Objective To probe the value of 3.0T MRI in the preoperative assessment of rectal carcinoma.Methods The study recruited 41 patients who were confirmed by biopsy of rectal carcinoma and underwent conventional MRI, high-resolution MRI and diffusion weighted imaging(DWI), the distance from the inferior part of tumor to transitional skin and the percentage of circumferential invasion were measured, the tumor's T staging, N staging,and the status of circumferential resection margin(CRM) and extramural vascular invasion(EMVI) were assessed.MRI findings were compared with endoscope and postoperative pathological results.Results MRI could accurately show the distance from the inferior part of tumor to transitional skin(P>0.05);The mean percentage of circumferential invasion for the tumor with T1-T2 and T3 were 61%,83% respectively (P>0.05);The total accuracy of T,N staging diagnose were 80.5%,75.6% respectively, which had a better consistent with pathological T,N staging(Kappa=0.564,0.634);The total accuracy of CRM and EMVI diagnose were 90.2%,73.2% respectively,which had a better or moderate consistent with pathological diagnose(Kappa=0.765,0.461).Conclusion 3.0T MRI has the unique application in the preoperative assessment of rectal carcinoma, which can provide more comprehensive information for clinic.

Osteoporosis （OP） and osteoarthritis （OA） are common bone diseases in clinic. OP is a systemic skeletal disease， and OA is a chronic degenerative joint disease with high prevalence and disability rates. With the advent of the aging population， the incidence rate of OA and OP is increasing year by year， and they have become common diseases of the elderly. The quality of life and physical and mental health of patients are severely affected by the above two bone diseases. Chinese medicine has a long history of treating bone diseases， with a good clinical effect on preventing and treating OP， OA， and other bone diseases with few side effects. It is one of the commonly used methods to treat bone diseases. Polysaccharides， as one of the active substances of Chinese medicine， have various pharmacological activities and a wide range of sources with low toxicity， and their effect cannot be ignored. The role of polysaccharides in the treatment of bone diseases has been deeply studied. It has been found that the mechanism of Chinese medicine polysaccharides in treating OP and OA involves multiple levels， targets， and pathways. Through the analysis and summary of the relevant literature on the mechanism of Chinese medicine polysaccharides in treating OP and OA， it was found that Chinese medicine polysaccharides mainly treated OP by regulating the bone dynamic balance between osteoblasts and osteoclasts and affecting bone marrow mesenchymal stem cells and bone microstructure. The mechanism of Chinese medicine polysaccharides in the treatment of OA is related to the regulation of chondrocyte growth， the increase in the proteoglycan and collagen content in the cartilage matrix， and the reduction of oxygen free radical content and inflammatory mediator level. This study aimed to further explore the internal relationship among mechanisms of Chinese medicine polysaccharides in the treatment of bone diseases， to provide relevant ideas for the study of Chinese medicine polysaccharides in the treatment of bone diseases.

Objective:To investigate the feasibility and clinical value of 4D flow magnetic resonance imaging (MRI) in evaluating hemodynamics of ischemic stroke patients with intracranial artery stenosis.Methods:Ischemic stroke patients with unilateral middle cerebral artery stenosis admitted from March 2017 to June 2018 in Beijing Tsinghua Changgung Hospital Stroke Center were prospectively enrolled. Time of flight magnetic resonance angiography was used to evaluate vascular stenosis, 4D flow MRI was used to measure net forward flow at the proximal of stenosis, and brain tissue perfusion was acquired simultaneously to validate flow.Results:A total of 33 patients with symptomatic middle cerebral artery stenosis were included [mean age: 56 years; male: 63.6% ( n=21)]. The flow rates among patients with stenosis of <30%, 30%-49%, 50%-69% and ≥70% were (3.56±1.08), (2.96±0.94), (3.72±0.60) and (2.50±1.03) ml/s individually, demonstrating a decreased flow in subjects with severe (≥70%) stenosis ( F=4.34, P=0.008). Further analysis about forward flow and brain tissue perfusion showed that the significant negative correlation between absolute flow rate or relative flow rate and relative time to peak could only be established in subjects with poor collateral (collateral score: 0-2), with r=-0.76 and -0.61 individually, both P<0.05. Conclusion:4D flow MRI could be used as a quantitative flow assessment in subjects with intracranial artery stenosis, and its association with distal brain tissue perfusion depends on collateral status.