title: Image quality assessment of an iterative reconstruction algorithm applied to abdominal CT imaging.
abstract: OBJECTIVE
  To compare the noise and accuracy on images of the whole porcine liver acquired with iterative reconstruction (IMR, Philips Healthcare, Cleveland, OH, USA) and filtered back projection (FBP) methods.
  
  
  METHODS
  We used non-enhanced porcine liver to simulate the human liver and acquired it 100 times to obtain the average FBP value as the ground-truth. The mean and the standard deviation ("inter-scan SD") of the pixel values on the 100 image acquisitions were calculated for FBP and for three levels of IMR (L1, L2, and L3). We also calculated the noise power spectrum (NPS) and the normalized NPS for the 100 image acquisitions.
  
  
  RESULTS
  The spatial SD for the porcine liver parenchyma on these slices was 9.92, 4.37, 3.63, and 2.30 Hounsfield units with FBP, IMR-L1, IMR-L2, and IMR-L3, respectively. The detectability of small faint features was better on single IMR than single FBP images. The inter-scan SD value for IMR-L3 images was 53% larger at the liver edges than at the liver parenchyma; it was only 10% larger on FBP images. Assessment of the normalized NPS showed that the noise on IMR images was comprised primarily of low-frequency components.
  
  
  CONCLUSIONS
  IMR images yield the same structure informations as FBP images and image accuracy is maintained. On level 3 IMR images the image noise is more strongly suppressed than on IMR images of the other levels and on FBP images.
authors.affiliation: Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto 862-0976, Japan. Electronic address: funama@kumamoto-u.ac.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, USA.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Taguchi
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Japan.
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.affiliation: Department of Diagnostic Radiology, Kumamoto Chuo Hospital, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Katahira
authors.affiliation: CT Clinical Science, Philips Electronics Japan, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tokuyasu
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000465:Algorithms; D000818:Animals; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D059629:Signal-To-Noise Ratio; D013382:Subtraction Technique; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Abdominal CT; Filtered back projection; Image quality; Iterative reconstruction; Porcine liver