title: MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction.
abstract: OBJECTIVE
  The purpose of this article is to assess the effect of the adaptive statistical iterative reconstruction (ASIR) technique on image quality in hip MDCT arthrography and to evaluate its potential for reducing radiation dose.
  
  
  METHODS
  Thirty-seven patients examined with hip MDCT arthrography were prospectively randomized into three different protocols: one with a regular dose (volume CT dose index [CTDIvol], 38.4 mGy) and two with a reduced dose (CTDIvol, 24.6 or 15.4 mGy). Images were reconstructed using filtered back projection (FBP) and four increasing percentages of ASIR (30%, 50%, 70%, and 90%). Image noise and contrast-to-noise ratio (CNR) were measured. Two musculoskeletal radiologists independently evaluated several anatomic structures and image quality parameters using a 4-point scale. They also jointly assessed acetabular labrum tears and articular cartilage lesions.
  
  
  RESULTS
  With decreasing radiation dose level, image noise statistically significantly increased (p=0.0009) and CNR statistically significantly decreased (p=0.001). We also found a statistically significant reduction in noise (p=0.0001) and increase in CNR (p≤0.003) with increasing percentage of ASIR; in addition, we noted statistically significant increases in image quality scores for the labrum and cartilage, subchondral bone, overall diagnostic quality (up to 50% ASIR), and subjective noise (p≤0.04), and statistically significant reductions for the trabecular bone and muscles (p≤0.03). Regardless of the radiation dose level, there were no statistically significant differences in the detection and characterization of labral tears (n=24; p=1) and cartilage lesions (n=40; p≥0.89) depending on the ASIR percentage.
  
  
  CONCLUSIONS
  The use of up to 50% ASIR in hip MDCT arthrography helps to reduce radiation dose by approximately 35-60%, while maintaining diagnostic image quality comparable to that of a regular-dose protocol using FBP.
authors.affiliation: 1 Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Rue du Bugnon 46, Lausanne 1011, Switzerland.
authors.forename: Frank
authors.initials: F
authors.lastname: Tobalem
authors.forename: Eric
authors.initials: E
authors.lastname: Dugert
authors.forename: Francis R
authors.initials: FR
authors.lastname: Verdun
authors.forename: Vincent
authors.initials: V
authors.lastname: Dunet
authors.forename: Julien G
authors.initials: JG
authors.lastname: Ott
authors.forename: Hannes A
authors.initials: HA
authors.lastname: Rudiger
authors.forename: Stephane
authors.initials: S
authors.lastname: Cherix
authors.forename: Reto
authors.initials: R
authors.lastname: Meuli
authors.forename: Fabio
authors.initials: F
authors.lastname: Becce
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001175:Arthrography / Q000379:methods*; D003627:Data Interpretation, Statistical; D005240:Feasibility Studies; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D007592:Joint Diseases / Q000000981:diagnostic imaging*; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: CT arthrography; hip; image quality; iterative reconstruction; radiation dose