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Pancreatic adenocarcinoma has a five-year survival rate of 4%. The diagnosis is most commonly made when it is too late to perform effective intervention, e.g., after local infiltration or metastasis has occurred. In those relatively fortunate patients who have resectable disease, surgery can extend longevity.
The goal of imaging pancreatic cancer is to detect lesions in patients with suspected disease and also to determine resectability of the tumor. Imaging is critical to appropriately select the patients who should undergo surgery and who may benefit from surgical intervention.
CT
Many radiologists believe that CT is the imaging procedure of choice in this regard. Multiphase thin-section helical CT has proved to be a clinical boon in the setting of pancreatic cancer. The positive predictive value for CT in determining unresectability is nearly 100%. Conventional CT is associated with a wide range of sensitivities for pancreatic tumor detection (67% to 97%). However helical CT has demonstrated a sensitivity in excess of 90%. Most false positives are due to focal parenchymal enlargement from chronic pancreatitis which can mimic tumor.
In most centers, CT has replaced transabdominal ultrasound for the evaluation of pancreatic cancer.
MRI and MR Cholangiopancreatography (MRCP)
The literature is conflicting on establishing the superiority of either CT or MRI in the setting of pancreatic cancer. However, MRI is generally considered a secondary modality after CT in the majority of institutions and is utilized usually when CT contrast is contraindicated in a patient undergoing evaluation for pancreatic cancer.
MRCP has been postulated as a noninvasive alternative to the gold standard—endoscopic retrograde cholangiopancreatography (ERCP). MRCP, in addition to being safer since it is noninvasive, can delineate the ductal system upstream of complete obstructions. When conventional MRI is added to MRCP in the evaluation of pancreatic lesions, sensitivity and specificity improve further.
It is expected that ERCP's role will decrease as helical CT, MRCP and endoscopic ultrasound are affirmed as the primary diagnostic techniques in the evaluation of patients presenting with documented or suspected pancreatic cancer. ERCP may eventually be reserved for the study of jaundiced patients with no mass demonstrable on conventional noninvasive studies. It may also be useful in establishing the site of obstruction and differentiating focal pancreatitis from tumor, and as a primary intervention-therapeutic technique while MCRP becomes the established first-line diagnostic technique.
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