Dark-lumen MR colonography with fecal tagging: a comparison of water enema and air methods of colonic distension for detecting colonic neoplasms

Abstract

The purpose was to evaluate MR colonography (MRC) with barium fecal tagging in detecting colorectal pathology and to determine how air-based and water-based colonic distension influences MRC. We studied 83 patients with high risk of colonic neoplasms. All received oral barium sulfate for colonic preparation before unenhanced and enhanced T1-weighted gradient-echo MRC using either water (n=54) or air (n=29) for colonic distension. Fecal tagging, distension, and artifacts were recorded. All patients underwent conventional colonoscopy within 2 weeks of MRC; the techniques were compared for detection of malignant neoplasms and polyps >or=1 cm, 6-9 mm, and <or=5 mm. Fecal tagging was "good" in 76% of the colonic segments in water-distended patients and 46% of air-distended patients. The degree of distension was "good" in 90.7% of water-distended patients and 44% of air-distended patients. Severe artifacts were present in 15% air-distended patients and 0.3% of water-distended patients. Both water-distended and air-distended MRC detected all malignant neoplasms and polyps >or=1 cm, but more air-distended MRC were excluded for poor quality. MRC with fecal tagging is useful for detecting lesions >or=1 cm. Air distension was inferior to water distension in most aspects. Water-based colonic distension should be used for barium-tagging MRC.

Current Status of MR Colonography

“…A number of preparation-free virtual colonoscopic techniques have been studied. Similar to stool tagging in CT colonography, ingestion of oral tagging contrast material has been used in MR colonography to adapt the signal of stool to that of the enema fluid (13)(14)(15)(16). The results are promising, but further research is required to optimize the technique.…”

“…Twenty-nine of these patients underwent air-based distention of the colon and 54 underwent water-based distention of the bowel for MR colonography (15). The degree of distention and quality of fecal tagging were superior with water-based distention.…”

“…One drawback of using barium as a tagging agent in MR colonography is the potential for constipation (15). In contrast, constipation has not been reported to be a major issue when gadolinium chelates are used for fecal tagging (54).…”