title: Digital Tomosynthesis: A Viable Alternative to Noncontrast Computed Tomography for the Follow-Up of Nephrolithiasis?
abstract: OBJECTIVE
  Digital tomosynthesis (DT) is a new X-ray-based imaging technique that allows image enhancement with minimal increase in radiation exposure. The purpose of this study was to compare DT with noncontrast computed tomography (NCCT) and to evaluate its potential role for the follow-up of patients with nephrolithiasis in a nonemergent setting.
  
  
  METHODS
  A retrospective review of patients with nephrolithiasis at our institution that underwent NCCT and DT from July 2012 to September 2013 was performed. Renal units (RUs) that did not undergo treatment or stone passage were randomly assigned to two blinded readers, who recorded stone count, size area (mm(2)), maximum stone length (mm), and location, for both DT and NCCT. Mean differences per RU were compared. Potential variables affecting stone detection rate, including stone size and body mass index (BMI), were evaluated. Interobserver agreement was determined using the intraclass correlation coefficient to measure the consistency of measurements made by the readers.
  
  
  RESULTS
  DT and NCCT demonstrated similar stone detection rates in terms of stone counts and stone area mm(2). Of the 79 RUs assessed, 41 RUs showed exact stone counts on DT and NCCT. The mean difference in stone area was 16.5 mm(2) (-4.6 to 38.5), p = 0.121. The mean size of the largest stone on NCCT and DT was 9.27 and 8.87 mm, respectively. Stone size and BMI did not cause a significant difference in stone detection rates. Interobserver agreement showed a strong correlation between readers and adequate reproducibility.
  
  
  CONCLUSIONS
  We found DT to be a comparable imaging modality to NCCT for the detection of intrarenal stones, without a significant effect from stone size and BMI and adequate reproducibility between multiple readers. DT appears to be an ideal alternative for following patients with nephrolithiasis due to its acceptable stone detection rates, low radiation exposure, and decreased cost compared to NCCT.
authors.affiliation: 1 Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Cabrera
authors.affiliation: 1 Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Kaplan
authors.affiliation: 2 Department of Urologic Surgery, University of California , Irvine, Orange, California.
authors.forename: Ramy F
authors.initials: RF
authors.lastname: Youssef
authors.affiliation: 1 Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.
authors.forename: Matvey
authors.initials: M
authors.lastname: Tsivian
authors.affiliation: 1 Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Shin
authors.affiliation: 1 Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.|3 Duke Clinical Research Institute, Duke University , Durham, North Carolina.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Scales
authors.affiliation: 1 Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Preminger
authors.affiliation: 1 Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Lipkin
mesh_terms: D003365:Costs and Cost Analysis; D005500:Follow-Up Studies; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging*; D008096:Lithotripsy / Q000379:methods; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods*; D011859:Radiography / Q000379:methods; D011897:Random Allocation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*