Role of Dual-Energy Computed Tomography in Characterization of Ureteric Calculi and Urinary Obstruction.

Anchal Singh,Mushahid Husain,Shreshtha Jain,Mazhar Khan,Poonam Yadav,Ahmad Umar Khan,Nazia Khan,Sachin Khanduri

doi:10.7759/cureus.8002

Abstract

ObjectiveThe present study was carried out to assess the accuracy of dual-energy computed tomography (DECT) in the morphological and chemical characterization of ureteric calculi along with the prediction of the grade of urinary obstruction.MethodsThis was a prospective observational study that included 100 cases with ultrasonography (USG)-diagnosed ureteric calculi that underwent surgery or had spontaneous expulsion of ureteric calculi. At enrolment, DECT was performed for an in vivo evaluation of volume, chemical composition, and grade of obstruction by subjective assessment of the perinephric edema. After surgical intervention, in vitro evaluation of volume was done by fluid displacement followed by infrared spectroscopy (IRS) for chemical composition. DECT findings were compared with the biochemical analysis and degree of obstruction was validated against excretory CT urograms. Sensitivity, specificity, and the positive predictive and negative predictive values of DECT were assessed.ResultsNo significant difference was observed between the mean volume of stones by fluid displacement (65.1±77.61 mm3) and DECT assessment (66.09±81.78 mm3). IRS revealed the composition of stones as hydroxyapatite, uric acid, cysteine, oxalic acid, and mixed type in 48, 23, 15, five, and nine cases. The sensitivity and specificity of DECT for hydroxyapatite, uric acid, cysteine, oxalic acid, and mixed types were 89.6% and 88.5%, 82.6% and 97.5%, 86.7% and 96.5%, 80% and 98.9%, and 88.9% and 98.9%, respectively. On CT urography, a total of 35 had a high-grade and 65 had a low-grade obstruction, whereas DECT revealed high- and low-grade obstructions in 42 and 58 cases. The sensitivity and specificity of DECT for a high-grade obstruction were 94.3% and 86.2%.ConclusionsThe findings of the study showed that DECT provides comprehensive information regarding the morphological, chemical, and anatomical characterization of ureteric stones.

Highlights

Urolithiasis is a common problem affecting 1%-5% of the population
The present study was carried out to assess the accuracy of dual-energy computed tomography (DECT) in the morphological and chemical characterization of ureteric calculi along with the prediction of the grade of urinary obstruction
In vitro evaluation of volume was done by fluid displacement followed by infrared spectroscopy (IRS) for chemical composition

Summary

Introduction

Urolithiasis is a common problem affecting 1%-5% of the population. It has a significant impact on the quality of life and leads to significant morbidity [1,2]. The study of urolithiasis is important because of the high recurrence rates and incidence and because of the complications that arise from it like hydronephrosis leading to renal failure in the long run if the stone partially obstructs the urinary tract [4]. Imaging techniques, such as urography and ultrasonography (USG), are helpful in characterizing the morphology, size, number, and, to a certain extent, volume of the ureteric calculi.

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Results

Conclusion