MR colonography proves effective, but no more palatable to patients

Although MR colonography (MRC) is proving to be an effective method of colorectal screening, patients are no more likely to accept it than optical colonoscopy, according to two studies presented at the RSNA meeting. Dr. Aoife Keeling of Beth Israel Deaconess Medical Center in Boston compared the relevant efficacy of air as an intraluminal contrast agent in MRC with optical colonoscopy. In a survey of 46 patients who underwent MRC and the conventional technique, MRC was highly effective in identifying clinically significant lesions, with 100% sensitivity and specificity in lesions greater than 10 mm. The method was less effective in small lesions: MRC had a 50% sensitivity rate and a 100% specificity rate for lesions between 6 mm and 9 mm in size. For polyps less than 5 mm in size, sensitivity was 15% and specificity was 98%.

A 7 mm adenoma identified using air as endoluminal contrast agent.
(Provided by A. Keeler)

While these results indicate that the technology is effective, other results revealed that patients are just as resistant to MRC as they are to optical colonoscopy. Keeling found that 35% preferred MRC over optical colonoscopy; 33% preferred colonoscopy to MRC; and 32% had no preference. In addition, patients reported slightly more discomfort with MRC, but more embarrassment with optical colonoscopy. Prof. Sonja Kinner of Universität Duisburg-Essen found similar results in her study of patient acceptance of MRC versus optical colonoscopy. Kinner analyzed questionnaires submitted by 284 patients. Patients rated the two procedures on a 10-point scale, with 1 indicating good acceptance and 10 indicating poor acceptance. MRC patients underwent fecal tagging procedures. Colonoscopy patients underwent full cathartic bowel preparations, as well as receiving sedatives and analgesics prior to colonoscopy.Kinner found no significant difference between the overall rating for the two procedures, with MRC receiving a mean acceptance rating of 3.4 compared to a mean rating of 3.0 for optical colonoscopy.Differences did exist when it came to different parts of the procedure, however. Patients rated ingestion of the electrolyte solution more unpleasant compared to ingestion of the tagging agent for MRC, while placement of the rectal tube and administration of water enema were rated the most unpleasant components of MRC. Kinner found no significant difference concerning preferences for future examinations: 46% of the patients indicated they would prefer MRC, while 43% voted for colonoscopy.