title: Evaluation of retrospective multisector and half scan ECG-gated multidetector cardiac CT protocols with moving phantoms.
abstract: OBJECTIVE
  We evaluated independently retrospective half scan and multisector mode manufacturer's protocols and compared them with modified acquisition protocols to determine optimal imaging parameters for cardiac scanning.
  
  
  METHODS
  Data were acquired using two fabricated gated moving phantoms. In half scan mode, the manufacturer's recommended pitch values were compared with adjacent values at different motion rates. In multisector mode, the manufacturer's protocols were compared with ones with different gantry speeds and pitch values at the same motion rates. Weighted CT dose indexes (CTDI) were obtained for all protocols. Gated and reformatted reconstructed images of the moving phantoms were evaluated.
  
  
  RESULTS
  In half scan mode, slightly better image quality was observed by lowering the pitch value, but with an increase of 6.3% of the weighted CTDI. Better results were obtained in multisector mode by lowering the pitch value up to 0.2, but with an increase of 14.3% of the weighted CTDI. Optimal images were obtained with the lowest temporal resolution.
  
  
  CONCLUSIONS
  Gated moving phantom studies offer the advantage of testing acquisition protocols of complex motions and of helping to establish appropriate protocols.
authors.affiliation: Massachusetts General Hospital, Department of Radiology, 55 Fruit Street, Boston MA 02114, USA. swicky@partners.org
authors.forename: Stephan
authors.initials: S
authors.lastname: Wicky
authors.forename: Michael
authors.initials: M
authors.lastname: Rosol
authors.forename: Leena M
authors.initials: LM
authors.lastname: Hamberg
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
authors.forename: Christian
authors.initials: C
authors.lastname: Enzweiler
authors.forename: Mike
authors.initials: M
authors.lastname: Graziano
authors.forename: Thomas
authors.initials: T
authors.lastname: Brady
mesh_terms: D004562:Electrocardiography; D006321:Heart / Q000000981:diagnostic imaging*; D008955:Models, Cardiovascular; D012371:Robotics; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*