title: Ultra-low-dose sequential computed tomography for quantitative lung aeration assessment-a translational study.
abstract: BACKGROUND
  Quantitative lung computed tomography (CT) provides fundamental information about lung aeration in critically ill patients. We tested a scanning protocol combining reduced number of CT slices and tube current, comparing quantitative analysis and radiation exposure to conventional CT.
  
  
  METHODS
  In pigs, CT scans were performed during breath hold in a model of lung injury with three different protocols: standard spiral with 180 mAs tube current-time product (Spiral180), sequential with 20-mm distance between slices and either 180 mAs (Sequential180) or 50 mAs (Sequential50). Spiral scans of critically ill patients were collected retrospectively, and subsets of equally spaced slices were extracted. The agreement between CT protocols was assessed with Bland-Altman analysis.
  
  
  RESULTS
  In 12 pigs, there was good concordance between the sequential protocols and the spiral scan (all biases ≤1.9%, agreements ≤±6.5%). In Spiral180, Sequential180 and Sequential50, estimated dose exposure was 2.3 (2.1-2.8), 0.21 (0.19-0.26), and 0.09 (0.07-0.10) mSv, respectively (p < 0.001 compared to Spiral180); number of acquired slices was 244 (227-252), 12 (11-13) and 12 (11-13); acquisition time was 7 (6-7), 23 (21-25) and 24 (22-26) s. In 32 critically ill patients, quantitative analysis extrapolated from 1-mm slices interleaved by 20 mm had a good concordance with the analysis performed on the entire spiral scan (all biases <1%, agreements ≤2.2%).
  
  
  CONCLUSIONS
  In animal CT data, combining sequential scan and low tube current did not affect significantly the quantitative analysis, with a radiation exposure reduction of 97%, reaching a dose comparable to chest X-ray, but with longer acquisition time. In human CT data, lung aeration analysis could be extrapolated from a subset of thin equally spaced slices.
authors.affiliation: Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, Genoa, Italy. lorenzo.ball@edu.unige.it.|Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands. lorenzo.ball@edu.unige.it.|Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany. lorenzo.ball@edu.unige.it.
authors.forename: Lorenzo
authors.identifier: http://orcid.org/0000-0002-3876-4730
authors.initials: L
authors.lastname: Ball
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Braune
authors.affiliation: Department of Anesthesia and Intensive Care, Ente Ospedaliero Galliera, Genova, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Corradi
authors.affiliation: Department of Anesthesia and Intensive Care, Ente Ospedaliero Galliera, Genova, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Brusasco
authors.affiliation: Department of Radiology, IRCCS AOU San Martino-IST, Genova, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Garlaschi
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kiss
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bluth
authors.affiliation: Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, Genoa, Italy.|Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Francesca
authors.initials: F
authors.lastname: Simonassi
authors.affiliation: Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, Genoa, Italy.|Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Alice
authors.initials: A
authors.lastname: Bergamaschi
authors.affiliation: Institute of Nuclear Medicine, Technische Universität Dresden, Dresden, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Kotzerke
authors.affiliation: Department of Intensive Care, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Schultz
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Dresden, Germany.
authors.forename: Marcelo Gama
authors.initials: MG
authors.lastname: de Abreu
authors.affiliation: Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Largo Rosanna Benzi 8, Genoa, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Pelosi
keywords: Computed tomography; Lung injury; Radiation dose