This document discusses biliary pathologies and gallbladder diseases. It describes the typical anatomy of the biliary system and variations. Common gallbladder diseases are discussed such as cholecystitis, gallbladder polyps, and gallbladder carcinoma. Causes of biliary obstruction like choledocholithiasis, primary sclerosing cholangitis, Mirizzi syndrome, and cholangiocarcinoma are summarized along with their imaging appearances on ultrasound, CT, and MRCP.

1. Biliary pathologies
By Navdeep Singh

2. • Typical pattern of intrahepatic biliary branching. Segments are numbered
according to the system of Couinaud. CHD = common hepatic duct, RHD = right
hepatic duct, LHD = left hepatic duct, RPSD = right posterior sectoral duct, RASD =
right anterior sectoral duct.

3. • Variations
of biliary
branching
patterns.
The more
common
are A, B
and C.

4. • Biliary duct
anatomy. CT-IVC
(surface
rendered
maximum
intensity
reformat)
shows
trifurcation at
the biliary
confluence
and segments
numbered
according to
Couinaud.
Arrowhead
shows right
anterior
sectoral duct;
arrow shows
right posterior
sectoral duct.

5. • Luschka describe an intrahepatic duct running
adjacent to the gallbladder fossa,
unaccompanied by a portal vein branch, and
emptying into either the right hepatic or
common hepatic duct.
• The term ‘cystohepatic duct’is probably best
reserved for small ducts that drain directly
into the gallbladder or cystic duct. The
significance of these variants is their proximity
to the gallbladder and the potential for injury
at cholecystectomy resulting in a bile leak.

6. GALLBLADDER ANATOMICAL
VARIANTS
• Agenesis of the gallbladder is extremely rare,
with a prevalence of 0.03–0.07 per cent.
• Double gallbladder occurs in about 0.03 per cent,
usually with a shared cystic duct, and the
accessory gallbladder is often diseased.
• True gallbladder septae are uncommon and when
occurring at the fundus form a Phrygian cap.
Frequently, an apparent septum is merely
gallbladder wall folding, which can vary with
patient position.

7. GALLBLADDER STONES
• Prevalence in adults in western community 15 per
cent.
• Asymptomatic in about 80 %.
• They confer small lifetime risk of developing
gallbladder carcinoma.
• About 70 per cent of gallbladder stones are solely
or predominantly cholesterol in type, with up to
30 per cent being black pigment stones composed
mainly of calcium bilirubinate.
• 20% radioopaque.

8. • US - echogenic foci producing acoustic shadows. Stone
mobility is frequently identifiable.
• The sensitivity of US is greater than 95 %.
• False-negative diagnoses are usually due to small
stones in patients in whom there is poor acoustic
access to the gallbladder because of obesity or other
unfavourable anatomy.
• False-negative diagnoses are reduced by careful US
technique including the use of tissue harmonic
imaging, and a variety of US probe and patient
positions.
• Small stones are differentiated from small polyps by
the demonstration of mobility or the presence of an
acoustic shadow.

9. • US shows multiple small shadowing stones. A
normal fold lies near the gallbladder neck

10. • Gallbladder
filled with
stones
producing
the ‘double-arc’
sign;
hypoechoic
line between
two
echogenic
lines (arrow).

11. • Sludge is commonly seen on US, in which it
appears as fine, nonshadowing dependent
echoes.
• It is composed of calcium bilirubinate granules,
cholesterol crystals and glycoproteins.
• It is more commonly seen in chronic fasting
states, critically ill patients, those receiving total
parenteral nutrition or ceftriaxone and in
pregnancy.
• Sludge resolves spontaneously in 50 per cent of
patients and gallstones will develop in 5–15 per
cent.

12. • Milk of calcium bile, or limey bile, is an
uncommon condition in which the gallbladder
bile becomes very viscous, probably as a result
of stasis, and contains a high concentration of
calcium bilirubinate.
• On US it causes diffuse echoes, similar to
sludge, but is more echogenic with a tendency
to layer out and produce an acoustic shadow.
• On CT and, occasionally, on plain radiographs
it is visible as layering high-density material.

13. • Milk of
calcium
bile
producing
fine
echoes
with a
dependen
t layer
that
shadows.

14. CHOLECYSTITIS
• 90–95 % of cases, is due to gallstones (acute calculous
cholecystitis).
• The positive predictive values of stones combined with
either tenderness localized to the gallbladder (positive
sonographic Murphy's sign), or the presence of a
gallbladder wall thickness of >3 mm, are 92 per cent and 95
per cent, respectively.
• Gallstone(s) may be impacted in the neck of the gallbladder
and this region must be carefully examined.
• Other US signs are gallbladder distension (diameter >5 cm),
pericholecystic fluid, gallbladder wall striations and,
occasionally, obvious wall hyperaemia on Doppler
examination.
• Fine echoes seen within the gallbladder may be seen due to
sludge or pus (gallbladder empyema).

15. • Acute cholecystitis. The gallbladder contains small stones in the neck
(Nos.1–4) and its wall shows oedematous thickening (5 mm thickness).

16. • CT is less accurate than US for acute
cholecystitis.
• The CT findings in acute cholecystitis include
gallbladder wall thickening, subserosal
oedema, gallbladder distension, high-density
bile, pericholecystic fluid and inflammatory
stranding in the pericholecystic fat.

17. • Acute
cholecystitis
on CT. The
gallbladder
wall is
thickened
with oedema
in the
adjacent fat.
There is no
abnormal
contrast
enhancement
in this case.

18. • Gangrenous cholecystitis
• irregularity or asymmetrical thickening of the
gallbladder wall, internal membranous echoes
resulting from sloughed mucosa and
pericholecystic fluid.
• The clinical findings, paradoxically, may diminish
with progression to gangrenous change.
• CT signs that suggest gangrenous cholecystitis
are gas in the wall or lumen, discontinuous
and/or irregular mucosal enhancement, internal
membranes representing sloughed mucosa and
pericholecystic abscess

19. • Acute cholecystitis with localized perforation on (A) US
and (B) CT. The thickened gallbladder wall shows a local
defect (arrow) and on CT there is small amount of
intraperitoneal fluid and oedema of adjacent fat.

20. • Emphysematous cholecystitis
• Accounts for only 1 %, but has a relatively high
mortality rate.
• It is more common in men.
• Diabetics, and stones are present.
• Diagnosis - intramural and/or intraluminal gas
caused by gas-forming organisms. On US
intramural gas appears as focal or diffuse bright
echogenic lines. Intraluminal gas, in the
nondependent portion of the gallbladder, causes
a curvilinear, brightly echogenic band with
shadowing, which can make recognition of the
gallbladder difficult and lead to a false-negative
US result.

21. • Emphysemat
ous
cholecystitis.
Image
showing
intramural
(arrow) as
well as
intraluminal
gallbladder
gas.

22. • Acalculous cholecystitis
• Usually seen in critically ill patirnts.
• US signs are gallbladder distension,
gallbladder wall thickening, echogenic
contents and, occasionally, sloughed
membranes/mucosa and pericholecystic fluid.
• A positive diagnosis is often difficult as sludge
and gallbladder distension may occur without
cholecystitis in this group of patients.
• Biliary scintigraphy is possibly the most
accurate modality.

23. • Chronic acalculous cholecystitis is a controversial
entity as there are no clear clinical, pathological
or imaging criteria for its diagnosis.
• US may show gallbladder wall thickening and, by
definition, no stones.
• Cholescintigraphy followed by the IV infusion of
cholecystokinin (CCK), or one of its analogues,
can be used to assess gallbladder contractibility.
• An ejection fraction greater than 35 per cent on
CCK-cholescintigraphy is generally taken to be an
indicator of gallbladder dysfunction and helps
select patients who may benefit from
cholecystectomy.

24. • GALLBLADDER POLYPS
• Majority of polyps are cholesterol and less often
adenomatous.
• Cholesterol polyps are usually 2–10 mm in size
whereas adenomas can be up to 2 cm.
• Cholesterol polyps are multiple and not often
associated with stones whereas adenomas tend to be
solitary and associated with stones.
• Appear as small echogenic nonshadowing foci
adherent to the gallbladder wall, often in a
nondependent portion.
• Polyps per se are usually of no significance, though a
diameter of >10 mm or local disruption of the adjacent
gallbladder wall suggests malignancy.

25. • Gallbladder polyps. (A) Solitary, nondependent
and nonshadowing polyp (arrow). (B) Multiple,
nonshadowing cholesterol polyps.

26. • GALLBLADDER CARCINOMA
• Uncommon malignancy that has a very poor prognosis.
• presents at a late stage in the sixth and seventh decades
with right upper-quadrant pain, often presenting as hilar
biliary obstruction.
• On imaging as focal or diffuse irregular thickening of the
gallbladder wall or as a larger mass in the gallbladder fossa
with little or no gallbladder lumen identifiable. Gallbladder
stones may appear to be ‘buried’ in the mass.
• Spread to lymph nodes around the portal vein relatively
early in its course and at presentation there may be nodal
masses extending down to the head of the pancreas.
• spreads to the adjacent liver (segments 4 and 5).
• D/D includes Mirizzi syndrome and metastases to the
gallbladder, which are uncommon but include melanoma

27. • Gallbladder carcinoma. (A) Polyp with breach of continuity of the
underlying wall (arrow). (B) Advanced carcinoma extending outside the
fundus, with a nodal metastasis posterior to the pancreatic head (arrow).
An associated stone can be seen in the gallbladder neck.

28. ROLE OF RADIOLOGY IN
INVESTIGATION OF JAUNDICE
• The questions that need to be addressed are:
• 1 Is bile duct obstruction present?
• 2 What is the anatomical level of obstruction?
• 3 What is the cause of the obstruction?
• 4 If the obstruction appears to be malignant:
• a There evidence of nonresectability?
• b In those patients with malignant hilar obstruction
who are unsuitable for surgical resection, what
approach should be taken to palliative stenting?

29. • Modified Bismuth
classification of
malignant hilar
biliary obstruction
based on proximal
extent of tumour.

30. • CHOLEDOCHOLITHIASIS
• 90 % of bile duct stones are secondary stones.
• USG - Most commonly used initial imaging
modality. Reports of its sensitivity vary greatly
with the upper range being 50–80 per cent.
The sensitivity in jaundiced patients tends to
be better.
• Positive stone diagnosis depends on the
demonstration of an intraductal echogenic
focus in both the longitudinal and transverse
planes.

31. • Choledocholithi
asis. Small
shadowing stone
(arrow) in dilated
bile duct.

32. • Choledocholithiasis. A distal common bile duct stone (arrow) is
slightly dense compared with the surrounding low-density bile.

33. • Choledochol
ithiasis. CT-IVC
shows a
small stone
within the
opacified
distal
common
bile duct.

34. • Choledocholithias
is. Single common
duct stone
(arrow) on thick-section,
oblique,
coronal MRCP.

35. • ERCP shows a
post-cholecystectomy
stricture (arrow)
which,
characteristically,
is very short.

36. • Primary sclerosing cholangitis
• 70 % of patients having a background of chronic inflammatory
bowel disease, usually ulcerative colitis.
• Characterized on cholangiography by multiple segments of
stricturing involving intrahepatic and/or extrahepatic ducts. A
characteristic feature in the common duct is diverticula-like out-pouchings.
• On USG, PSC is characterized by bile duct wall thickening which is
most pronounced at sites of stricturing, and the diverticula-like out-pouchings
may be seen as local echogenic foci in the duct wall.
• Well-established PSC is associated with areas of atrophy and
hypertrophy within the liver, best seen with CT or MRI.
• Bile duct stones occur in about 10 %.
• Cholangiocarcinoma occurs in about 10 % and is notoriously difficult
to diagnose early. It should be suspected if there is progressive duct
dilatation proximal to a stricture, or if a nodule >1 cm in diameter is
identified.

37. • Primary sclerosing cholangitis. CT-IVC (maximum intensity,
oblique coronal reformat) shows multiple intrahepatic and
extrahepatic segments of stricturing.

38. • Primary sclerosing cholangitis. Typical bile
duct wall thickening on US (arrows).

39. • Mirizzi syndrome
• is characterized by narrowing of the common duct
caused by inflammation and fibrosis related to chronic
gallstone disease.
• Typically a stone is impacted in the neck of the
gallbladder, the cystic duct, or cystic duct remnant. A
fistula may develop between the gallbladder or cystic
duct and the common duct and the stone may partially
or totally pass into the common duct.
• The level of stricturing varies, being most common in
the upper and middle common duct.
• On cholangiography the stricture is usually smooth, 2–
3 cm in length, and often has a concavity toward the
right.
• USG - there is ductal dilatation down to the level of a
stone that is not clearly within the common duct.

40. • Mirizzi syndrome. MRCP (A) shows a stricture of the lower common
duct caused by a stone (arrow) lying in an expanded cystic duct on
ERCP (B). Multiple gallbladder stones are also seen.

41. • Recurrent pyogenic cholangitis
• also referred to as oriental cholangiohepatitis, occurs
mainly in South-East Asia or its emigrants.
• Characterized by recurrent episodes of cholangitis, bile
duct stones, biliary dilatation and strictures.
• Infection is due to enteric bacteria that are thought to be
responsible for stone formation, although parasites, in
particular Clonorchis sinensis, may play a partial role.
• The stones are more often intrahepatic, can be very
extensive, and are composed of calcium bilirubinate, often
visible on CT as high densities within dilated intrahepatic
ducts.
• US shows duct dilatation and stones that may not shadow.
• Cholangiography by any technique shows duct dilatation
and multiple stones, which may be widespread or
segmental, and duct strictures are common.

42. • Recurrent
pyogenic
cholangitis.
Multiple
high-density
stones lie in
dilated
ducts within
an atrophic
left lobe.

45. • CHOLANGIOCARCINOMA
• Arises from the bile duct epithelium and that tends to
spread by local infiltration.
• Approximately 60 per cent arise in the perihilar region
(Klatskin tumours), less than 30 per cent arise in the
distal common duct, and less than 10 per cent are
diffuse or multifocal.
• Present as malignant hilar biliary obstruction.
• Their appearance on imaging varies with size and
pathological type. Most of the exophytic tumours are
less than 5 cm and the infiltrating stenotic tumors are
usually less than 1–2 cm in diameter.
• On US the tumours appear as nodules or focal bile duct
wall thickening, which are usually slightly hyperechoic.

46. • On CT the nodules are usually isodense or slightly
hypodense compared with liver and are more easily
seen on dual-phase contrast-enhanced imaging;
• the infiltrating stenotic type tend to enhance in the
arterial phase and the exophytic are more conspicuous
on portal phase contrast-enhanced imaging, where
they appear less dense than liver. Delayed phase
imaging to 10–20 min may show late tumour
enhancement.
• On MRI the tumours are hypointense on T1 and
hyperintense on T2 and show some progressive
enhancement on dynamic imaging.
• The proximal extent of the stricturing, which critically
affects treatment options, is well shown with MRCP,
which performs better than US and CT and is
comparable to direct cholangiography .

47. • Small hilar
cholangiocar
cinoma
(arrowhead)
producing
obstruction
of the right
posterior
sectoral duct
(short
arrow), right
anterior
sectoral duct
(long arrow)
and left
hepatic duct.
(A) Thick
section
oblique
coronal
MRCP. (B)
Axial portal
phase CT. (C)
Longitudinal
US. (D)
Transverse
colour
Doppler US
(open arrow:
normal left
portal vein).

48. • Carcinoma of
the pancreas.
PTC shows a
distal
common duct
stricture that
is tight and is
shouldered
proximally

49. Figure 36.38 Carcinoma of the pancreas. ERCP shows adjacent strictures (arrows) of the
common bile duct and pancreatic duct (‘double duct sign’).