Retrospective Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 14, 2015; 21(34): 9993-9998
Published online Sep 14, 2015. doi: 10.3748/wjg.v21.i34.9993
Detection of gallbladder stones by dual-energy spectral computed tomography imaging
An-Liang Chen, Ai-Lian Liu, Sheng Wang, Jing-Hong Liu, Ye Ju, Mei-Yu Sun, Yi-Jun Liu
An-Liang Chen, Ai-Lian Liu, Sheng Wang, Jing-Hong Liu, Ye Ju, Mei-Yu Sun, Yi-Jun Liu, Department of Radiology, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, Liaoning Province, China
Author contributions: Chen AL, Liu AL, and Wang S designed the research; Chen AL, Wang S, Ju Y, and Liu YJ performed the research; Liu JH and Sun MY analyzed the data; Chen AL, Liu AL, and Wang S wrote the paper; all authors have read and approved the final version to be published.
Institutional review board statement: This retrospective study was approved by the Ethics Committee in The First Affiliated Hospital of Dalian Medical University.
Conflict-of-interest statement: There is no conflict of interest in this study.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at cjr.liuailian@vip.163.com. No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Ai-Lian Liu, PhD, Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian 116011, Liaoning Province, China. cjr.liuailian@vip.163.com
Telephone: +86-411-83635963 Fax: +86-411-83622844
Received: March 25, 2015
Peer-review started: March 27, 2015
First decision: May 18, 2015
Revised: June 2, 2015
Accepted: June 26, 2015
Article in press: June 26, 2015
Published online: September 14, 2015
Processing time: 173 Days and 16.5 Hours
Abstract

AIM: To evaluate the detectability of gallbladder stones by dual-energy spectral computed tomography (CT) imaging.

METHODS: Totally 217 patients with surgically confirmed gallbladder stones were retrospectively analyzed who underwent single-source dual-energy CT scanning from August 2011 to December 2013. Polychromatic images were acquired. And post-processing software was used to reconstruct monochromatic (40 keV and 140 keV) images, and calcium-lipid pair-wise base substance was selected to acquire calcium base images and lipid base images. The above 5 groups of images were evaluated by two radiologists separately with 10-year experience in CT image reading. In the 5 groups of images, the cases in the positive group and negative group were counted and then the detection rate was calculated. The inter-observer agreement on the scoring results was analyzed by Kappa test, and the scoring results were analyzed by Wilcoxon test, with P < 0.05 indicating that the difference was statistically significant. The stone detection results of the 5 groups of images were analyzed by χ2 test.

RESULTS: There was good inter-observer agreement (κ= 0.772). In 217 patients with gallbladder stones, there was a statistically significant difference in stone visualization between spectral images (40 keV, 140 keV, calcium base and lipid base images) and polychromatic images (P < 0.05). 40 keV monochromatic images were better than 140 keV monochromatic images (4.90 ± 0.35 vs 4.53 ± 1.15, P < 0.05), and calcium base images were superior to lipid base images (4.91 ± 0.43 vs 4.77 ± 0.63, P < 0.05), but there was no statistically significant difference between 40 keV monochromatic images and calcium base images (4.90 ± 0.35 vs 4.91 ± 0.43, P > 0.05). In 217 gallbladder stone patients, there were 21, 3, 28, 5 and 12 negative stone cases in polychromatic images, 40 keV images, 140 keV images, calcium base images and lipid base images, respectively, and the differences among the five groups were statistically significant (P < 0.05).

CONCLUSION: Monochromatic images and base substance images have a good clinical prospect in the iso-density stone detection.

Keywords: Gallbladder stone; Computed tomography; Spectral imaging

Core tip: In traditional computed tomography (CT), gallbladder stones are indicated directly by high-density or low-density stones and indirectly by dilation of the intrahepatic biliary duct, left and right hepatic ducts, biliary duct and gallbladder. However, it is difficult to diagnose iso-density gallbladder stones, because gallbladder stones and bile are difficultly distinguished by traditional CT due to a same density. The development of spectral imaging recoups the defects of traditional CT in the diagnosis of iso-density stones. In spectral imaging, base substance images and low keV images are both promising to improve the detection rate of gallbladder stones; they provide a new approach for the differential diagnosis of gallbladder stones, and the reliable information for the clinical treatment of gallbladder stones.