Background: Radiomics can yield minable information from medical images, which can facilitate computer-aided diagnosis. However, the lack of repeatability and reproducibility of radiomic features (RFs) may hinder their generalizability in clinical applications. Objectives: The aims of this study were to explore 3 main sources of variability in RFs, investigate their influencing magnitudes and patterns, and identify a subset of robust RFs for further studies. Materials and Methods: A chest phantom with nodules was scanned with different computed tomography (CT) scanners repeatedly with varying acquisition and reconstruction parameters (April-May 2019) to evaluate 3 sources of variability: test-retest, inter-CT, and intra-CT protocol variability. The robustness of the RFs was measured using the concordance correlation coefficient, dynamic range, and intraclass correlation coefficient (ICC). The influencing magnitudes and patterns were analyzed using the Friedman test and Spearman rank correlation coefficient. Stable and informative RFs were selected, and their redundancy was eliminated using hierarchical clustering. Clinical validation was also performed to verify the clinical effectiveness and potential enhancement of the generalizability of radiomics research. Results: A total of 1295 RFs that showed all 3 sources of variability were included. The reconstruction kernel and the iteration level showed the greatest (ICC, 0.35 ± 0.31) and the least (ICC, 0.63 ± 0.27) influence on magnitudes. The different sources of variability showed relatively consistent patterns of influence (false discovery rate <0.001). Finally, we obtained a subset of 19 stable, informative, and nonredundant RFs under all 3 sources of variability. These RFs exhibited clinical effectiveness and showed better prediction performance than unstable RFs in the validation dataset (P = 0.017, Delong test). Conclusions: The stability of RFs was affected to different degrees by test-retest and differences in CT manufacturers and models and CT acquisition and reconstruction parameters, but the influences of these factors showed relatively consistent patterns. We also obtained a subset of 19 stable, informative, and nonredundant RFs that should be preferably used to enhance the generalizability of further radiomics research.

AIM: To systematically evaluate the association between nailfold capillaroscopic findings and diabetic retinopathy (DR) and compare findings in diabetic patients with and without DR. METHODS: PubMed, Web of Science, and Embase databases were searched from inception to February 2024. The quality of the included studies was evaluated using a National Institutes of Health (NIH) Quality Assessment tool for Observational Cohort and Cross Sectional Studies. Meta-analysis was conducted to compare the findings of nailfold capillaroscopy between diabetic patients with or without DR. Subgroup analysis was employed to investigate the source of heterogeneity. RESULTS: Totally 12 studies with 1349 diabetic patients were included, of which 628 had DR. The overall quality of included studies was acceptable. Patients with DR had increased arteriolar diameters [mean difference (MD): 2.68, 95% confidence interval (CI): 0.64-4.72] and a higher risk of developing nailfold capillaroscopic abnormalities, including bushy capillaries [odds ratio (OR): 2.82, 95%CI: 1.65-4.80], neoformation (OR: 4.61, 95%CI: 3.15-6.76), megacapillaries (OR: 8.37, 95%CI: 5.07-13.80), tortuosity (OR: 7.29, 95%CI: 2.76-19.22), microhemorrhages (OR: 6.16, 95%CI: 2.48-15.26), meandering capillaries (OR: 4.68, 95%CI: 1.05-20.80) and avascular areas (OR: 7.92, 95%CI: 2.68-23.38). The presence of tortuous capillary was more common in DR in India than in Turkey, while avascular area in the nailfolds was linked to DR only in India (OR: 11.28, 95%CI: 3.91-32.60). Among the nailfold capillaroscopic abnormalities, tortuosity, microhemorrhage, and meandering capillary showed no significant correlation with the severity of DR, except for avascular area (P=0.04). CONCLUSION: There are significant associations between nailfold capillaroscopic findings and the presence of DR, supporting its potential as a non-invasive technique for monitoring microvascular changes in diabetic patients. However, further research is needed to validate its utility as an early screening tool for microvascular complications in diabetes.