Biliary System
Bile, required for the digestion of food, is excreted by the
liver into passages that carry bile toward the hepatic
duct, which joins with the cystic duct (carrying bile to and
from the gallbladder) to form the common bile duct,
which opens into the intestine.
Gallbladder
The gallbladder functions as a resevoir for bile produced
by the liver. It is 7-10cm long, 3cm wide at its broadest
measure, and has a capacity of 30-50ml.
The gallbladder is divided into 3regions :
fundus, body, and neck.
Bile produced by the left and right portions of the liver travel through the right and left
hepatic ducts (1-2mm in diameter). These two ducts join to form the common hepatic
duct.
The union of the common hepatic duct and cystic duct forms the common bile duct (up
to 6mm in diameter. Diameter increase 0.5-1mm per decade).
The common bile duct passes posterior to the first portion of the duodenum. It then
descends via a groove on the superolateral portion of the posterior head of the
pancreas, sometimes traveling through the pancreas head.
At the head of the pancreas, the common bile duct meets the pancreatic duct, and they
exit into the second part of the duodenum, forming the hepatopancreatic ampulla (or
ampulla of Vater).
(Imaging Modalities)
Indirect Imaging:
Indirect imaging involves noninvasive radiologic techniques
including:
US,
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plain film,
CT,
(MRCP)
Oral ,IV Cholecystography
Nuclear IDA scan
(Cholescintigraphy)
Direct Imaging:
involves invasive radiologic
procedures, which include:
 ERCP
 Operative and T-tube
cholangiogram
 PTC
Plain Radiography
To detect either stones, calcification or gas in the biliary system.
Emphysematous cholecystitis
Porcelain GB
Ultrasound
Is the first and the most commonly obtained method of examination
in patients with RUQ pains, abnormal LFTs, or suspected liver
masses.
Is a noninvasive and excellent screening tool.
Used to evaluate the presence of bile duct obstruction and
gallstones as well as to distinguish a solid lesion from a cystic one.
The patient should be NPO (nothing-by-mouth) for imaging the
biliary tract with ultrasound. Fasting distends the gallbladder and bile
ducts and reduces bowel gas that may obscure visualization of
portions of the gallbladder. Food may increase the thickness of the
gallbladder wall imitating pathological wall thickening. Four hours is
sufficient fasting for small children, and 6-8 hours for age 12 to adult.
They should be told not to smoke during the fasting period since
smoking causes the bile ducts to contract.
Technique of exam
Begin the exam with the patient in the supine position .
The patient can be moved to the left posterior oblique
,left decubitus or even upright position.
Obtain full length of gallbladder from the portal vein to
fundus (7-10cm) and transverse images (3cm) at
representative levels. Measure GB wall thickness (up to
3mm) perpendicular to wall.Document any stones or
biliary dilatation.
If stones are seen, evaluate if they are mobile or
impacted. Move the patient into upright or lateral decubitus
positions to demonstrate stone mobility.
Rolling stone sign - movement of gallstones with GB with
position change
Note the change of position of the stones from (near the
neck of GB )to its fundus when he changed his position
from supine to decubitus position
Obtain full length of common bile duct (CBD) or
as much as possible, and measure CBD
diameter(N up to 6mm till the age of 60 then it
increases 1mm each year).
Acquire longitudinal and transverse views of
pancreatic head.
Endoscopic Ultrasonography
EUS uses ultrasound probes carried on endoscopes,
so that ultrasound images can be obtained from inside
the gastrointestinal tract.
Using ultrasound imaging from inside the body helps
prevent the artifacts that can occur when imaging
through the abdominal and chest wall. Degradation of
the image by bone, fat, and bowel gas can be avoided.
In addition, higher frequencies of ultrasound can be
used. The higher the frequency the shorter the
penetration depth, but because EUS places the
ultrasound probe by endoscopy very close to the area
to be examined, the smaller imaging area is not a
problem
Note the stone(red arrow)causing strong Note the stone within the dilated CBD
acoustic shadowing (yellow arrow) is seen
within the dilated CBD
Computed Tomography (CT)
While CT is not the imaging modality of choice for visualizing
the biliary tree directly it is useful in diagnosing liver,
gallbladder, and pancreatic disease.
CT can identify pathological dilation of the intra&extrahepatic
bile ducts it also can help in identification of the cause of
obstruction as it can detect pancreatic cancer with 100%
accuracy , The sensitivity for identifying bile duct stones is
low; however, in a few cases a stone in the bile ducts can be
identified.
CT also can identify gallstones, cholecystitis &GB cancer
Note the dilatation of the biliary radicals at the first image ,can you identify
the cause at the second image (cancer head of pancreas)
Common bile duct stone & GB stones
Spiral CT cholangiography
3-D CTC as a non-invasive and sensitive technique for the diagnosis of biliary diseases
with high diagnostic accuracy will greatly increase the detection rate of biliary diseases .
Technique of CT cholangiography
One hundred milliliters of cholangiographic contrast material iotroxate
meglumine (Biliscopin) is infused IV over a period of 30 min, and helical
CT cholangiography was performed 30 min later. After rolling the patient
to mix bile and contrast material in the gallbladder
Multi-slice helical CT, using scanning mode HQ, 120 kV, 270-280 mA, 0.8
s/r, pitch 3, with table incrementation rate of 11.25 mm/s. The scope of
scanning covered the whole biliary tree. 5 mm in thickness at 5 mm
intervals was used, followed by an overlapping reconstruction of 3.75
mm in thickness at 2.0 mm intervals, or 3.75 mm in thickness at 3.75 mm
intervals, followed by an overlapping reconstruction of 2.5 mm in
thickness at 1.0 mm intervals. Among the three-phase enhancement
scanning, the portal phase was selected for a reconstruction of 3.75 mm
in thickness at 2.0 mm intervals.
All imaging data were sent to the workstation .Based on actual
requirements, maximum density projection (MIP), minimum density
projection (MinP), surface shaded display (SDD), CT virtual endoscopy
(CTVE)
Magnetic resonance
cholangiopancreatography (MRCP)
MRCP is a non-invasive technique that delineates the pancreatic and
biliary ductal systems, while providing projectional and cross sectional
images of the ducts. MRCP does not require administration of IV contrast
material; it is based on T2-weighted images, which depict static fluid
(including bile and pancreatic secretions), with a higher signal
intensity. MRCP also avoids the invasive complications of ERCP. With
the recent improvements in MRCP, it is superceding ERCP for many of its
diagnostic indications. MRCP is inferior to ERCP in several respects
however. The spatial resolution of MRCP is lower than that of
ERCP. Furthermore, ascites or fluid collections in the upper abdomen can
interfere with the visualization of the pancreatic and biliary ducts.
Technique of MRCP
MRCP images are taken in axial, coronal, and 3-D
formats providing imaging referencing in multiple planes.
It is important that the entire gallbladder, biliary ducts,
and pancreas are included in the axial, coronal, and 3-D
images. Two techniques are combined for imaging the
biliary tract: multisection thin-slice and single-slice thickslab MRCP. Studies show that these techniques should
be combined in the imaging protocol to get the most out
of the unenhanced and enhanced MR scan.
Intravenously administered fentanyl before MRCP has
been shown to improve the qualitative and quantitative
visualization of the biliary tree. The reason for both
techniques is that single-shot thin-slice imaging is
superior to multisection thin slice for bile duct imaging.
Oral Cholecystography
The oral cholecystogram (OCG) is a purely historical
examination that studied the opacification of the gallbladder. This
study was once the diagnostic standard for imaging the gallbladder
before ultrasound and CT reached the current level of image
quality. The basic process involved the patient not eating any fatty
foods, or being N.P.O (nothing by mouth) about 6 hours before
ingesting oral contrast media. This was in the form of tablets (brand
name-Telopaque), that when dissolved the media is absorbed into
liver and secreted in bile
Nuclear IDA scan
(Cholescintigraphy)
It uses the radioisotope imino diacetic acid (IDA) to image part of the
biliary system. In the past the IDA scan has been called the HIDA
scan. The most common reason for physicians requesting this scan is
to evaluate the:
1-functioning of the cystic duct in case of suspected cholecystitis
2-can also detect biliary obstruction,
3- bile leak,
4- Atresia.
The IDA scan is a dynamic scan that assesses function of the
gallbladder and cystic duct patency. Technetium-99m-IDA agents
such as Choletec or Hepatolite are administered intravenously. These
agents are bilirubin analogues having the same biliary uptake as
bilirubin used to make bile, but are not conjugated to bilirubin. Then
they are secreted into the biliary tract allowing them to be taken up by
the liver and secreted into the biliary tract and concentrated in the
normal functioning gallbladder. When the biliary tract is functioning
properly the entire bilirubin pathway from filling of the gallbladder to
passage into the common bile duct and duodenum should be
visualized.
Endoscopic Retrograde
Cholangiopancreatography (ERCP)
ERCP is a combined endoscopic and radiographic procedure that
images the biliary and pancreatic ducts. ERCP is performed with a sideviewing duodenoscope which has an instrumentation channel that
allows for the insertion of the cannulation catheter into the major or
minor duodenal papilla. A water-soluble contrast agent (60 % iodine) is
injected into the ductal system using fluoroscopy for imaging. It is
important to obtain adequate ductal filling without over-distending the
system. (During interventional procedures, a guide-wire can be inserted
through the cannulation catheter, for subsequent insertion of additional
instruments like papillotomes, drainage devices, cytology brush,
etc.) Althought ERCP is an important diagnostic tool in the evaluation of
patients with suspected biliary and pancreatic disorders, MRCP is
superceding ERCP for some of its indications.
ERCP Indications
>Biliary disease
--Jaundice
--Cholestasis
--Cholangitis
--Choledocholithiasis/gallstones
--Tumors
--Primary biliary sclerosis
>Pancreatic Disease
--Acute gallstone pancreatitis
--Recurrent acute pancreatitis
--Chronic pancreatitis
--Pancreatic pseudocyst, abcess
--Pancreatic tumors>Pre- and/or post-op duct eval
>Evaluation post liver transplant
>Sphincter of Oddi manometry
>Unexplained upper abdominal pain
>Therapeutic interventions
--Biopsy/cytology
--Sphincterotomy
--Stone extraction
--Lithotripsy
--Stent placement
--Balloon dilation of strictures
--Pseudocyst drainage
--Irradiation
ERCP complications
Complication
1. Pancreatitis
Mechanism/comment
1.
2. Cholangitis
2.
3. Infection
4. Perforation
5. Significant
bleeding
3.
Secondary to over-distention of
pancreatic ducts with contrast
extravisation into parenhymal
tissue,
Antibiotics are initiated if biliary
obstruction is present and
cannot be relieved. Most
common organisms include
GNR (E. coli, Klebsiella)
Bacteremia, pseudocyst, and
abcess formation
4.
5.
Sphincterotomy, ampulla in
duodenal diverticulum
Sphincterotomy
PostOperative Cholangiography
(T-tube Cholangiogram)
Postoperative t-tube cholangiography is performed to exclude a
retained bile duct calculus or to assess for any surgical
complications such as a bile duct leak before removal of the t-tube.
The study is usually performed 7-10 days after surgery.
Percutaneous Transhepatic
Cholangiography (PTC)
This is another radiographic study that is purely historical
and is not done in modern radiographic imaging. It was
both a diagnostic procedure in cases of suspected
obstructive jaundice, and therapeutic in that dilated bile
ducts could be drained during the procedure.
Occasionally a stone could be removed by this procedure
eliminating the risk of open surgical intervention. Today
there are many other invasive procedures with lower risk
than PTC. This study was a type of invasive
cholangiography that involved direct puncture of the
biliary ducts. A fine needle was passed from the skin
surface through the liver into a biliary duct. Risk of the
procedure included possible puncture of the lung,
bleeding from the liver and vascular injury. This was not
an easy procedure to perform so benefit of the procedure
had to far outweigh its risk before it was performed.
Developmental anomalies&Normal
variants
Gallbladder ectopia.
Intrahepatic gallbladder
(GB) demonstrated on
CT scan
Gallbladder ectopia.
Situs inversus with leftsided gallbladder
The phrygian cap
Double gall bladder
Choledochal cyst
Type I
Caroli's disease
Anatomic variants in the
cystic duct