Diagnostic validity of dual-energy CT in determination of urolithiasis chemical composition: In vivo analysis

Abstract

Purpose: To prospectively assess the ability of Dual-energy CT (DECT) for determining the composition of urinary tract calculi in vivo. Subjects and methods: 60 patients (34 men and 26 women; age range 22–68 years; mean age 42 ± 10.3 years) with urolithiasis were examined with DECT using a protocol that included 100/Sn140 kV. The calculi were categorized as uric acid, cysteine, and calcium oxalate or phosphate in accordance with their attenuation values at 100/Sn140 kV. Chemical analysis of the calculi was used as reference standard. Results: 84 calculi were identified in 60 patients (58 calculi were found in renal calyces, 14 in ureters, 10 in the renal pelvis, and two in the bladder). The DECT correctly revealed calculus composition in 76/84 (90.5%) of the patients. The DECT is highly reliable in discriminating uric acid from non-uric acid calculi in 82/84 (97.6%) of the patients. The sensitivity and specificity in distinguishing uric acid from non-uric acid calculi were 100% and 96.9% respectively. Calcified calculi were difficult to be discriminated. Mixed calculi were excluded from the study. Conclusion: DECT allow the correct description of urinary calculus composition in vivo.

Keywords

• DECT
• Urolithiasis
• Uric acid
• Chemical compositions