title: Magnetic resonance colonography in the detection of colonic neoplasm in high-risk and average-risk individuals.
abstract: 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.
authors.affiliation: Department of Medicine & Therapeutics, the Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
authors.forename: Wai K
authors.initials: WK
authors.lastname: Leung
authors.forename: Wynnie W M
authors.initials: WW
authors.lastname: Lam
authors.forename: Justin C Y
authors.initials: JC
authors.lastname: Wu
authors.forename: Nina M C
authors.initials: NM
authors.lastname: So
authors.forename: Sara S L
authors.initials: SS
authors.lastname: Fung
authors.forename: Francis K L
authors.initials: FK
authors.lastname: Chan
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.forename: Deacons T K
authors.initials: DT
authors.lastname: Yeung
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
mesh_terms: 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