To assess the following:

• Size

• Capsular contour (smooth, coarse, lobulated)

• Parenchymal echogenicity

• Vascularity

• Biliary tree

• Masses or collections

 

Limitations

• Obesity and patients with severe metabolic disorders such as haemochromatosis and fatty infiltration will reduce the scan's detail and diagnostic yield.

 

Patient Preparation

• Ideally, fast the patient for 6 hours to reduce bowel gas and prevent gall bladder contraction.

 

Equipment setup

• Depending on the size of the patient, a curved linear array 2-6Mhz.

• If there is nodularity of the liver border, then a linear array with a 7-12MHZ frequency will better appreciate this. Good colour/power / Doppler capabilities when assessing vessels or vascularity of a structure.

• Be prepared to change the probe's focal zone position and frequency output (or probes) to assess both superficial and deeper structures adequately.

 

Common Pathology

• Fatty liver

• Liver cysts

• Haemangioma

• Portal hypertension

• Portal vein thrombosis

• Hepatic vein thrombosis

• Liver abscess/collection

• Cirrhosis

• Trauma

• Metastases

• HCC

• Abscess

 

Scanning Technique

1. Begin by doing a full survey sweep through the liver.

2. You will need the patient to take deep inspiration to visualise the superior borders of the liver fully. Look in transverse up and down the left lobe from a subcostal approach. Look in transverse through the right lobe, subcostal or intercostally.

3. Roll the patient in a left lateral decubitus position for assessment of the Rt lobe only after checking for fluid. Bowel gas can overlie the liver in a subcostal approach, so getting the patient to distend their abdomen can help with visualisation.

4. Also, looking intercostally between each rib space can ensure complete visualisation.

 

Look For:

• Homogeneous vs Attenuative(normal vs fatty)

• Smooth vs coarse echotexture

• Intrahepatic duct (normal or prominent)

• Echogenicity (mild/moderate/ severe)

• Focal lesion (yes or no)

• Size: To measure the size of the liver, use a sagittal approach in the mid-clavicular line. Measure from the diaphragm to the inferior border on the bmode image. This can be very subjective. - Look at the lower edge of the liaboutn to the Rt kidney. It should finish halfway down the kidney. B-mode image, an enlarged liver will have rounded borders.

Once you have thoroughly scanned through the liver, then start taking images.

Normal Liver Measurements

• We need to be able to determine such conditions as hepatomegaly, splenomegaly, renal impairment and abdominal aortic aneurysm.

• It needs to be a consistent measurement to compare sizes over time.

• The callipers must be positioned in the same position between sonographers for accuracy.

• The upper border lies in the right midclavicular line at the 5th intercostal space.

• Most people have the lower border extending to the lower costal margin.

• If measured in the mild hepatic line with a large field of view, it should measure <16cm from the posterior diaphragm to the lower anterior edge. However, organ size increases with gender, age,height, weight and body surface area.

• If the measurement is made from the anterior diaphragm to the lower edge of the liver in the midclavicular line, it should be no >13cm (ref Ultrasonography . An introduction to the standard structure and Functional Anatomy: WB Saunders; 1995. Curry RA and Tempkin BB.)

TIP: Be careful not to get confused with Riedel’s lobe, as it can increase the measurement.

• Any liver series should include the following minimum images;

1. Longitudinal

• Left lobe

• Caudate lobe

• IVC

• Porta hepatis

• Comparison to Rt Kidney

2. Transverse

• Left lobe

• Left hepatic vein

• Left portal vein

• Right portal vein

3. Middle and Right hepatic vein.

4. Demonstrate hepatorenal flow in the portal vein.

5. Demonstrate hepatic vein flow.

6. Document the normal anatomy. Any pathology found in 2 planes, including measurements and any vascularity.

 

Please note that an image must not be taken if it does not have a vessel, ie. Portal or hepatic vein because you must be able to identify which segment of the liver the image has been taken in. Look at the flow direction in the portal vein by scanning intercostally to get optimal directional flow with colour Doppler Us.e spectral Doppler to demonstrate hepatomegaly or hepatofugalflow. In a fatty liver, the hepatic veins can be assessed, and a spectral Doppler can be used to visualise a typical waveform with the atrial contraction.

• Remember that the images are only a sample of what you have seen. If you miss the pathology, then it does not matter how perfect the images are.