[1] Sahlgrens Univ Hosp, Dept Radiol, SE-41345 Gothenburg, Sweden
[2] Karolinska Univ Hosp, Dept Surg, Huddinge, Sweden
[3] Boras Cent Hosp, Dept Gen Surg, Boras, Sweden
[4] Sahlgrens Univ Hosp, Dept Otorhinolaryngol, SE-41345 Gothenburg, Sweden
[5] Sahlgrens Univ Hosp, Dept Surg, SE-41345 Gothenburg, Sweden