Correlation of imaging and function in chronic pancreatitis.

Chronic pancreatitis is a slowly progressive disease. Initially, only focal changes occur, but diffuse structural abnormalities accompanied by various degrees of functional impairment are seen in the late stage. Morphological abnormalities in chronic pancreatitis can now be detected with high accuracy by several imaging methods. The most sensitive method is ERP, which is able to detect slight ductal changes at an early stage. High-resolution US has become a valid alternative to CT for the visualization of parenchymal abnormalities. However, CT is more accurate than US in detecting small cysts and calcifications. By comparing ductal abnormalities (ERP) and parenchymal lesions (CT, US) with pancreatic function impairment, it has become quite clear that the morphofunctional correlation is tight only in the "late" or severe stages of chronic pancreatitis. In "early" or "moderate" stages of chronic pancreatitis, correlation of the degree of morphological abnormalities and pancreatic dysfunction is frequently poor. Studies comparing the value of the different imaging methods with pancreatic function tests in the diagnosis of chronic pancreatitis have found ERP and the duodenal intubation SC test to have the highest diagnostic accuracies. Correlation between the degree of ductal abnormalities (ERP) and pancreatic dysfunction in the SC test, and between the degree of parenchymal abnormalities (CT and US) and the SC test both proved significant. However, prediction of exocrine function based on morphological alterations, or vice versa, is not possible. The value of combining function testing with imaging is enhancement of the diagnostic accuracy in the presence of only "mild" morphologic abnormalities detected with the imaging techniques. In advanced stages of chronic pancreatitis, function testing is a valid complementary tool to characterize the clinical stage of the disease and may have an impact on therapeutic decisions in patients with advanced stages of chronic pancreatitis. Invasive function testing (SC test) can be replaced by oral pancreatic function tests, which yield equivalent results or clinical decisions.