Journal Article

Dual-layer spectral detector CT: non-inferiority assessment compared to dual-source dual-energy CT in discriminating uric acid from non-uric acid renal stones ex vivo

Duan, Xinhui, Leyendecker, John R, Antonelli, Jodi A, Ananthakrishnan, Lakshmi, Abbara, Suhny, Yin Xi, Kolitz, Elysha M, Fielding, Julia R, Goerne, Harold, Lewis, Matthew A, Pearle, Margaret S, Lenkinski, Robert E

2018

Overview

PurposeTo assess the non-inferiority of dual-layer spectral detector CT (SDCT) compared to dual-source dual-energy CT (dsDECT) in discriminating uric acid (UA) from non-UA stones.MethodsFifty-seven extracted urinary calculi were placed in a cylindrical phantom in a water bath and scanned on a SDCT scanner (IQon, Philips Healthcare) and second- and third-generation dsDECT scanners (Somatom Flash and Force, Siemens Healthcare) under matched scan parameters. For SDCT data, conventional images and virtual monoenergetic reconstructions were created. A customized 3D growing region segmentation tool was used to segment each stone on a pixel-by-pixel basis for statistical analysis. Median virtual monoenergetic ratios (VMRs) of 40/200, 62/92, and 62/100 for each stone were recorded. For dsDECT data, dual-energy ratio (DER) for each stone was recorded from vendor-specific postprocessing software (Syngo Via) using the Kidney Stones Application. The clinical reference standard of X-ray diffraction analysis was used to assess non-inferiority. Area under the receiver-operating characteristic curve (AUC) was used to assess diagnostic performance of detecting UA stones.ResultsSix pure UA, 47 pure calcium-based, 1 pure cystine, and 3 mixed struvite stones were scanned. All pure UA stones were correctly separated from non-UA stones using SDCT and dsDECT (AUC = 1). For UA stones, median VMR was 0.95–0.99 and DER 1.00–1.02. For non-UA stones, median VMR was 1.4–4.1 and DER 1.39–1.69.ConclusionSDCT spectral reconstructions demonstrate similar performance to those of dsDECT in discriminating UA from non-UA stones in a phantom model.

• Publisher: Springer Nature B.V
• Subject: Calcification (ectopic) / Calcium / Cystine / Data processing / Diagnostic systems / Health care / Image processing / Image segmentation / Kidney stones / Median (statistics) / Nephrolithiasis / Pixels / Scanners / Spectra / Statistical analysis / Stone / Struvite / Uric acid / X-ray diffraction