing the catheter in real-time within the arterial network is important for selective embolization within the MR gantry. To achieve this, a new MR-compatible catheter tracking technology based on optical shape sensing is used.
  
  
  METHODS
  This paper proposes a vessel-based registration pipeline to co-align this novel catheter tracking technology to the patient's diagnostic MR angiography (MRA) with 3D roadmapping. The method first extracts the 3D hepatic arteries from a diagnostic MRA based on concurrent deformable models, creating a detailed representation of the patient's internal anatomy. Once the optical shape sensing fibers, inserted in a double-lumen catheter, is guided into the hepatic arteries, the 3D centerline of the catheter is inferred and updated in real-time using strain measurements derived from fiber Bragg gratings sensors. Using both centerlines, a diffeomorphic registration based on a spectral representation of the high-level geometrical primitives is applied.
  
  
  RESULTS
  Results show promise in registration accuracy in five phantom models created from stereolithography of patient-specific vascular anatomies, with maximum target registration errors below 2 mm. Furthermore, registration accuracy with the shape sensing tracking technology remains insensitive to the magnetic field of the MR magnet.
  
  
  CONCLUSIONS
  This study demonstrates that an accurate registration procedure of a shape sensing catheter with diagnostic imaging is feasible.
authors.affiliation: Department Computer and Software Engineering, Ecole Polytechnique de Montréal, Montréal, QC, Canada.
authors.forename: Koushik
authors.initials: K
authors.lastname: Mandal
authors.affiliation: Department Physics Engineering, Ecole Polytechnique de Montreal, Montréal, QC, Canada.
authors.forename: Francois
authors.initials: F
authors.lastname: Parent
authors.affiliation: Department Computer and Software Engineering, Ecole Polytechnique de Montréal, Montréal, QC, Canada.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Martel
authors.affiliation: Department Physics Engineering, Ecole Polytechnique de Montreal, Montréal, QC, Canada.
authors.forename: Raman
authors.initials: R
authors.lastname: Kashyap
authors.affiliation: Department Computer and Software Engineering, Ecole Polytechnique de Montréal, Montréal, QC, Canada. samuel.kadoury@polymtl.ca.|Centre Hospitalier de l'Université de Montréal Research Center, Montréal, QC, Canada. samuel.kadoury@polymtl.ca.
authors.forename: Samuel
authors.initials: S
authors.lastname: Kadoury
mesh_terms: D002404:Catheterization / Q000379:methods*; D006499:Hepatic Artery / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008113:Liver Neoplasms / Q000098:blood supply* / Q000175:diagnosis; D018810:Magnetic Resonance Angiography / Q000379:methods*
keywords: Catheter tracking; Intra-arterial therapy; Magnetic resonance navigation; Optical shape sensing; Vessel registration