title: Predictive value of low tube voltage and dual-energy CT for successful shock wave lithotripsy: an in vitro study.
abstract: This study investigates the capabilities of low tube voltage computed tomography (CT) and dual-energy CT (DECT) for predicting successful shock wave lithotripsy (SWL) of urinary stones in vitro. A total of 33 urinary calculi (six different chemical compositions; mean size 6 ± 3 mm) were scanned using a dual-source CT machine with single- (120 kVp) and dual-energy settings (80/150, 100/150 Sn kVp) resulting in six different datasets. The attenuation (Hounsfield Units) of calculi was measured on single-energy CT images and the dual-energy indices (DEIs) were calculated from DECT acquisitions. Calculi underwent SWL and the number of shock waves for successful disintegration was recorded. The prediction of required shock waves regarding stone attenuation/DEI was calculated using regression analysis (adjusted for stone size and composition) and the correlation between CT attenuation/DEI and the number of shock waves was assessed for all datasets. The median number of shock waves for successful stone disintegration was 72 (interquartile range 30-361). CT attenuation/DEI of stones was a significant, independent predictor (P < 0.01) for the number of required shock waves with the best prediction at 80 kVp (β estimate 0.576) (P < 0.05). Correlation coefficients between attenuation/DEI and the number of required shock waves ranged between ρ = 0.31 and 0.68 showing the best correlation at 80 kVp (P < 0.001). The attenuation of urinary stones at low tube voltage CT is the best predictor for successful stone disintegration, being independent of stone composition and size. DECT shows no added value for predicting the success of SWL.
authors.affiliation: Department of Urology, University Hospital Zürich, University of Zürich, Zürich, Switzerland.
authors.forename: Remo
authors.initials: R
authors.lastname: Largo
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zürich, Raemistrasse 100, 8091, Zürich, Switzerland.
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzmann
authors.affiliation: Department of Urology, University Hospital Zürich, University of Zürich, Zürich, Switzerland.
authors.forename: Christian D
authors.initials: CD
authors.lastname: Fankhauser
authors.affiliation: Department of Urology, University Hospital Zürich, University of Zürich, Zürich, Switzerland.
authors.forename: Cédric
authors.initials: C
authors.lastname: Poyet
authors.affiliation: Department of Urology, University Hospital Zürich, University of Zürich, Zürich, Switzerland.
authors.forename: Pirmin
authors.initials: P
authors.lastname: Wolfsgruber
authors.affiliation: Department of Urology, University Hospital Zürich, University of Zürich, Zürich, Switzerland.
authors.forename: Tullio
authors.initials: T
authors.lastname: Sulser
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zürich, Raemistrasse 100, 8091, Zürich, Switzerland.
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zürich, Raemistrasse 100, 8091, Zürich, Switzerland. sebastian.winklhofer@usz.ch.|Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave, M-372, Box 0628, San Francisco, CA, 94143-0628, USA. sebastian.winklhofer@usz.ch.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Winklhofer
mesh_terms: D011211:Electric Power Supplies; D006801:Humans; D066298:In Vitro Techniques; D008096:Lithotripsy; D011237:Predictive Value of Tests; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D014545:Urinary Calculi / Q000000981:diagnostic imaging* / Q000628:therapy*
keywords: Computed tomography; Extracorporeal shockwave lithotripsy; Kidney calculi