Computed tomographic and magnetic resonance colonography: challenge for colonoscopy

Computed tomographic (CT) and magnetic resonance (MR) colonography are new noninvasive techniques to examine the colon.

A literature search was performed through 2/1/2012, and relevant studies included in the review.

MR colonography is evolving, and holds the promise that it may achieve high-level sensitivity for adenomas and cancers without exposure to radiation. CT colonography is much more mature at this point in time, and has received great attention in the last decade as a colon imaging tool, including potentially as a primary colon cancer screening method. Its accuracy for detection of polypoid lesions ≥ 1 cm is high, likely close to that of colonoscopy. New techniques focusing on minimally prepped CT colonography hold the potential of making the procedure more widely accepted. While radiation exposure with CT colonography is a concern, this risk is likely very modest, particularly if used in patients over the age of 50. CT colonography, while a viable colon cancer screening modality in the USA, could not be widely implemented, largely because of lack of standards for training and reading, and because the number of skilled readers is limited.

MR and CT colonography are relatively novel and exciting modalities that can be used to identify colonic lesions. They promise a high level of sensitivity and pose essentially no (MR) or modest (CT) risks. Future investigation will likely lead to wider acceptance of both of these tests, including perhaps to their use in colon cancer screening programs.