[1] Univ Toronto, St Michaels Hosp, Dept Med Imaging, Toronto, ON, Canada
[2] Harvard Univ, Sch Med, Dept Radiol, Boston, MA 02115 USA
[3] Beth Israel Deaconess Med Ctr, Dept Radiol, New York, NY 10003 USA
[4] Dr Everett Chalmers Hosp, Dept Radiol, Fredericton, NB, Canada
[5] Ottawa Hosp, Dept Pathol & Lab Med, Ottawa, ON, Canada
[6] Mayo Clin, Dept Radiol, Scottsdale, AZ USA