Prospective Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Sep 28, 2016; 8(9): 809-815
Published online Sep 28, 2016. doi: 10.4329/wjr.v8.i9.809
Effects of oral contrast on dose in abdominopelvic computed tomography with pure iterative reconstruction
Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O’Connor, Michael M Maher
Kevin P Murphy, Liam J Healy, Lee Crush, Maria Twomey, Fiachra Moloney, Sylvia Sexton, Owen J O’Connor, Michael M Maher, Department of Radiology, Cork University Hospital, A0001 Cork, Ireland
Author contributions: Murphy KP was the primary author and drafted the manuscript; Healy LJ, Crush L and Twomey M collected the data; Sexton S performed the studies and collected data; Moloney F, O’Connor OJ and Maher MM performed image analysis and edited the manuscript.
Institutional review board statement: The study received institutional board approval from the Cork Clinical Research Ethics Committee, Lancaster Hall, 6 Little Hanover Street, Cork, Ireland.
Informed consent statement: Informed consent was not deemed necessary for this study. Clinical and radiological data was collected prospectively in an anonymised fashion and no patient underwent additional procedures or investigations as a result of inclusion in the study. No potential risks to patients were identified. The clinical research ethics committee granted approval for the study without a requirement of consent from each patient.
Conflict-of-interest statement: All authors declare no conflicts of interest.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at fiachramoloney@hotmail.com.
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: Fiachra Moloney, FFR, RCSI, Department of Radiology, Cork University Hospital, 1 Bishopstown Road, Wilton, A0001 Cork, Munster, Ireland. fiachramoloney@hotmail.com
Telephone: +353-21-4922000 Fax: +353-21-4922002
Received: April 13, 2016
Peer-review started: April 15, 2016
First decision: May 19, 2016
Revised: June 23, 2016
Accepted: August 11, 2016
Article in press: August 15, 2016
Published online: September 28, 2016
Processing time: 167 Days and 16.7 Hours
Abstract
AIM

To assess the effect of neutral (NC) and positive (PC) oral contrast use on patient dose in low-dose abdominal computed tomography (CT).

METHODS

Low-dose clinically indicated CTs were performed on 79 Crohn’s patients (35 = PC, 1 L 2% gastrografin; 44 = NC, 1.5 L polyethylene glycol). Scanner settings for both acquisitions were identical apart from 25 s difference in intravenous contrast timing. Body mass index (BMI), scan-ranges, dose-length product and size-specific dose estimated were recorded. Data was reconstructed with pure model-based iterative reconstruction. Image quality was objectively and subjectively analysed. Data analysis was performed with Statistical Package for Social Scientists.

RESULTS

Higher doses were seen in neutral contrast CTs (107.60 ± 78.7 mGy.cm, 2.47 ± 1.21 mGy vs 85.65 ± 58.2 mGy.cm, 2.18 ± 0.96 mGy). The difference was significant in 2 of 4 BMI groups and in those that had both NC and PC investigations. Image-quality assessment yielded 6952 datapoints. NC image quality was significantly superior (P < 0.001) (objective noise, objective signal to noise ratio, subjective spatial resolution, subjective contrast resolution, diagnostic acceptability) at all levels. NC bowel distension was significantly (P < 0.001) superior.

CONCLUSION

The use of polyethylene glycol as a neutral OC agent leads to higher radiation doses than standard positive contrast studies, in low dose abdominal CT imaging. This is possibly related to the osmotic effect of the agent resulting in larger intraluminal fluid volumes and resultant increased overall beam attenuation.

Keywords: Radiation dose; Low dose computed tomography; Abdominal imaging; Oral contrast; Computed tomography

Core tip: The use of neutral oral contrast agent results in higher radiation doses than standard positive contrast studies when performed low dose abdominopelvic computed tomography imaging. This likely relates to the osmotic effect of the agent resulting in larger intraluminal fluid volumes and resultant increased overall beam attenuation.