Identification of ureteral stones at reduced radiation exposure: a pilot study comparing conventional versus digital low-dosage linear slot scanning (Lodox®) radiography.

Abstract

Digital low-dosage, linear slot scanning radiography (Lodox®) is an imaging modality that can emit down to one-tenth the radiation of conventional X-ray systems. We prospectively evaluated Lodox® as a diagnostic imaging modality in patients with ureterolithiasis. Conventional kidney-ureter-bladder (KUB) X-ray and Lodox® were performed in 41 patients presenting with acute flank pain due to unilateral ureteral stone confirmed by computed tomography. KUB X-ray and Lodox® images were then reviewed by four blinded readers (urology expert/resident, radiology expert/resident). Identification rates were compared using Pearson's Chi square test. The impact of different parameters on stone identification by Lodox® was evaluated using logistic regression and generalized linear mixed models. Inter-reader agreement was tested using Cohen's kappa coefficient. Median stone size was 5mm (range 2-12), median stone density was 800 HU (range 200-1500). The identification rates of the urology expert were 68% for KUB X-ray and 90% for Lodox® (p = 0.014), and for all four readers 61% for KUB X-ray and 62% for Lodox® (p = 0.8). Radiation exposure for KUB X-ray and Lodox® was 0.45mSv (SD ± 0.64) and 0.027mSv (SD ± 0.038), respectively. Multivariable analyses showed an association between stone identification by Lodox® and stone size (p < 0.001), stone density (p = 0.005), lower body mass index (p = 0.005), and reader (p < 0.001). The high identification rates and low radiation doses of Lodox® make it a promising imaging modality for the diagnosis of ureteral stones. Further validation in larger cohorts, including performance evaluation for renal stones, is warranted. http://www.controlled-trails.com/ISRCTN12915426.