Comparison of two diffusion weighted MR protocols for detecting Differences in Microvasculature in chronic Pancreatitis and Pancreas Cancer
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- Institutt for fysikk 
Pancreatic cancer is a type of cancer with high mortality. Unspecific, or the absence of, symptoms result in late diagnosis, which is fatal when the only curable treatment is surgical removal of the tumor. Differentiating pancreatic cancer from chronic pancreatitis is especially challenging. \\Studies show that the intravoxel incoherent motion-model in diffusion weighted MR imaging have promising result in differentiating pancreatic cancer from chronic pancreatitis, due to significant difference in the perfusion fraction. \\ At St. Olavs Hospital a traditional diffusion weighted protocol is applied as a standard protocol in the diagnosis of pancreatic cancer. Since this protocol does not differentiate between pancreatic cancer and chronic pancreatitis a new diffusion weighted protocol for detecting differences in microvasculature in chronic pancreatitis and pancreatic cancer is under development.\\In this work the image quality in two imaging protocols are compared. One is a respiratory triggered protocol and the second is a free breathing protocol where a median image was calculated in order to overcome motion artifacts. These protocols were added to the standard MRI examination, in a 1.5 tesla MR-scanner at St. Olavs Hospital, in 8 patients scheduled for clinical MR of pancreas. \\Images from 7 patients were used to compare image quality in the terms of ghosting, sharpness and signal-to-noise ratio. The image quality were superior in the respiratory triggered images, less ghosting, higher sharpness and a significant higher signal-to-noise ratio compared to the free breathing images. One patient with high suspicion of tumor was included at the end of the study, as a proof of method and to evaluate whether the image quality was sufficient. The simplified model relative enhanced diffusion (RED) was used in the data analysis. Based on this single patient the RED model seems promising. Based on the work present in this thesis it was concluded that the respiratory triggered protocol, due to the highest image quality, should be the base for further development of a new diffusion weighted protocol for pancreas. With the quality of the respiratory triggered images the RED model is promising and should be subject for further investigation.