MR colonography without colonic cleansing: A new strategy to improve patient acceptance

OBJECTIVE. MR colonography permits accurate detection of colonic polyps lar ger than 8 mm. Patient acceptance remains limited because of the need for b owel cleansing. The aim this study was to develop and assess a strategy obv iating colonic cleansing by performing MR colonography in conjunction with fecal tagging based on the oral administration of barium. SUBJECTS AND METHODS. Six healthy volunteers and six patients with suspecte d colorectal tumors, undergoing conventional colonoscopy within 1 week of M R imaging, were included in this study. For fecal tagging, 200 mL of a bari um-containing contrast agent was ingested with each of four principal meals preceding the examination. For MR colonography, the colon was filled with a barium. and water mixture while gadobenate dimeglumine (0.2 mmol/kg) was injected IV. RESULTS. The combination of fecal tagging and colonic filling with barium r esulted in a homogeneously low signal throughout the colonic lumen in all 1 2 subjects. IV injection of gadolinium caused avid enhancement of the colon ic wall. Similarly, lesions arising from the colonic wall enhanced avidly. In the six evaluated patients, MR colonography correctly identified two col onic carcinomas in two patients and one polyp in each of another two patien ts. CONCLUSION. Fecal tagging obviates bowel cleansing and should, therefore, e nhance patient acceptance for MR colonoscopy. Barium used as the tagging ag ent is promising because it is inexpensive, commercially available, and cha racterized by an excellent safety profile.