Objective To define the value of DCE and DWI in assessing malignant and benign lesion in periamapullary regions . Methods The data of dynamic contrast enhancement magnetic resonance imaging (DCE‐MRI) and diffusion‐weighted imaging(DWI) of 43 patients (32 malignant and 11 benign lesions) were analyzed retrospectively ,who have been diagnosed as biliary strictures in ampullary regions .One radiologist compared the signal intensity of DCE‐MRI and DWI of malignant and benign periamapullary le‐sions .Two other radiologists assessed data of DCE‐MRI and data of combined DCE‐MRI and DWI from those periamapullary lesions respectively .And then we compared the diagnostic sensitivity and specificity of each type of data by receiver operating characteristic (ROC) curve analysis .Results Malignant and benign periamapullary lesions showed no statistically significant difference on DCE‐MRI;Malignant periampullary lesion were more frequently appeared hyperintense than benign lesions on DWI ,and hypointense on ADC (P<0 .001) .Diagnostic accuracy improved from 84 .4% to 96 .9% and 87 .7% to 96 .6% for both reviewers after adding DWI on diagno‐sis of malignant periampuullary lesions .Conclusion The combination of DCE‐MRI and DWI can improve the diagnostic accuracy for differentiating malignant from benign strictures in the periampullary region .

Objective To study the CT and MRI characteristics of myxoid soft tissue tumours.Methods Fifty-three myxoid soft tissue tumours pathologically confirmed were retrospectively studied.MR and CT scan were performed before operation.Noncontrast T1 and T2 weighted images,fat-suppressed T2 weighted images were obtained before contrast-enhanced scan with fat-suppressed T1 weighted sequence was underwent.Plain and contrast-enhanced CT was performed with tube potential of 120 kV,matrix 512 × 512,and automatic tube current modulation technique.Results There were 18 myxoid liposarcoma,3 ganglioneuroma,8 myxofibrosarcoma,2 extraskeletal myxoid chondrosarcoma,10 intramuscular myxoma,and 2 juxta-articular myxoma.Microscopic examination showed myxoid soft tissue tumours which were consisted of abundant myxoid stroma with tumour cells and blood vessels associated with fibrous bands.Low density in CT images,hypointensity in T1 weighted images,significantly hyperintense in T2 weighted images were their common manifestations in the area of abundance of extracellular myxiod matrix.Plain CT images demonstrated equidensite,T1 weighted images isointensity,and fat-suppressed T1 weighted images significant enhancement relatively in the areas of increased number of tumor cells.Hemorrhage,necrosis and capsule of the lesion were revealed in high grade malignant tumors.The septa can be identified in most of myxoid tumours of soft tissue.Conclusion CT and MRI can definitely show the image characteristics of myxiod soft tissue tumours,which can help make a qualitative diagnosis before operation.