2012 DUAL-ENERGY VERSUS CONVENTIONAL COMPUTED TOMOGRAPHY IN DETERMINING STONE COMPOSITION

Abstract

You have accessJournal of UrologyImaging/Radiology: Uroradiology (I)1 Apr 20132012 DUAL-ENERGY VERSUS CONVENTIONAL COMPUTED TOMOGRAPHY IN DETERMINING STONE COMPOSITION Eric Wisenbaugh, Robert Paden, Alvin Silva, and Mitchell Humphreys Eric WisenbaughEric Wisenbaugh Phoenix, AZ More articles by this author , Robert PadenRobert Paden Phoenix, AZ More articles by this author , Alvin SilvaAlvin Silva Phoenix, AZ More articles by this author , and Mitchell HumphreysMitchell Humphreys Phoenix, AZ More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.2431AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The successful treatment of urolithiasis can be largely dependent on stone composition, yet there is no reliable method of composition determination with conventional imaging. While uric acid stones can be differentiated from calcium stones on the basis of Hounsfield-Units (HU), accurately differentiating other subtypes remains elusive. Dual-energy computed tomography (DECT) is a promising imaging modality that has the potential to improve our current ability to determine different stone phenotypes and compositions. Our goal was to compare the accuracy between conventional single-energy and dual-energy CT in predicting stone composition. METHODS A total of 32 renal stones with known composition were placed in a phantom water bath and scanned using fast-switched kV DECT at 80 and 140kV (GE Discovery 750 HD, Milwaukee, WI. Images were viewed on a processing workstation capable of displaying pixel values for monochromatic images from 40 to 140 KeV. Stones were composed of uric acid, cystine, struvite, and calcium oxalate. A region of interest (ROI) was encircled on each stone and a spectral curve was created demonstrating the change of HU across the KeV spectrum. Sample curves were compared to curves of known materials from the National Institute of Standards and Technology to determine the best fit for each stone. Composition using single-energy CT was determined by measuring the HU for a ROI at 120KeV and comparing them to known HU values attained from the literature. RESULTS Included were 29 stones large enough to allow a ROI that fit completely within the stone. Of these, single-energy measurements accurately identified 12 of 29 stones of all composition (44%), while the DECT spectral curves correctly identified 20 (74%). When analyzed by stone type, single-energy vs. DECT correctly identified 12 vs. 12 of the twelve uric acid stones, 0 vs. 3 of the six struvite stones, 0 vs. 3 of the five cystine stones and 0 vs. 2 of the four calcium oxalate stones, respectively. When classified simply as uric acid vs. non-uric acid stones, single-energy CT could accurately differentiate only 3 of 15 non-uric acid stones (20%), compared to 14 of 15 (93%) for DECT. CONCLUSIONS Dual-energy CT appears to be superior to conventional CT in differentiating stone composition, and is particularly accurate in detecting uric acid vs. non-uric acid stones. This may serve as an important adjuvant modality that could guide important treatment decisions for kidney stone patients. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e826-e827 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Eric Wisenbaugh Phoenix, AZ More articles by this author Robert Paden Phoenix, AZ More articles by this author Alvin Silva Phoenix, AZ More articles by this author Mitchell Humphreys Phoenix, AZ More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...