Objective:To investigate the feasibility of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)parameters in differentiating musculoskeletal tumors with different behaviours of pathological findings before therapy.Methods:A total of 34 subjects of musculoskeletal tumors were in-volved in this retrospective analysis.DCE-MRI was performed using a fat-saturated 3 D VIBE (volumetric interpolated breath-hold exam)imaging sequence with following parameters:FA,10 degree;TR/TE, 5.6/2.4 ms;slice thickness,4.0 mm with no intersection gap;field of view,310 mm ×213 mm;ma-trix,256 ×178;voxel size,1 .2 mm ×1 .2 mm ×4.0 mm;parallel imaging acceleration factor.The ac-tuation time for the DCE-MRI sequence was 255 s with a temporal resolution of 5 s and 40 image vo-lumes.Using pathological results as a gold standard,tumors were divided into benign,borderline and malignant tumors.Toft’s model was used for calculation of Ktrans (volume transfer constant),Ve (extra-vascular extracellular space distribute volume per unit tissue volume)and Kep(microvascular permeability reflux constant).Those parameters were compared between the lesions and the control tissues using paired t-tests.The one-way analysis of variance was used to assess the difference among benign,border-line and malignant tumors.P values <0.05 difference was statistically significant.Results:Based on the WHO Classification of Tumours of Soft Tissue and Bone(2012)criteria,34 patients were divided into three groups:1 1 for benign tumors,12 for borderline tumors,and 1 1 for malignancies.Compared with control tissues,Ktrans and Kepshowed no difference,but Ve was increased in benign tumors,Kep showed no diffe-rence,butKtransandVewereincreasedinborderlinetumors, Ktrans,KepandVewereincreasedin malignant tumors.Ktrans(P<0.001 )and Kep (P<0.01 )were significantly higher in malignant tumors than in benign and borderline tumors,but did not show any difference between benign tumors and border-line tumors.Ve was significantly higher in malignant tumors than in benign (P<0.05),but did not show any difference between malignant and borderline tumors,benign tumors and borderline tumors (P >0.05 ).Conclusion:DCE-MRI technique is useful to evaluate the pathological behaviour of musculoske-letal tumors.The quantitative analysis of DCE parameters in conjunction with conventional MR images can improve the accuracy of musculoskeletal tumor qualitative analysis.

Objective:To evaluate the efficacy and safety of enteral extended biliary stenting for biliary stricture.Methods:A multicenter retrospective cohort study was conducted on data of 550 patients with obstructive jaundice due to extrahepatic bile duct stricture between February 2006 and April 2020. Patients were assigned to conventional group (undergoing conventional biliary stent placement) and extended group (undergoing enteral extended biliary stent placement). Propensity score was used to match the basic data of patients of the two groups. Then the stent patency time, bilirubin difference before and after 1 week operation, incidence of complications and hospital stay were compared between the two groups.Results:Among the 550 patients, clinical data of 20 cases were missing and 35 failed to be followed up. Finally, 326 patients were enrolled to the study after propensity score matching with 163 cases in each group. The patency time of extended group was 111.0 (82.0, 192.0) days, which was longer than that of conventional group with patency time of 93.0 (70.0, 141.8) days ( Z=3.260, P=0.001). Total bilirubin difference value of pre-operation and post-operation was less in extended group [51.2 (26.0, 114.7) μmol/L VS 46.0 (13.9, 81.1) μmol/L, Z=2.095, P=0.036]. The rate of early adverse events [4.3% (7/163) VS 3.7% (6/163), P=0.079] and median in-patient days (10.0 days VS 10.0 days, P=0.379) were similar in the two groups. Conclusion:Enteral extended biliary stent is effective and safe for treatment of biliary stricture, which can prolong the patency time without increasing postoperative complications and hospital stay.