title: Pelvic Beam-Hardening Artifacts in Dual-Energy CT Image Reconstructions: Occurrence and Impact on Image Quality.
abstract: OBJECTIVE
  The purpose of this study was to describe the frequency and appearance of beam-hardening artifacts on rapid-kilovoltage-switching dual-energy CT (DECT) image reconstructions of the pelvis.
  
  
  METHODS
  Monochromatic (70, 52, and 120 keV) and material decomposition CT images (iodine-water and water-iodine) from consecutive pelvic rapid-kilovoltage-switching DECT scans were retrospectively evaluated. We recorded the presence, type (high versus low attenuation), and severity of beam-hardening artifacts (Likert scale from 0, barely seen, to 4, severe), clarity of anatomic delineation (Likert scale from 0, unimpaired, to 4, severely impaired) and SD of CT numbers, iodine and water concentrations, and gray-scale values for artifact-affected regions and corresponding unaffected reference tissue. A pelvic phantom was scanned and evaluated in a similar manner. Wilcoxon signed rank and paired t tests were used to compare results between the image reconstructions.
  
  
  RESULTS
  Beam-hardening artifacts were seen in all image reconstructions in all 41 patients (22 men, 19 women; mean age, 57 years; range 22-86 years) who met the inclusion criteria. The median artifact severity score was worse for water-iodine and iodine-water images (score of 3 for each) than for 70-keV (score 1), 52-keV (score 2), and 120-keV (score 1) images (all p < 0.001). The anatomic delineation was worse (p < 0.001) for water-iodine and iodine-water images than for monochromatic images. Higher CT number SD values, material concentrations, and gray-scale values were found for areas affected by artifacts than for reference tissues in all datasets (all p < 0.001). Similar results were seen in the phantom study.
  
  
  CONCLUSIONS
  Beam-hardening artifacts are prevalent in pelvic rapid-kilovoltage-switching DECT and more severe in material decomposition than monochromatic image reconstructions.
authors: 1 Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, M-372, San Francisco, CA 94143-0628.|2 Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors: Sebastian
authors: S
authors: Winklhofer
authors: 1 Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, M-372, San Francisco, CA 94143-0628.
authors: Jack W
authors: JW
authors: Lambert
authors: 1 Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, M-372, San Francisco, CA 94143-0628.
authors: Yuxin
authors: Y
authors: Sun
authors: 1 Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, M-372, San Francisco, CA 94143-0628.
authors: Zhen Jane
authors: ZJ
authors: Wang
authors: 1 Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, M-372, San Francisco, CA 94143-0628.
authors: Derek S
authors: DS
authors: Sun
authors: 1 Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, M-372, San Francisco, CA 94143-0628.
authors: Benjamin M
authors: BM
authors: Yeh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
keywords: artifact; beam hardening; bladder; dual-energy CT