New Technology: Stones
Moderated Poster Session
MP22-15 - Efficacy of Single-source Rapid kv-Switching Dual-energy CT for Characterization of Non-uric Acid Renal Stones: a Prospective Ex-vivo Study Using Anthropomorphic Phantom
Saturday, September 22
2:00 PM - 4:00 PM
Location: Room 252B
Introduction & Objective :
To investigate the accuracy of rapid kV-switching single-source dual-energy computer tomography for prediction of classes of non-uric acid stones.
Non-uric-acid renal stones retrieved via percutaneous nephrolithotomy were prospectively collected between January 2017 and February 2018 in a single institution. Only stones >5mm and with pure composition (i.e. >80% composed of one element) were studied. Stone composition was determined using Fourier Transform Infrared Spectroscopy. The stones were scanned in 32 cm-wide anthropomorphic whole body phantom in a location mimicking the kidneys. Image acquisition was performed using a single-source rapid-kVp switching CT scanner. The effective atomic number (Zeff) and the attenuation (HU) at 40 kev, 70 kev, and 140 kev virtual monochromatic sets of images were extracted by placing a ROI at the largest cross-sectional areas. Ratios between the attenuations at different energy levels were calculated. Mean values of different stone classes were compared using ANOVA and student t-test. Difference between the actual class of stone and the predicted class of stone based on vendor-recommended Zeff thresholds were assessed. A p-value
The final study sample included 31 stones from 31 patients consisting of 2 (6%) struvite, 4 (13%) cystein and 25 (81%) calcium-based pure stones. The mean size of the stones was 9.9 ± 2.4 mm. The mean Zeff of the stones was 12.0±0.41 for calcium-based, 10.1 ± 0.14 for struvite, and 9.9 ± 0.57 for cystein stones which were statistically different (p
Zeff has superior performance to HU and attenuation ratios for differentiation of different classes of non-uric-acid stones.