The document provides guidance on identifying liver structures using ultrasound imaging. It describes the typical sonographic appearance of the liver as having a homogeneous texture with medium echogenicity. Portal and hepatic veins within the liver appear as anechoic tubular or round structures. The document outlines how to differentiate portal veins from hepatic veins based on their direction of flow and whether their walls appear echogenic. It includes labeled ultrasound images demonstrating the structures discussed.

1. Week One: Your First Scanning Experience Thanks to the U.S. National Archives’ for the flicker image.No known copyright restrictions.

2. Sonographic Appearance of the Liver The liver is described as having a medium level homogenous echo-texture. Portal and hepatic veins can be seen scattered throughout the entire liver parenchyma. Because vessels are fluid filled, they will appear anechoic (without echo). When the vessels appear “tubular”, they are in their longest cross section and when the vessels appear “round” they are in their shortest cross section. No matter what cross section a vessel is in, long or short, they will always appear anechoic.

4. The bright reflective line demonstrates the diaphragm that divides the liver from the lungs; it appears echogenic.

5. The shape of the diaphragm helps to differentiate that this is a sagittal cross section.

6. A few small vessels can be seen scattered throughout the liver, these represent hepatic and portal veins (two small arrows). These small vessels are not major landmarks for the portal or hepatic systems.Diaphragm

8. The shape of the diaphragm helps to differentiate this image as a sagittal cross section. The diaphragm is seen as rounded in a sagittal cross section.

9. Both the portal and hepatic veins can be seen as anechic structures, some long and tubular and others short and circular. Portal Vein Hepatic Vein

11. Portal veins enter the liver at the portahepatis. The main portal vein is the confluence of three smaller veins; spleen, IMV and SMV. In a transverse cross section the long lengths (tubular appearance) of both the larger hepatic and portal veins, are more typically seen.

12. Figure 3. Transverse Superior Cross Section of the Liver When you see the right, middle, and left hepatic veins draining into the IVC (as demonstrated in this image), you will have demonstrated the correct landmark to indicate that you are in a superior transverse cross section of the of the liver (make sure to document this image). IVC IVC

13. Figure 4. Transverse Mid Cross section of the Liver The portal vein is seen entering the liver at the mid section of the liver, which is considered the level of the portahepatis (where the portal vein and hepatic artery enter the liver). Note: The transverse mid liver cross section is one cross sectional level below the transverse superior liver cross section (as see on figure 3). Portal vein

15. Portal veins usually have echogenic walls. Differentiating between hepatic and portal wall echogenicity is another sonographic characteristic that will help you determine which vessels you are evaluating.

17. Figure 6. Transverse superior cross section of the Liver Scanning the liver in a transverse cross section, when angling superior, toward the patient’s head, you will encounter the right, middle and left hepatic veins (RHV, MHV, LHV) as they drain into the inferior vena cava (IVC). Note: The hepatic veins do not typically have echogenic walls, however if the ultrasound beam hits a hepatic vein at a 90 degree (as seen in this image) only that portion of the hepatic vein will appear to have an echogenic wall, this is due to the difference in interface of the two tissue structures at 90 degrees to the transducer. LHV MHV RHV Echogenic Hepatic vein wall IVC