title: Metal artifact reduction software used with abdominopelvic dual-energy CT of patients with metal hip prostheses: assessment of image quality and clinical feasibility.
abstract: OBJECTIVE
  The objective of our study was to determine the feasibility of using Metal Artifact Reduction (MAR) software for abdominopelvic dual-energy CT in patients with metal hip prostheses.
  
  
  METHODS
  This retrospective study included 33 patients (male-female ratio, 19:14; mean age, 63.7 years) who received total hip replacements and 20 patients who did not have metal prostheses as the control group. All of the patients underwent dual-energy CT. The quality of the images reconstructed using the MAR algorithm and of those reconstructed using the standard reconstruction was evaluated in terms of the visibility of the bladder wall, pelvic sidewall, rectal shelf, and bone-prosthesis interface and the overall diagnostic image quality with a 4-point scale. The mean and SD attenuation values in Hounsfield units were measured in the bladder, pelvic sidewall, and rectal shelf. For validation of the MAR interpolation algorithm, pelvis phantoms with small bladder "lesions" and metal hip prostheses were made, and images of the phantoms both with and without MAR reconstruction were evaluated.
  
  
  RESULTS
  Image quality was significantly better with MAR reconstruction than without at all sites except the rectal shelf, where the image quality either had not changed or had worsened after MAR reconstruction. The mean attenuation value was changed after MAR reconstruction to its original expected value at the pelvic sidewall (p < 0.001) and inside the bladder (p < 0.001). The SD attenuation value was significantly decreased after MAR reconstruction at the pelvic sidewall (p = 0.019) but did not show significant differences at the bladder (p = 0.173) or rectal shelf (p = 0.478). In the phantom study, all lesions obscured by metal artifacts on the standard reconstruction images were visualized after MAR reconstruction; however, new artifacts had developed in other parts of the MAR reconstruction images.
  
  
  CONCLUSIONS
  The use of MAR software with dual-energy CT decreases metal artifacts and increases diagnostic confidence in the assessment of the pelvic cavity but also introduces new artifacts that can obscure pelvic structures.
authors.affiliation: 1 Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea.
authors.forename: Seung Chol
authors.initials: SC
authors.lastname: Han
authors.forename: Yong Eun
authors.initials: YE
authors.lastname: Chung
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.forename: Kwan Kyu
authors.initials: KK
authors.lastname: Park
authors.forename: Myeong Jin
authors.initials: MJ
authors.lastname: Kim
authors.forename: Ki Whang
authors.initials: KW
authors.lastname: Kim
mesh_terms: D000465:Algorithms; D016477:Artifacts; D005240:Feasibility Studies; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008670:Metals; D008875:Middle Aged; D015588:Observer Variation; D010388:Pelvis / Q000000981:diagnostic imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D011860:Radiography, Abdominal / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D008670:Metals
keywords: Metal Artifact Reduction software; abdominal dual-energy CT; metal hip prosthesis; pelvic cavity; phantom