Diagnostic ultrasound ( PDFDrive )

CHAPTER 6 The Biliary Tree and Gallbladder 169
A
B
C
FIG. 6.5 Harmonic and Spatial Compound Imaging
of Biliary Tree. (A) View of the common hepatic duct
using fundamental frequencies (B) with harmonic imaging
and (C) harmonic imaging and spatial compounding. The
arrow points to nonshadowing debris. There is progressively
increased contrast to noise, effectively clearing the artifactual,
low-level echoes over the luid-illed duct and increasing
the conspicuity of debris (arrow) within it. All three images
were obtained within 6 seconds of each other.
I II III IV
FIG. 6.6 Todani Classiication System for Choledochal Cysts. Type I cyst: diffuse dilation of the extrahepatic bile duct; this is the most
common type (80%). Type II cyst: true diverticulum of the bile duct; very rare. Type III cyst: also called choledochocele; diffuse dilation of the
very distal (intraduodenal) common bile duct. Type IV cyst: multifocal dilations of the intrahepatic and extrahepatic bile ducts. Type V cyst, Caroli
disease, is omitted because it is not a true choledochal cyst. (With permission from Todani T, Watanabe Y, Narusue M, et al. Congenital bile duct
cysts: classiication, operative procedures, and review of thirty-seven cases including cancer arising from choledochal cyst. Am J Surg.
1977;134:263-269. 12 )
with type IVa, are associated with an abnormally long common
channel (>20 mm) between the distal bile duct and the pancreatic
duct. his long common channel could allow for relux of
pancreatic juices into the CBD, causing dilation, but this remains
controversial. 9,13 Type II cysts are true diverticula of the bile
ducts and are very rare. Type III cysts, the “choledochoceles,”
are conined to the intraduodenal portion of the CBD. Type IVa
cysts are multiple intrahepatic and extrahepatic biliary dilations,
whereas type IVb cysts are conined to the extrahepatic biliary
tree. Caroli disease has been classiied as a type V cyst, but it