title: Prospective Randomized Trial on Radiation Dose Estimates of CT Angiography Applying Iterative Image Reconstruction: The PROTECTION V Study.
abstract: OBJECTIVE
  The purpose of this study was to assess the potential of iterative image reconstruction (IR) of images for radiation dose reduction in coronary computed tomography angiography (CTA). Therefore, IR in combination with 30% tube current reduction was compared with standard scanning with filtered back projection (FBP) reconstruction.
  
  
  BACKGROUND
  Lately, new IR techniques with advanced raw data processing have been introduced by different computed tomography vendors, thus allowing for either image noise reduction at unchanged radiation dose levels or radiation dose reductions at comparable image noise levels.
  
  
  METHODS
  In this prospective, multicenter, multivendor noninferiority trial, we randomized 400 consecutive patients to 1 of 2 groups: a control group using standard FBP image reconstruction and standard tube current or an interventional group using IR technique and 30% tube current reduction. The primary endpoint was to demonstrate noninferiority in image quality (IQ) in the IR group. IQ was assessed on a 4-point scale (1, nondiagnostic IQ; 4, excellent IQ). Secondary endpoints included total radiation dose estimates and the rate of downstream testing during 30-day follow-up.
  
  
  RESULTS
  Median IQ in the IR group was noninferior compared with the conventional FBP group (IR, 3.5 [interquartile range: 3.0 to 4.0]; FBP, 3.4 [interquartile range: 2.8 to 4.0], p for noninferiority <0.016). The radiation exposure was significantly lower in the IR group (median dose-length-product 157 [interquartile range: 114 to 239] mGy·cm vs. 222 [interquartile range: 141 to 319] mGy·cm for IR vs. FBP, respectively, p < 0.0001). The rate of downstream testing did not differ significantly (7.7% vs. 7.9% for IR vs. FBP, respectively, p = 0.94).
  
  
  CONCLUSIONS
  Coronary CTA image quality is maintained with the combined use of a 30% reduced tube current and IR algorithms when compared with conventional FBP image reconstruction techniques and standard tube current. (Prospective Randomized Trial On RadiaTion Dose Estimates Of CT AngIOgraphy In PatieNts: NCT01453712).
authors.affiliation: Medizinische Klinik und Poliklinik I der Ludwig-Maximilians-Universität München, Munich, Germany; Institut für Radiologie und Nuklearmedizin; Deutsches Herzzentrum München; Klinik an der Technischen Universität München, Munich, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Deseive
authors.affiliation: National Institutes of Health, Bethesda, Maryland.
authors.forename: Marcus Y
authors.initials: MY
authors.lastname: Chen
authors.affiliation: Klinik für Innere Medizin III, Universitätsklinikum Heidelberg; Heidelberg, Germany.
authors.forename: Grigorios
authors.initials: G
authors.lastname: Korosoglou
authors.affiliation: Department of Radiology, St. Paul's Hospital, University of British Columbia, Vancouver, Canada.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Leipsic
authors.affiliation: Department of Internal Medicine, University of Rome Tor Vergata and Clinica Paideia, Rome, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Martuscelli
authors.affiliation: Departamento de Tomografía Computada e Investigación de Diagnóstico Maipú, Buenos Aires, Argentina.
authors.forename: Patricia
authors.initials: P
authors.lastname: Carrascosa
authors.affiliation: Department of Radiology, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Saeed
authors.initials: S
authors.lastname: Mirsadraee
authors.affiliation: University of Maryland School of Medicine, Baltimore, Maryland.
authors.forename: Charles
authors.initials: C
authors.lastname: White
authors.affiliation: Institut für Radiologie und Nuklearmedizin; Deutsches Herzzentrum München; Klinik an der Technischen Universität München, Munich, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hadamitzky
authors.affiliation: Institut für Radiologie und Nuklearmedizin; Deutsches Herzzentrum München; Klinik an der Technischen Universität München, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Martinoff
authors.affiliation: Medizinische Klinik und Poliklinik I der Ludwig-Maximilians-Universität München, Munich, Germany; Institut für Radiologie und Nuklearmedizin; Deutsches Herzzentrum München; Klinik an der Technischen Universität München, Munich, Germany.
authors.forename: Anna-Leonie
authors.initials: AL
authors.lastname: Menges
authors.affiliation: Institut für Klinische Radiologie, Ludwig-Maximilians-Universität München, Munich, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Bischoff
authors.affiliation: Medizinische Klinik und Poliklinik I der Ludwig-Maximilians-Universität München, Munich, Germany; Institut für Radiologie und Nuklearmedizin; Deutsches Herzzentrum München; Klinik an der Technischen Universität München, Munich, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Massberg
authors.affiliation: Medizinische Klinik und Poliklinik I der Ludwig-Maximilians-Universität München, Munich, Germany; Institut für Radiologie und Nuklearmedizin; Deutsches Herzzentrum München; Klinik an der Technischen Universität München, Munich, Germany. Electronic address: joerg.hausleiter@med.uni-muenchen.de.
authors.forename: Jörg
authors.initials: J
authors.lastname: Hausleiter
mesh_terms: D000465:Algorithms; D017023:Coronary Angiography; D019223:Densovirinae; D007091:Image Processing, Computer-Assisted; D011446:Prospective Studies; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed
keywords: computed tomography angiography; coronary; iterative image reconstruction; radiation dose