Research On Evaluating The Spleen Injury In Acute Pancreactitis On Based Of Multi-exponential Models Of ME-DWI

Part 1 Assessment of Spleen Dysfunction in Acute Pancreatitis Based on IVIM-DWI Imaging CharacteristicsObjective:To evaluate spleen dysfunction in acute pancreatitis based on imaging characteristics from Intravoxel Incoherent Motion(IVIM).Methods: According to the inclusion criteria and exclusion criteria,a total of 57 patients with acute pancreatitis(the experimental group)and 19 healthy volunteers(the control group)were randomly selected in Affiliated Hospital of North Sichuan Medical College.Conventional abdominal MRI and multi-b value DWI imaging were administrated to the two groups,and data were respectively transmitted into the image post-processing station.Two experienced radiologists observed and confirmed Regions of Interest(ROI)to spleen of the two groups and conducted multipoint measurement to the Apparent Diffusion Coefficient(ADC)values of the bi-exponential model:slow ADCmono,fast ADCmono,Ff ADCmono,slow ADCbi,fast ADCbi and Ff ADCbiwere measured.Inter-observers agreement between the two radiologists was calculated by Intraclass Correlation Coefficient(ICC).The rank Wilcoxon test were adopted between groups.Receiver Operating Characteristic Curve(ROC)analysis was used to analyze the parameters value with statistical difference,the area under the curve?the ADC value threshold?sensitivity and specificity were calculated and analyzed.What's more,slow ADCmono,fast ADCmono,Ff ADCmono,slow ADCbi,fast ADCbi and Ff ADCbi were compared among different severities of acute pancreatitis for the experimental group.Results: The values of the parameters between the two radiologists were consistent range of the Intra-class Correlation Coefficient(ICC)was 0.5570~0.9520,There were significant differences in slow ADCmono ?slow ADCbi and fast ADCbi between the experimental group and the control group(P<0.05),but no significant difference was found in fast ADCmono,Ff ADCmono and Ff ADCbi(P>0.05).ROC curve showed that slow ADCmono,slow ADCbi,fast ADCbi had higher diagnostic value(area under the ROC : 0.6840mm2,0.6560mm2 and 0.6550mm2,respectively),the ADC value threshold was 0.5960×10-3mm2/s,0.5370×10-3mm2/s and 20.40×10-3mm2/s,respectively;the sensitivity value was 92.98%,70.18% and 47.37%,respectively;the specificity value was 42.11%,63.16% and 84.21%,respectively.What's more,there were no significant differences in slow ADCmono,fast ADCmono,Ff ADCmono,slow ADCbi,fast ADCbi and Ff ADCbi between different severities of the experimental group acute pancreatitis(P>0.05)Conclusion:Acute pancreatitis can lead to changes in the functional metabolism of the spleen.the parameter(slow ADCmono,slow ADCbi and fast ADCbi)values of IVIM-DWI are helpful to the quantitative analysis of early change and have certain diagnostic efficacy.Part2 Study of Spleen Heterogeneity in Acute Pancreatitis Based on SEM-DWI AssessmentObjective:To evaluate spleen heterogeneity in acute pancreatitis based on imaging characteristics from Stretched Exponential Model DWI(SEM-DWI).Methods: According to the inclusion criteria and exclusion criteria,a total of 54 patients with acute pancreatitis(the experimental group)and 28 healthy volunteers(the contrast group)were randomly selected in the Affiliated Hospital of North Sichuan Medical College.Conventional abdominal MRI-DWI imaging with multi-b values and multi-gradient diffusion directions were administrated to the two groups,and data were respectively transmitted into the image post-processing station.It was observed and confirmed Regions of Interest(ROI)to every third part of the largest spleen slice of the two groups and conducted multi-point measurement to the parameters values of the stretched exponential model: DDC and ? were measured.Intra-class Correlation Coefficient(ICC)was calculated.DDC and ? were compared between the two groups and among different severity of acute pancreatitis for the experimental group.Receiver Operating Characteristic Curve(ROC)analysis was used to analyze the parameter values with statistical difference,the area under the curve,the parameters value threshold,sensitivity and specificity were calculated and analyzed.particularly,diagnostic efficiency of spleen heterogeneity in acute pancreatitis were analyzed.Results:In the experimental and contrast group,the DDC and ? value were(0.6342±0.2330)×10-3mm2/s,0.6180±0.1280 and(0.7150±0.2510)×10-3 mm2/s,0.6870±0.0990,respectively.There were significant differences in DDC and ? between the experimental group and the contrast group(P<0.05).ROC curve showed that DDC and ? had higher diagnostic value(area under the ROC:0.6410mm2 and 0.6650mm2 respectively).The DDC and ? value thresholds were 0.2460×10-3mm2/s and 0.3820,respectively;the sensitivity values were 38.89% and 70.37%,respectively;the specificity values were 85.71% and 67.86%,respectively.What's more,there were significant differences in DDC and ? between different severity of the experimental group acute pancreatitis(FDDC=11.348,PDDC=0.000;F?=3.735,P?=0.0310).Among them,there were significant differences in DDC between the mild and moderately severe groups,and between the mild and severe groups(P=0.000?P=0.0030).There was significant difference in ? between the mild and moderately severe groups.The rest of different severity of the experimental group had no significant difference.Conclusion: The parameter(DDC??)values of SEM-DWI are helpful to evaluate spleen heterogeneity in acute pancreatitis.Moreover,spleen heterogeneity has certain significant difference along with different severity of the experimental group.