Objective:To explore the value of synthetic MRI in quantitative monitoring of knee joint structural and cartilage changes of amateur marathon runners before and after the whole marathon.Methods:Totally 26 amateur marathon enthusiasts from Zhuhai City, Guangdong Province were recruited from October 2019 to January 2020. The right knee joints were scanned 1 week before the race and within 48 h after the race. The scanning sequence included the three-dimensional proton density weighted image with isotropic (3D-CUBE-PD) sequence and synthetic MRI sequence. The conventional contrast weighted images T 1WI, T 2WI, proton density (PD) weighted imaging, short-T 1 inversion recovery (STIR) and T 1, T 2, PD mapping were obtained by the latter scans. The 3D-CUBE-PD sequence was used as a reference to evaluate the detection of knee joint lesions. The knee articular cartilage was divided into 8 subregions: central medial femoral condyle (CMFC), posterior medial femoral condyle (PMFC), central lateral femoral condyle (CLFC), posterior lateral femoral condyle (PLFC), medial tibia plateau (MTP), lateral tibia plateau (LTP), patella and trochlear. Based on the synthetic MRI quantitative mapping, the T 1, T 2 and PD values of each cartilage subregion were measured independently by 2 radiologists. The ICC was used to evaluate the consistency of the measurement between observers. The T 1, T 2 and PD values of knee cartilage before and after marathon exercise were compared by Wilcoxon signed rank test. Results:The 2 radiologists had good consistency in the measurement of T 1, T 2 and PD values of knee articular cartilage with the ICC values of 0.912, 0.933 and 0.954, respectively. The synthetic MRI quantitative mapping sequence can detect all cartilage damage ( n=3) and joint effusion ( n=15), and 7 of 9 meniscus injuries were detected. The T 1, T 2 and PD values of the knee cartilage as a whole before the race were higher than those after race, and the differences were statistically significant (all P<0.05). The T 1 values were statistically significant except patellar cartilage and trochlear cartilage, and T 2 values were significantly different in the CMFC, LTP, MTP ( P<0.05). Conclusion:Synthetic MRI has a good display of knee joint structural lesions, and its quantitative parameters T 1, T 2 and PD can detect the changes of knee cartilage before and after marathon.

Objective To construct nomograms using data extracted from the surveillance,epidemiology,and end results(SEER)program database to predict overall survival(OS)and cancer-specific survival(CSS)for patients with choroidal melanoma(CM),and to evaluate the epidemiological characteristics,survival periods,and prognos-tic factors of CM patients.Methods Data on patients diagnosed with CM from 2010 to 2020 were extracted from the SEER database.The included patients were randomly divided into a training set(n=1,841)and a validation set(n=789)at a 7:3 ratio.Univariate Cox regression analysis was conducted in the training set,followed by in-corporation into a multivariate Cox proportional hazards regression model.Independent influencing factors were screened in the multivariate Cox regression model to construct nomograms predicting 3-year and 5-year OS and CSS for CM.Decision curve analysis(DCA)was used to assess the clinical utility of the prediction models by quantif-ying the net benefit of the nomograms in decision-making support,and comparisons were made with the SEER stage model.Individual risk scores were obtained based on the established nomograms.Results A total of 2,630 pa-tients were included in the study.The results indicated that gender,age,liver metastasis,surgery,radiotherapy,and chemotherapy were independent risk factors affecting OS in CM patients.Age,liver metastasis,surgery,and chemotherapy were independent risk factors affecting CSS in CM patients.The nomograms for 3-year and 5-year OS and CSS showed strong discriminative ability.Furthermore,in the validation set for OS and CSS,DCA indicated that the nomograms had good clinical potential.Kaplan-Meier(K-M)curves demonstrated that in both the training and validation sets,patients in the high-risk group had significantly lower OS and CSS rates compared to those in the low-risk group.Conclusion Age,liver metastasis,surgery,and chemotherapy are common predictors of OS and CSS in CM patients.A relatively comprehensive and accurate prognostic nomogram model based on the SEER database has been established.After calibration and further refinement,this nomogram model can be applied clini-cally to guide the treatment and prognosis of patients.

C57/B6J mice were fixed in traditional fixative(4％formaldehyde solution,the same below)and novel fixative respectively,and the routine procedure of paraffin section preparation was performed,as well as the novel fixative was validated in HE-stained paraffin sections of the eyes of mice and human embryos in the age-related macular degeneration(AMD)model.Compared with the traditional fixative,the quality of the paraffin sections treated with the novel fixative was better than that of the traditional fixative,and successfully simulated the changes of the retinal layers of AMD mice at different time periods.The novel fixative is feasible for the preparation of high-quality retinal paraffin sections,which lays the foundation for subsequent studies on retinal paraffin sections.