Abstract: To explore the latent profiles of physical activity among junior and senior high school students and the association with short-video addiction, so as to provide evidence for the prevention of short-video addiction among adolescents. Methods: In November 2024, a stratified random sampling method was used to select 20 840 students from 120 junior and senior high schools in Guangdong Province. Physical activity and short-video addiction were assessed using International Physical Activity Questionnaire and Short-video Addiction Scale. Latent profile analysis was used to identify latent classes of physical activity. The robust three-step approach was used to examine the effects of demographic variables, including sex, school stage, age, and residence, on profile membership, and the Bolck-Croon-Hagenaars (BCH) method was used to compare short-video addiction levels across profiles after adjusting for demographic variables. Results: Four latent profiles of physical activity in junior and senior high school students were identified:low-frequency low-duration profile ( n =1 668, 8.00%), weekday high-frequency activity profile ( n = 12 408 , 59.54%), weekday low-frequency activity profile ( n =5 107, 24.51%), and high frequency high-duration profile ( n = 1 657 , 7.95%). With the high-frequency high-duration profile as the reference, girls were more likely to be assigned to the weekday high-frequency activity profile and less likely to be in the low-frequency low-duration profile compared with boys ( B =0.27, -0.33 ); senior high school students had higher odds of membership in the other three profiles than junior high school students ( B =0.63- 1.09 ); increasing age was associated with increased odds of the low-frequency low-duration profile ( B =0.11); rural students were less likely to belong to the other three profiles than urban students ( B =-0.97 to -0.79) (all P <0.01). After adjusting for demographic variables, short-video addiction scores differed significantly across physical activity profiles in junior and senior high school students ( χ 2=390.23, P <0.01), with scores decreasing in the following order:low-frequency low-duration profile, weekday low-frequency activity profile, weekday high-frequency activity profile, and high-frequency high-duration profile. Conclusions Short-video addiction levels vary across different physical activity patterns in junior and senior high school students. Overall, participants with high-frequency and high-duration participation score the lowest, whereas those with low-frequency and low-duration participation score the highest.

The incidence of rectal cancer gradually increased in our country in recent years.Preoperative imaging methods are used to accurately display the lesions of rectal cancer,providing accurate quantitative diagnostic information,therefore being important to formulate reasonable and individualized therapy clinically.Intra-voxel incoherent motion (IVIM) is a multi parameter imaging technology.IVIM can provide the diffusion and perfusion information from the molecular level.Theoretically,the microstructure information of internal rectal cancer cell density and the vascular density,and the tumor cell metabolism can be displayed quantitatively with IVIM imaging,which can reflect the heterogeneity of the tumor and its degree during different periods.The application status and the future development of IVIM technique in management of rectal cancer were reviewed in this article.

Objective To explore the diagnostic value of intravoxel incoherent motion diffusion-weighted imaging(IVIM-DWI)in diagnosis of different pathological types of lung cancer.Methods 45 patients were performed traditional MR and multi-b value DWI scan by GE discovery 750 MR.The values of Slow-ADC,Fast-ADC and ffast measured on a AW4.5 workstation were analyzed between the different pathological types of lung cancers.The correlations between these IVIM-DWI parameters and the serum tumor markers of lung cancer were analyzed.The diagnostic efficiency of these parameters were evaluated by receiver operator characteristic curve (ROC).Results 27 cases NSCLC(13 cases squamous carcinoma;14 cases adenocarcinoma )and 18 cases SCLC were finally included in this study.There were significant differences in Slow-ADC values between SCLC group and NSCLC group (P =0.00),the adenocarcinoma group (P=0.03),the squamous carcinoma group(P=0.01).There were no significant difference in Fast-ADC as well as ffast value between any two groups.The AUC of Slow-ADC value was 0.874.There existed negative correlation between squamous cell carcinoma antigen(SCC-Ag)of squamous carcinoma group and Slow-ADC(r=-0.730).Conclusion The Slow-ADC of IVIM-DWI parameters is useful in differential diagnosis of NSCLC and SCLC,which has the largest diagnostic efficiency.The correlation between SCC-Ag and Slow-ADC value has a certain meaning in diagnosing different pathological types of lung cancers.