[Normal intrahepatic vessels. Remarks on their echographic image].

The sonographic appearances of intrahepatic vessels are demonstrated by the basic principles of ultrasonography. All intrahepatic vessels have a sonolucent lumen which may be blurred because of the slice-thickness effects. The vascular walls are detected only when they are perpendicularly struck by the ultrasound beam. The portal branches are visualized with satellite echoes which are reflections from the intraparenchymal hepatic arteries and/or biliary ducts, and from the collegenous sheath of the portal triad. These echoes are blended with the wall-echoes of the portal veins as to the major branches. For smaller branches they remain visible when the incidence of the ultrasound beam becomes less accurate, whereas the echoes from the portal veins tend to disappear. The echoes related to the hepatic veins only come from the walls of the veins, which are usually of medium size.