Comparison of pineapple juice and mannitol as oral contrast agents for magnetic resonance enterography

INTRODUCTION: We aimed to compare the degree of bowel distension and image quality between pineapple juice and different mannitol concentrations, as well as patients' acceptance and side effects of these different magnetic resonant enterography (MRE) oral contrast agents.

MATERIALS AND METHODS: Seventy-five participants underwent MRE as an initial investigation or follow-up for inflammatory bowel disease. A systematic sampling method was used to divide the participants into three different groups: group 1 received 6.7% mannitol concentration, group 2 received 3.3% mannitol concentration and group 3 received pineapple juice as an oral contrast agent during their MRE examination. The degree of bowel distension on MRE images was assessed by a radiologist by measuring the bowel diameter from inner wall to inner wall at specified levels, while qualitative analysis was evaluated based on the presence of artefacts. All patients were asked to score their acceptance of the oral contrast and were asked about side effects such as diarrhoea, abdominal discomfort and vomiting.

RESULTS: All patients were able to completely ingest 1.5L of oral contrast. The mean diameter of bowel distension was 2.1cm in patients who received 6.7% mannitol concentration, 2.0cm in patients who received 3.3% mannitol concentration and 1.6 cm in patients who received pineapple juice. Twothirds of patients who received 6.7% mannitol and 3.3% mannitol solutions had good-quality MRE images, but 68% of patients who received pineapple juice had poor-quality MRE images. Twenty-four patients (96%) who received pineapple juice rated it as slightly acceptable and acceptable but only 12 patients (48%) who received 6.7% mannitol solution rated it as slightly acceptable and acceptable. Eighty-eight percent of patients who received 6.7% mannitol solution experienced at least one form of side effect as compared to 44% of patients who received 3.3% mannitol solution and 18% of patients who received pineapple juice.

CONCLUSION: Optimum small bowel distension and good image quality can be achieved using 3.3% mannitol concentration as an oral contrast agent. Increase in mannitol concentration does not result in significant improvement of small bowel distension or image quality but is instead related to poorer patient acceptance and increased side effects. Pineapple juice is more palatable than mannitol and produces satisfactory small bowel distension. However, the small bowel distension is less uniform when using pineapple juice with a considerable presence of artefacts. Mannitol, 3.3% concentration, is therefore recommended as an endoluminal contrast agent for bowel in MRE.