[1] McMaster Univ, Dept Radiol, Hamilton, ON L8N 3Z5, Canada
[2] Dartmouth Hitchcock Med Ctr, Dept Radiol, Lebanon, NH 03766 USA
[3] Dartmouth Coll Sch Med, Dept Community & Family Med, Ctr Evaluat Clin Sci, Hanover, NH USA
[4] Univ Toronto, Dept Hlth Adm, Toronto, ON M5S 1A1, Canada
[5] Univ Toronto, Dept Anesthesiol, Toronto, ON, Canada
[6] Univ Washington, Dept Radiol, Seattle, WA 98195 USA
[7] Univ Washington, Dept Neurosurg, Seattle, WA 98195 USA
[8] Univ Michigan, Dept Radiol, Ann Arbor, MI 48109 USA
[9] Univ Penn, Med Ctr, Dept Radiol, Philadelphia, PA 19104 USA
[10] Univ Penn, Med Ctr, Dept Epidemiol, Philadelphia, PA 19104 USA
[11] Univ Penn, Med Ctr, Dept Informat & Comp Sci, Philadelphia, PA 19104 USA
[12] Univ British Columbia, Dept Radiol, Vancouver, BC, Canada
[13] Univ Chicago Hosp, Dept Radiol, Chicago, IL 60637 USA
[14] St Vincents Univ Hosp, Dept Radiol, Dublin, Ireland
[15] McMaster Univ, Med Ctr, Dept Nucl Med, Hamilton, ON, Canada
[16] Childrens Hosp, Dept Pediat & Child Hlth, Winnipeg, MB R3A 1S1, Canada
[17] McMaster Univ, Div Gastroenterol, Hamilton, ON, Canada
[18] McMaster Univ, Fac Hlth Sci, Hamilton, ON, Canada