title: Experimental 16-row CT evaluation of in-stent restenosis using new stationary and moving cardiac stent phantoms: experimental examination.
abstract: OBJECTIVE
  The aim of this study was to evaluate in-stent restenosiss using a newly developed stationary and moving cardiac stent phantom with three built-in artificial stenoses and a 16-row MDCT.
  
  
  METHODS
  A newly developed coronary stent phantom with three artificial stenoses--low (approx. 30 %), medium (approx. 50 %) and high (approx. 70 %)--was attached to a moving heart phantom and used to evaluate the ability of 16-row MDCT to visualize in-stent restenosis. High resolution scans (16 x 0.75 mm, 250 mm FOV) were made to identify the baseline for image quality. The non-moving phantom was scanned (16 x 0.75 mm, routine cardiac scan protocol) first without and then with implementation of an ECG signal at various simulated heart rates (HR 40 to 120 bpm) and pitches (0.15 to 0.3). The moving cardiac phantom was scanned at the same simulated heart rates but at a pitch of 0.15. Images were reconstructed at every 10 % of the RR interval using a multi-cycle real cone-beam reconstruction algorithm. Multi-planar reformations (MPR) were made for the image evaluation. The image quality was assessed using a three-point scale, and stent patency and stenoses detection were evaluated using a four-point scale. To evaluate the image quality and to grade the stent stenoses, the median values were calculated while considering the reconstruction interval.
  
  
  RESULTS
  The image quality for the static phantom was adequate in 97 % of the measurements. In this phantom, every stenosis was detected independent of the pitch and heart rate used. The dynamic stent phantom yielded the best results at 0 %, 40 %, and 50 % of the RR interval at a pitch of 0.15. The low stenosis was visible at a simulated heart rate of up to 80 bpm. Patency can be detected at heart rates greater than 80 bpm.
  
  
  CONCLUSIONS
  The newly developed moving stent phantom allowed a nearly in-vivo condition for detecting re-stenoses within a stent. In this phantom study the use of a 16-row MDCT allowed the detection of re-stenosis within a coronary stent at a heart rate of up to 80 bpm. This phantom can then be used for future studies, e. g. with a 64-row MDCT.
authors.affiliation: Klinik und Poliklinik für Diagnostische und Interventionelle Radiologie, Universitätsklinikum Hamburg-Eppendorf. j.yamamura@uke.uni-hamburg.de
authors.forename: J
authors.initials: J
authors.lastname: Yamamura
authors.forename: U
authors.initials: U
authors.lastname: van Stevendaal
authors.forename: R
authors.initials: R
authors.lastname: Köster
authors.forename: M
authors.initials: M
authors.lastname: Grass
authors.forename: G
authors.initials: G
authors.lastname: Adam
authors.forename: P G
authors.initials: PG
authors.lastname: Begemann
mesh_terms: D016477:Artifacts; D017023:Coronary Angiography / Q000295:instrumentation*; D023903:Coronary Restenosis / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D009200:Myocardial Contraction / Q000502:physiology; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D015607:Stents; D036542:Tomography, Spiral Computed / Q000295:instrumentation*