[1] Danderyd Hosp, Karolinska Inst, Dept Surg, Stockholm, Sweden
[2] Danderyd Hosp, Karolinska Inst, Dept Radiol, Stockholm, Sweden
[3] Danderyd Hosp, Karolinska Inst, Dept Clin Sci, Stockholm, Sweden
[4] Univ Minnesota, Div Colon & Rectal Surg, Minneapolis, MN USA