Studies Of High Resolution Diffusion Weighted Imaging Of Chronic Pancreatitis

Part I High-Resolution DWI with Reduced Field of View forChronic Pancreatitis at3.0T MROBJECTIVE: To compare the artifact and the image quality between diffusion weightedimaging with reduced field of view (rFOV DWI) and single shot echo planar imagingdiffusion weighted (ss-EPI DWI) of healthy pancreas. To investigate the value of rFOVDWI for diagnosing CP.MATERIALSAND METHODS:38patients with CP and36healthy volunteersunderwent respiratory triggered rFOV DWI and ordinary DWI with ss-EPI (b=0,600s/mm~2). Artifacts and subjective image quality scores were compared between rFOVDWI and ordinary DWI. ADC values of rFOV DWI of CP and normal pancreas werecarefully measured. Wilcoxon signed-rank test was used for compared the difference ofartifacts and subjective image quality scores between rFOV DWI and ordinary DWI. Thedifference of ADC values of rFOV DWI between CP and normal pancreas was analyzedby independent-samples t test.RESULTS: As theb=0s/mm~2与b=600s/mm~2,imaging at rFOV DWI showedsignificantly higher image quality and lower artifacts than ordinary DWI. The score ofthe artifact and image quality between rFOV DWI and ordinary DWI was significantlydifferent (P <0.001). The ADC value of rFOV DWI of CP was significantly lower thanthat of normal pancreas (P <0.001).CONCLUSIONS:rFOV DWI could reduce the artifact and improve the image qualitycompared to ordinary DWI. rFOV DWI could be helpful to diagnose CP. Part II Studies of Multi b-values DWI in Assessing ChronicPancreatitis at3.0T MROBJECTIVE: To assess the value of multi b-values DWI using biexponential model fordiagnosis CP. To investigate the value of parameters derivedby biexponential model andmonoexponetial model in evaluating the atrophy of CP. To investigate clinical value ofmulti b-values for identifying CP with/without exocrine pancreatic insufficiency orendocrine pancreatic insufficiency.MATERIALSAND METHODS:48patients with chronic pancreatitis and36healthyvolunteers underwent DWI with9b-values up to1000s/mm~2on3.0T MR system.ADCtotand D*, D, f was calculated by monoexponetial model and biexponential modelrespectively. Mann-Whitney U test was used for compare the difference of ADCtot, D*, D,f between CP and normal pancreas. Dependency of D*, D, f on atrophy rate wascharacterized using a Spearman rand-order correlation test. The difference between CPwith/without exocrine pancreatic insufficiency or endocrine pancreatic insufficiency wascompared by Kruskal-Wallis H test.RESULTS: There were significant differences in ADCtot, D*, D between CP and normalpancreas (P <0.001). ADCtot, D*, D in CP was significant lower in chronic pancreatitisthan normal pancreas, while difference of f between CP and normal pancreas showed nostatistical significance (P=0.322>0.05). Across the atrophy rate spectrum, it showednegative correlation between atrophy rate and D*in CP(r=-0.316，P=0.029<0.05).There are no correlation between atrophy rate and D, f (P>0.05). Kruskal-Wallis H testshowed no difference between CP with/without exocrine pancreatic insufficiency orendocrine pancreatic insufficiency(P>0.05).CONCLUSIONS:ADCtot、D*、D could be helpful to diagnose CP. D*could reflect theperfusion information of CP. The more CP atrophied, the less pancreatic blood flowwould be. ADCtot, D*, D, f is difficult diagnosing CP with/without exocrine pancreaticinsufficiency or endocrine pancreatic insufficiency.