Radiation-Induced Changes in Structural Network in Patients with Nasopharyngeal Carcinoma

Radiation therapy (RT) is the standard radical treatment for nasopharyngeal carcinoma (NPC), and has produced excellent effects in terms of survival rate [1, 2]. However, one of the serious complications gave rise by the RT is brain injury. Previous studies have found that RT could cause brain structural abnormalities on gray matter and white matter. Nevertheless, the RT effects on the network level should be further investigated. Herein, we explored changes on the structural network for patients with NPC induced by RT. The structural magnetic resonance data (sMRI) were used to investigate the structural network in 20 NPC patients after and before radiotherapy. After constructing the structural network, we examined the radiation-induced changes in topology properties of small world network using graph theoretical analysis. Our results found that both the before and after radiotherapy groups showed small world properties. Compared with the before radiotherapy (pre-RT) group, the after radiotherapy (post-RT) group had lower global and local efficiency, longer shortest path length, and less clustering coefficient. In addition, the hub regions in the post-RT group were significantly different from the pre-RT group. Our findings exhibited the architecture of network topology and information transfer efficiency became poor in post-RT group. We speculated radiation therapy might induce the differences. The results can provide a new perspective to explore and diagnose radiation-induced brain injury and evaluate the effect of radiotherapy.