Magnetic resonance colonography in the detection of colonic neoplasm in high-risk and average-risk individuals.
OBJECTIVE
Magnetic resonance colonography (MRC) is a new noninvasive diagnostic modality for colorectal cancer. However, the use of MRC in the detection of colorectal neoplasm in average-risk individuals remains unknown. This study determined the performance and the patient's preference of MRC in the detection of colorectal neoplasm.


METHODS
Both high-risk (i.e., symptoms suggestive of colorectal neoplasm, positive fecal occult blood test, history of colorectal cancer in one or more first-degree relatives) and average-risk (i.e., asymptomatic individuals >50 yr) individuals were recruited. MRC was performed immediately prior to conventional colonoscopy (CC) by using air inflation without contrast. The finding on CC together with histology was used as a gold standard. Patients' pain and discomfort score were recorded immediately and 24 h after the procedure. They were also asked about their preferences for the two procedures.


RESULTS
A total of 165 patients (79 average risk and 86 high risk) were recruited. Eight patients had incomplete MRC and one patient had failed CC. Of the remaining 156 patients, 4 were found to have colonic cancer and 31 were found to have 67 polyps. MRC correctly identified 3 cancers (sensitivity 75%, specificity 99.3%) and 4 patients with colonic polyps (sensitivity 12.9% and specificity 97.6%). Sensitivity of MRC tended to be lower in polyps <10 mm in size and in average-risk individuals. The mean procedure time of CC was significantly shorter than MRC (13.6 +/- 6.7 vs 20.6 +/- 2.7 min, p < 0.001). Although there was no significant difference in the pain and discomfort scores of the 2 procedures, 75% of patients preferred CC to MRC.


CONCLUSIONS
The performance of MRC when used in the detection of colonic neoplasm in average-risk individuals is unsatisfactory.
Leung
Wai K
WK
Department of Medicine & Therapeutics, the Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
Lam
Wynnie W M
WW
Wu
Justin C Y
JC
So
Nina M C
NM
Fung
Sara S L
SS
Chan
Francis K L
FK
To
Ka-Fai
KF
Yeung
Deacons T K
DT
Sung
Joseph J Y
JJ
D003106:Colon / Q000473:pathology*; D003111:Colonic Polyps / Q000175:diagnosis; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D003951:Diagnostic Errors; D006801:Humans; D008279:Magnetic Resonance Imaging; D012307:Risk Factors; D012680:Sensitivity and Specificity