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Chapter 31 / HPB Imaging (Including IR, Ultrasound, MRI, CT, Nuclear Medicine) 391
body habitus or clinical condition. e success rate of obtaining a diagnos-
tic study is very high; therefore, ultrasound should be considered as the rst
line of study for primary gallbladder pathology (Fig. 31.2). e examination
can be performed at the bedside and, since no ionizing radiation is used, is
safe in pregnant and pediatric patients.
Computed Tomography
e gallbladder in fasting patients is nearly always identied on CT scans of
the upper abdomen. Although calcied gallstones are frequently visible, CT
is not used as a primary examination for detecting gallstones because of its
lower sensitivity for gallstones and higher cost compared with ultrasound.
e main indication for CT in gallbladder disease is for the diagnosis and
staging of gallbladder carcinoma and evaluation of the complications of
cholecystitis such as perforation and pericholecystic abscess.
Cholescintigraphy
Cholescintigraphy is used primarily for the diagnosis of acute cholecysti-
tis. is study is performed by injecting Technetium-99m iminodiacetic
acid (
99m
Tc-IDA) compounds intravenously, and the tracer is taken up by
the liver and rapidly excreted into bile without undergoing conjugation,
allowing visualization of the gallbladder and bile ducts. Serial images are
obtained up to 1 hour. Delayed imaging up to 4 hours and possibly 24 hours
may be necessary in some instances. Nonlling of the gallbladder on cho-
lescintigraphy indicates functional obstruction of the cystic duct and is
highly sensitive and specic for the diagnosis of acute cholecystitis in the
appropriate clinical setting (Fig. 31.3). Other uses for scintigraphic evalua-
tion of the biliary tract include assessment of gallbladder ejection fraction,
patency or bile leak after cholecystectomy, or biliary enteric anastomoses.
FIGURE 31.2 Abnormal gallbladder by ultrasound. Gray-scale image of the gallbladder and
liver is shown. There is a round gallstone (GS) located within the neck of the gallbladder;
note the posterior shadowing seen as black. There is abnormal and irregular gallbladder
wall thickening (arrow). Comet tail artifacts visualized in the gallbladder wall indicates ade-
nomyomatosis of the gallbladder. This is a diagnosis specically made by the ultrasound.
Section IV / Multidisciplinary HPB Care392
Long-term function of Roux-en-Y biliary–enteric anastomosis may be eval-
uated by scintigraphy with delayed imaging.
BILIARY AND PANCREATIC DUCTAL SYSTEM
Ultrasound and CT, because of wide availability and ease of performance as
well as high diagnostic accuracy, are the rst-line imaging techniques for
evaluation of the biliary tree. Magnetic resonance cholangiopancreatogra-
phy (MRCP) is assuming a larger role as a rapid, accurate, and noninvasive
method of evaluating the bile ducts. Currently, MRCP is replacing diag-
nostic endoscopic retrograde cholangiopancreatography (ERCP) in many
instances. Biliary scintigraphy has a limited role in biliary imaging, used
mainly for conrming acute cholecystitis and identifying bile leaks.
Ultrasound
Evaluation of the bile ducts in search of stones, masses, or obstructions is
one of the main applications for ultrasound. Real-time ultrasound read-
ily depicts dilated biliary ducts, which, in most instances, is indicative of
biliary obstruction. e extrahepatic bile duct can be seen in most patients
regardless of body habitus or clinical condition. e most distal common
bile duct (CBD) is more dicult and frequently impossible to image by
transabdominal ultrasound because of overlying gas in the duodenum and
colonic hepatic exure.
Computed Tomography
Although ultrasound continues to be used as the initial screening test for
biliary disease, CT is as eective as is sonography in determining the caliber
FIGURE 31.3 Normal cholescintigram. Frontal view taken 60 minutes after injection of
radioisotope shows normal lling of the gallbladder (GB
). There is excretion of radioisotope
into the common bile duct (CBD) as well. These ndings exclude possibility of acute chole-
cystitis with very high specicity. Normal uptake within the liver is seen as well.
Chapter 31 / HPB Imaging (Including IR, Ultrasound, MRI, CT, Nuclear Medicine) 393
of intra- and extrahepatic ducts. In addition, because of more complete
delineation of the total length of the CBD, CT may be more useful than sonog-
raphy for precisely dening the site and cause of biliary obstruction. Also, if
ultrasound results are equivocal, CT may be used to rene the data or con-
rm anatomy. In addition, CT can often dierentiate benign from malignant
causes of obstruction and can provide guidance for biopsy and staging of
malignancies. CT cholangiography, using oral or intravenous cholecystogra-
phy agents, has been widely used in Europe and has been used on a limited
basis in some centers in the United States to evaluate ductal pathology.
Magnetic Resonance Cholangiopancreatography
MRCP is the most eective, safe, noninvasive MR imaging technique for
evaluation of the pancreaticobiliary ductal system. e usefulness and
accuracy of MRCP have been established in the evaluation of suspected
pancreaticobiliary pain, choledocholithiasis, malignant obstruction, con-
genital anomalies, and postsurgical alterations of the biliary tract and pan-
creas. Contrast administration is not necessary in the evaluation of patients
with suspected choledocholithiasis.
MRCP is mainly based on acquisition of heavily T2-weighted images,
with variants of fast spin echo (FSE) sequences; however, examination
should also include routine MRI images for a complete evaluation. e
diagnostic accuracy of MRCP is comparable to that of ERCP in the evalu-
ation of choledocholithiasis, malignant obstruction, and anatomic variants
of the pancreaticobiliary tract (Fig. 31.4). Visualization of the pancreatic
duct is often substantially improved with the use of the hormone secretin,
FIGURE 31.4 Choledocholithiasis visualized by MRCP. Coronal MRCP image shows multiple
lling defects (arrow) within the distal common bile duct causing intra- and extrahepatic
ductal dilatation.
Section IV / Multidisciplinary HPB Care394
which stimulates the pancreas to secrete a signicant amount of uid while
transiently increasing sphincter of Oddi tone. Utilization of secretin is rec-
ommended in cases where detailed evaluation of the pancreatic duct is
desired. Although the role of MRCP in the evaluation of biliary diseases is
expanding, the major disadvantage of MRCP is that it is purely diagnostic
and does not provide an access for therapeutic intervention. MRCP is the
modality of choice for follow-up after some pancreatic operations such as
pancreatoduodenectomy, where ERCP is challenging.
Percutaneous Transhepatic Cholangiography and ERCP
Percutaneous transhepatic cholangiography (PTC) and ERCP are invasive
methods and usually reserved for patients requiring interventions such as
biliary drainage, stone extraction, stent placement, stricture dilatation,
and biopsy. Both techniques allow direct opacication of the biliary tree
but require invasive access and have limited diagnostic use. e choice of
procedure for direct cholangiography depends on a number of factors: the
clinical situation, the potential for therapeutic intervention, and the avail-
ability of a skilled endoscopist or interventional radiologist. Both proce-
dures allow transformation of a diagnostic study to a variety of therapeutic
maneuvers. e overall complication rate for PTC is 3.5%, which less than
the 10% complication rate seen with ERCP.
PANCREAS
e pancreas is one of the most challenging organs to image in the abdomen.
e small size of the organ and its deep location requires high-resolution
imaging. Comprehensive imaging of the pancreas should show pancreatic
and biliary ductal anatomy, help detect and characterize parenchymal dis-
ease, delineate extrapancreatic extension of a mass or inammatory pro-
cess, and evaluate the vascular anatomy.
Ultrasound
Sonography is a practical and inexpensive option for evaluation of the pan-
creas, but it is operator dependent and usually limited in patients with large
body habitus. Ultrasound examination of the pancreas is best performed on
the fasting patient to reduce the amount of gas and food in overlying bowel.
Without patient preparation, the overlying gastric air commonly obscures
this organ, particularly the tail of the pancreas. Intraoperative sonography
is very useful.
Computed Tomography
MDCT is the rst-line imaging technique for the pancreas. It is unaected
by bowel gas or large body habitus and is widely available, fast, and rela-
tively easily performed. Multiphasic studies are the primary modality used
for evaluation and posttreatment follow-up of the pancreatic adenocar-
cinoma and hypervascular pancreatic tumors including islet cell tumors.
However, CT can be confounded by a morphologic overlap and is insensi-
tive in dierentiating cystic neoplasms. In such cases, MRI of the pancreas
is recommended for further evaluation.
MRI with MRCP
MRI with MRCP examination is commonly performed together for a com-
plete evaluation of the pancreas. MRI has an advantage over CT by better
depicting the internal morphology of pancreatic cysts due to the superior
soft tissue contrast. is improved resolution facilitates recognition of
septa, nodules, and depiction of the duct. Disadvantages of MRI include
Chapter 31 / HPB Imaging (Including IR, Ultrasound, MRI, CT, Nuclear Medicine) 395
lower spatial resolution, insensitivity to detect calcications, and motion-
related artifacts. e contraindications to the use of MR contrast agents are
severe allergy, pregnancy, and end-stage renal dysfunction.
Cystic lesions in the pancreas constitute a diverse category including
inammatory lesions as well as neoplasms ranging from benign lesions
to low-grade indolent neoplasia to frankly malignant tumors. One of the
most common diagnostic challenges in characterization of cystic pancre-
atic neoplasms is distinguishing isolated side branch intraductal papillary
mucinous neoplasm (IPMN) from other cystic lesions such as mucinous
cystic neoplasms or pseudocyst (Fig. 31.5). Ductal dilation may provide
evidence of chronic pancreatitis, but it may also indicate that an IPMN is
of the main duct or mixed type. ese types of IPMN are more likely to be
malignant than is the more common side-branch type; therefore, a cyto-
logic evaluation may be necessary in these patients. Improvement in the
visualization of the duct has been reported with the use of the hormone
secretin, which stimulates the pancreas to secrete a signicant amount of
uid, while transiently increasing the tone of the sphincter of Oddi. MRCP
is also valuable providing noninvasive evaluation of the chronic pancre-
atitis by showing the ductal ectasia, atrophy, or strictures with upstream
dilatation (Fig. 31.6).
PET Scan
CT and MRI are used primarily to image pancreatic ductal adenocarcinoma,
but they may be limited in the setting of enlargement of the pancreatic head
without discrete mass or mass-forming pancreatitis. Metabolic imaging
may be applied to improve preoperative diagnostic accuracy and poten-
tially limit adverse outcomes from inappropriate surgical interventions.
Studies have demonstrated the relatively high sensitivity and specicity
FIGURE 31.5 Pancreatic cystic neoplasms imaged by MRCP. This coronal maximum inten-
sity projection image shows multiple round cystic lesions arising from the pancreas (open
arrows) most likely representing an IPMN. The main pancreatic duct appears normal (short
arrows). MRI with MRCP provides superior image depiction compared to other cross-
sectional modalities such as CT.
Section IV / Multidisciplinary HPB Care396
of PET in distinguishing benign and malignant lesions in the pancreas in
comparison to CT. e primary challenge faced by PET–CT in the imag-
ing of pancreatic cancer pertains to altered glucose metabolism created by
glucose intolerance and diabetes seen in these patients. is clinical situa-
tion may create false-negative ndings in patients who are hyperglycemic
or have inadequately controlled blood glucose levels. False negatives may
also result when the tumor is less than 1 cm, such as in small ampullary
carcinomas. False positives are mainly the result of inammation secondary
to pancreatitis.
Suggested Readings
Gore RM, Levine MS. Textbook of gastrointestinal radiology, 3rd ed. Philadelphia, PA:
Saunders/Elsevier, 2008.
Semelka RC. Abdominal-pelvic MRI, 2nd ed. Hoboken, NJ: Wiley-Liss, 2006:1427, xi
Siegelman ES. Body MRI, 1st ed. Philadelphia, PA: Saunders, 2005:527, ix
Webb WR, Brant WE, Helms CA. Fundamentals of body CT, 2nd ed. Philadelphia, PA:
Saunders, 1998:363, xii.
FIGURE 31.6 Pancreatic duct stricture visualized by MRCP. Coronal MRCP image demon-
strates marked dilatation of the main pancreatic the duct within the body and tail (short
arrow). This dilatation is clearly secondary to a stricture within the head of the pancreas
(long arrow).
397
INTRODUCTION
Gastrointestinal endoscopy oers a multitude of diagnostic and therapeutic
options for patients with pancreatic disease. Pancreatobiliary endoscopy
derives from endoscopic retrograde cholangiopancreatography (ERCP) and
endoscopic ultrasound (EUS), although gastroduodenal stenting is increas-
ingly utilized for patients with unresectable pancreatic cancer and gastric
outlet obstruction as well. is chapter reviews the indications, benets,
and limitations of ERCP, EUS, and gastroduodenal stenting, with a particular
focus on pancreatic cancer and chronic pancreatitis (CP).
ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY
ERCP is an endoscopic technique that emerged in the 1970s where a side-
viewing upper endoscope (a.k.a., duodenoscope) is advanced per oral to
the level of the major and minor papilla, allowing instruments to access
the bile and pancreatic ducts under endoscopic and uoroscopic guidance.
Traditionally, these ducts are opacied after the injection of iodinated contrast
and visualized uoroscopically. In certain circumstances such as complex
choledocholithiasis or indeterminate strictures, a single-operator, beroptic
cholangiopancreatoscope or mother–daughter scope can be advanced into
the pancreatobiliary ducts for direct visualization. In its nascence, ERCP was
a diagnostic tool in an era where cross-sectional imaging of the pancreas and
bile ducts was extremely limited. Now, ERCP is primarily reserved for therapy,
including stone extraction, stricture dilation, or biliary drainage. ERCP has
substantial morbidity that mirrors some low- to moderate-risk surgical proce-
dures, including acute pancreatitis (5% to 15%), hemorrhage (1%), cholangitis
(1%), perforation (0.5%), and rarely death (0.1%).
ENDOSCOPIC ULTRASOUND
EUS combines a exible endoscope with an ultrasound transducer (newer
models are electronic, although older versions are mechanical) that permits
full-thickness visualization of the gastrointestinal wall and surrounding
structures, including the pancreas and extrahepatic biliary tree. Radial echo-
endoscopes provide a circumferential view at right angles to the scope shaft,
whereas linear echoendoscopes yield a 270-degree oblique view that is in the
same plane as the scope shaft, permitting the passage of instruments under
ultrasound guidance. EUS-guided ne needle aspiration (EUS–FNA) can be
performed through a linear echoendoscope with limited risks of bleeding,
perforation, and infection, the latter occurring rarely in the setting of cyst
aspiration. Most complications from EUS and ERCP are managed medically
and are self-limiting, but serious complications such as severe necrotizing
pancreatitis, hemorrhage (refractory to endoscopic and/or percutaneous
treatment), and perforation may require surgical intervention.
Endoscopy in HPB Surgery
Including ERCP and EUS
Wesley D. Leung and Gregory A. Coté
32
Section IV / Multidisciplinary HPB Care398
PREPROCEDURE EVALUATION
EUS and ERCP are performed most commonly on an outpatient basis.
e procedures can be performed with moderate sedation in some cases,
although facilities are increasingly utilizing monitored anesthesia care or
general anesthesia as the preferred approach. For elective cases, patients
should fast for 2 hours (clear liquids) and 8 hours (solid food) before the
procedure. Ideally, anticoagulants (e.g., warfarin) and antiplatelet agents
(e.g., clopidogrel) should be held for 5 to 7 days, particularly in the setting of
EUS–FNA or ERCP with sphincterotomy. As a general rule, an international
normalized ratio (INR) less than 1.5 and platelet count greater than 50,000
are preferred, particularly if therapeutic maneuvers are anticipated (i.e.,
endoscopic sphincterotomy or EUS–FNA). Aspirin ≤325mg by mouth daily
probably does not impact the risk of postprocedure hemorrhage.
For ERCP, patients are preferably sedated in the prone position to opti-
mize uoroscopic visualization and to keep the duodenoscope in a stable
“hockey-stick” conguration at the level of the papilla (Fig. 32.1). Patients
undergoing EUS are typically sedated in the left lateral position, similar
to a standard esophagogastroduodenoscopy (a.k.a., upper endoscopy).
Following either procedure, patients who are at a moderate to high risk for
FIGURE 32.1 Endoscopic retrograde cholangiopancreatography. A retrograde cholangio-
gram is performed with the duodenoscope in a “hockey-stick” conguration in the sec-
ond portion of the duodenum. This patient is a 53-year-old woman with idiopathic CP and
jaundice. She has segmental narrowing in the intrapancreatic segment of the bile duct
consistent with a CP–induced bile duct stricture.
Chapter 32 / Endoscopy in HPB Surgery Including ERCP and EUS 399
complications should be kept fasting or advanced to clear liquids only and
resume normal diet the next morning in the absence of concerning signs/
symptoms. Patients who are at low risk of complications can gradually
advance their diet over 4 to 6 hours.
ERCP IN THE SETTING OF PERIAMPULLARY MALIGNANCY
With improvements in cross-sectional imaging and EUS, the role of ERCP
for the diagnosis of periampullary malignancy (distal cholangiocarcinoma
and pancreatic ductal adenocarcinoma [PDAC], in particular) is increas-
ingly limited. ERCP remains the procedure of choice for biliary drainage, if
indicated, and is a medium for obtaining tissue samples.
Periampullary malignancies may present with a bile duct stricture that
can be challenging to distinguish from a benign bile duct stricture, such as
from CP. Malignant biliar y strictures often have a length greater than 10mm,
a ragged contour, xed lling defect, and/or shouldering above the stric-
ture (abrupt transition in appearance from normal to stricture) (Fig. 32.2).
e malignant potential of proximal common hepatic duct or bifurcation
strictures is generally higher than that of distal bile duct strictures, often
due to cholangiocarcinoma or portal lymphadenopathy causing extrinsic
compression.
FIGURE 32.2 Malignant distal bile duct stricture. A 63-year-old woman presented with
painless jaundice and was found to have a pancreatic head mass on EUS performed imme-
diately prior to ERCP. EUS–FNA conrmed the presence of PDAC. Retrograde cholangiogram
reveals a discrete common bile duct stricture with abrupt “shouldering” of the upstream,
dilated common hepatic duct. This cholangiogram is highly suggestive of a malignant bile
duct stricture, as in this case.
Section IV / Multidisciplinary HPB Care400
Tissue Sampling
ERCP-based tissue sampling is usually performed with a cytologic brush or
forceps biopsies. e sensitivity of cytologic brushings from bile duct stric-
tures is approximately 30% to 40% and specicity approaching 100%. Brush
cytology in primary biliary tumors has a higher sensitivity than in extrin-
sic tumors (pancreatic or metastatic) (80% vs. 35%). Fewer studies have
addressed the yield of cytologic brushings of pancreatic ducts. e accu-
racy is estimated to be 72%, and using a technique of collecting pancreatic
juice above a stricture, a sensitivity and specicity of 93% and 100%, respec-
tively, can be obtained. However, risks of pancreatitis and hemorrhage in
the upstream pancreatic duct should be considered. In patients with PSC,
diagnosing malignancy can be dicult, and cholangiography increases the
specicity and positive predictive value for cholangiocarcinoma when com-
bined with tumor markers (carbohydrate antigen 19-9) and cross-sectional
imaging. ere is no clinically signicant dierence in diagnostic yield
between cytologic brushes produced by dierent manufacturers.
e sensitivity of forceps biopsy ranges from 43% to 88% with specic-
ity similar to brush cytology (approaching 100%). Flexible forceps permit
easier biliary cannulation than do stier ones. e combination of cytologic
brushing and forceps biopsy increased sensitivity by 15% in one report but
a smaller benet in another study. Another study found that combination
of cytologic brushing, forceps biopsy, and endoscopic ne needle aspiration
was more sensitive (73% to 77%) than was each approach alone. Aspiration
of bile for cytologic analysis is rarely used because of low sensitivity of 6%
to 32%.
In some cases, methods such as digital image analysis (DIA) and uo-
rescence in situ hybridization (FISH) can improve the sensitivity of cytology
alone. DIA quanties the amount of cellular DNA by measuring the inten-
sity of nuclei stained with a dye that binds to nuclear DNA. FISH uses a uo-
rescently labeled probe to detect chromosomal abnormalities in cells. FISH
increases sensitivity of cytology to a greater degree than does DIA. However,
there is the potential for false positives with either technique, particularly
in cases of primary sclerosing cholangitis (PSC). erefore, a positive FISH
alone in the absence of a positive cytology specimen needs to be considered
with the rest of the clinical picture.
Miniature endoscopes can be used to visualize the bile (cholangios-
copy) and pancreatic (pancreatoscopy) ducts. Traditional mother–daughter
systems required two operators to maneuver the duodenoscope and the
cholangioscope independently. A single-operator, beroptic cholangioscope
(Spyglass, Boston Scientic Corp.) is available; while this facilitates direct
visualization of the bile and pancreatic ducts, its impact on conrming the
presence or absence of malignancy remains unclear.
TREATMENT OF JAUNDICE
e location of malignant biliary obstruction inuences the ecacy of
endoscopic biliary drainage (distal better than perihilar). e endoscopic
management of proximal bile duct strictures (bismuth II–IV) and bile duct
obstruction are not discussed in this review. ERCP is typically preferred
to percutaneous transhepatic cholangiography (PTC) for biliary drainage
because an external drain is avoided. e short-term (<90 day) success of
ERCP in achieving biliary drainage in the setting of distal bile duct obstruc-
tion is 80% to 90%. Complications may occur in up to 10% of patients,
including cholangitis, perforation, bleeding, and post-ERCP pancreatitis.
Plastic biliary stents are relatively inexpensive and easily removable com-
pared to self-expandable metallic stents (SEMS). However, SEMS have a