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Objective To investigate the diagnostic value of contrast-enhanced CT and MR diffusion-weighted imaging (DWI) in differentiating autoimmune pancreatitis (AIP) from pancreatic carcinoma (PC).Methods Twelve patients with AIP (AIP groups) and 15 patients with PC (PC groups) were included in this study.Contrast-enhanced CT and DWI were performed in all patients.The manifestations of the pancreatic lesions,pancreatic duct and bile duct were observed.The CT attenuation values and the apparent diffusion coefficient (ADC) values of the lesions were calculated.Frequencies of the CT manifestations,and the mean CT attenuation values,and the ADC values were compared between the two groups.Results Most of the AIP showed diffuse enlargement,sausage shape,peripancreatic capsule,penetrating sign of pancreatic duct and thickness of the bile duct.The frequencies of the findings mentioned above were significantly different between AIP and PC (P＜0.05).The CT attenuation values of the lesions,and the rate of lesions' CT attenuation values to livers' in 3 phases of contrast enhanced CT were significantly different between AIP and PC (P＜0.05).The ADC values of AIP were significantly lower than that of PC (P＜0.05).Conclusion The changes of morphology of pancreas,pancreatic and bile duct may facilitate in differentiating AIP from PC.Quantitative analysis of CT attenuation values and ADC values measured on MR images may be helpful in differentiating AIP from PC.
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Objective:To explore the calvarial critical size defect (CSD)in rats with type 2 diabetes mellitus(T2DM).Methods:T2DM model of SD rats(weighted 300-320 g)was induced by high fat and high sugar diet and low dose intraperitoneal streptozotocin (STZ)injection.The rats with T2DMand the normal controls were divided into 4 groups(n=3)respectively.Defects with the diame-ter(mm)of 2,3,4 and 5 were made on the central calvaria of each rat.General observation,X-ray examination and histological study were performed 8 weeks postoperatively.Results:In the T2DM group,only the defects of 2 mm diameter were healed completely,X-ray resistance and new bone formation were observed;the defects of 3,4 and 5 mm diameter were unhealed,X-ray transmission was observed and newly formed bone was insufficient.In the control group,the defects of 2,3 and 4 mm diameter were healed completely, X-ray resistance and new bone formation were observed;the defects of 5 mm diameter were unhealed,X-ray transmission was ob-served,newly formed bone was insufficient.Conclusion:The calvarial CSD of T2DM rat model can be defined as the defect with the diameter of 3 mm.
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Objective To study the deformation and mechanical characteristics during expansion process of vascular stent in realistic stenosis model, so as to provide scientific references for interventional treatment and stent design. Methods The carotid vessel model and plaque model of patient were built by using 3D reconstruction method, and the stent model with I-shaped link was established by using Pro/E; ABAQUS/Standard was used to simulate the radial expansion (the first stage) and radial contraction (the second stage) of the stent in real stenosis model, and a realistic model of blood vessel with plaque was also established to make contrast test. Results In the first stage, radial expansion of the stent was formed. The maximum contact area was generated between the outer surface of the stent and the inner surface of the plaque/arterial wall, and the maximum stresses on the stent, plague and arterial wall were 515.000, 2.482, 1.053 MPa, respectively. In the second stage, the radial contraction of the stent resulted in “dog-bone” effect. Many gaps between the stent and vessel wall was formed, and the maximum stresses on the stent, plague and arterial wall were 464.500, 0.954, 0.316 MPa, respectively. In contrast test, the maximum stresses on stenotic vessel and stent were 0.9, 414.1 MPa in the second stage. Conclusions Compared with the model in contrast test, the stenosis model differentiating the component of vascular tissues is more consistent with the real situation of stenotic vessels, by more truly showing deformation and mechanical characteristics of the stent and blood vessel. The stent causes the maximum damage to plaque and inner wall of blood vessel in the first stage, while “dog-bone” effect of the stent is an important influencing factor that results in the gaps between the stent, plague and blood vessel. These research findings may provide significant guidance for selecting stent in interventional treatment and improving stent design.