Improvement of distension and mural visualization of bowel loops using neutral oral contrasts in abdominal computed tomography

Comparison of Mannitol, Water, and Iodine-Based Oral Contrast in the Evaluation of the Bowel by Multi-Detector Computed Tomography

Background and objectives

To perform contrast-enhanced computed tomography (CECT) of the abdomen with water, mannitol, or iodinated positive contrast as an oral contrast agent, and compare the distension and enhancement pattern of the bowel.

Methods

This was a prospective observational study conducted on 90 patients over a period of 12 months who were referred for CECT abdomen. Patients were randomly divided into three groups (30 each) and were given water, mannitol, or positive oral contrast before the CECT study. Quantitative and qualitative analysis of the bowel for distension, mural fold pattern, and enhancement was analyzed at various anatomical levels. A qualitative examination of bowel loops was done in the three groups by using a continuous 4-point scale.

Results

The mean distension at the duodenum was 1.89 ± 0.33 cm (mean ± SD) with water, 2.28 ± 0.36 cm with mannitol, and 2.01 ± 0.33 cm with positive oral contrast. Overall, maximum luminal distension was seen at the level of the duodenum, followed by the jejunum across all the groups. Bowel characteristics were far superior in the mannitol group compared to water and positive oral contrast at all anatomical levels.

Conclusion

Small bowel distension was excellent with mannitol, followed by positive oral contrast, and least with water. Mural characteristics and enhancement patterns were better with mannitol as compared with water and with positive oral contrast.

Preprocedural fasting for contrast-enhanced CT: when experience meets evidence

Traditional preparatory fasting policy prior to iodinated contrast media (ICM) assisted contrast-enhanced CT (CECT) examinations lacks methodologically acceptable evidence. Considering the possible negative effects of preprocedural fasting, the latest European Society of Urogenital Radiology guidelines V10.0 and American Committee of Radiology 2021 guidelines clearly state that preprocedural fasting is not recommended prior to routine intravenous ICM administration. This comprehensive and detailed Review presents the current global dietary preparation policies, potential harm of excessive fasting, and a systematical and well-bedded description of practice advancements of dietary preparation. The evidences revealed that there has been no single instance of vomiting-associated aspiration pneumonia due to the undemanding implementation of preparatory fasting prior to CECT yet. Non-fasting would not increase the incidence of emetic symptoms and the risk of aspiration pneumonia. Not every patient should undergo all CECT examinations without preparatory fasting. There is still much more refinement to be done on the preparatory fasting policy. Changes in traditional preparatory fasting policy will make positive and significant implications on clinical practice. This Review aims to provide operational guidance and suggestions for practitioners and policymakers, motivate efficient, reasonable, safe and normative ICM usage, and achieve optimal patient clinical benefits and high-quality radiological care practices.

A novel food-based foam as oral contrast agent with negative Hounsfield units for demarcation of small bowel loops on abdominal CT: tolerability and bowel distension in 25 volunteers

BACKGROUND

Diseases of the bowel are not always displayed on conventional abdominal computed tomography (CT). The studied oral contrast agent aims to improve this.

PURPOSE

To investigate whether the use of a novel oral contrast for abdominal CT enables the same diagnostic advantages as seen in magnetic resonance imaging (MRI).

MATERIAL AND METHODS

Twenty-five consented volunteers drank up to 1400 mL of a stable, drinkable foam. Comments on acceptance and side effects were noted immediately and 24 h later. Foam palatability was documented through interviews, and distribution in the small bowel by Hounsfield units from the CT software. The CT results were compared with age- and sex-matched controls, pretreated according to routine. A non-enhanced abdominal CT protocol of lowest possible radiation dose was used. External referees evaluated all data obtained.

RESULTS

Foam was considered odd to swallow, and fullness was reported by all volunteers after 950 mL. Five had difficulties in drinking the last 320 mL and two abstained from it. All adverse symptoms were mild. The distribution in the small bowel was on par with standard agents. Foam density revealed stability with intraluminal values of around -550 HU from stomach to terminal ileum, satisfying the requirement of a great bowel lumen-to-wall contrast. External reviewers re-evaluated all our data, and one predicted the foam to offer a potential for improved diagnostics.

CONCLUSION

A CT true-negative bowel filling agent was formulated, with high acceptance, few side effects, and a potential to mimic T1-weighted MRI images.