Objective To investigate the value of MR perfusion parameters and ADC in the diagnosis of pancreatic cancer and pancreatic mass at 3.0 T MR. Methods Twenty healthy volunteers and 25 patients with pancreatic cancers proven by pathological results underwent MR PWI at a 3.0 T scanner. A two-compartment model was used to quantify Ktrans, Kep and Ve in the pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue. All parameters among different tissues were analyzed and compared with ANONA. Fifteen normal volunteers and 58 patients, including 30 patients with pancreatic cancer (proven histopathologically), 9 patients with pancreatitis pseudotumor (4 patients proven by histopathological results, 5 patients proven by follow-up after treatment), 9 patients with solid pseudopapillary tumor of pancreas (SPTP, proven histopathologically) and 10 patients with pancreatic neuroendocrine tumor (PET, proven by histopathology), underwent respiratory-triggered DWI on 3.0 T. ADC values of normal pancreas and all types of pancreatic lesions were statistically analyzed and compared with ANONA. ROC curve was used to analyze the diagnostic power of ADC value. Results Ktrans of pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue were (1.66±1.25), (3.77±2.67),(1.16±0.94) and (2.69±1.46)/min respectively(F=8.160, P＜0.01). LSD test showed that Ktrans in the pancreatic cancer was statistically lower than that in normal pancreas (P=0.011)and adjacent pancreatic tissue(P=0.002). Kep of pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue were (2.53±1.55), (5.64±2.64), (1.70±0.91) and (4.28±1.64)/min respectively(F=4.544, P＜0.01). LSD test revealed that Kep in pancreatic cancer was statistically lower than that in normal pancreatic tissue (P=0.035)and adjacent pancreatic tissue(P=0.041). The median of Ve among the pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue were 0.926, 0.839, 0.798 and 0.659 respectively (χ2=12.040,P＜0.01). Ve in pancreatic cancer was statistically higher than that in normal pancreatic tissue (P=0.002). ADC values of the pancreatic cancer, pancreatitis pseudotumor, SPTP, PET and normal pancreas were(1.57±0.26)×10-3,(1.19±0.15)×10-3,(1.05±0.35)×10-3,(1.62±0.41)×10-3 and (1.82±0.25)×10-3 mm2/s(F=21.681, P＜0.01). LSD test showed there were significant statistical differences in ADC values among pancreatic cancer, pancreatitis pseudotumor and normal pancreatic tissue (P＜0.01). ROC curve disclosed that the sensitivity, specificity, positive predictive value and negative predictive value were 86.7%, 88.9%, 96.3% and 66.7% respectively, when ADC≥1.33×10-3 mm2/s was used as a cutoff value for differential diagnosis of PDCA from MLP. The sensitivity, specificity, positive predictive value and negative predictive value were 77.8%, 100.0%, 100.0% and 83.3% respectively when ADC≤1.25×10-3 mm2/s was used as a cutoff value for differential diagnosis of SPTP from PET. Conclusion Compared to normal pancreatic tissue, pancreatic cancer usually had a lower Ktrans, Kep and larger Ve. ADC values from respiratory-triggered DWI were well related to histopathological features of pancreatic entities and may be helpful in the differential diagnosis.

Objective To compare the MR features of small hepatocellular carcinoma (sHCC) and small intrahepatic mass-forming cholangiocarcinoma (sIMCC) (≤ 3 cm) and improve the accuracy in diagnosis.Methods Imaging studies of 318 patients with 351 sHCCs and 42 patients with 47 sIMCCs were retrospectively reviewed.Signal intensity on T2WI and on each phase of dynamic enhanced imaging,enhancement patterns,and accompanying findings of the two groups were compared by qualitative and quantitative studies.The qualitative imaging features of tumors were compared by the x2 test and the Fisher exact test,and the statistically significant variables obtained from univariate analysis were used to conduct multivariate stepwise logistic regression analysis.Enhancement pattern between sHCCs with elevated AFP and normal AFP were assessed by thex2 test.Results Multivariate analysis indicated that signal features of enhancement pattern and the accompanying findings of tumor capsule and hepatic capsule retraction were key predictors in differentiating sHCC from sIMCC:Wash-out pattern (276/351) with enhanced tumor capsule (275/351) highly indicated sHCC,while progressive enhancement pattern (27/47) with hepatic capsule retraction (8/47) indicated the diagnosis of sIMCC (P ＜ 0.01).Compared with sHCC with normal AFP,atypical patterns as progressive (n =4) and stable enhancement (n =32) were more commonIy seen in lesions with elevated AFP,dynamic enhancement pattern was different between the two subgroups (x2 =8.241,P ＜ 0.05).Conclusions Enhancement patterns and the accompanying tumor capsule and hepatic capsule retraction were the most important predictors in differentiating sHCC from sIMCC.In addition,enhancement pattern was relatively more typical in sHCCs with normal AFP which provided valuable information in diagnosis for clinicians.

Objective To evaluate MDCT findings and characteristics of metastatic pancreatic tumors. Methods A total of 23 cases with metastatic pancreatic tumors were collected and the CT findings including the size, number, location, density patterns, enhancement patterns and secondary signs (dilatation of the pancreatic duct and/or bile duct, involvement of peripancreatic vessels, atrophy of distal pancreas) were analyzed retrospectively. Results A total of 35 metastatic pancreatic tumors were identified in the 23 patients. Tumors were multiple in 7 patients, the other 16 patients had single metastatic pancreatic tumor. The mean maximum diameter of the tumors was 3. 3 cm; the majority was located in the pancreatic body/tail. Thirty tumors demonstrated no enhancement in the arterial phase, and in the portal phase 23 tumors were hypodensive compared with normal pancreatic tissue, 4 tumors were isodense and 3 tumors showed a peripheral rim of enhancement. Five tumors showed markedly enhancement in the arterial and portal phase. Only 1 patients had dilated biliary and pancreatic duct, and 2 patients had dilated pancreatic duct. Only 1 case demonstrated involvement of splenic vein. 13 of the 23 patients had extra-pancreatic metastasis. Conclusions Pancreatic metastasis showed certain imaging characteristics. The accuracy of CT diagnosis could be improved by understanding of these CT findings and clinical features.

Objective To investigate the diagnostic value of different DWI sequences for pancreatic cancer on a 3.0 T MR scanner.Methods Different DWI acquisitions based on SE-EPI sequence were preoperatively performed in 30 patients with pancreatic cancer proven by histopathology on a 3.0 T MR scanner.The patients included 17 males and 13 females.Their age ranged from 39 to 72 years with mean of (57.6 ± 14.9) years.The b values were 0 and 600 s/mm2 and the following sequences were included:breath-hold DWI with MPG pulses in X,Y,Z direction (BH600ALL),breath-hold DWI with MPG pulses in Z direction(BH600SI),respiratory-triggered DWI with MPG pulses in X,Y,Z direction (TRIG600ALL),respiratory-triggered DWI with MPG pulses in X,Y,Z direction and inversion recovery for fat saturation (TRIG600ALL+FS) and free-breathing DWI with MPG pulses in X,Y,Z direction and inversion recovery for fat saturation (FB600ALL+ FS).C,CNR and ADC of pancreatic cancer were caculated and compared among different DWI sequences by statistic mathed.Results CNR (F =11.444,P ＜ 0.001) and C (F =5.447,P ＜ 0.05) of pancreatic cancer displayed noticeably statistical difference among BH600ALL、BH600SI、TRIG600ALL、TRIG600ALL + FS and FB600ALL + FS DWI sequences by ANOVA.Among those five different DWI sequences,the highest CRN of pancreatic cancer was observed in TRIG600ALL and TRIG600ALL + FS(the values were 16.45 ± 10.37 and 13.38 ± 9.10 respectively),while the highest C of pancreatic cancer was noticed in TRIG600ALL + FS (0.39 ±0.15).ADC of pancreatic cancer had no statistical difference among BH600ALL,BH600SI,TRIG600ALL,TRIG600ALL + FS and FB600ALL + FS DWI sequences by Kruskal-Wallis test.For BH600ALL and BH600SI,there were no statistical difference among ADC of pancreatic cancer,adjacent pancreatic tissue and distal pancreatitis by ANOVA.While for all TRIG600ALL,TRIG600ALL + FS and FB600ALL + FS,there were statistical difference among ADC of pancreatic cancer,adjacent pancreatic tissue and distal pancreatitis by ANOVA (F values were 5.353,15.976 and 14.556 respectively,P ＜ 0.05).ADC of pancreatic cancer was statistically lower than that of adjacent pancreatic tissue and distal pancrcatitis on all TRIG600ALL,TRIG600ALL + FS and FB600ALL +FS (P ＜ 0.05).Conelusion Compared to other four DWI sequences,TRIG600ALL + FS had higher C and CNR in pancreatic cancer,and measurement of ADC value was helpful to disclose the histopathological state in pancreatic cancer,adjacent pancreatic tissue and distal pancreatitis.

Objective To analyze MR imaging appearance of pancreatic neuroendocrine neoplasms (pNEN) and to investigate the practical value of MR imaging appearance in predicting pathological grade of pNEN. Methods All data of 35 patients with pathologically proven pNEN were retrospectively reviewed. MR examinations of the abdomen were performed on all these patients before operation and the data of clinical, pathological and MR imaging were intact. Both plain scan and contrast-enhanced MR scan were performed on each patient. Histopathological grade of pNEN was defined as: G1, G2, and G3 according to World Health Organization classification of tumours of the digestive system guidelines(2010). Image analysis included tumor location, number, size, shape, lesion margins, signal intensity, enhancement pattern, main pancreatic duct dilatation, extrapancreatic spread, and metastases of lymph node and liver. The comparison of quantitative index between G1 and G2 group was performed with t test. Categorical variables were tested using Fisher exact test. Results Thirty five lesions were found in 35 patients, with 14 lesions in G1, 19 lesions in G2, and 2 lesions in G3.Thirty three lesions appeared as a solid mass, and 2 lesions appeared as a cystic lesion. Significant gender-based difference was found between G1 group and G2 group (P<0.05). No significant age-based or endocrine function difference was found between the G1 group and G2 group(P>0.05). Of the 35 lesions, 27 lesions were round in shape, while other 8 lesions were irregular. There were 18 lesions with clear margin, and the margins in other 17 lesions were blurred. Main pancreatic duct dilatation was found in 3 cases(1 in G2, 2 in G3). Significant differences in tumor diameter, shape, margin, signal intensity on precontrast images, extrapancreatic spread and metastases were found between G1 group and G2 group(P<0.05). No significant difference was found in main pancreatic duct dilatation or signal intensity on all enhancement phases between G1 group and G2 group. The 2 lesions in G3 group appeared mild contrast enhancement with degrees lower than the pancreas in all enhancement phases. Conclusion MR imaging features such as tumor diameter, shape, margin, signal intensity on precontrast images, extrapancreatic spread and metastases may preoperatively predict the pathological graden of pNEN.

Objective To investigate rare and atypical imaging manifestations of abdominal lesions associated with IgG4-related disease (IgG4-RD).Methods Forty-one patients with IgG4-RD proved histopathologically or clinically were investigated retrospectively.All the patients underwent precontrast and dynamic enhancement scan of the abdomen.CT was performed in 32 patients and MR imaging in 27 patients (including both of CT and MRI in 18 patients).Whether tissue and organs of the abdomen were involved was observed,especially rare and atypical imaging manifestations including focal pancreatic lesion,pseudocyst and (or) abscess as well as calcification of pancreas,peripheral blood vessels of pancreas involvement and mass-like lesions were existed.Involvement of the organs including liver,gallbladder,spleen,gastrointestinal tract,mesentery and their manifestations were also observed.Results One to four abdominal organs were involved,the numbers of involved organs were as follows:one organ in 13 patients (31.7％),two organs in 12 patients (29.3％),three organs in 13 patients (31.7％),and four organs in 4 patients (7.3％).The most commonly involved organ of the abdomen was the pancreas which was found in 35 patients.Abdominal extrapancreatic lesions were found in 33 patients.Focal involvement of pancreas as a rare manifestation showed in 11 cases (11/35,31.4％).The patterns were focal and multifocal.Rare cases showed pseudocysts (3/35,8.6％) and abscess was found in 1 case.Capsule-like rim was present around the pancreas lesions in 25 cases.Ten cases showed thick and wide rim with unclear boundaries with adjacent blood vessels,and 7 of them showed the peripheral blood vessels surrounded.Bile duct involvement was observed in 26 patients,and gallbladder involvement was observed in only 2 of them.Rare renal involvement patient has mass-like lesion,with hypointensity on T2WI,then showed decreased enhancement and gradually delayed enhancement.One retroperitoneal fibrosis patient also showed mass-like lesion as an atypical and rare manifestation.Three IgG4-related liver inflammatory pseudotumors were found in 2 patients.Lesions showed iso or hypointensity on T2WI,continuously enhancement,with abnormal edge ring.Mesentery involvement was found in 1 patient.Conclusion Several abdominal lesions associated with IgG4-RD have rare and atypical imaging manifestations.There are specific imaging characteristics,which are helpful for most accurate diagnosis of IgG4-RD.

Objective To investigate the CT and MRI findings of primary hepatic neuroendocrine carcinomas.Methods Imaging findings of 6 patients with pathologically confirmed hepatic neuroendocrine carcinomas were retrospectively analyzed.Four patients underwent plain CT and contrast enhanced CT examinations.The other 2 patients underwent plain MRI and contrast enhanced MRI.Results One out of the 6 cases manifested multicentric tumor which appeared as one large tumor surrounded with multiple small nodules peripherally,and the tumors of the other 5 cases were solitary.On plain CT images,all lesions were well-defined and hypoattenuating with central areas of even lower density except punctuate calcifications at tumor periphery in 1 case.On pre-contrast MRI,the cases manifested heterogeneous low signal intensity on T1 wI and slightly high intensity on T2 WI.On dynamic contrast enhanced CT and MRI,Tumors manifested slight to mild enhancement in arterial phase,slight enhancement in portal venous phase or delayed phase with no enhancement in the center,accompanied by dislocation of surrounding vessels.There Was no lymphadenopathy in peritoneal cavity and retroperitoniurm. Conclusion CT and MRI scanning can demonstrate specific features of primary hepatic neuroendocrine carcinoma,which may help the diagnosis and differential diagnosis of the tumor.

Objective To analyze the CT appearances with pathologic correlation and improve the recognition of pancreatic mucinous cystadenoma/cystadenocarcinoma.Methods CT findings in 20 patients with pathologically proven pancreatic mucinous cystic tumor were retrospectively and jointly reviewed by two observers blinded to the pathological results.All patients underwent precontrast and postcontrast helical CT.The number,size,location,and margins of the lesions were observed,along with wall thickness,septation,calcification witllin the lesions.and presence of mural nodules and their enhancement.The findings of malignant and benign tumors were compared.Results Twelve cases of mucinous cystadenoma.3 borderline cystadenomas and 5 cystadenocacinomas were included in this study.Sixteen tumors(16/20)were located at pancreatic body or tail.The findings of thick walsl,calcifications and mural nodules appeared in 4,2 and2 cases respectively in benign mucinous cystic tumors,while appeared in 7,5,and 5 cases respectively in malignant mucinous cystic tumom.Presence of tIlick walls.calcifications and mural nodules in the lesions were significantly associated with malignancy(P＜0.05).Conclusion CT manifestations of pancreatic mucinous neoplasm are variable,but has some specific radiographic features.A combination of CT findings is helpful ifl differentiation of malignant and benign pancreatic mucinous adenomas.

Objective To express the recombinant caspid of genotype 4 hepatitis E virus(HEV) ORF2. Methods HEV recombinant capsid protein D66 was expressed in E. coli, using the ORF2 fragment (aa368-606, obtained from swine bile) of genotype 4 HEV. Results The recombinant capsid proteins D66 self-assemble to be particle with a radius of 13 nm through dimeric form in neutral solution. Coated particles reacted well with sera obtained from patients during acute or recovered phase of HEV infection. Immunofluorescence and immnoblot assay suggested that D66 bound and penetrated HepG2 cell lines, and the process of attachment was blocked by sera collected from patients during acute or recovered phase of HEV infection.Conclusion Recombinant D66 particles simulate the structure at the surface of genotype 4 HEV well and specifically adhere and penetrate the host cells, which lays the foundation for the investigation of the molecular mechanism of genotype 4 HEV infection.

ObjectiveTo investigate the CT and MRI imaging characteristics of autoimmune pancreatitis and its clinical value.MethodsFourteen patients(13males, 1female, mean age 58.3 years) with autoimmune pancreatitis proved histopathologically or clinically were enrolled in the study.Clinical data was studied retrospectively.Among those patients,CT was performed on 12 cases and MR imaging was performed on 8 patients,6 patients underwent both CT and MR imaging.ResultsAll 14 patients had enlargement of the pancreas,which could be divided into three types including diffuse type ( n =7 ),focal type ( n =5 ) and mixed type ( n =2 ).On plain CT the pancreas was of isodensity ( n =5 ) or mild hypodensity ( n =7).In one case there was several small hypodensity cystic lesions within and around the pancreas that was rarely seen in other autoimmune pancreatitis cases.Pancreatic lesions as shown by MRI were all mildly hypointense on T1WI and mildly hyperintense on T2WI,all displayed lesions were detected as high-signal intensity areas on DWI. By medium contrast,autoimmune pancreatitis lesions demonstrated “ snow-like” heterogeneously decreased enhancement on artery phase of dynamic contrast enhanced imaging and then showed gradually delayed enhancement on portal venous phase and later phases.“Capsule-like” rim was present around the autoimmune pancreatitis lesions in 9 cases.Main pancreatic duct was irregular in shape in 4 cases and slightly dilated in 5 patients.Strictures of lower common bile duct and upper bile duct dilatation as well as thickening and enhancement of the bile duct wall were found in 9 cases.Peripheral vascular involvement was seen in 4 cases. Abdominal lymphadenopathy at hepatic portal was observed in 1 patient.Two cases showed tiny decreased enhancement lesions in the kidneys.Steroid therapy was given in 10 cases,all pancreatitis lesions ameliorated as showed by follow-up imaging examinations.ConclusionsAIP specific CT and MRI imaging findings are common in most patients which help establish the diagnosis and differential diagnosis of AIP.