title: Noncontrast computed tomography factors that predict the renal stone outcome after shock wave lithotripsy.
abstract: OBJECTIVE
  Extracorporeal shock wave lithotripsy (ESWL) is a popular treatment for nephrolithiasis. We took advantage of noncontrast abdominal computed tomography (NCCT) to search the possible prognostic factors including abdominal fat distribution influencing stone-free rate.
  
  
  METHODS
  From August 2008 to August 2010, 145 patients who had renal calculus and had undergone ESWL were retrospectively reviewed. All of them received NCCT assessment before ESWL and were followed up after 1 month for stone clearance. These patients were divided into two groups: one was the stone-free group and the other was the residual-stone group. Affecting parameters included stone size, location, stone surface area, Hounsfield unit density (HU density), skin-to-stone distance (SSD), and abdominal fat area as analyzed between these two groups.
  
  
  RESULTS
  Of 145 patients, 70 were stone-free and 75 had residual stone after ESWL treatment and 1-month follow-up. From univariate analysis, stone size, HU density, SSD, and stone surface area were significant predicting factors for ESWL success. On multivariate analysis, the important factors influencing ESWL outcomes were HU density and stone surface area (odds ratio 1.002 vs. 77.18, respectively; P<.05). Abdominal fat accumulation and distribution had no significant difference between these two groups.
  
  
  CONCLUSIONS
  This study revealed that stone size, HU density, SSD, and stone surface area were associated with stone-free rate after ESWL treatment. Therefore, these factors could be used to assess the feasibility of ESWL before deciding the treatment strategy. Abdominal fat distribution had no significant impact on ESWL outcome for renal stones.
authors.affiliation: Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Urology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan.
authors.forename: Hsiang-Ying
authors.initials: HY
authors.lastname: Lee
authors.affiliation: Division of Statistical Analysis, Department of Medical Research, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yi-Hsin
authors.initials: YH
authors.lastname: Yang
authors.affiliation: Department of Urology, Cishan Hospital, Ministry of Health and Welfare, Kaohsiung, Taiwan.
authors.forename: Yi-Lun
authors.initials: YL
authors.lastname: Lee
authors.affiliation: Department of Urology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan.
authors.forename: Jung-Tsung
authors.initials: JT
authors.lastname: Shen
authors.affiliation: Department of Urology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan.
authors.forename: Mei-Yu
authors.initials: MY
authors.lastname: Jang
authors.affiliation: Department of Radiology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan.
authors.forename: Paul Ming-Chen
authors.initials: PM
authors.lastname: Shih
authors.affiliation: Department of Urology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan; Department of Urology, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan.
authors.forename: Wen-Jeng
authors.initials: WJ
authors.lastname: Wu
authors.affiliation: Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Yii-Her
authors.initials: YH
authors.lastname: Chou
authors.affiliation: Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Urology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan; Department of Urology, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan; Graduate Institute of Medical Science, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: juanuro@gmail.com.
authors.forename: Yung-Shun
authors.initials: YS
authors.lastname: Juan
mesh_terms: D050153:Abdominal Fat / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging / Q000628:therapy*; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D053040:Nephrolithiasis / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Noncontrast computed tomography; Outcomes; Renal stones; Shock wave lithotripsy