In a study published in the August issue of Gastroenterology, 70 consecutive patients who had been referred for conventional colonoscopy underwent MRC prior to colonoscopy.
"MRC could already be considered for screening patients at normal risk for colon cancer."
Dr Guiseppe Pappalardo.
Patients undergoing MRC take a standard bowel preparation on the day before examination.
Immediately before examination patients are given 5mg scopolamine intravenously to optimise colonic distention.
Patients lie in a supine position as the bowel is filled with 1500-2000mL of water spiked with 15-20mL of gadopentate solution.
As the colon fills with water, it is monitored with imaging equipment to produce a 3D picture of the bowel from rectum to cecum.
The location and size of any endoluminous lesions were recorded and compared with the results of the conventional colonoscopy, which followed the MRC.
Dr Papparlardo reports that MRC achieved a sensitivity of 96% in detecting endoluminal lesions, compared with 98% for conventional colonoscopy.
MRC had 100% sensitivity in detecting endoluminal lesions greater than 10mm.
Magnetic resonance colonography generally caused less discomfort than colonoscopy. 22.4% of the patients in the study reported severe discomfort during colonoscopy, whilst no-one experienced this level of discomfort during MRC.
The similarity in diagnostic accuracy of MRC and colonoscopy, but the greater comfort of the new technique, suggest MRC may be a useful alternative to conventional colonoscopy.
The current expense of the technology required for MRC remains a barrier to its widespread use in screening programs. However, Dr Papparlardo believes that screening with magnetic resonance colonography, followed by colonoscopy if necessary, would allow earlier diagnosis for colorectal cancer.