The pathogenesis of Biliary Atresia appears to be multifactorial,
but the cause is not understood yet.
Congenital malformation such heterotaxia,
spleen anomalies (polysplenia,
and preduodenal portal vein,
has been reported in 20% of the cases with biliary atresia.
It has also been associated with prenatal exposure to viruses (Cytomegalovirus and rotavirus).
We present a review of the disease,
the imaging findings and the current management.
We include patients with diagnosis of biliary atresia confirmed by biopsy in our hospital.
KASAI CLASSIFICATION (Figure 1).
• TYPE I: Obliteration of common bile duct with patent cystic and common hepatic duct
• TYPE II
IIa: Obliteration of common hepatic duct.
A cyst at hilum can be present (cystic biliary atresia)
IIb: Obliteration of common hepatic duct,
cystic and common bile duct
• TYPE III: Obliteration of left and right main hepatic ducts at the level of porta hepatis (most common,
Ultrasound is the first imaging tool used for screening for infantile cholestasis.
Absent gallbladder (Gallbladder ghost triad) and triangular cord sign are the best imaging signs for BA in ultrasound.
The Triangular Cord (TC) sign has a high specificity (89%–100%),
consist in a fibrotic remnant of the obliterated cord with surrounding fibrosis in the periportal connective tissue,
is defined as a echogenic cone-shaped or tubular-shaped mass cranial to the bifurcation of the portal vein (transverse or longitudinal scan).
Presence of hepatic artery flow at the hepatic surface at US Doppler exam has been reported.
GALLBLADDER GHOST TRIAD
• atretic gallbladder (length < 19 mm)
• irregular or lobular contour
• indistinct wall with lack of complete echogenic mucosal lining.
CT and MRI are used in order to define the extension of the disease and to establish the presence of associations.
Normal or high signal of the liver on T1WI shows functional tissue,
and high signal area on T2WI shows tissue damaged by inflammation and/or progressive fibrosis.
MRI helps to define the biliary tree and evaluate postoperative changes.
Consist in a cavernous ectasia of the intrahepatic bile ducts that leads to remodeling of ducts with inflammation and segmental dilatation.
Features include segmental saccular dilatation with focal narrowing of the biliary tree.
There is communication with biliary tree.
Central dot sign: Enhancing tiny dots represent portal radicles within dilated intrahepatic bile ducts.
Congenital dilatation of the bile ducts with segmental cystic formation maintaining communication with biliary tree.
What should the report include?
· Present/Absent biliary tree or gallblader
· Communications between the cysts and the biliary ducts.
· Portal vein hypoplasia or portal hypertension signs.
· Associations: Polysplenia.