[Quantitative CT analysis technique for determining the extent of silica-induced fibrosis in silicosis]

Objective: To investigate the feasibility of computed tomography (CT) quantitative analysis in assessing the degree of silicosis fibrosis induced by silicon dioxide (SiO(2)) . Methods: In March 2024, twenty specific pathogen-free (SPF) male C57BL/6J mice were randomly divided into a control group and a model group (n=10 per group). Each group was further subdivided into 28-day and 56-day subgroups (n=5 per subgroup). The model group received a single intratracheal instillation of 50 μl of sterile SiO? suspension at a concentration of 200 mg/ml via a non-surgical tracheal approach, while the control group received an equal volume of normal saline using the same method. At 28 and 56 days post-modeling, pulmonary function tests were performed, hydroxyproline (HYP) content in lung tissue was measured, and histopathological changes were evaluated by hematoxylin-eosin (HE) and Masson staining. Additionally, micro-CT scanning of lung tissue was conducted. Intergroup comparisons were performed using the t-test or a two-way analysis of variance (ANOVA) followed by post-hoc tests. Spearman rank correlation analysis was used to evaluate the correlation between CT quantitative parameters and Masson staining quantitative results. Results: At 56 days, compared with the control group, the model group showed significantly lower tidal volume (TVb) and significantly higher respiratory frequency (f), expiratory time (Te), and inspiratory time (Ti) (all P<0.001). HYP concentration in lung tissue was also significantly increased (P<0.05). At 28 days, HYP concentration in the model group was significantly higher than that in the control group (P<0.01). The volume percentages of non-normally ventilated lung regions in the control and model groups were 30.54% and 50.99% at 28 days, and 37.40% and 61.60% at 56 days, respectively; all differences were statistically significant (P<0.01). Spearman rank correlation analysis revealed a significant positive correlation between the volume fraction of non-normally ventilated lung regions and Masson staining collagen fiber content in the model group (r(s)=0.68, P=0.035), whereas no statistically significant correlation was observed in the control group (r(s)=0.54, P=0.114) . Conclusion: CT quantitative analysis demonstrates a favorable correlation with the pathological severity of silicosis fibrosis, suggesting that micro-CT may serve as a reliable non-invasive imaging tool for evaluating silicosis fibrosis.