title: Effect of high-pitch dual-source CT to compensate motion artifacts: a phantom study.
abstract: OBJECTIVE
  To evaluate the potential of high-pitch, dual-source computed tomography (DSCT) for compensation of motion artifacts.
  
  
  METHODS
  Motion artifacts were created using a moving chest/cardiac phantom with integrated stents at different velocities (from 0 to 4-6 cm/s) parallel (z direction), transverse (x direction), and diagonal (x and z direction combined) to the scanning direction using standard-pitch (SP) (pitch = 1) and high-pitch (HP) (pitch = 3.2) 128-detector DSCT (Siemens, Healthcare, Forchheim, Germany). The scanning parameters were (SP/HP): tube voltage, 120 kV/120 kV; effective tube current time product, 300 mAs/500 mAs; and a pitch of 1/3.2. Motion artifacts were analyzed in terms of subjective image quality and object distortion. Image quality was rated by two blinded, independent observers using a 4-point scoring system (1, excellent; 2, good with minor object distortion or blurring; 3, diagnostically partially not acceptable; and 4, diagnostically not acceptable image quality). Object distortion was assessed by the measured changes of the object's outer diameter (x) and length (z) and a corresponding calculated distortion vector (d) (d = √(x(2) + z(2))).
  
  
  RESULTS
  The interobserver agreement was excellent (k = 0.91). Image quality using SP was diagnostically not acceptable with any motion in x direction (scores 3 and 4), in contrast to HP DSCT where it remained diagnostic up to 2 cm/s (scores 1 and 2). For motion in the z direction only, image quality remained diagnostic for SP and HP DSCT (scores 1 and 2). Changes of the object's diameter (x), length (z), and distortion vectors (d) were significantly greater with SP (overall: x = 1.9 cm ± 1.7 cm, z = 0.6 cm ± 0.8 cm, and d = 1.4 cm ± 1.5 cm) compared to HP DSCT (overall: x = 0.1 cm ± 0.1 cm, z = 0.0 cm ± 0.1 cm, and d = 0.1 cm ± 0.1 cm; each P < .05).
  
  
  CONCLUSIONS
  High-pitch DSCT significantly decreases motion artifacts in various directions and improves image quality.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 101, 8091 Zurich, Switzerland. Electronic address: nadja.amacker@usz.ch.
authors.forename: Nadja A
authors.initials: NA
authors.lastname: Farshad-Amacker
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Sebastian
authors.initials: S
authors.lastname: Leschka
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenfelder
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D009038:Motion; D015588:Observer Variation; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*
keywords: Phantom; high-pitch dual-source CT; motion artifacts