title: Accuracy comparison of a 16 and 64 multidetector-row computed tomography scanner to image small high-density structures.
abstract: OBJECTIVE
  The accuracy in imaging small high-density structures is compared for 16 and 64 multidetector-row computed tomography (MDCT) scanners.
  
  
  METHODS
  Phantom experiments and different quantification methods are used to establish size measurement accuracy, object signal, and image noise, for both MDCT systems.
  
  
  RESULTS
  At similar scanning doses, image noise is larger ( approximately 55%) for the 64 MDCT compared with the 16 MDCT, leading to lower signal-to-noise ratios ( approximately 28% for objects <2 mm). Object spread in the xy-plane is similar for both systems; while it is reduced along the z-axis (by approximately 0.18 mm) for the 64 MDCT. Measurement accuracy of the 64 MDCT is not significantly higher (P < 0.05) compared with the 16 MDCT when using a relative-threshold corresponding to 50% of the object maximum attenuation value. However, when using a fixed-threshold, interscanner and interprotocol measurement differences are statistically significant (eg, volume relative errors are reduced by approximately 17% on average for the 64 MDCT).
  
  
  CONCLUSIONS
  Measurement accuracy of the 16 and 64 MDCT scanners is not significantly different when using a 50% relative threshold. However, image noise is significantly larger for the 64 MDCT. Compared with a fixed-threshold based method, the 50% relative-threshold strongly reduces interscanner and interprotocol measurement dependency and improves accuracy.
authors.affiliation: Department of Radiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands. m.rollanohijarrubia@erasmusmc.nl
authors.forename: Empar
authors.initials: E
authors.lastname: Rollano-Hijarrubia
authors.forename: Rik
authors.initials: R
authors.lastname: Stokking
authors.forename: Wiro J
authors.initials: WJ
authors.lastname: Niessen
mesh_terms: D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D019904:Polymethyl Methacrylate; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015898:Tomography Scanners, X-Ray Computed / Q000592:standards*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*
chemical_list: D019904:Polymethyl Methacrylate