AJR 2005; 185:432-435
© American Roentgen Ray Society
MR Cholangiopancreatography Diagnosis of Juxtapapillary Duodenal Diverticulum Simulating a Cystic Lesion of the Pancreas: Usefulness of an Oral Negative Contrast Agent
Silvio Mazziotti1,
Chiara Costa2,
Giorgio Ascenti1,
Michele Gaeta1,
Alessia Pandolfo1 and
Alfredo Blandino1
1 Department of Radiological Sciences, University of Messina, via Consolare
Valeria, Gazzi, Messina, Italy 98100.
2 Department of Social Medicine, Occupational Medicine Section, University of
Messina, Gazzi, Messina, Italy.
Received June 7, 2004;
accepted after revision September 22, 2004.
Address correspondence to S. Mazziotti
(smazziotti{at}unime.it).
Introduction
Duodenal diverticulum is a herniation of the mucosa and muscularis mucosae
through the intestinal wall. In 90% of cases it is asymptomatic and is
detected incidentally during radiologic or endoscopic investigation of the
upper gastrointestinal tract for unrelated diseases
[1–3].
However, in about 10% of cases, patients with duodenal diverticula undergo
cross-sectional imaging techniques such as CT or MRI, owing to the onset of
biliopancreatic disease symptoms
[4].
Duodenal diverticula are usually easily recognized on CT or MRI when
completely filled with gas or a combination of fluid and gas
[2,
4,
5]. However, it has been
recently reported that if its content is purely fluid, the radiologist
interpreting CT or MR images can potentially misinterpret a duodenal
diverticulum as a cystic tumor of the pancreas
[6].
We present two patients with initial MR cholangiopancreatography (MRCP)
findings suggestive of cystic pancreatic lesion. The prompt oral
administration of a superparamagnetic iron oxide contrast agent allowed in all
cases the correct diagnosis of duodenal diverticulum in subsequent MRCP
images.
Case Reports
Case 1
A 58-year-old woman working as a farmer for more than 3 decades underwent
routine clinical examination and blood analyses for periodic medical
surveillance at the Occupational Medicine ward of our institution. She
complained of frequent dyspepsia associated with elevated liver-function
tests.
Gray-scale sonography of the abdomen revealed a mild dilatation of the
common bile duct (CBD) and extrinsic compression of its distal tract by a
round hypoanechoic lesion localized in the cephalic region of the pancreas,
suggestive of cystic neoplasm of the pancreatic head. This suspicion was
enhanced by the chronic, long-term occupational exposure of the subject to
organochlorine pesticides [7].
The patient was thus transferred to a surgical ward to complete the diagnostic
course and proceed to appropriate treatment.
To better define these findings, the patient underwent MRCP. MRI was
executed on a 1.5-T superconducting system (Magnetom Vision, Siemens) with a
phased-array body coil. Two standard MR cholangiographic techniques were
applied, the single-shot RARE and multislice HASTE sequences. The following
imaging parameters were used for the thick-slab RARE sequence: TR/effective
TE, infinite/1,100; flip angle, 150°; echo spacing, 10.2 msec; echo-train
length, 240; slab thickness, 50 mm; acquisition time, 7 sec. The following
parameters were used for the multislice HASTE sequence: TR (considered as time
between two excitations)/effective TE 8.20/66; flip angle, 140–180°;
echo-train length, 128; slab thickness, 4 mm; number of slices, 13;
acquisition time, 13 sec. Fat suppression was used only with thick-slab RARE
sequences to reduce fat signal during acquisition.
With the RARE sequence, we performed six scans focused on the CBD, rotated
by 30° with respect to each other and beginning from the coronal plane. A
HASTE sequence was applied twice in the axial and coronal planes with the use
of a gap-and-fill technique. Images were obtained in an interleaved fashion to
reduce "cross-talk" artifacts. All images were obtained during one
breath-hold.
MRCP confirmed dilatation of the CBD and revealed extrinsic compression of
its distal portion by a 15-mm cystic process adjacent to the uncinate process
and the second portion of the duodenum, hyperintense on both thick-slab RARE
and HASTE sequences (Figs. 1A
and 1B). To allow differential
diagnosis between cystic pancreatic neoplasm and duodenal diverticulum, 400 mL
of a superparamagnetic iron oxide contrast agent (ferumoxsil, Lumirem;
Guerbet) was promptly administered orally to the patient. MRCP images
performed immediately after oral contrast administration suppressed the fluid
signal in the duodenum and showed signal voiding of the lesion due to filling
of the diverticulum with a negative contrast agent, thus allowing exclusion of
the cystic tumor of the pancreatic head (Figs.
1C and
1D).
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Fig. 1A —58-year-old woman with CBD dilatation and cystic process in
region of pancreatic head detected on abdominal sonography. Precontrast axial
(A) HASTE MR image and oblique coronal RARE (B) MR
cholangiopancreatography (MRCP) show 20-mm cystic process (asterisk)
in region of uncinate process, causing common bile duct dilatation (c).
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Fig. 1B —58-year-old woman with CBD dilatation and cystic process in
region of pancreatic head detected on abdominal sonography. Precontrast axial
(A) HASTE MR image and oblique coronal RARE (B) MR
cholangiopancreatography (MRCP) show 20-mm cystic process (asterisk)
in region of uncinate process, causing common bile duct dilatation (c).
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Fig. 1C —58-year-old woman with CBD dilatation and cystic process in
region of pancreatic head detected on abdominal sonography. Postcontrast axial
(C) HASTE MR image and RARE (D) MRCP show filling of lesion with
negative contrast agent (arrows), suggesting diagnosis of duodenal
diverticulum.
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Fig. 1D —58-year-old woman with CBD dilatation and cystic process in
region of pancreatic head detected on abdominal sonography. Postcontrast axial
(C) HASTE MR image and RARE (D) MRCP show filling of lesion with
negative contrast agent (arrows), suggesting diagnosis of duodenal
diverticulum.
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Fig. 1E —58-year-old woman with CBD dilatation and cystic process in
region of pancreatic head detected on abdominal sonography. Spot radiograph
from upper gastrointestinal barium series confirms presence of juxtapapillary
diverticulum (asterisk).
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Fig. 2A —57-year-old man scheduled for laparoscopic cholecystectomy.
Precontrast coronal MR cholangiogram (A) shows choledocolitiasis with
mild dilatation of common bile duct (CBD); 15-mm cystic process is also
visible at level of pancreatic head (asterisk). On both RARE
(B) and HASTE (C) postcontrast images, filling of diverticulum
with oral contrast agent is clearly detectable. Filling of diverticulum
(asterisk) determines mild compression and dislocation of adjacent
CBD and Wirsung (arrows).
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Fig. 2B —57-year-old man scheduled for laparoscopic cholecystectomy.
Precontrast coronal MR cholangiogram (A) shows choledocolitiasis with
mild dilatation of common bile duct (CBD); 15-mm cystic process is also
visible at level of pancreatic head (asterisk). On both RARE
(B) and HASTE (C) postcontrast images, filling of diverticulum
with oral contrast agent is clearly detectable. Filling of diverticulum
(asterisk) determines mild compression and dislocation of adjacent
CBD and Wirsung (arrows).
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Fig. 2C —57-year-old man scheduled for laparoscopic cholecystectomy.
Precontrast coronal MR cholangiogram (A) shows choledocolitiasis with
mild dilatation of common bile duct (CBD); 15-mm cystic process is also
visible at level of pancreatic head (asterisk). On both RARE
(B) and HASTE (C) postcontrast images, filling of diverticulum
with oral contrast agent is clearly detectable. Filling of diverticulum
(asterisk) determines mild compression and dislocation of adjacent
CBD and Wirsung (arrows).
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Thereafter, the upper gastrointestinal barium examination definitively
confirmed the presence of a juxtapapillary diverticulum located at the medial
wall of the second portion of the duodenum
(Fig. 1E).
Case 2
A 57-year-old man scheduled for laparoscopic cholecystectomy underwent MRCP
with the same equipment and procedure described for the previous case.
Precontrast images showed choledocolitiasis and consequent mild dilatation of
the CBD. At the level of the pancreatic head, strictly adjacent to the main
pancreatic duct and CBD, a 15-mm cystic process was visible
(Fig. 2A).
MRCP images acquired immediately after oral administration of the negative
contrast agent showed the elimination of the bright signal intensity of the
lesion, allowing exclusion of a cystic neoplasm of the pancreatic head (Figs.
2B and
2C).
Discussion
Duodenal diverticula are acquired outpouchings of the mucosa and muscularis
mucosae; 90% of them are on the medial aspect of the duodenum, where
penetrating vessels cause potential weak spots in the bowel wall. The
incidence of duodenal diverticula increases with age, and they are slightly
more common in women than in men
[3].
Although duodenal diverticula are a very common anomaly (incidentally
discovered in 14.5% of barium examinations of the upper gastrointestinal
tract), serious complications resulting from their presence are rare. The
clinical presentation is typically characterized by nonspecific abdominal
symptoms
[1–3,
5].
The majority of duodenal diverticula are discovered incidentally on upper
gastrointestinal studies or on endoscopic examination and are not recognized
on cross-sectional imaging because of their small size
[3,
5,
8]. Juxtapapillary diverticula
arise within a radius of 2–3 cm from the papilla of Vater. Patients with
a juxtapapillary diverticulum commonly undergo cross-sectional imaging
techniques (CT or MRI) if they have biliopancreatic disease symptoms
[4].
The diverticulum is usually well depicted on CT or MRI if it is filled with
fluid and air and located in the characteristic periampullary region
[2,
4,
5]. However, the radiologist
may find it difficult to distinguish duodenal diverticula on CT or MR if their
content is purely fluid, as recently described by Macari et al.
[6] in a report of seven
patients with duodenal diverticula in whom initial CT or MRI findings were
suggestive of a cystic pancreatic mass. In fact, differential diagnosis of a
cystic lesion in the region of the head of the pancreas includes cystic
pancreatic neoplasm, pseudocyst, and duodenal diverticula; in these cases,
careful scrutiny of images for evidence of small amounts of gas or
air–fluid levels should be made, especially on MRI. The authors conclude
that if diagnosis is in doubt, follow-up imaging or an upper gastrointestinal
barium examination should be considered to confirm the presence of a duodenal
diverticulum [6].
In our cases, MRCP performed before oral contrast administration showed a
hyperintense cystic lesion in the region of the pancreatic head. In one
patient, the lesion caused extrinsic compression of the lower portion of the
CBD with consequent upstream mild extra-hepatic biliary dilatation. The prompt
oral administration of a negative contrast agent directly allowed us to
clearly show in all subjects the presence of a juxtapapillary duodenal
diverticulum; the diagnosis was further confirmed in the first patient by the
subsequently performed barium study, considered the technique of choice for
the imaging of diverticula.
MRCP is a noninvasive imaging technique that has proved accurate in the
diagnosis of biliary obstruction. Single-shot RARE and multislice HASTE
sequences allow quick and high-quality imaging of the biliary system.
In the presence of duodenal diverticulum completely filled with fluid, the
oral administration of a superparamagnetic iron oxide contrast agent allows an
immediate diagnosis, without the need for follow-up imaging or upper
gastrointestinal barium examination to exclude the presence of a pancreatic
cystic process.
A limitation of our approach is that in many centers, routine MRCP is not
monitored by a radiologist. Consequently, our technique of administering a
negative oral contrast agent could require the patient to return for an
additional examination. However, as reported in the literature
[9–11],
oral administration of a negative contrast agent can improve the overall
quality of all abdominal MR hydrographic techniques by suppressing
interference from intestinal fluid.
In our opinion, the prompt oral administration of a superparamagnetic iron
oxide contrast agent could be routinely performed in the same session by the
technician when MRCP precontrast images show superimposition of hyperintense
bowel-loop fluids.
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Introduction
Case Reports
