title: 256-MDCT for evaluation of urolithiasis: iterative reconstruction allows for a significant reduction of the applied radiation dose while maintaining high subjective and objective image quality.
abstract: OBJECTIVE
  Multidetector CT (MDCT) is the established imaging modality in diagnostics of urolithiasis. The aim of iterative reconstruction (IR) is to allow for a radiation dose reduction while maintaining high image quality. This study evaluates its performance in MDCT for assessment of urolithiasis.
  
  
  METHODS
  Fifty-two patients underwent non-contrast abdominal MDCT. Twenty-six patients were referred to MDCT under suspicion of urolithiasis, and examined using a dose-reduced scan protocol (RDCT). Twenty-six patients, who had undergone standard-dose MDCT, served as reference for radiation dose comparison. RDCT images were reconstructed using an IR system (iDose4™, Philips Healthcare, Cleveland, OH, USA). Objective image noise (OIN) was recorded and five radiologists rated the subjective image quality independently. Radiation parameters were derived from the scan protocols.
  
  
  RESULTS
  The CTDIvol could be reduced by 50% to 5.8 mGy (P < 0.0001). The same reduction was achieved for DLP and effective dose to 253 ± 27 mGy*cm (P < 0.0001) and 3.9 ± 0.4 mSv (P < 0.0001). IR led to a reduction of the OIN of up to 61% compared with classic filtered back projection (FBP) (P < 0.0001). The OIN declined with increasing IR levels. RDCT with FBP showed the lowest scores of subjective image quality (2.32 ± 0.04). Mean scores improved with increasing IR levels. iDose6 was rated with the best mean score (3.66 ± 0.04).
  
  
  CONCLUSIONS
  The evaluated IR-tool and protocol may be applied to achieve a considerable radiation dose reduction in MDCT for diagnostics of urolithiasis while maintaining a confident image quality. Best image quality, suitable for evaluation of the entire abdomen concerning differential diagnoses, was achieved with iDose6.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Medical Center Würzburg, Würzburg, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Veldhoen
authors.forename: Azien
authors.initials: A
authors.lastname: Laqmani
authors.forename: Thorsten
authors.initials: T
authors.lastname: Derlin
authors.forename: Murat
authors.initials: M
authors.lastname: Karul
authors.forename: Diego
authors.initials: D
authors.lastname: Hammerle
authors.forename: Jan-Hendrik
authors.initials: JH
authors.lastname: Buhk
authors.forename: Susanne
authors.initials: S
authors.lastname: Sehner
authors.forename: Hans D
authors.initials: HD
authors.lastname: Nagel
authors.forename: Felix
authors.initials: F
authors.lastname: Chun
authors.forename: Gerhard
authors.initials: G
authors.lastname: Adam
authors.forename: Marc
authors.initials: M
authors.lastname: Regier
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001822:Body Burden; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D015588:Observer Variation; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052878:Urolithiasis / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: iterative reconstruction; multidetector computed tomography; urolithiasis