Demonstrating the Efficacy of Dual Energy Computer Tomography with Gemstone Spectral Imaging Software to Determine Mixed and Single Composition ex vivo Urolithiasis

Daniel Magee,1 Feroza Jeewa,1 Matthew Vinh-Hoan Dinh Chau,1 Pamphila Lovelle Loh,1 Begona Ballesta Martinez,1– 3 Manmeet Saluja,1 Ivan H Aw,1 Mikhail Lozinskiy,1 Sunny Lee,1 Melanie Rosenberg,4 Yuigi Yuiminaga1 1Department of Urology, Royal Perth Hospital, Perth, WA, Australia; 2Department of Urology, University of Patras, Patras, Greece; 3University of La Laguna, SC de Tenerife, Spain; 4Senior Radiographer, Department of Radiology, Royal Perth Hospital, Perth, WA, AustraliaCorrespondence: Daniel Magee, Department of Urology, Royal Perth Hospital, Wellington Street, Perth, WA, 6000, Australia, Tel +61 9224 2931, Email [email protected]: To assess the capability of determining the mixed chemical composition of urinary stones using spectral imaging properties of Dual Energy Computed Tomography (DECT) Gemstone Spectral Imaging (GSI) software.Material and Methods: Twenty-six single and 24 mixed composition ex vivo urinary stones with known chemical composition determined by Fourier-transform infrared spectroscopy (FTIR) prior to this project were scanned with DECT imaging and GSI in vitro. The major components of the stones included Uric Acid (UA), Calcium Oxalate (CaOx), Calcium Phosphate (CaP), Magnesium Ammonium Phosphate (MAP), and Cystine (Cys). A histogram to display the distribution of the effective atomic number (Z-eff) of each pixel of the tested area, spectral curve (40– 140 keV, with 10 keV interval) and Hounsfield Units (HU) of each stone scanned was provided with analysis of monochromatic images at 140 keV in the axial plane.Results: The overall pooled sensitivity, specificity, and accuracy of DECT for identifying major stone composition were 0.802, 0.831, and 0.807, respectively, with a 95% confidence interval. Accuracy was 100% for identifying UA and Cys stones.Conclusion: DECT is a superior imaging modality when compared to low dose computed tomography kidney ureter bladder scans. It allows for improved characterization of major components of urinary stones, in an accurate, non-invasive approach to pre-treatment. This can translate to urologists having greater confidence in determining patient suitability for medical or surgical management of their renal stones, in clinical practice.Keywords: endourology, basic research, dual energy computer tomography, DECT, GSI, gemstone spectral imaging