Researchers from Germany have reported that magnetic resonance (MR) colonography screening in an average risk population had a sensitivity of 83% and a specificity of 90.2% for detection of adenomatous polyps >5 mm. The details of this study appeared in an early online publication in Gut on March 6, 2007.[1]

There has been significant progress in the development of CT and MR colonography as alternatives to conventional optical colonoscopy. The disadvantages of optical colonoscopy are the need for sedation, the need for bowel cleansing and the low but clear risk of perforation. In addition, the results of colonoscopy are highly dependent on the skill of the endoscopist. CT and MR colonography can be performed without sedation but bowel cleansing is still required. Researchers have attempted to develop scanning techniques that do not require bowel cleansing, with the most progress being made with MR technology.

In the current study, researchers used 5% Gastrografin, 1% Bariumsulfate and 0.2% Locust bean gum for tagging. These agents were taken for two days prior to MR colonography. No bowel cleansing was administered but all patients had a rectal water enema. All 315 patients in this study underwent optical colonoscopy for correlation of findings on MR. They reported a failure rate of 4% due to non-tagged fecal material. These authors reported false positive findings in 19 patients and detection of only 6 of 153 lesions <5 mm. They also reported that only 9 of 127 hyperplastic polyps were visualized. These authors concluded that fecal tagged MR colonography was suitable for screening purposes and provided good accuracy for detection of relevant adenomatous colorectal lesions > 5 mm. They suggested that further improvement in this technique was possible.

Comments: These are interesting findings and indicate further progress in the development of MR colonography techniques. The ability to screen for colorectal cancer without bowel prep would make this more acceptable to larger numbers of individuals. Similar studies are also being conducted with CT colonographic techniques.[2]

References:

[1] Kuehle CA, Langhorst J, Ladd SC, et al. MR colonography without bowel cleansing – a prospective cross-sectional study in a screening population. Gut. 2007;Published online First: 6 March 2007.

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