title: Establishing composition and structure of intact urinary calculi by x-ray coherent scatter for clinical laboratory investigations.
abstract: OBJECTIVE
  Current urinary stone analysis techniques are limited in their abilities to simultaneously characterize composition and structure. Laboratory techniques such as IRS and x-ray diffractometry require small powdered samples for analysis, rendering composition results dependent on the choice of sample and its preparation. We investigated the application of x-ray CS analysis to identify topographic urinary stone composition ex vivo. CS is essentially a transmission based x-ray diffractometry method that depends on molecular structure and, therefore, can distinguish different compounds. Diagnostic x-ray equipment facilitates the examination of structural arrangements of minerals in intact calculi.
  
  
  METHODS
  Tomographic images of intact calculi CS properties were acquired with a purposely built scanner. Composition is extracted from CS by fitting a library of common pure stone component CS signatures to those of the unknown sample in each image pixel. Two zones per stone were isolated (powdered) for IRS composition analysis for comparison with CS maps at these locations. Each stone was also independently analyzed for bulk composition by IRS analysis.
  
  
  RESULTS
  CS composition maps revealed the spatial arrangement of minerals in intact calculi. IRS results showed good agreement with CS in the selected regions of interest. Bulk composition by IRS was noted to miss some important stone components, indicating that the choice of sample may skew composition results.
  
  
  CONCLUSIONS
  CS from diagnostic x-rays can be used to identify structure and composition in mixed urinary calculi nondestructively. The tissue specific CS images presented support the development of CS analysis as a means of identifying stone composition characteristics in the laboratory.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.
authors.forename: Melanie T M
authors.initials: MT
authors.lastname: Davidson
authors.forename: Deidre L
authors.initials: DL
authors.lastname: Batchelar
authors.forename: Ben H
authors.initials: BH
authors.lastname: Chew
authors.forename: John D
authors.initials: JD
authors.lastname: Denstedt
authors.forename: Ian A
authors.initials: IA
authors.lastname: Cunningham
mesh_terms: D018360:Crystallography, X-Ray; D006801:Humans; D014545:Urinary Calculi / Q000737:chemistry*