Dr. Quencer, Dr. Kambadakone, Dr. Sahani, and Dr. Guimaraes are at the Division of Abdominal Imaging and Intervention, Massachusetts General Hospital, Boston, MA.
In Part 2 of this two-part article, the authors discuss imaging manifestations of various abnormalities affecting the pancreas.
of pancreatic conditions is a challenge to physicians due to the
anatomical location of the organ deep within the abdomen.
with multidetector computed tomography (MDCT) and magnetic resonance
imaging (MRI) along with the use of 3-dimensional(3D) imaging play a
critical role in the evaluation of pancreatic diseases.
Specific types of pancreatitis
rare form occurs in the spaces between the head of the pancreas, the
second portion of the duodenum, and the CBD. The inflammatory
involvement results in scar-tissue formation in the pancreatico-duodenal
groove and subsequent cystic dystrophy of heterotopic pancreatic tissue
in the duodenal wall.6,16 Imaging features include
inflammatory involvement of the pancreas and medial wall of the
duodenum,with cystic changes limited mostly to the pancreatico-duodenal
groove (Figure 10). Groove pancreatitis can occasionally mimic
pancreatic adenocarcinoma given its focal nature, its propensity to
cause strictures of the bile and pancreatic ducts, and its fibrotic
character, which leads to decreased enhancement and T1 hypointensity.
Findings favoring groove pancreatitis over adenocarcinoma include cystic
changes within the lesion, smooth rather than abrupt narrowing of the
pancreatic and CBD, and a sheet-like mass rather than a rounded mass.
pancreatitis, first described in 1995, is pathologically characterized
by dense inflammatory infiltrates of lymphocytes and plasma cells around
the small- to medium-sized pancreatic ducts with associated fibrosis.
The clinical presentation is similar to pancreatic cancer, with weight
loss and obstructive jaundice, but presents with the absence of severe
attacks of abdominal pain seen with acute pancreatitis. Extrapancreatic
manifestations are observed in 19% to 50% of cases and include
multifocal biliary strictures, renal lesions from tubulointerstitial
nephritis, retroperitoneal fibrosis, Sjogren’s syndrome, and
inflammatory bowel disease (Figures 11 and 12). Serum IgG4levels are
characteristically elevated and a level > 135 mg/dL is 95% accurate
and 97% specific in making the diagnosis. Elevation of IgG4is rare in
pancreatic cancer and is observed only in 10% of cases. A combination of
imaging findings, serologic, or histologic criteria are necessary to
diagnose autoimmune pancreatitis (Table 3).17-19
pancreatitis has typical imaging features. Classically it is described
as diffuse pancreatic enlargement, which becomes featureless secondary
to loss of normal pancreatic lobulations, foreshortening of the
pancreatic tail and a peripheral rind or ‘wrapping’ around the pancreas,
which appears hypodense on CT and as hypointense on both T1 and T2
images (Figure 13). Pancreatic ductal irregularities are often seen as
ductal strictures or diffuse narrowing.20 Autoimmune
pancreatitis can also present as a focal mass, which often poses a
diagnostic dilemma (Figure 14). The differences and similarities in
imaging features of focal autoimmune pancreatitis and pancreatic
adenocarcinoma are listed in Table 4.
chronic form, tropical pancreatitis has unique clinical,
epidemiological and imaging features. It characteristically presents at a
young age (mean age 12.5 years, M:F, 1.6 to 5:1), leads to early
development of diabetes, has a specific geographic distribution (India,
Asia, South America), and is associated with malnutrition, which is
thought to be a cause, not an effect. Another potential etiology is a
mutation of the serine protease inhibitor Kazal type 1 (SPINK1) gene.21 On
imaging, there is significant atrophy of the pancreas, marked
dilatation of the pancreatic duct, and large intrapancreatic ductal
stones, which have been reported up to 5 cm in size. This disease is
associated with a marked predisposition to pancreatic adenocarcinoma,
which occurs at an early average age of 45 years.6
Cystic pancreatic lesions
utilization of cross-sectional imaging, such as MDCT and MR, has led to
an increased detection of cystic pancreatic lesions with nearly a third
of cases being diagnosed in asymptomatic patients (Tables 5 and 6) and a
prevalence of incidental cystic lesions on CT being present in 2.6% of
examinations.22 Despite the significant overlap in the
imaging features of pancreatic cystic lesions, MDCT andMRI are fairly
accurate in the characterization of these lesions. Occasionally, EUS
with or without aspiration/biopsy might be necessitated for
characterization prior to surgical intervention.
Intraductal papillary mucinous neoplasm (IPMN)
are commonly encountered cystic lesions of the pancreas and can be
classified based on involvement of the main duct and side branch. There
is the main duct IPMN, side branch IPMN, and combined IPMN (involving
both main duct and side branch). Main duct IPMNs cause diffuse
enlargement of the pancreatic duct and do not present as cystic lesions
of pancreas. Up to 40% of main ducts IPMNs have malignant features at
diagnosis and they are often surgically resected. The features on
imaging suggestive of malignancy in main duct IPMNs include enhancing
mural nodules or main duct dilatation > 1 cm. On the other hand, side
branch IPMNs (also known as branch duct IPMNs) are less likely to be
malignant and are often followed up on serial imaging. Side branch IPMNs
have a macrolobulated or ‘cluster of grapes’ appearance on imaging. The
most characteristic imaging feature is the communication of the lesion
with the main pancreatic duct, which differentiates them from mucinous
cystic neoplasms. A typical finding on ERCP is the so called ‘bulging
papilla’ secondary to increased mucin production by the lesions.
Demonstration of communication with the pancreatic duct with MRCP or
ERCP is of paramount importance in diagnosing IPMNs as this limits the
differential diagnosis of a cystic lesion to IPMN and pseudocysts, which
are the only other cystic lesions to demonstrate ductal communication.
Surgical resection is performed in symptomatic patients or in those
lesions that demonstrate suspicious features on follow up imaging, such
as enhancing mural modules, a size > 3cm and concomitant main
pancreatic ductal dilatation.2,23 In asymptomatic patients
with side branch IPMNs measuring < 3 cm without solid nodules,
follow-up imaging is recommended for detection of suspicious features.
Serous cystadenoma (SCA)
known as microcystic adenomas, serous cystadenomas do not have
malignant potential. Therefore, resection is only indicated when they
become symptomatic due to mass effect. They typically affect older
females and are associated with von Hippel-Lindau disease. SCAs favor
the pancreatic head and are composed of multiple tiny cysts (> 6
cysts measuring 1 mm to 2 cm). Characteristically, these lesions will
have a central scar, which can sometimes calcify and has a predilection
for the pancreatic head. These lesions may grow up to 4 mm per year. The
diagnosis of a serous cystadenoma can be made with confidence when a
lesion demonstrates the classic imaging appearance of a multi-lobulated
external border, thin enhancing septa in a honeycomb-like appearance,
and a central scar, which occasionally calcifies. Atypical appearances
can be seen. For example, occasionally the cysts can be too small to
resolve even with MRI or high-frequency EUS and appear to have a solid
appearance. Additionally, these lesions, instead of having numerous tiny
cysts, can have a few larger cysts (oligocystic or macrocystic
variant),lack a central scar and can be located in the pancreatic body
or tail, and therefore mimic a mucinous cystic neoplasm. EUS-guided
aspiration can confirm the diagnosis in atypical cases by establishing
the presence of glycogen rich epithelial cells and absence of mucin.2,24
Mucinous cystic neoplasm
known as mucinous macrocystic neoplasm, these lesions, unlike their
microcystic counterparts, have malignant potential or are frankly
malignant at diagnosis. Therefore, surgical resection is indicated.
These lesions demonstrate a 9:1 female-to-male incidence. They are more
common in the pancreatic tail and contain a few large mucin-containing
cysts (< 4 cysts larger than 2 cm). On imaging, these lesions tend to
have a smooth outer contour and a few septae, which can occasionally be
enhancing and thick (Figures 15 and 16). Enhancing nodular and
papillary projections may occasionally be seen. When suspected, EUS
aspiration will be performed before surgical excision to exclude other
cystic lesions, including a pseudocyst and serous cystadenoma. The fluid
aspirated will contain thick mucin and an elevated level of tumor
markers, such as carcinoembryonic antigen (CEA) and CA-19-9.1,24,25
Cystic neuroendocrine tumors
tumors, as discussed below, can sometimes undergo cystic degeneration
and mimic a cystic neoplasm. The outer wall of the lesion will often be
spared from cystic degeneration and therefore demonstrate features
consistent with neuroendocrine tumor, specifically avid early
enhancement (Figure 17).
Solid pseudopapillary tumor (SPT)
known as solid-cystic papillary epithelial neoplasms (SPEN), these
lesions are unique among the cystic pancreatic neoplasms in that they
tend to affect young patients (20-30 yrs). Affected patients tend to be
African American or Asian and female. The appearance of these lesions is
varied, but they are classically large, well encapsulated, and of
variable internal characteristics with areas of hemorrhagic necrosis
(Figures 18 and 19). The prognosis is good with a 5-year survival
estimated at 97% after surgical resection.26
cystic lesions seen in other solid organs in the abdomen, true cysts
are rare and almost never occur in a normal patient population. When
present, true cysts are often multiple rounded and well defined lesions.
Evidence of underlying conditions, such as von Hippel-Lindau disease,
polycystic kidney disease, and cystic fibrosis, are often apparent on
imaging (Figure 20).
Solid pancreatic tumors
an estimated 43,140 new cases of pancreatic adenocarcinoma in the U.S.
in 2010 and a 5-year-survival rate of < 5%, pancreatic adenocarcinoma
is the fourth-leading cause of cancer death in the U.S. Pancreatic
adenocarcinoma is primarily a disease of the elderly with80% of cases
affecting patients in the sixth or eighth decade and accounts for 95% of
all malignant pancreatic lesions.27 Surgical resection of
localized tumors allows cure, but only about 15% to 20% of new cases are
candidates for surgical resection at presentation. Complete resection
with negative margins without lymph nodal involvement gives the best
possible 5-year survival rates of up to 25% to 30%. CA19-9 may be
elevated in up to 80% of cases, but has limited sensitivity to identify
patients with small tumors amenable to surgical resection.CA-19-9 is
mainly useful in follow-up of patients undergoing treatment and when a
rise in CA-19-9 precedes imaging manifestation. While there is an
association between chronic pancreatitis, diabetes, and pancreatic
adenocarcinoma, the causal relationship is uncertain. Smoking has been
shown to be associated with 2 times the increased risk of developing
pancreatic adenocarcinoma. While rare, it is interesting to note that
rare genetic syndromes, such as familial atypical multiple mole melanoma
syndrome (FAMMM), hereditary pancreatitis, and Putz-Jeghers syndrome
are associated with a 20- to 130-fold increased risk of pancreatic
MDCT of the pancreas is the modality of choice for diagnosis and
staging of pancreatic carcinoma and involves acquisition of images in
the pancreatic phase instead of the arterial phase. MDCT has a dual role
in pancreatic cancer which includes lesion detection, localization and
characterization; and secondly, in the determination of tumor
resectability. Although ultrasound and MRI may playa role in the initial
diagnosis of pancreatic carcinoma, MDCT is preferred for diagnosis and
staging. On US, they are seen as ill-defined hypoechoic lesions within
the pancreas. On T1-weighted MRI, the mass will be hypointense to normal
the pancreas. On both MDCT andMR, pancreatic cancer appears as a
hypoenhancing mass with focal contour abnormality. The hypoenhancement
is accounted for by the desmoplastic and hypovascular nature of the
tumor. On dynamic images, the pancreatic phase shows the greatest
attenuation differentiation and is therefore more sensitive than the
portal-venous phase in detection of these lesions. However, in up to 10%
of cases, pancreatic cancer can be iso-attenuating to pancreatic
parenchyma, and therefore secondary signs provide a clue to diagnosis.
These secondary signs include pancreatic ductal dilatation and
parenchymal atrophy distal to the lesion with abrupt change in ductal
caliber at the site of lesion (Figure 21).While MDCT is about 95%
accurate in diagnosing pancreatic cancer, approximately 5% of patients
undergo surgical resection for benign disease, such as chronic
pancreatitis or focal AIP. On T2W MR imaging, the lesion itself will
often be inconspicuous, but secondary signs of upstream pancreatic
ductal dilatation or focal contour abnormality of the pancreas may be
True determination of resectability of borderline tumors
will be made at the time of laporotomy. The signs of potential
resectability at laparotomy include demonstration of a normal fat plane
between the celiac axis or SMA, and a patent SMV and portal vein. The
definition of unresectable is ever-changing and dependent on surgeons
and institutional protocols. The following are the current CT findings
that are consistent with nonresectable pancreatic cancer: The first sign
of unresectability is distant metastases. While MDCT will often detect
larger hepatic metastases,it is limited in detecting small hepatic
metastases as well as peritoneal metastatic deposits. Therefore,
patients often undergo diagnostic laparoscopy for inspection of the
omentum prior to surgical resection. The second sign is locally advanced
arterial or venous involvement. SpecificMDCT findings consistent with
locally advanced unresectable pancreatic cancer include arterial
encasement of the celiac trunk, hepatic artery,or SMA. Arterial
encasement > 180 degree would not only make tumor resection
technically impossible but is also associated with a high rate of
neoplastic involvement within the mesenteric neural plexus.8
Therefore, even if resection of the main mass were feasible, residual
disease would make it oncologically unsound; however, this concept is
being challenged in a recent paper.28 Venous involvement will only preclude potential respectability in cases where surgical reconstruction is technically impossible.8
are tumors which are considered by CT criteria to be borderline
resectable. Findings on CT consistent with borderline resectability
include tumors that about < 180 degrees of the circumference of SMA
or celiac artery (Figure 22). With short segment encasement of the
common hepatic artery surgeons can often perform resection with
grafting, a technically feasible, and oncologic sound technique. While
clearly enlarged and distant lymph nodes are consistent with
nonresectable tumors, imaging alone is inaccurate in assessment of lymph
nodal involvement with metastases. Additionally, positive lymph nodes
within the resection bed may be removed at the time of surgery leaving
the patient with no residual disease.
Using these parameters, CT
is about 95% accurate in precluding truly unresectable patients from
undergoing an unnecessary attempted Whipple’s procedure. However, only
about 50% of cases thought to be resectable at CT are truly resectable
at the time of laparotomy. In cases in which the pancreatic cancer is
determined either by CT or laparotomy to be borderline but unresectable,
attempts made to convert the patient to a surgical candidate by giving
neoadjuvant chemotherapy and/or external beam radiation therapy and then
Pancreatic endocrine tumors
referred to as pancreatic islet cell tumors, these arise from
pancreatic ductal cells and despite resemblance to normal islet cells
histologically, they are appropriately termed as pancreatic endocrine
tumors. There are 7 different types of pancreatic endocrine tumors, the
most common of which are insulinomas, gastrinomas, and nonfunctional
tumors (Table 7). Pancreatic endocrine tumors account for only 1% to 2%
of all pancreatic neoplasms and affect only 1 in 100,000 persons. The
typical age of onset is in the fourth or fifth decade.Most of these
pancreatic endocrine tumors occur sporadically; however, certain
syndromes, such as an MEN1, Von Hippel-Lindau,neurofibromatosis, and
tuberous sclerosis, increase the likelihood of developing these tumors
at a younger age. Pancreatic endocrine tumors are considered malignant
based on biologic behavior (extra-pancreatic invasion or metastatic
disease), not pathologic findings. The so-called functioning pancreatic
endocrine tumors often produce characteristic clinical symptoms
depending on the hormone excreted.
endocrine tumors produce symptoms solely due to mass-effect, such as
abdominal pain, weight loss, and jaundice.29,30
endocrine tumors are highly vascular lesions leading to the
characteristic finding of early and avid contrast enhancement.
homogeneous enhancement is the rule for smaller lesions, while larger
lesions may show areas of necrosis and cystic degeneration and have
heterogeneous or only peripheral enhancement (Figures 23 and 24). Unlike
pancreatic adenocarcinomas, pancreatic endocrine tumors are more
conspicuous on the early arterial phase and stand out as
hyperattenuating compared to the normal pancreas. Most tumors appear
well circumscribed, but larger and malignant tumors may demonstrate
poorly defined borders. Nonfunctioning pancreatic endocrine tumors,
either because of their inherently aggressive behavior or delay in
presentation, are seen with metastasis in about 70% of cases. On MRI,
these tumors are T1 hypointense and characteristically, but variably, T2
hyperintense. Indium-111 octreotide scans can be used and are most
helpful in identifying subtle foci of metastatic disease in patients
whose tumor is known from pathologic examination tobe well
differentiated and contain somatostatin receptors. Pancreatic endocrine
tumors may sometimes be peripancreatic, such as duodenal, in location.30
The overall sensitivity of Indium-111 octreotide scintigraphy for
diagnosis of pancreatic neuroendocrine tumors is high with 80% to 100%
sensitivity for carcinoids and 60% to 90% for pancreatic NETs.
of scanning protocols as well as knowledge of the various maladies of
the pancreas and the role of imaging in the clinical management of
patients with pancreatic disorders allows the radiologist to play a
large role in the diagnosis and management of inflammatory as well as
neoplastic disorders of the pancreas.
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- Mulkeen A, Yoo, P, Cha C. Less common neoplasms of the pancreas. World J Gastroenterol. 2006;12:3180-3185.
- Roth CG, Deshmukh S. MRI of the pancreaticobiliary system. In: Roth CG ed. Fundamentals of body MRI. Philadelphia, PA: Elsevier Saunders; 2012: 129-199.
- Shanbhogue A, Fasih N, Surabhi V, et al. A Clinical and radiologic review of uncommon types and causes of pancreatitis. Radiographics. 2009;29: 1003-1026.
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- Balthazar EJ. Acute pancreatitis: Assessment of severity with clinical and CT Evaluation. Radiology. 2002;223:603-613.
Singla A, Csikesz N, Simons J, et al. National hospital volume in acute
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- Baron TH, Morgan DE. Acute necrotizing pancreatitis. N Engl J Med. 1999;340:1412-1417.
- Balthazar EJ, Robinson DL, Megibow AJ, Ransson JH. Acute pancreatitis: Value of CT in establishing prognosis. Radiology. 1990;174:331-336.
- Banks PA. Infected necrosis: Morbidity and therapeutic consequences. Hepatogastoenterology. 1991;38:116-119.
Leung TK, Lee CM, Lin SY, et al. Computed tomography severity index is
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- Braganza J, Lee S, McCloy R, McMahon M. Chronic pancreatitis. Lancet. 2011;377:1184-1197.
- Blasbalg R, Baroni RH, Costa DN, Marchado MC. MRI features of groove pancreatitis. AJR Am J Roentgenol. 2007;789:73-80.
- Pezzilli R, Imbrogno A, Fabbri D. Autoimmune pancreatitis management: reflections on the past decade and the decade to come. Expert Rev Clin Immunol. 2012; 8:115-117.
Psarras K, Baltatzis ME, Pavlidis ET, et al. Autoimmune pancreatitis
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- Okazaki K, Kawa S, Kamisawa T, et al. Clinical diagnostic criteria of autoimmune pancreatitis. J Gastroenterol. 2006;41:626-631.
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- Lee F, Raleigh J. Tropical calcific pancreatitis. N Engl J Med. 2011; 13;365:1425.
- Laffan TA, Horton KM, Klein AP, et al. Prevalence of unsuspected pancreatic cysts on MDCT. AJR Am J Roentgenol. 2008;191:802-807.
- Augustin VT, Vandermeer TJ. Intraductal papillary mucinous neoplasm: A clinicopathologic review. Surg Clin North Am. 2010;90:377-398.
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- de Jong K, Bruno MJ, Fockens P. Epidemiology, diagnosis, and management of cystic lesions of the pancreas. Gastroenterol Res Pract. 2012;147465. Epub 2011.
- Igbinosa O. Pseudopapillary tumor of the pancreas. An algorithmic approach. JOP. 2011;12: 262-265.
- Saif MW. Pancreatic neoplasm in 2011: An update. JOP. 2011;12:316-321.
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