title: [CT SCAN as a predictor of composition and fragility of urinary lithiasis treated with extracorporeal shock wave lithotripsy in vitro].
abstract: OBJECTIVE
  To evaluate the ability of non contrast computed tomography (NCCT) to predict stone composition and fragility for treatment with extracorporeal shock wave lithotripsy (ESWL).
  
  
  METHODS
  27 stones of about 10 mm from patients who had undergone different endourological procedures were collected. All patients had been evaluated with NCCT. To perform in vitro ESWL an experimental device was designed. Three thousand pulses were applied with 17.2 Kv intensity using an electromagnetic generator (Lithostar) to all stones. Composition of each fragment was studied with crystallographic study. Results were statistically analyzed with Student Test, Chi2 Test and multivariate study.
  
  
  RESULTS
  In vitro ESWL had a success rate of 59.26%. Average stone HU, grouped by composition: cistine 1015 HU, Calcium monohydrate oxalate 1193 HU, uric acid 419 HU, dihydrate calcium oxalate 2122 HU, struvite 1543 HU and basic phosphate magnesium 1517 HU. A statistically significant relationship was found between values which were lower than 500 HU and uric acid composition (p=0.0006), as well as values higher than 2000 HU and composition of dihydrated calcium acid (p=0.0244). In the group of stones with less than 1000 HU (n=11) efficacy was 81.1%, whereas it was 43.75% in the others (p=0.0479). We found a statistically significant relationship between uric acid and effectiveness (p=0.021). There was not statistically significant relationship between size and treatment effectiveness.
  
  
  CONCLUSIONS
  The use of NCCT will allow predicting stone composition and fragility.
authors: Centro de Litiasis, Servicio de Urología, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina. patricio.garcia@hospitalitaliano.org.ar
authors: Patricio
authors: P
authors: García Marchiñena
authors: Nicolás
authors: N
authors: Billordo Peres
authors: Juan
authors: J
authors: Liyo
authors: Jorge
authors: J
authors: Ocantos
authors: Mariano
authors: M
authors: Gonzalez
authors: Alberto
authors: A
authors: Jurado
authors: Francisco
authors: F
authors: Daels
mesh_terms: D003461:Crystallography; D006801:Humans; D066298:In Vitro Techniques; D008096:Lithotripsy; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed; D014545:Urinary Calculi / Q000737:chemistry* / Q000000981:diagnostic imaging / Q000628:therapy*