title: Model-based iterative reconstruction for improvement of low-contrast detectability in liver CT at reduced radiation dose: ex-vivo experience.
abstract: OBJECTIVE
  To compare low-contrast detectability, and qualitative and quantitative image parameters on standard and reduced radiation dose abdominal CT reconstructed with filtered back projection (FBP) and model-based iterative reconstruction (MBIR).
  
  
  METHODS
  A custom built liver phantom containing 43 lesions was imaged at 120 kVp and four radiation dose levels (100% = 188 mAs, 50%, 25%, and 10%). Image noise and contrast-to-noise ratios (CNR) were assessed. Lesion detection and qualitative image analysis (five-point Likert scale with 1 = worst, 5 = best for confidence) was performed by three independent radiologists.
  
  
  RESULTS
  CNR on MBIR images was significantly higher (mean 246%, range 151-383%) and image noise was significantly lower (69%, 59-78%) than on FBP images at the same radiation dose (both p < 0.05). On MBIR 10% images, CNR (3.3 ± 0.3) was significantly higher and noise (15 ± 1HU) significantly lower than on FBP 100% images (2.5 ± 0.1; 21 ± 1 HU). On 100% images, lesion attenuation was significantly lower with MBIR than with FBP (mean difference -2 HU). Low-contrast detectability and qualitative results were similar with MBIR 50% and FBP 100%.
  
  
  CONCLUSIONS
  Low-contrast detectability with MBIR 50% and FBP 100% were equal. Quantitative parameters on even lower dose MBIR images are superior to 100%-dose FBP images. Some attenuation values differ significantly with MBIR compared with FBP.
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland. Electronic address: danielahusarik@yahoo.com.
authors.forename: D B
authors.initials: DB
authors.lastname: Husarik
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Alkadhi
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland.
authors.forename: G D
authors.initials: GD
authors.lastname: Puippe
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland.
authors.forename: C S
authors.initials: CS
authors.lastname: Reiner
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland.
authors.forename: N C
authors.initials: NC
authors.lastname: Chuck
authors.affiliation: Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Morsbach
authors.affiliation: Department of Radiology, Spitalzentrum Biel AG, Biel, Switzerland.
authors.forename: Z
authors.initials: Z
authors.lastname: Szucs-Farkas
authors.affiliation: Department of Radiology and Nuclear Medicine, University Hospital Basel, Basel, Switzerland.
authors.forename: S T
authors.initials: ST
authors.lastname: Schindera
mesh_terms: D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*