Objective: To evaluate the performance of 5T magnetic resonance imaging (MRI) in visualizing dental pulp and periodontal ligament (PDL) tissues in vivo in the young adult population, thereby providing a basis for the application of high-field MRI technology in clinical oral examinations. Methods: The study was approved by the Ethics Committee of the hospital. A total of 15 healthy volunteers (413 permanent teeth altogether) were recruited and underwent full-mouth 5T MRI scans. Among them, six volunteers (168 permanent teeth) also received both 3T MRI and cone-beam computed tomography (CBCT) scans. Two dental specialists independently evaluated the imaging quality of the dental pulp and PDL on the images using a 5-point Likert scale and recorded the number of detectable root canals for each tooth. Inter-rater agreement was assessed using weighted kappa statistics and intraclass correlation coefficient (ICC). Non-parametric tests were employed to compare differences in imaging performance among different tissue structures, tooth positions, and imaging modalities. Results: 5T MRI can achieve in vivo imaging for most dental pulp tissues and partial periodontal membrane structures. There was a high level of agreement between the two raters in their imaging scores for the dental pulp and PDL (dental pulp κ = 0.934, PDL κ = 0.737). The imaging scores for dental pulp were significantly higher than those for PDL (P < 0.001), and the scores for molar dental pulp were lower than those for premolars and anterior teeth. In the multimodal comparison involving six volunteers, the raters showed good consistency in scoring dental pulp and PDL imaging across 5T MRI, 3T MRI, and CBCT, as well as in root canal counts (5T MRI for dental pulp κ = 0.971, 3T MRI for dental pulp κ = 0.933, CBCT for dental pulp κ = 0.964; 5T MRI for PDL κ = 0.625, 3T MRI for PDL κ = 0.667, CBCT for PDL κ = 0.571; ICC for root canal counts all ≥ 0.990). The imaging scores for dental pulp and PDL using 5T MRI were significantly higher than those using 3T MRI (dental pulp: P < 0.001; PDL: P = 0.022), but there was no statistically significant difference in the detection rate of the number of root canals between the two (P > 0.05). Although the imaging scores for dental pulp and PDL as well as the detection rate of the number of root canals with 5T MRI were inferior to those with CBCT (dental pulp: P < 0.001; PDL: P = 0.02; number of root canals: P < 0.05), 5T MRI can truly achieve "direct imaging" of these two soft tissues. Conclusion 5T MRI enables effective in vivo direct imaging of dental pulp and PDL tissues in the young adult population, indicating its potential clinical application value in the diagnosis and treatment of pulp and periodontal diseases.

Objective:To investigate the risk factors of muscle necrosis in patients with acute compartment syndrome（ACS）.Methods:A retrospective case-control study was conducted for clinical data of 111 ACS patients admitted to West China Hospital, Sichuan University from January 2010 to December 2020, including 84 males and 27 females; age 18-76 years [45（36, 55）years]. Muscle necrosis was presented in 35 patients（necrotic muscle group）, but was not seen in 76 patients（non-necrotic muscle group）. The univariate analysis was performed for the two groups in the demographic data（sex, age, ethnicity, body mass index, smoking history, chronic comorbidities）, injury patterns [ mechianism of injury（low energy injury, high energy injury, crush injury, other injury）, time from injury to treatment, first visit or not, combination with bone fracture or not, open injury or not, presence of tension blisters or not], medical treatment（number of debridements, fasciotomy or not）and laboratory indicators [hemoglobin（Hb）, platelet count（PLT）, white blood cell count（WBC）, prothrombin time（PT）, international normalized ratio（INR）, partially activated prothrombin time（APTT）, fibrinogen（FIB）, D-Dimer（D-D）, alanine aminotransferase（ALT）, aspartate aminotransferase（AST）, albumin（ALB）, intravenous blood glucose（GLU）, creatine kinase（CK）, peak value of CK during hospitalization（natural logarithmic conversion, lnCK）, serum sodium（NA）, serum potassium（K）, serum calcium（CA）]. Further multivariate logistic regression was performed to analyze the independent risk factors of muscle necrosis in ACS patients.Results:The univariate analysis showed that there were statistically significant differences between the two groups in the mechanism of injury, first visit or not, combination with bone fracture or not, number of debridements, Hb, PT, INR, D-D, AST, ALB, GLU, CK and lnCK（ P<0.05）, while not in the basic data, time from injury to treatment, open injury or not, presence of tension blisters or not, fasciotomy or not, PLT, WBC, APTT, FIB, ALT, NA, K and CA（ P>0.05）. The multivariate logistic regression analysis showed that high energy injury（ OR=5.143, 95% CI 1.216-21.758, P<0.05）, crush injury（ OR=22.313, 95% CI 2.625-189.635, P<0.05）, other mechanism of injury（ OR=9.019, 95% CI 1.036-78.554, P<0.05）, first visit or not（ OR=0.071, 95% CI 0.006-0.819, P<0.05）, Hb（ OR=0.979, 95% CI 0.961-0.998, P<0.05）, GLU（ OR=1.218, 95% CI 1.020-1.455, P<0.05）and lnCK（ OR=1.805, 95% CI 1.235-2.639, P<0.05）were significantly related with muscle necrosis. Conclusion:The mechanism of injury, first visit or not, Hb, GLU and lnCK are the independent risk factors of muscle necrosis in patients with ACS.

Objective To explore the clinicopathological characters of T2 gastric cancer and the value of MSCT in the preop‐erative TNM staging of T2 gastric cancer .Methods A total of 93 patients with T2 gastric cancer were included in our study and un‐derwent preoperative MSCT staging ,who were confirmed by pathologic results .Then the results were compared with those of path‐ologic TNM staging .Also the clinicopathological features of the T2 gastric cancer were analyzed .Results There were no statistical‐ly significant differences in the clinicopathological characters among T2a and T2b patients (P>0 .05) .Comparing with pathologic TNM stage ,the T staging accuracy of MSCT was 91 .40% (85/93) ,the N staging accuracies of CT was 66 .67% (62/93) ,in which , 68 .18% (30/44) ,65 .00% (26/40) ,60 .00% (3/5) and 75 .00% (3/4) were for pN0 ,pN1 ,pN2 and pN3 .And the TNM staging ac‐curacies of CT was 67 .74% (63/93) ,in which ,68 .18% (30/44) ,64 .10% (25/39) ,60 .00% (3/5) and 100% (5/5) were for stageⅠ ,Ⅱ ,Ⅲ and Ⅳ .Conclusion There are no significant different on clinicopathology features among T2a and T2b patients .MSCT can clearly determine the preoperative TNM staging of T2 gastric cancer .