Development of qualitative and quantitative analysis for pancreatic exocrine function : a novel approach using diffusion-weighted MR images

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The aim of this study was to visualize and quantify the degree of water diffusion in the pancreatic parenchyma and to evaluate exocrine function in different part of the pancreas non-invasively.First, optimal imaging parameters of diffusion-weighted MRI were determined by agar phantom experiment. Determined basic imaging parameters were modified by applying normal volunteers, then final optimal imaging parameters of diffusion-weighted MRI was obtained. By an original plan, we intend to use secretin, which stimulate exocrine pancreatic glands and increase pancreatic water content, in order to evaluate pancreatic exocrine function separately (head, body, and tail). However, sale of secretin was canceled and secretin could not be used routinely. Instead of clinical trial, we did a limited study. We evaluated diffusion-weighted MRI of the normal pancreas before and after administration of secretin which we stocked. As expected, pancreatic parenchymal signal change was observed. It was prov … More ed that our hypothesis was right.We gave up evaluating separate pancreatic exocrine function due to lack of secretin, then we evaluate the usefulness of apparent diffusion coefficiency (ADC) value on diffusion-weighted MRI. We compared ADC value of pancreatic parenchyma between normal volunteers and patients with chronic pancreatitis. The result showed that ADC values of chronic pancreatitis were significantly lower than those of normal volunteers. Furthermore, we observed that ADC values of chronic pancreatitis decreased according to disease severity.It is considered that diffusion-weighted MRI using imaging parameters we determined in this study was applied not only in the pancreas but also in other regions. We applied our MRI method to various other organs, such as kidney, uterus, ovary, prostate, and evaluated its efficacy. As a result, diffusion-weighted MRI played an important role in differentiating neoplastic lesions in those organs. This fact reveals that our method has a great potential in diagnosis of various lesions. Less