[1] Univ Helsinki, Dept Otorhinolaryngol Head & Neck Surg, HUSLAB, Helsinki, Finland
[2] Univ Helsinki, Dept Radiol, HUSLAB, Helsinki, Finland
[3] Univ Helsinki, Dept Pathol, HUSLAB, Helsinki, Finland
[4] HUS Helsinki Univ Hosp, Helsinki, Finland
[5] Turku Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Turku, Finland
[6] Karolinska Inst, Div Ear Nose & Throat Dis, Dept Clin Sci Intervent & Technol, Stockholm, Sweden
[7] Karolinska Hosp, Stockholm, Sweden
[8] East Tallinn Cent Hosp, Dept Radiol, Tallinn, Estonia