title: Differentiation of calcium oxalate monohydrate and calcium oxalate dihydrate stones using quantitative morphological information from micro-computerized and clinical computerized tomography.
abstract: OBJECTIVE
  We differentiated calcium oxalate monohydrate and calcium oxalate dihydrate kidney stones using micro and clinical computerized tomography images.
  
  
  METHODS
  A total of 22 calcium oxalate monohydrate and 15 calcium oxalate dihydrate human kidney stones were scanned using a commercial micro-computerized tomography scanner with a pixel size of 7 to 23 μm. Under an institutional review board approved protocol, image data on 10 calcium oxalate monohydrate and 9 calcium oxalate dihydrate stones greater than 5 mm were retrieved from a total of 80 patients who underwent clinical dual energy computerized tomography for clinical indications and had stones available for infrared spectroscopic compositional analysis. Micro and clinical computerized tomography images were processed using in-house software, which quantified stone surface morphology with curvature based calculations. A shape index was generated as a quantitative shape metric to differentiate calcium oxalate monohydrate from calcium oxalate dihydrate stones. Statistical tests were used to test the performance of the shape index.
  
  
  RESULTS
  On micro-computerized tomography images the shape index of calcium oxalate monohydrate and calcium oxalate dihydrate stones significantly differed (ROC curve AUC 0.92, p <0.0001). At the optimal cutoff sensitivity was 0.93 and specificity was 0.91. On clinical computerized tomography images a significant morphological difference was also detected (p = 0.007). AUC, sensitivity and specificity were 0.90, 1 and 0.73, respectively.
  
  
  CONCLUSIONS
  On micro and clinical computerized tomography images a morphological difference was detectable in calcium oxalate monohydrate and calcium oxalate dihydrate stones larger than 5 mm. The shape index is a highly promising method that can distinguish calcium oxalate monohydrate and calcium oxalate dihydrate stones with reasonable accuracy.
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Xinhui
authors.initials: X
authors.lastname: Duan
authors.forename: Mingliang
authors.initials: M
authors.lastname: Qu
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: James
authors.initials: J
authors.lastname: Trevathan
authors.forename: Terri
authors.initials: T
authors.lastname: Vrtiska
authors.forename: James C
authors.initials: JC
authors.lastname: Williams
authors.forename: Amy
authors.initials: A
authors.lastname: Krambeck
authors.forename: John
authors.initials: J
authors.lastname: Lieske
authors.forename: Cynthia
authors.initials: C
authors.lastname: McCollough
mesh_terms: D019540:Area Under Curve; D002129:Calcium Oxalate / Q000032:analysis* / Q000737:chemistry; D016001:Confidence Intervals; D003937:Diagnosis, Differential; D006801:Humans; D066298:In Vitro Techniques; D007669:Kidney Calculi / Q000737:chemistry* / Q000000981:diagnostic imaging; D008838:Microcomputers; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D002129:Calcium Oxalate