Secretin-Enhanced MRCP: Proceed With Cautious Optimism
Secretin-Enhanced MRCP: Proceed With Cautious Optimism
Secretin-Enhanced MRCP: Proceed With Cautious Optimism
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PANCREAS
Secretin-Enhanced MRCP:
Proceed With Cautious Optimism
Nisha I. Sainani, MD1 and Darwin L. Conwell, MD2
Gastroenterologists are often evaluating patients with minimal abnormalities on routine serologic or imaging tests and
chronic abdominal pain of unknown origin (1). The diagnosis of early or minimal-change chronic pancreatitis is often
considered as a cause of this common clinical presentation
(2). It is widely accepted that the diagnosis of early chronic
pancreatitis remains difficult primarily because of a paucity
of pancreatic radiological abnormalities and the inability to
safely obtain histological biopsy (3). When the initial diagnostic evaluation is inconclusive, a referral is often made to
a tertiary center for advanced imaging, endoscopy, and pancreas secretory physiology testing. Patients evaluated at most
academic centers generally undergo a battery of studies
including various combinations of endoscopic ultrasound,
endoscopic retrograde pancreatography (ERCP), dynamic
pancreas computed tomography scan, magnetic resonance
imaging (MRI), and hormone-stimulated pancreas function tests. Currently, pancreas function tests and ERCP
are considered the most accurate methods and the nonhistologic, surrogate gold standards for the detection of
chronic pancreatitis (4). Although pancreatic function studies
have shown excellent diagnostic accuracy at detecting moderate chronic pancreatitis, they are not universally available,
and the invasiveness of ERCP has caused it to no longer be
used as a diagnostic modality. Thus, the search for a safe and
universal and readily available test to detect early chronic
pancreatitis continues (5).
MRI, with its better soft-tissue resolution and capability to visualize the ductal system by means of magnetic
resonance pacreaticocholangiography (MRCP), acquired
either as two-dimensional or three-dimensional images, has
emerged as a diagnostic tool to evaluate patients with suspected pancreatic disease (6). MRI has great appeal to generalists and subspecialists as it can evaluate the parenchymal
and ductal changes noninvasively, without radiation, and
does not cause procedure-related pancreatitis as its endoscopic equivalent, retrograde pancreatogram (ERCP), does.
Department of Radiology, Division of Abdominal Imaging and Intervention, Harvard Medical School, Brigham and Womens Hospital, Boston, Massachusetts,
USA; 2Department of Medicine, Center for Pancreatic Disease, Harvard Medical School, Brigham and Womens Hospital, Boston, Massachusetts, USA.
Correspondence: Darwin L. Conwell, MD, Cleveland Clinic, Gastroenterology, 9500 Euclid Ave., Cleveland, Ohio 44195, USA. E-mail: dconwell@partners.org
Received 28 January 2009; accepted 4 February 2009
2009 by the American College of Gastroenterology
PANCREAS
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Editorial
CONFLICT OF INTEREST
PANCREAS
values than expected because of the effect of perfusion. Secretin has also been shown to increase pancreas blood flow and
perfusion. The increased mobility of the water molecules and
increased circulation in the capillaries of the pancreas might
be quantified through DWI. In general, increases in diffusion
and perfusion cause decreases in signal intensity on DW MR
images and increases in apparent diffusion coefficient values.
Several experimental flow measurement studies assessing pancreatic perfusion have shown that chronic pancreas fibrosis is
associated with a reduction in parenchyma perfusion. Therefore, DW may be able to recognize pancreatic fibrosis/chronic
pancreatitis. In fact, a recent publication has shown that DWI
has promise as a noninvasive method to assess pancreas exocrine function in chronic pancreatitis (12).
The initial excitement of any new imaging and diagnostic
test needs to be interpreted with caution until the appropriate
prospective clinical trials have been performed to determine
its true accuracy and clinical efficacy. Furthermore, experience
with the test over time generally will determine its true role as
it is applied to the clinical care of patients with various presentations. In addition, MRCP reports need to be standardized
and to document findings in a systematic and regimented protocol that is universally accepted. Similar excitement had been
reported earlier in the initial experience with endoscopic ultrasonography only to find out that at least five criterianot three
criteria as initially reportedare needed to make a definitive
diagnosis of chronic pancreatitis (1315). These facts should be
kept in mind when interpreting MRI findings in the evaluation
of early chronic pancreatitis.
In conclusion, on the basis of this investigation and findings
by others, it appears that S-MRCP improves visualization of the
pancreatic ducts and detects morphological changes that have
been ascribed earlier to patients with chronic pancreatitis. But
caution needs to be exercised when trying to interpret these
structural abnormalities. As the investigators rightly report,
some of the changes may be age related, nonspecific, and of
unknown clinical significance. Although secretin-enhanced
MRI is an exciting technological advance, and most pancreatologists believe it should be considered in the evaluation of
patients with perplexing signs and symptoms suggestive of early
pancreatic disease, prospective comparison trials with a reference standard test or long-term follow-up are clearly needed.
And in fact, a multicenter trial is currently under way and we
await the results of this study with cautious optimism.
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