title: Observer Performance in the Detection and Classification of Malignant Hepatic Nodules and Masses with CT Image-Space Denoising and Iterative Reconstruction.
abstract: OBJECTIVE
  To determine if lower-dose computed tomographic (CT) scans obtained with adaptive image-based noise reduction (adaptive nonlocal means [ANLM]) or iterative reconstruction (sinogram-affirmed iterative reconstruction [SAFIRE]) result in reduced observer performance in the detection of malignant hepatic nodules and masses compared with routine-dose scans obtained with filtered back projection (FBP).
  
  
  METHODS
  This study was approved by the institutional review board and was compliant with HIPAA. Informed consent was obtained from patients for the retrospective use of medical records for research purposes. CT projection data from 33 abdominal and 27 liver or pancreas CT examinations were collected (median volume CT dose index, 13.8 and 24.0 mGy, respectively). Hepatic malignancy was defined by progression or regression or with histopathologic findings. Lower-dose data were created by using a validated noise insertion method (10.4 mGy for abdominal CT and 14.6 mGy for liver or pancreas CT) and images reconstructed with FBP, ANLM, and SAFIRE. Four readers evaluated routine-dose FBP images and all lower-dose images, circumscribing liver lesions and selecting diagnosis. The jackknife free-response receiver operating characteristic figure of merit (FOM) was calculated on a per-malignant nodule or per-mass basis. Noninferiority was defined by the lower limit of the 95% confidence interval (CI) of the difference between lower-dose and routine-dose FOMs being less than -0.10.
  
  
  RESULTS
  Twenty-nine patients had 62 malignant hepatic nodules and masses. Estimated FOM differences between lower-dose FBP and lower-dose ANLM versus routine-dose FBP were noninferior (difference: -0.041 [95% CI: -0.090, 0.009] and -0.003 [95% CI: -0.052, 0.047], respectively). In patients with dedicated liver scans, lower-dose ANLM images were noninferior (difference: +0.015 [95% CI: -0.077, 0.106]), whereas lower-dose FBP images were not (difference -0.049 [95% CI: -0.140, 0.043]). In 37 patients with SAFIRE reconstructions, the three lower-dose alternatives were found to be noninferior to the routine-dose FBP.
  
  
  CONCLUSIONS
  At moderate levels of dose reduction, lower-dose FBP images without ANLM or SAFIRE were noninferior to routine-dose images for abdominal CT but not for liver or pancreas CT.
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Joel G
authors.initials: JG
authors.lastname: Fletcher
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Lifeng
authors.initials: L
authors.lastname: Yu
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Zhoubo
authors.initials: Z
authors.lastname: Li
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Armando
authors.initials: A
authors.lastname: Manduca
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Blezek
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: David M
authors.initials: DM
authors.lastname: Hough
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Sudhakar K
authors.initials: SK
authors.lastname: Venkatesh
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Brickner
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Cernigliaro
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Amy K
authors.initials: AK
authors.lastname: Hara
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Fidler
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: David S
authors.initials: DS
authors.lastname: Lake
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Maria
authors.initials: M
authors.lastname: Shiung
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: David
authors.initials: D
authors.lastname: Lewis
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Shuai
authors.initials: S
authors.lastname: Leng
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Kurt E
authors.initials: KE
authors.lastname: Augustine
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Rickey E
authors.initials: RE
authors.lastname: Carter
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: David R
authors.initials: DR
authors.lastname: Holmes
authors.affiliation: From the Departments of Radiology (J.G.F., L.Y., Z.L., D.M.H., S.K.V., J.L.F., M.S., D.L., S.L., C.H.M.), Physiology and Biomedical Engineering (A.M., D.S.L., K.E.A., D.R.H.), Information Technology (D.J.B.), and Biomedical Statistics and Informatics (R.E.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Eau Claire, Wis (G.C.B.); Department of Radiology, Mayo Clinic, Jacksonville, Fla (J.C.C.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.H.).
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: McCollough
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008113:Liver Neoplasms / Q000145:classification* / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*