Biliary Quiz

Questions Robyn Boman/Genevieve Carbonatto

1. What is the sonographic appearance of adenomyomatosis?

Adenomyomatosis presents with

  1. Thickening of the gall bladder wall which may be diffuse or segmental
  2. Accumulation of cholesterol crystals within the wall of the gallbladder which do not move when the patient moves and which cause a V shaped reverberation artifact on 2D and colour Doppler
  3. The crystals are not associated with acoustic shadowing

Below  (A) small hyperechoic foci in GB wall, (B) comet tail artifact in patient with cholecystitis and adenomyomatosis

A                                                                                 B

 

Reference: Adenomyomatosis and the gallbladder – Radiopaedia

2. What is the normal thickness of the gallbladder and what are some causes of GB wall thickening?

The wall thickness of the GB should be less than 3 mm

Causes of GB wall thickening include

Physiological:

  • Postprandial

Inflammatory disease of the GB

  • acute cholecystitis
  • chronic cholecystitis
  • sclerosing cholangitis
  • AIDS
  • Crohn’s disease

Non inflammatory disease of the GB

  • Adenomyomatosis
  • carcinoma of the GB
  • leukaemia
  • multiple myeloma

Oedema of the GB

  • Ascites
  • Hypoalbuminaemia
  • heart failure
  • portal hypertension
  • renal disease
  • malignant lymphatic obstruction/lymphoma

Adjacent inflammatory disease

  • acute viral hepatitis
  • alcoholic hepatitis
  • acute pancreatitis
  • pericholecystic abscesses
  • pyelonephritis

Reference : Clinical Ultrasound Paul Allen 3rd edition 

3. Describe the sonographic appearance of sludge in the gallbladder and the differential diagnoses.

Sludge will appear as low level echoes layering in the dependant portion of the gallbladder. It does not cause acoustic shadowing. Sludge will move when the patient moves. Sludge is caused by calcium salts that have precipitated from the bile however it can be caused by pus in the context of cholecystitis or blood in trauma. It may be seen in association with stones.

The differential diagnosis includes

  • “pseudo sludge” which are echoes due to slice thickness or sidelobe artifacts. These echoes are not present in all views and are not gravity dependent
  • cancer of the gallbladder if the sludge is “tumified”.This is when it appears almost solid and sometimes does not move when the patient moves.  One way of differentiating cancer or a soft tissue mass from tumified  sludge is by putting colour Doppler over the area. There will be no vascularisation if sludge is present.

Reference : Clinical Ultrasound Paul Allen 3rd edition 

4. Describe the appearance of a fatty liver  optimisation of an ultrasound image required for a fatty/fibrotic liver ultrasound.

Fatty liver is the commonest abnormal finding on an abdominal ultrasound. On ultrasound the liver appears very bright or white compared to the parenchyma of the normal kidney. The echo pattern is fine and uniform.There may be loss of intrahepatic vessel wall definition with impaired view of the diaphragm.  One problem with scanning is that fatty livers cause attenuation of ultrasound both through absorption and scatter of soundwaves making it difficult to penetrate the liver with ultrasound.

To optimise the image it may be necessary to

  1. increase the depth
  2. decrease the frequency
  3. increase the overall gain

Reference : Clinical Ultrasound Paul Allen 3rd edition 

5. What manoeuvres can improve visualisation of the liver ?

  1. Breath holding
  2. Inspiration (will bring the liver down below the ribs)
  3. Abdominal distension (ask the patient to push their abdomen out)
  4. Change of patient position (examining in the left lateral position will drop the liver away from the ribs and move the bowel away from the liver)

6. What are the sonographic characteristics of the normal gallbladder?

  • The GB is highly variable in size. It may be up to 12 cm in length. 9 -11 cm is considered to be the normal size of the GB with a width of 4 cm
  • Older patients and diabetics may have atonic gallbladders causing them to become large
  • Prolonged fasting may also cause a distended GB
  • The lax appearance of a normal large GB differentiates it from a hydropic GB due to GB outlet obstruction. A hydropic GB appears more like a balloon under pressure.
  • The normal GB should have an echo free lumen

Reference : abdominal ultrasound step by step Berthold Block 3rd edition

7. What is the best way of measuring the GB wall thickness?

  • The transducer  should be perpendicular to the gallbladder wall to get a crisp visualisation of the wall
  • The GB wall thickness should be measured in the transverse plane at the anterior wall of the GB. This is because measuring the posterior wall may be innacurate due to acoustic enhancement.
  • The overall gain should be reduced
  • Adjustment of the focal zone to the area of interest (GB wall) will improve visualisation of the wall
  • Measurements are made outer wall to outer wall

8. What are some causes for not visualising the GB?

  • Prior cholecystectomy – elderly patients may have forgotten the operation and subtle scars may be overlooked. Always look for a scar if you are not able to see the GB
  • Obesity – it may be difficult to see the GB in obese patients. Using the liver as an acoustic window through the flank rather than subcostally may help in identifying the GB
  • Postprandial contraction – The GB contracts after meals and even milky drinks or even coffee or nicotine . Always ask the patient when they last ate or drank. Blow is atypical postprandial GB

  • Shrunken gallbladder – The gallbladder may shrink from chronic inflammation. The bile becomes viscid and sludge or gallstones may form causing loss of fluid in the GB and making it difficult to see.
  • The GB can be filled with stones causing a wall-echo- shadow appearance

 

Reference : abdominal ultrasound step by step Berthold Block 3rd edition

9.  What are the ultrasound signs of acute cholecystitis?

  • Stones in the GB neck
  • Thickening of the GB wall
  • Pericholecystic fluid
  • Sludge
  • Distended and tense GB
  • +ve Murphy’s sign
  • Gas in the GB wall

10. What is the normal size of the CBD?

  • < 6 mm until age 50
  • < 8 mm if over age 50
  • up to 1 cm if the patient has had a cholecystectomy

 

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