[1] Univ Hosp N Norway, Dept Med, N-9038 Tromso, Norway
[2] Univ Hosp, Rikshosp, Dept Med, Div Haematol, N-0027 Oslo, Norway
[3] Univ Hosp N Norway, Dept Radiol, N-9038 Tromso, Norway
[4] Univ Hosp, Rikshosp, Dept Radiol, N-0027 Oslo, Norway
[5] Univ Tromso, Inst Clin Med, Dept Med, Ctr Atherothrombot Res Tromso, N-9038 Tromso, Norway