Objective To investigate the value of MRI of the sternal end of clavicle in bone age assessment in Chinese population,especially its applicability in the determination of criminal responsible age.Methods A total of 431 patients aged from 10.00 to 29.99 years with neck or chest MRI were retrospectively collected.According to the Schmeling grading method,the epiphyseal development of the clavicle MRI was divided into five grades.The consistency of methods was evaluated.The correlation and general descriptive analysis between MRI grades and age was analyzed.The sex difference was analyzed.Curve fitting was used to establish a nonlinear model between age and grades.Results The grades of clavicle MRI showed a significant age-related trend(Figure 2),and the correlation was 0.861(0.887 in males and 0.840 in females).Except for grade 1,there was no significant difference between males and females in other grades.The minimum age of male grade 3 was greater than 14 years old,and the minimum age of female grade 3 was greater than 16 years old.The minimum age in grade 4 and grade 5 was over 18 years old in both sexes.The best curve fitting model was cubic model for both sexes(R2=0.805 for men and 0.722 for women).Conclusion Clavicle MRI can be used for the assessment of bone age in Chinese population.Complete epiphyseal plate closure can be used as a reliable indicator for the determination of age at 18 years old,and it is expected to achieve radiation-free forensic bone age assessment.

Objective To investigate the value of MRI of the sternal end of clavicle in bone age assessment in Chinese population,especially its applicability in the determination of criminal responsible age.Methods A total of 431 patients aged from 10.00 to 29.99 years with neck or chest MRI were retrospectively collected.According to the Schmeling grading method,the epiphyseal development of the clavicle MRI was divided into five grades.The consistency of methods was evaluated.The correlation and general descriptive analysis between MRI grades and age was analyzed.The sex difference was analyzed.Curve fitting was used to establish a nonlinear model between age and grades.Results The grades of clavicle MRI showed a significant age-related trend(Figure 2),and the correlation was 0.861(0.887 in males and 0.840 in females).Except for grade 1,there was no significant difference between males and females in other grades.The minimum age of male grade 3 was greater than 14 years old,and the minimum age of female grade 3 was greater than 16 years old.The minimum age in grade 4 and grade 5 was over 18 years old in both sexes.The best curve fitting model was cubic model for both sexes(R2=0.805 for men and 0.722 for women).Conclusion Clavicle MRI can be used for the assessment of bone age in Chinese population.Complete epiphyseal plate closure can be used as a reliable indicator for the determination of age at 18 years old,and it is expected to achieve radiation-free forensic bone age assessment.

Objective To study the iodine nutritional status in the key population in Tianjin before and after the implementation of the new standards of iodized salt content, and to provide a scientific basis for iodine supplementation. Methods According to the method of population proportion sampling, the family edible salt samples, the urinary iodine and goiter of children aged 8-10 years and the urinary iodine level of pregnant women were investigated before the adjustment of salt iodine content (2005, 2011) and after the adjustment (2014, 2017). The results were compared and analyzed. Results The median of salt iodine after the adjustment (26.05mg/kg) was significantly lower than that of before (30.20mg/kg, Z=12.867, P<0.001). After adjustment, the coverage of iodized salt, the qualified rate of iodized salt, and the qualified iodized salt consumption rate were 78.68%, 81.01%, and 63.74%, respectively, and there were statistically significant differences from before adjustment (92.44%, 96.78%, 89.47%, respectively) (χ²=221.916, 309.405, 540.148, respectively, P <0.001). The median urinary iodine in children aged 8 to 10 years decreased from 210.10μg/L to 172.08μg/L, and the difference was statistically significant before and after adjustment (Z=3.351, P<0.001). The thyroid goiter rate of children decreased from 2.21% to 2.05%, and the difference was not statistically significant between the groups (χ²=0.196, P=0.658). After stratified analysis based on salt iodine content, it was found that among children who took iodized salt and qualified iodized salt, the median urine iodine after adjustment was lower than that before adjustment, and the difference was statistically significant (Z=2.726, 2.742, all P<0.001), but the proportion of urine iodine at an appropriate level was higher than before adjustment. The median urine iodine of pregnant women increased from 145.20μg/L to 147.17μg/L, and there was no significant difference before and after adjustment (Z=1.121, P=0.162). The proportion of pregnant women with median urinary iodine from 150 to 250μg/L was significantly higher in post-adjustment (31.02%) than that of pre-adjustment (24.53%, χ²=4.769, P=0.029). Conclusion After adjusting the salt iodine content in Tianjin, children's iodine nutrition was optimized from a higher level to an appropriate level, and thyroid goiter rate of children remained at low level. The iodine nutrition of pregnant women was slightly lower than adequate level, but the proportion of pregnant women at the adequate level increased. The new standard of iodine salt was appropriate, but the proportion of children with urine iodine <100μg/L increased, which needs to be monitored. At the same time, the iodized salt coverage rate and the qualified iodized salt consumption rate did not reach the elimination standard of iodine deficiency diseases, and the supervision of the salt industry market should be strengthened.