Chronic Pancreatitis
In advanced or longstanding chronic pancreatitis, the diagnosis is usually easy to establish with cross-sectional imaging [e.g., computed tomography (CT)], although differentiating chronic pancreatitis from pancreatic malignancy may be difficult. Diagnosis in earlier stages is often difficult and has relied on endoscopic ultrasonography (EUS) or pancreatic function testing (PFT). The main agent for PFT, secretin, has been unavailable in the United States for more than a year and has only recently again become available for use. PFT is still only performed at a few centers in the United States, although data support it as the most sensitive test for early diagnosis.
EUS has been shown to be more sensitive than cross-sectional imaging and is commonly used for diagnosis, and particularly for early diagnosis of chronic pancreatitis. A new scoring system for EUS diagnosis of chronic pancreatitis, the Rosemont criteria, is used by some but does not appear to be any more accurate, reproducible, or precise than previous nomenclature using minimal standard terminology. A recent study noted that many EUS reports do not even specify the nine separate minimal standard terminology criteria in patients with suspected chronic pancreatitis, averaging only five, suggesting a need for quality improvement in EUS reports. A challenge in the use of EUS for early diagnosis of chronic pancreatitis has been the realization that similar endosonographic changes within the pancreas can be appreciated in patients who are elderly, who smoke or drink alcohol, who have diabetes or chronic renal failure, and who have had a recent episode of acute pancreatitis. Attempts to improve EUS diagnosis include the use of contrast-enhanced EUS and computer aided image analysis to differentiate chronic pancreatitis from pancreatic malignancy. Recently, Iglesias-Garcia and DomÃnguez-Muñoz concluded that quantitative elastography performed during EUS can aid in diagnosing pancreatitis in the nonadvanced stage. They evaluated 191 patients prospectively and found that the accuracy of quantitative EUS-elastography was highly correlated with EUS imaging evidence of chronic pancreatitis and provided objective information to complement the more qualitative EUS image criteria. Elastography, such as EUS imaging features, is also affected by age in that aging produces a stiffer pancreas at elastography, a key diagnostic feature of chronic pancreatitis. Contrast-enhancing low mechanical index (CELMI) and high mechanical index techniques (CEHMI) have also become available for EUS. Hocke et al. compared elastography with CEHMI-EUS and CELMI-EUS in discriminating focal chronic pancreatitis and pancreatic cancer and found CEHMI-EUS to be more reliable.
Similar efforts to improve the accuracy of MRI in early diagnosis and in differentiating chronic pancreatitis from pancreatic cancer include the use of secretin infusions to estimate pancreatic function and techniques including spectroscopy, spin labeling, and quantitative assessment of individual MRI features. Despite these advances, the ability to diagnose early chronic pancreatitis by either EUS or MRI remains plagued by high rates of both false positive and false negative results.
Direct PFT, using secretin, can be performed with either a Dreiling tube or an endoscope. A recent retrospective analysis of 20 patients with an abnormal pancreatic function test but no other imaging evidence of chronic pancreatitis who were followed for 1–11 years noted that 45% ultimately developed obvious chronic pancreatitis, compared with 3% of 70 patients with an initial normal function test. Although direct pancreatic function tests appear to be very good at ruling out chronic pancreatitis in patients with possible early chronic pancreatitis, there are a substantial number of false positive results. Direct pancreatic function tests such as the secretin test are being used less with the more widespread availability of modern imaging techniques such as CT, MRI, and EUS.
Diagnosis of Chronic Pancreatitis
In advanced or longstanding chronic pancreatitis, the diagnosis is usually easy to establish with cross-sectional imaging [e.g., computed tomography (CT)], although differentiating chronic pancreatitis from pancreatic malignancy may be difficult. Diagnosis in earlier stages is often difficult and has relied on endoscopic ultrasonography (EUS) or pancreatic function testing (PFT). The main agent for PFT, secretin, has been unavailable in the United States for more than a year and has only recently again become available for use. PFT is still only performed at a few centers in the United States, although data support it as the most sensitive test for early diagnosis.
EUS has been shown to be more sensitive than cross-sectional imaging and is commonly used for diagnosis, and particularly for early diagnosis of chronic pancreatitis. A new scoring system for EUS diagnosis of chronic pancreatitis, the Rosemont criteria, is used by some but does not appear to be any more accurate, reproducible, or precise than previous nomenclature using minimal standard terminology. A recent study noted that many EUS reports do not even specify the nine separate minimal standard terminology criteria in patients with suspected chronic pancreatitis, averaging only five, suggesting a need for quality improvement in EUS reports. A challenge in the use of EUS for early diagnosis of chronic pancreatitis has been the realization that similar endosonographic changes within the pancreas can be appreciated in patients who are elderly, who smoke or drink alcohol, who have diabetes or chronic renal failure, and who have had a recent episode of acute pancreatitis. Attempts to improve EUS diagnosis include the use of contrast-enhanced EUS and computer aided image analysis to differentiate chronic pancreatitis from pancreatic malignancy. Recently, Iglesias-Garcia and DomÃnguez-Muñoz concluded that quantitative elastography performed during EUS can aid in diagnosing pancreatitis in the nonadvanced stage. They evaluated 191 patients prospectively and found that the accuracy of quantitative EUS-elastography was highly correlated with EUS imaging evidence of chronic pancreatitis and provided objective information to complement the more qualitative EUS image criteria. Elastography, such as EUS imaging features, is also affected by age in that aging produces a stiffer pancreas at elastography, a key diagnostic feature of chronic pancreatitis. Contrast-enhancing low mechanical index (CELMI) and high mechanical index techniques (CEHMI) have also become available for EUS. Hocke et al. compared elastography with CEHMI-EUS and CELMI-EUS in discriminating focal chronic pancreatitis and pancreatic cancer and found CEHMI-EUS to be more reliable.
Similar efforts to improve the accuracy of MRI in early diagnosis and in differentiating chronic pancreatitis from pancreatic cancer include the use of secretin infusions to estimate pancreatic function and techniques including spectroscopy, spin labeling, and quantitative assessment of individual MRI features. Despite these advances, the ability to diagnose early chronic pancreatitis by either EUS or MRI remains plagued by high rates of both false positive and false negative results.
Direct PFT, using secretin, can be performed with either a Dreiling tube or an endoscope. A recent retrospective analysis of 20 patients with an abnormal pancreatic function test but no other imaging evidence of chronic pancreatitis who were followed for 1–11 years noted that 45% ultimately developed obvious chronic pancreatitis, compared with 3% of 70 patients with an initial normal function test. Although direct pancreatic function tests appear to be very good at ruling out chronic pancreatitis in patients with possible early chronic pancreatitis, there are a substantial number of false positive results. Direct pancreatic function tests such as the secretin test are being used less with the more widespread availability of modern imaging techniques such as CT, MRI, and EUS.