[1] UNIV TORONTO, DEPT MED, TORONTO, ON, CANADA
[2] UNIV TORONTO, DEPT PATHOL, TORONTO, ON, CANADA
[3] UNIV TORONTO, DEPT RADIOL, TORONTO, ON M5S 1A1, CANADA
[4] UNIV TORONTO, DEPT PREVENT MED & BIOSTAT, TORONTO, ON, CANADA
[5] TORONTO HOSP, CLIN EPIDEMIOL UNIT, TORONTO, ON M5T 2S8, CANADA
[6] MAYO CLIN, DEPT COLORECTAL SURG, ROCHESTER, MN USA
[7] MAYO CLIN, DEPT RADIOL, ROCHESTER, MN USA
[8] MAYO CLIN, DEPT MED, ROCHESTER, MN USA
[9] MAYO CLIN, DEPT MED, JACKSONVILLE, FL USA
[10] MAYO CLIN, DEPT PATHOL, ROCHESTER, MN USA