title: High-resolution 3D X-ray imaging of intracranial nitinol stents.
abstract: BACKGROUND
  To assess an optimized 3D imaging protocol for intracranial nitinol stents in 3D C-arm flat detector imaging. For this purpose, an image quality simulation and an in vitro study was carried out.
  
  
  METHODS
  Nitinol stents of various brands were placed inside an anthropomorphic head phantom, using iodine contrast. Experiments with objects were preceded by image quality and dose simulations. We varied X-ray imaging parameters in a commercially interventional X-ray system to set 3D image quality in the contrast-noise-sharpness space. Beam quality was varied to evaluate contrast of the stents while keeping absorbed dose below recommended values. Two detector formats were used, paired with an appropriate pixel size and X-ray focus size. Zoomed reconstructions were carried out and snapshot images acquired. High contrast spatial resolution was assessed with a CT phantom.
  
  
  RESULTS
  We found an optimal protocol for imaging intracranial nitinol stents. Contrast resolution was optimized for nickel-titanium-containing stents. A high spatial resolution larger than 2.1 lp/mm allows struts to be visualized. We obtained images of stents of various brands and a representative set of images is shown. Independent of the make, struts can be imaged with virtually continuous strokes. Measured absorbed doses are shown to be lower than 50 mGy Computed Tomography Dose Index (CTDI).
  
  
  CONCLUSIONS
  By balancing the modulation transfer of the imaging components and tuning the high-contrast imaging capabilities, we have shown that thin nitinol stent wires can be reconstructed with high contrast-to-noise ratio and good detail, while keeping radiation doses within recommended values. Experimental results compare well with imaging simulations.
authors.affiliation: Faculty Electrical Engineering, Signal Processing Systems group (SPS), Eindhoven University of Technology (TU/e), Laplace Building 028, Postbox 513, 5600MB, Eindhoven, The Netherlands. r.m.snoeren@tue.nl
authors.forename: Rudolph M
authors.initials: RM
authors.lastname: Snoeren
authors.forename: Michael
authors.initials: M
authors.lastname: Söderman
authors.forename: Johannes N
authors.initials: JN
authors.lastname: Kroon
authors.forename: Ruben B
authors.initials: RB
authors.lastname: Roijers
authors.forename: Peter H N
authors.initials: PH
authors.lastname: de With
authors.forename: Drazenko
authors.initials: D
authors.lastname: Babic
mesh_terms: D000497:Alloys; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D015607:Stents; D014057:Tomography, X-Ray Computed; D014965:X-Rays
chemical_list: D000497:Alloys; C013616:nitinol