Diagnostic value of different rectal contrast agents for the detection of colorectal diseases by multislice CT

Purpose: Assessment of 3 different rectal contrast agents (water, methylcellulose, ultrasound gel) for their suitability for colorectal imaging in multislice CT (MS-CT). Methods: 115 patients with colorectal diseases underwent MS-CT with varying, rectal contrast agents in a prospective study. Images were assessed by 2 independent CT-experienced radiologists. 6 criterias were evaluated, using a 5-point scale. Results: Methylcellulose (MC) proved to be significantly superior to ultrasound gel (US). Especially, differentiation of healthy and diseased bowel and bowel wall and lumen were aided, which was proven by quantitative analysis of attenuation values. Rectal distension is greater using MC or US than for water. More proximal parts of the colon could be better distended with water. The interobserver correlation was good (kappa 0.76). Conclusions: Rectal filling with MC significantly improves diagnostic confidence in colorectal examinations. Ease of administration and lack of problems suggest its use as a clinical routine tool.