Published online Sep 28, 2016. doi: 10.4329/wjr.v8.i9.809
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
To assess the effect of neutral (NC) and positive (PC) oral contrast use on patient dose in low-dose abdominal computed tomography (CT).
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.
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.
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.
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.