[1] Univ Birmingham, Heartlands Hosp, BASIL Trial Off, Res Inst, Birmingham B9 5SS, W Midlands, England
[2] Univ Edinburgh, Med Stat Unit, Edinburgh EH8 9YL, Midlothian, Scotland
[3] Univ Edinburgh, Wolfson Unit Prevent Peripheral Vasc Dis, Edinburgh EH8 9YL, Midlothian, Scotland
[4] Royal Edinburgh Infirm, Dept Med Imaging, Edinburgh, Midlothian, Scotland
[5] Newcastle Univ, Freeman Hosp, Dept Vasc Surg, Newcastle Upon Tyne, Tyne & Wear, England