Plain Water as a Neutral Enteric Contrast Agent in CT Enterography: Performance Evaluation and Comparison with Mannitol

Abstract

Background: Computed Tomography Enterography (CTE) is a pivotal imaging modality for detailed evaluation of the small bowel. Optimal luminal distension achieved by oral contrast agents significantly enhances image quality and diagnostic accuracy. However, the comparative efficacy of plain water versus osmotic agents like mannitol remains insufficiently explored.

Objective: To prospectively compare plain water and 3% mannitol as neutral oral contrast media in CT enterography in terms of bowel luminal distension, mucosal visualization, image quality, and patient tolerability.

Methods: One hundred fifty patients undergoing CT enterography were randomized to receive either 1500 ml of plain water or 1500 ml of 3% mannitol solution orally over 45 minutes. Jejunal and ileal loop diameters were quantitatively measured on CT images by two blinded radiologists. Mucosal fold visualization was graded on a 3-point scale. Patient-reported tolerability and adverse events were recorded.

Results: Jejunal distension showed no significant difference between the groups (water: 13.92 ± 3.24 mm; mannitol: 13.95 ± 3.36 mm; p > 0.05). Ileal loops were significantly more distended with mannitol (18.76 ± 2.70 mm) compared to water (16.89 ± 2.85 mm; p < 0.001). Mucosal visualization scores were superior in the mannitol group, with more ileal loops achieving optimal fold clarity (65% vs. 40%; p < 0.05). Patient tolerability and minor adverse events were comparable.

Conclusions: Mannitol provides significantly better distal small bowel distension and mucosal visualization than plain water in CT enterography, without compromising patient comfort. Mannitol is thus the preferred neutral oral contrast medium for enhanced diagnostic quality in small bowel imaging.