Objective: To investigate whether bone age (BA) of children living in Tibet Highland could be accurately assessed using a fully automated artificial intelligence (AI) system. Methods：: Left hand radiographs of 385 children (300 Tibetan and 85 immigrant Han) aged 4–18 years who presented to the largest medical center of Tibet between September 2013 and November 2019 were consecutively collected. From these radiographs, BA was determined using the Greulich and Pyle (GP) method by experts in a consensus manner; furthermore, BA was estimated by a previously reported artificial intelligence (AI) BA system based on Han children from southern China. The performance of the AI system was compared with that of experts by using statistical analysis. Results: Compared with the experts’ results, the accuracy of the AI system for Tibetan and Han children within 1 year was 84.67 and 89.41%, respectively, and its mean absolute difference (MAD) was 0.65 and 0.56 years, respectively. The discrepancy in hand-wrist bone maturation was the main cause of low accuracy of the system in the 4- to 6-year-old group. Conclusion: The AI BA system developed for Han Chinese children living in flat regions could enable to assess BA accurately in Tibet where medical resources are limited. Advances in knowledge: AI-based BA system may serve as an effective and efficient solution to assess BA in Tibet.

Objective: To compare the clinical characteristics, treatment timelines, and short-term outcomes of patients with acute ischemic stroke (AIS) who developed stroke at extremely high altitude or in lowland areas and received intravenous thrombolysis, and to investigate factors associated with failure to achieve the recommended door-to-needle time (DNT). Methods: This two-center retrospective cohort study included consecutive patients with AIS treated with intravenous alteplase between January 2019 and February 2026 at Xizang Autonomous Region People’s Hospital and West China Hospital, Sichuan University. Demographic and clinical data, laboratory findings, onset-to-door time, DNT, onset-to-needle time, and in-hospital outcomes were collected. Binary logistic regression was used to identify factors associated with DNT > 60 min. Results: Among 348 patients, 170 were in the high-altitude group and 178 in the lowland group. High-altitude patients were younger, had higher rates of smoking and alcohol consumption, lower oxygen saturation, and higher red blood cell counts and hemoglobin levels (all p < 0.001). DNT was significantly longer at high altitude (p < 0.001). No significant differences were found in discharge NIHSS scores, early neurological improvement, favorable functional outcome, hemorrhagic transformation, or in-hospital mortality (all p > 0.05), although the study was underpowered to detect clinically meaningful differences in hemorrhagic transformation and in-hospital mortality. High-altitude setting remained independently associated with DNT > 60 min after adjustment (aOR, 5.381; 95% CI, 3.068–9.438; p < 0.001), reflecting a composite of altitude-related and center-specific factors. Conclusions: This study provides real-world clinical evidence on intravenous alteplase thrombolysis for patients with AIS at high altitude and helps address the limited efficacy and safety data available for high-altitude populations in previous thrombolysis studies. The comparable short-term neurological outcomes suggest that thrombolysis is feasible in this setting, although the limited statistical power for secondary safety outcomes warrants confirmation in larger studies. The longer DNT observed at the high-altitude center likely reflects both altitude-related and center-specific operational factors, and further research is needed to clarify their relative contributions. These findings may provide a clinical basis for assessing the applicability of reperfusion strategies in the unique high-altitude environment.