2187 BRUSHITE STONE FRAGILITY IN SHOCK WAVE LITHOTRIPSY IS NOT PREDICTED BY CT VISIBLE STRUCTURE OR HOUNSFIELD UNITS

Abstract

You have accessJournal of UrologyImaging/Radiology: Uroradiology II1 Apr 20122187 BRUSHITE STONE FRAGILITY IN SHOCK WAVE LITHOTRIPSY IS NOT PREDICTED BY CT VISIBLE STRUCTURE OR HOUNSFIELD UNITS James Williams, Tariq Hameed, Syed Aftab, James Lingeman, and James McAteer James WilliamsJames Williams Indianapolis, IN More articles by this author , Tariq HameedTariq Hameed Indianapolis, IN More articles by this author , Syed AftabSyed Aftab Indianapolis, IN More articles by this author , James LingemanJames Lingeman Indianapolis, IN More articles by this author , and James McAteerJames McAteer Indianapolis, IN More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2361AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Brushite stones are challenging as they recur frequently and are often resistant to breakage by shock wave lithotripsy (SWL). With other stone types it has been shown in laboratory studies that visibility of structure in stones using helical computed tomography (helical CT) correlates with easier breakage with SWL. The objective of this study was to test brushite stones for similar correlation of stone fragility with internal stone structure visible by CT. METHODS Fifty-two brushite stones, ranging in size from 5 to 12 mm, were scanned by micro CT, weighed, hydrated, and placed within a saline radiological phantom containing 3% iodine to emulate body tissue. The stones were scanned using a 256-slice Brilliance iCT scanner (Philips Healthcare), and the images evaluated for visibility of internal structural features. The stones were then treated by SWL in vitro, and the number of SWs needed to break each stone to completion (fragments < 2 mm) was recorded. Fragments were analyzed using IR spectroscopy to assess stone mineral purity. RESULTS The number of SWs to break each stone, normalized to stone weight, did not differ by Hounsfield unit value (P=0.84), or CT-visible structure that could be identified consistently (unanimous opinion only, P =0.053) by all observers; however, observer agreement was low (kappa=0.3) in the identification of CT-visible structure. Fragility of stones was highly correlated with stone density and with brushite content (both P <0.001), with stones of nearly pure brushite requiring the most SWs to break. When all observations of CT-visible structure were used in analysis by logistic fit, there was poor correlation between stone structure and fragility, with low sensitivity (0.62), low specificity (0.51), and an overall area under the receiver operating characteristic (ROC) curve of only 0.64. CONCLUSIONS SWL fragility of brushite stones did not correlate with internal structure discernable using helical CT. However, fragility did correlate with stone density and increasing brushite mineral content, which is consistent with clinical experience with brushite stone patients. Thus, current technology in diagnostic CT does not provide a means to predict if brushite stones will break well using SWL. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e882 Peer Review Report Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information James Williams Indianapolis, IN More articles by this author Tariq Hameed Indianapolis, IN More articles by this author Syed Aftab Indianapolis, IN More articles by this author James Lingeman Indianapolis, IN More articles by this author James McAteer Indianapolis, IN More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...