Figure 1. (a) Longitudinal duplex ultrasound image through the right superficial temporal artery showing irregular lumenal stenosis and mural thickening. (b) Transverse duplex ultrasound image showing the "halo" effect due to mural oedema. (c) Longitudinal duplex ultrasound image through the right superficial temporal artery in a normal control subject. (d) Transverse duplex ultrasound image through the same unaffected vessel, showing normal appearance of the arterial wall.