title: Reduced-dose low-voltage chest CT angiography with Sinogram-affirmed iterative reconstruction versus standard-dose filtered back projection.
abstract: OBJECTIVE
  To evaluate image quality of low-voltage chest computed tomographic (CT) angiography with raw data-based iterative reconstruction (sonogram-affirmed iterative reconstruction) in comparison with image quality of standard-dose standard-voltage filtered back projection (FBP) CT.
  
  
  METHODS
  This prospective study was approved by the institutional review board, and the informed consent requirement was waived. Eighty consecutive patients who were referred for follow-up chest CT angiography underwent reduced-dose CT (hereafter, T2 examination) under technical conditions similar to those of the initial examination (hereafter, T1 examination), except the voltage selection was reduced by 20 kV with adaptation of the tube current to ensure a 50% reduction in CT dose index, and regular FBP was replaced by iterative reconstruction with sonogram-affirmed iterative reconstruction. The two techniques were compared by using paired tests (Student t test, Wilcoxon test, or McNemar test, according to the nature of variables).
  
  
  RESULTS
  When compared with standard-dose T1 studies, reduced-dose T2 images showed: (a) significantly less objective noise at the level of the trachea on mediastinal and lung parenchymal images (P < .001) and no significant difference in objective noise at the level of the aorta on mediastinal images (P = .507); (b) significantly higher signal-to-noise and contrast-to-noise (P < .001) ratios; (c) similar visual perception of noise on mediastinal (P = .132) and lung (P = .366) images, mainly rated as moderate; and (d) similar overall subjective image quality (P = .405).
  
  
  CONCLUSIONS
  Raw data-based iterative reconstruction yielded equivalent subjective and improved objective image quality of low-voltage half-dose CT angiograms compared with standard-dose FBP CT images for an average dose-length product of less than 80 mGy · cm in this population.
  
  
  BACKGROUND
  http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120414/-/DC1.
authors.affiliation: Departments of Thoracic Imaging and Medical Statistics, Hôpital Calmette (EA 2694 Université Lille Nord de France, Boulevard Jules Leclercq, 59037 Lille, France.
authors.forename: François
authors.initials: F
authors.lastname: Pontana
authors.forename: Julien
authors.initials: J
authors.lastname: Pagniez
authors.forename: Alain
authors.initials: A
authors.lastname: Duhamel
authors.forename: Thomas
authors.initials: T
authors.lastname: Flohr
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Faivre
authors.forename: Colm
authors.initials: C
authors.lastname: Murphy
authors.forename: Jacques
authors.initials: J
authors.lastname: Remy
authors.forename: Martine
authors.initials: M
authors.lastname: Remy-Jardin
mesh_terms: D000792:Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D013902:Radiography, Thoracic / Q000379:methods*; D059629:Signal-To-Noise Ratio; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*