Virtual MR Pancreatoscopy in the Evaluation

Rakesh Kalapala
1
, Lingareddy Sunitha
2
, Reddy D Nageshwar
1
, Guduru V Rao
1
,
Sandeep Lakhtakia
1
, Manu Tandan
1
, Vijay B Nori
2
1
Department of Gastroenterology, Asian Institute of Gastroenterology;
2
Department of Radiology, Lucid Medical Diagnostics. Hyderabad, Andhra Pradesh, India
Summary
The main pancreatic duct and the common
bile duct can be evaluated with a variety of
evolving invasive and non-invasive
techniques. Virtual CT pancreatoscopy
obtained using special computer software is a
recent non-invasive innovation which shows
the details of the ductal surface (endoluminal
view) with greater precision. The use of
special computer software in MRI in order to
obtain pancreatic ductal surface details or a
virtual MR pancreatoscopy has not been
described up to now. We report a short series
of four patients suffering from chronic
pancreatitis who underwent virtual MR
pancreatoscopy with an impact on their
management and clinical outcome.
Introduction
Advances in computer technology have led to
novel medical imaging techniques. Virtual
endoscopic imaging is one such innovation,
where the endoscopic details of a specified
region in the human body can be generated by
three dimensional reconstruction using
computed tomography (CT) [1]. The key
advantage of this “fly-through” technique of
mucosal surface visual inspection is that the
patient does not have to go through the rigor
of regular invasive endoscopy. This
innovation has proved itself in virtual
colonoscopy [2], virtual upper GI endoscopy,
virtual bronchoscopy [3] and virtual
enteroscopy.
The main pancreatic duct and the common
bile duct can be evaluated with a variety of
evolving invasive and non-invasive
techniques. Endoscopic retrograde cholangio-
pancreatography (ERCP) is an accurate but
invasive procedure for imaging of the
pancreatic duct and/or common bile duct.
However, with its inherent associated
potential complications, diagnostic ERCP has
been replaced by magnetic resonance cholangio-
pancreatography (MRCP). Endoscopic ultra-
sonography (EUS) is an excellent
investigative modality but has some
disadvantages. It is a semi-invasive method
and requires sedation. It also needs
considerable expertise and may also over
diagnose early chronic pancreatitis. Intra-
ductal ultrasound (IDUS), using thin mini-
probes, is currently the investigation of choice
for evaluating fine pancreatic duct wall
details.
A mother-and-baby pancreatoscope is another
invasive procedure utilized for pancreatic or
biliary ductal surface evaluation. Virtual CT
pancreatoscopy, obtained using special
computer software, is a recent non-invasive
innovation which shows the details of ductal
surface (endoluminal view) with greater
precision. This has recently been used to
differentiate intraductal papillary mucinous
neoplasm (IPMN) from chronic pancreatitis [3].

Page 2
JOP. J Pancreas (Online) 2008; 9(2):220-225.
JOP. Journal of the Pancreas - http://www.joplink.net - Vol. 9, No. 2 - March 2008. [ISSN 1590-8577]
221
The use of special computer software in MRI
to obtain pancreatic ductal surface details or
virtual MR pancreatoscopy has not been
described up to now as a PubMed search has
disclosed.
We report a short series of four patients
suffering from chronic pancreatitis who
underwent virtual MR pancreatoscopy with an
impact on their management and clinical
outcome.
Method
3D MRCP was carried out on a 1.5T HDx GE
MR (General Electric, Milwaukee, WI, USA)
machine with the following parameters: TR-
3750, TE-74/EF, FOV-32x32, 256x256
matrix, NEX-0.75. A virtual pancreatoscopy
was reconstructed and the images were
obtained on an Advantage work station ADW
4.3 (General Electric, Milwaukee, WI, USA),
using a navigation technique with a surface
shaded display after adjusting the threshold
values to attain maximum fluid intensity. The
reconstruction was done by a radiologist. A
higher matrix of 512x512 was also tried but it
did not make any significant difference in the
resolution of virtual reconstruction.
Case 1
A 35-year-old male patient presented with
recurrent attacks of pancreatitis of three years
duration. Imaging using transabdominal
ultrasound and contrast-enhanced computer-
ized tomography (CECT) confirmed changes
of chronic pancreatitis with a dilated
pancreatic duct. MRCP showed a grossly
dilated main pancreatic duct (1.4 cm) with
ectasia of the side branches (4-5 mm).
Multiple intraductal filling defects of varying
sizes (2-8 mm) were noted in the head of the
pancreas. Virtual MR pancreatoscopy
imaging demonstrated the side branch ectasia
and a cluster of intraductal calculi in the
region of the head. Extracorporeal shock
wave lithotripsy (ESWL) followed by ERCP
was performed with main pancreatic duct
clearance and stenting (Figure 1; Videoclip
1).
Case 2
A 28-year-old male patient presented with
recurrent attacks of pancreatitis together with
underlying chronic calcific pancreatitis. He
had associated exocrine and endocrine
insufficiency. CECT of the abdomen showed
a narrowed main pancreatic duct in the head
region with upstream ductal dilation. MRCP
showed abrupt narrowing of the main
pancreatic duct in the head region with a 10x9
mm hypointense filling defect. The rest of the
pancreatic duct showed diffuse severe
dilatation (20 mm) and side branch ectasia (10
Figure 1. ERCP shows the pancreatic duct stent
inserted into the dilated duct (post ESWL).
Videoclip 1

Page 3
JOP. J Pancreas (Online) 2008; 9(2):220-225.
JOP. Journal of the Pancreas - http://www.joplink.net - Vol. 9, No. 2 - March 2008. [ISSN 1590-8577]
222
mm). Virtual MR pancreatoscopy
demonstrated a large oval calculus in the
head. ESWL followed by ERCP was
performed with main pancreatic duct
clearance (Figure 2; Videoclip 2).
Case 3
A 34-year-old male patient presented with
recurrent attacks of acute pancreatitis of one
year duration. CECT of the abdomen showed
evidence of chronic pancreatitis with
intraductal calculi. MRCP showed severe
cystic dilatation of the main pancreatic duct in
the head and uncinate process with multiple
intra-ductal filling defects (sizes: 5-18 mm).
The rest of the duct in the body and tail region
showed mild to moderate irregular dilatation
(6-7 mm) and side branch ectasia (1-2 mm)
with no obvious intra-ductal filling defects.
Virtual MR pancreatoscopy showed smooth
Figure 2. MRCP shows abrupt narrowing of the main
pancreatic duct in the head region with side branch
ectasia.
Videoclip 2
Figure 3. ERCP shows an irregular dilated pancreatic
duct with cleared protein plugs.
Videoclip 3

Page 4
JOP. J Pancreas (Online) 2008; 9(2):220-225.
JOP. Journal of the Pancreas - http://www.joplink.net - Vol. 9, No. 2 - March 2008. [ISSN 1590-8577]
223
navigation in the dilated pancreatic duct.
However, there was no clear demonstration of
the calculus located at the genu of the main
pancreatic duct. ERCP was done with
pancreatic sphincterotomy and a partial
clearance of the protein plugs (Figure 3;
Videoclip 3).
Case 4
A 32-year-old male patient with recurrent
attacks of acute pancreatitis of 18 month
duration had a space occupying lesion in the
head region of the main pancreatic duct.
CECT of the abdomen showed changes due to
chronic pancreatitis. MRCP showed moderate
dilatation of the main pancreatic duct
(maximum diameter: 9 mm) with mild to
moderate side branch ectasia (2-4 mm). There
was an oval filling defect measuring 9x8 mm
in the pancreatic duct in the region of the
head. Virtual MR pancreatoscopy clearly
showed side branch ectasia as well as the
calculus. ERCP with sphincterotomy was
followed by clearance of the head calculus
(Figure 4; Videoclip 4).
Discussion
Evaluation of the pancreatic duct and the
common bile duct with ERCP is a well-
established, but invasive, procedure. ERCP is
dependent on operator skill and experience,
along with associated procedure related
complications, and its access time generally
varies between 15 to 20 minutes. Virtual MR
pancreatoscopy takes about 8-10 minutes for
the acquisition of the sequences and another 5
minutes for reconstruction. EUS is a good
investigative modality for chronic
pancreatitis. However, EUS has certain
disadvantages; it is a semi-invasive method
and requires sedation. It also needs
considerable expertise and may also over
diagnose early chronic pancreatitis. Virtual
CT pancreatoscopy is a recent non-invasive
armamentarium in the evaluation of the
pancreatic duct, especially in diagnosing
mucin-producing pancreatic tumors [4] and
IPMNs [5].
Virtual MR pancreatoscopy appears to be a
feasible technique for endoluminal imaging of
the pancreatic duct. This novel method
provides an excellent internal surface display
of the pancreatic duct which simulates “fly-
through” endoscopy. This is an established
technique for differentiating between IPMNs
and chronic pancreatitis. The main pancreatic
duct and its side branches are visualized with
clarity displaying finer details. Although the
dilatation of the main pancreatic duct and its
side branches varied from mild to severe
Figure 4. MRCP shows moderate dilatation of the
main pancreatic duct with an oval filling defect
measuring 9x8 mm in the region of the head.
Videoclip 4

Page 5
JOP. J Pancreas (Online) 2008; 9(2):220-225.
JOP. Journal of the Pancreas - http://www.joplink.net - Vol. 9, No. 2 - March 2008. [ISSN 1590-8577]
224
chronic pancreatitis, it did not hinder the
resolution and finer surface detail on virtual
imaging. The size and volume of the intra-
ductal calculi can be calculated with
reasonable precision which would help in
follow-up cases of chronic pancreatitis after
pancreatic endotherapy or ESWL.
The only problem encountered was in the
visualization of calculi lodged at the normal
angulation or genu along the course of the
main pancreatic duct. It was difficult to
navigate at the bends and turns of the main
pancreatic duct as well as in the severe side
branch ectasia in uncinate the process forming
a cystic lesion. The artifacts which hinder
visualization can be eliminated from an
intraluminal view by modifying the threshold
settings. However, this compromises accurate
demonstration of the anatomy. The virtual
images depicted the intra-luminal nature and
shape of an impacted stone and abrupt
obstruction or stenosis of the duct.
We present an analysis of an innovative
technique carried out on a small sample size.
We found that this technique is non-invasive,
delineates the main pancreatic duct anatomy,
mainly intra-luminal in greater detail, thus we
can differentiate between calculi and protein
plugs. There are no reports about this
modality in the literature and we feel this will
be add more information both as a diagnostic
modality in chronic pancreatitis as well as
deciding which patients would benefit from
therapeutic ERCP (for small main pancreatic
duct calculi extraction and ESWL followed
by main pancreatic duct clearance in large
calculi). This new imaging technique may
provide a major role in delineating the
intraluminal main pancreatic duct anatomy
and hence a better therapeutic approach for
endotherapy. However, further studies with a
larger number of cases are needed in order to
establish the efficacy of this technique in
regular clinical practice as a diagnostic
modality in the armamentarium of chronic
pancreatitis.
Conclusion
Virtual MR pancreatoscopy is a new
development of MRCP which allows
endoluminal viewing of the dilated pancreatic
duct and its side branches. Although this was
evaluated in a small group of patients, the
method appears promising, especially in
evaluating patients with dilated pancreatic
ducts. The cases presented here highlight MR
pancreatoscopy as a reliable non-invasive
option for the diagnosis of chronic
pancreatitis. The results seen in current
studies are encouraging, especially in the
evaluation of a dilated pancreatic duct.
However, future large volume comparative
studies with EUS or other modalities will be
required to validate these findings.
Received December 26
th
, 2007 - Accepted,
February 18
th
, 2008
Keywords Cholangiopancreatography, Endoscopic
Retrograde; Cholangiopancreatography, Magnetic
Resonance; Lithotripsy; Pancreatic Ducts
Conflict of interest The authors have no
potential conflicts of interest
Correspondence
Reddy D Nageshwar
Asian Institute of Gastroenterology
6-3-661, Somajiguda
Hyderabad, 500 082
India
Phone: +91-40.2337.8888
Fax: +91-40.2332.4255
E-mail: aigindia@yahoo.co.in
Document URL: http://www.joplink.net/prev/200803/21.html
References
1. Rubin GD, Beaulieu CF, Argiro V, Ringl H,
Norbash AM, Feller JF, et al. Perspective volume
rendering of CT and MR images: applications for
endoscopic imaging. Radiology 1996; 199:321-30.
[PMID 8668772]
2. Fenlon HM, Nunes DP, Schroy PC 3rd, Barish
MA, Clarke PD, Ferrucci JT. A comparison of virtual
and conventional colonoscopy for the detection of
colorectal polyps. N Engl J Med 1999; 341:1496-503.
[PMID 10559450]
3. Vining DJ, Liu K, Choplin RH, Haponik EF.
Virtual bronchoscopy. Relationships of virtual reality
endobronchial simulations to actual bronchoscopic
findings. Chest 1996; 109:549-55. [PMID 8620734]

Page 6
JOP. J Pancreas (Online) 2008; 9(2):220-225.
JOP. Journal of the Pancreas - http://www.joplink.net - Vol. 9, No. 2 - March 2008. [ISSN 1590-8577]
225
4. Nakagohri T, Jolesz FA, Okuda S, Asano T,
Kenmochi T, Kainuma O, et al. Virtual pancreatoscopy
of mucin-producing pancreatic tumors. Comput Aided
Surg 1998; 3:264-8. [PMID 10207651]
5. Nakagohri T, Morikawa H, Kawai T, Konishi D,
Takahashi S, Gotoda N, et al. Virtual pancreatoscopy.
Journal of Biliary Tract & Pancreas 2006; 27:325-8

There are no products listed under this category.