PMC

Extracranial color-coded duplex sonography of the internal jugular vein (IJV) and common carotid artery (CCA) in a transverse (top) and longitudinal (bottom) plane. Blood flow direction in the IJV seems to vary at different time points using a transverse insonation (top left: orthograde flow, blue coded; top right: retrograde flow, red-coded). Additional insonation in the longitudinal plane shows the continuous orthograd flow, blue-coded.

Postural changes of blood flow direction in the vertebral vein (VV) and internal jugular vein (IJV) in a healthy subject. Retrograde blood flow in the VV (top) and IJV (central) in supine position turning into an orthograd flow in both vessels after postural change toward the sitting position (bottom) (VV not shown). Note the orthograd flow in the vertebral artery (VA) and common carotid artery (CCA).

Transcranial color-coded duplex sonography of the basal vein of Rosenthal (BVR) with low flow velocity and pulsatility together with the posterior cerebral artery (PCA) with high flow velocity and pulsatility using a transtemporal axial approach at the mesencephalic plane. Notice the physiologic change of blood flow direction with a red-coded flow toward the probe (top) in the proximal and blue-coded away from the probe (bottom) in the distal part of the BVR as well as in the PCA.