title: Role of dual-source dual-energy computed tomography versus X-ray crystallography in prediction of the stone composition: a retrospective non-randomized pilot study.
abstract: OBJECTIVE
  We aimed to evaluate the accuracy of determining stone composition with dual-source (DS) dual-energy (DE) computed tomography (CT).
  
  
  METHODS
  A total of 142 patients, diagnosed with urolithiasis and had complete medical records, were included in the study. The number, dimensions, location and CT density of the stones, and dose-length products and effective radiation dose were recorded for every patient. Stone compositions determined with DECT by two radiologists separately were compared with crystallography method.
  
  
  RESULTS
  Among 138 stones with a crystallographic result out of 187 stones evaluated, 58 calcium oxalate, 42 hydroxyapatite, 24 uric acid and 10 cystine stones were detected. DECT showed a sensitivity and negative predictive value of 68.67 and 67.5 % for calcium oxalate. Moreover, DECT was found to be very useful in predicting hydroxyapatite and cystine stones with a 100 % sensitivity and negative predictive value. Cohen kappa correlation test showed a substantial agreement (κ = 0.682) between crystallographic analysis and prediction with DECT-analysis, which was statistically significant (p < 0.001).
  
  
  CONCLUSIONS
  In this retrospective study, an unenhanced DECT was found to be accurate for in vivo determination of stone type, and thus it can be used easily without any extra burden to the patient or cost while providing additional information.
authors.affiliation: School of Medicine, Department of Urology, Selcuk University, Konya, Turkey. drmuratakand@yahoo.com.
authors.forename: Murat
authors.initials: M
authors.lastname: Akand
authors.affiliation: School of Medicine, Department of Radiology, Selcuk University, Konya, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Koplay
authors.affiliation: School of Medicine, Department of Radiology, Selcuk University, Konya, Turkey.
authors.forename: Necat
authors.initials: N
authors.lastname: Islamoglu
authors.affiliation: School of Medicine, Department of Urology, Selcuk University, Konya, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Gul
authors.affiliation: School of Medicine, Department of Urology, Selcuk University, Konya, Turkey.
authors.forename: Ozcan
authors.initials: O
authors.lastname: Kilic
authors.affiliation: Department of Inspection and Evaluation, Turkish Republic Ministry of Health, General Directorate of Health Services, Ankara, Turkey.
authors.forename: Merter Bora
authors.initials: MB
authors.lastname: Erdogdu
mesh_terms: D000328:Adult; D002129:Calcium Oxalate / Q000032:analysis; D018360:Crystallography, X-Ray; D003553:Cystine / Q000032:analysis; D017886:Durapatite / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014527:Uric Acid / Q000032:analysis; D014545:Urinary Calculi / Q000737:chemistry* / Q000000981:diagnostic imaging*
chemical_list: D002129:Calcium Oxalate; D014527:Uric Acid; D003553:Cystine; D017886:Durapatite
keywords: Computed tomography; Dual energy; Hounsfield unit; Stone type; Urolithiasis