title: Coronary stent imaging with dual-source CT: assessment of lumen visibility using different convolution kernels and postprocessing filters.
abstract: BACKGROUND
  Assesment of the coronary arteries after stent placement using coronary computed tomography angiography (CCTA) currently requires reconstruction of images with soft kernels for the assessment of atherosclerotic plaques and dedicated edge enhancing kernels for the evaluation of the stent lumen.
  
  
  OBJECTIVE
  To evaluate a two-dimensional filter tool that provides instant postprocessing of images reconstructed with soft kernels into edge-enhanced images and vice versa and thus may eliminate the need for two separate reconstrcutions for the assessment of coronary artery stents using CCTA.
  
  
  METHODS
  Twenty stents with a diameter of 3.0 mm placed in a vascular phantom were scanned with a dual-source CT using standard parameters. Images were reconstructed with a soft B30f and an edge-enhancing B46f kernel and postprocessed with the corresponding filter algorithm (F30 for B30f images; F46 for B46f images). The resulting four data-sets were evaluated for lumen visibility, intraluminal attenuation, and image noise by two independent readers. Results were validated in vivo against invasive coronary angiography in data-sets from patients with coronary artery stents.
  
  
  RESULTS
  Average intraluminal attenuation was 552.6 HU, 527.3 HU, 207.9 HU, and 267.5 HU for B30f, F30, B46f, and F46 images, respectively (P < 0.0001). Average image noise was 11.3, 10.6, 19.2, and 15.0 HU, respectively (P < 0.0001). The visible stent diameter was significantly higher in the B46f (59.6%) and F46 images (54%) compared to the B30f (48.3%) and F30 (51.5%) images (P < 0.0001). In the patient study, lumen assessability was significantly better in B46f images than in F46 images. Sensitivity for stenosis detection was best in the original B46f images with a sensitivity of 67% and a specificity of 94%.
  
  
  CONCLUSIONS
  The postprocessing filter reduces image noise, however currently it does not offer an alternative to image reconstruction using the edge-enhancing kernels for the evaluation of the stent lumen.
authors.affiliation: Department of Clinical Radiology, University of Muenster, Münster, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Ulrich
authors.affiliation: Department of Clinical Radiology, University of Muenster, Münster, Germany.
authors.forename: Matthias C
authors.initials: MC
authors.lastname: Burg
authors.affiliation: Siemens Medical Solutions, Computed Tomography CTE PA, Forchheim, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Raupach
authors.affiliation: Department of Clinical Radiology, University of Muenster, Münster, Germany Department of Radiology, University Hospital of Cologne, Cologne, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Bunck
authors.affiliation: Department of Clinical Radiology, University of Muenster, Münster, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schuelke
authors.affiliation: Department of Radiology, University Hospital of Cologne, Cologne, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Maintz
authors.affiliation: Department of Clinical Radiology, University of Muenster, Münster, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Heindel
authors.affiliation: Department of Clinical Radiology, University of Muenster, Münster, Germany Department of Diagnostic and Interventional Radiology, Esslingen Hospital, Esslingen, Germany seifarth@uni-muenster.de.
authors.forename: Harald
authors.initials: H
authors.lastname: Seifarth
mesh_terms: D000465:Algorithms; D001807:Blood Vessel Prosthesis; D017023:Coronary Angiography / Q000295:instrumentation / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000601:surgery; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015607:Stents; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Coronary CT angiography; cardiac CT; image noise; image reconstruction; stent