Contrast-Enhanced Helical CT of Choledocholithiasis
Frank H. Miller1,
Caroline M. Hwang1,
Helena Gabriel1,
Lori A. Goodhartz1,
Anees J. Omar2 and
Willis G. Parsons, III3
1 Department of Radiology, Northwestern University Medical School, 676 N. St.
Clair St., Ste. 800, Chicago, IL 60611.
2 Department of Medicine, Evanston Hospital, 2650 Ridge Ave., Evanston, IL
60201.
3 Department of Gastroenterology, Northwestern University Medical School,
Chicago, IL 60611.
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Fig. 1. —Illustration of stones in common bile duct as seen on
contrast-enhanced CT; appearance of stone can vary depending on slice of
examination. On left, dotted lines passing through common bile duct represent
scan obtained at each level, and images on right show CT appearance of stones.
Slice 1 shows fluid attenuation in lumen of bile duct without stone. Slice 2
shows target sign. Crescent and rim signs are shown at slices 3 and 4,
respectively. Slice 5 shows stone completely filling duct. (Modified and
reprinted with permission from
[10])
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Fig. 2A. —84-year-old man with common bile duct stone exhibiting target
sign. On contrast-enhanced helical CT scan, choledocholithiasis is represented
as central density (arrowhead) surrounded by hypoattenuating ampulla
of Vater (arrow). In this particular scan, stone is seen as
heterogeneous with center showing lower density.
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Fig. 2B. –84-year-old man with common bile duct stone exhibiting target
sign. ERCP image confirms presence of stone (arrow) in common bile
duct, which was pushed superiorly before it was surgically removed.
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Fig. 3. —50-year-old man with stone in distal common bile duct
presenting as rim sign on contrast-enhanced helical CT scan. Faint rim of
increased density (arrow) is visible along peripheral margin of
low-density calculus.
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Fig. 4A. —88-year-old woman with common bile duct stone displaying
crescent and target signs. On contrast-enhanced CT scan, stone (straight
arrow) with density of soft tissue is surrounded by crescent-shaped lower
density bile (curved arrow).
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Fig. 4B. —88-year-old woman with common bile duct stone displaying
crescent and target signs. Contrast-enhanced CT scan obtained at level
inferior to A shows same stone (arrow) completely surrounded
by bile (target sign). Note how appearance of stone changes on different CT
slices.
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Fig. 4C. —88-year-old woman with common bile duct stone displaying
crescent and target signs. ERCP image also shows stone (arrow) is
present.
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Fig. 5. —33-year-old woman with calcified stone (arrow) in
common bile duct seen on contrast-enhanced CT scan. Because of their density,
calcified stones are easier to detect than—but are not as common
as—cholesterol stones.
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Fig. 6. —90-year-old woman with common bile duct stone. On
contrast-enhanced CT scan, stone (curved arrow) appears as
soft-tissue density in distal portion of common bile duct. Note difference in
appearance of soft-tissue stone from calcified gallstones (straight
arrows). Dilated intrahepatic duct is indicated by arrowhead.
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Fig. 7. —91-year-old woman with stone in common bile duct seen as
subtly increased density (straight arrow) in hypoattenuating bile on
contrast-enhanced CT scan. Stone has similar attenuation to surrounding bile,
making diagnosis difficult. Note incidentally discovered low-density gallstone
(arrowhead) in markedly thickened gallbladder (curved
arrow).
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Fig. 8. —32-year-old man with HIV cholangiopathy and false-positive
finding on contrast-enhanced CT scan. Contrast-enhancing mucosa
(arrow) mimics appearance of stone.
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Fig. 9. —25-year-old woman who had undergone cholecystectomy and
presented with abdominal pain. On contrast-enhanced CT scan, area of increased
density (arrow) presumably caused by artifact is seen in
hypoattenuating bile, a finding that is suggestive of stone and led to
false-positive diagnosis. On ERCP images (not shown), no stone was
identified.
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Fig. 10A. —51-year-old woman with common bile duct cast stone in
cirrhotic liver that was missed on CT. Contrast-enhanced CT scan shows faint
subtle increase in density (arrow) in common bile duct that was
initially thought to represent enhancing mucosa.
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Fig. 10B. —51-year-old woman with common bile duct cast stone in
cirrhotic liver that was missed on CT. ERCP image shows cast (arrows)
in common bile duct that gastroenterologist classified as atypical stone.
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Copyright © 2003 by the American Roentgen Ray Society.
