title: Sub-milliSievert (sub-mSv) CT colonography: a prospective comparison of image quality and polyp conspicuity at reduced-dose versus standard-dose imaging.
abstract: OBJECTIVE
  To prospectively compare reduced-dose (RD) CT colonography (CTC) with standard-dose (SD) imaging using several reconstruction algorithms.
  
  
  METHODS
  Following SD supine CTC, 40 patients (mean age, 57.3 years; 17 M/23 F; mean BMI, 27.2) underwent an additional RD supine examination (targeted dose reduction, 70-90%). DLP, CTDI(vol), effective dose, and SSDE were compared. Several reconstruction algorithms were applied to RD series. SD-FBP served as reference standard. Objective image noise, subjective image quality and polyp conspicuity were assessed.
  
  
  RESULTS
  Mean CTDI(vol) and effective dose for RD series was 0.89 mGy (median 0.65) and 0.6 mSv (median 0.44), compared with 3.8 mGy (median 3.1) and 2.8 mSv (median 2.3) for SD series, respectively. Mean dose reduction was 78%. Mean image noise was significantly reduced on RD-PICCS (24.3 ± 19HU) and RD-MBIR (19 ± 18HU) compared with RD-FBP (90 ± 33), RD-ASIR (72 ± 27) and SD-FBP (47 ± 14 HU). 2D image quality score was higher with RD-PICCS, RD-MBIR, and SD-FBP (2.7 ± 0.4/2.8 ± 0.4/2.9 ± 0.6) compared with RD-FBP (1.5 ± 0.4) and RD-ASIR (1.8 ± 0.44). A similar trend was seen with 3D image quality scores. Polyp conspicuity scores were similar between SD-FBP/RD-PICCS/RD-MBIR (3.5 ± 0.6/3.2 ± 0.8/3.3 ± 0.6).
  
  
  CONCLUSIONS
  Sub-milliSievert CTC performed with iterative reconstruction techniques demonstrate decreased image quality compared to SD, but improved image quality compared to RD images reconstructed with FBP.
  
  
  CONCLUSIONS
  • CT colonography dose can be substantially lowered using advanced iterative reconstruction techniques. • Iterative reconstruction techniques (MBIR/PICCS) reduce image noise and improve image quality. • The PICCS/MBIR-reconstructed, reduced-dose series shows decreased 2D/3D image quality compared to the standard-dose series. • Polyp conspicuity was similar on standard-dose images compared to reduced-dose images reconstructed with MBIR/PICCS.
authors.affiliation: Departments of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Sciences Center, 600 Highland Ave, Madison, WI, 53792-3252, USA, mlubner@uwhealth.org.
authors.forename: Meghan G
authors.initials: MG
authors.lastname: Lubner
authors.forename: B Dustin
authors.initials: BD
authors.lastname: Pooler
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Kitchin
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.forename: David H
authors.initials: DH
authors.lastname: Kim
authors.forename: Alejandro
authors.initials: A
authors.lastname: Munoz del Rio
authors.forename: Guang-Hong
authors.initials: GH
authors.lastname: Chen
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
mesh_terms: D000465:Algorithms; D002985:Clinical Protocols; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods / Q000592:standards; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods / Q000592:standards; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods