The microdamage of "morphologically normal white matter" in patients with nasopharyngeal carcinoma after radiotherapy and its correlation with the irradiation dose
Ren Wenting1, Sun Chao2, Wu Runye1, Cao Ying1, Liang Xin3, Xu Yingjie1, Ma Pan1, Han Fei1, Lu Ting4, Yi Junlin1, Dai Jianrong1
1Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing 100021,China; 2Department of Ultrasound,National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College (PUMC),Beijing 100021,China; 3Department of Statistics,National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College(PUMC),Beijing 100021,China; 4Department of Radiation Oncology,Qinghai Red Cross Hospital,Xining,810000,China
Objective To explore the correlation between microdamage in white matter and radiotherapy dose at early stage after radiotherapy (RT) in patients with nasopharyngeal carcinoma (NPC). Methods Thirty-three patients who were initially diagnosed with NPC were recruited and received diffusion tensor imaging (DTI) scan and neuro-cognitive scale test within 1 week before RT and the first day after RT. DTI-related characteristic parameters including fractional anisotropy (FA),mean diffusivity (MD),axial diffusivity (λ‖),and radial diffusivity (λ⊥) were calculated based on whole-brain voxel analysis method. Paired t-test was conducted to evaluate statistical significance between pre-RT and post-RT groups. In the subgroup analysis, all the subjects were divided into 3 groups according to the average dose of temporal lobe, and each group was set with an equal dose interval range. The DTI-related parameters of whole brain pre-RT and post-RT in each group were statistically compared. All the statistical results were corrected by FDR with a threshold of P<0.05 and clusters>100. Results FA, MD, λ‖ and λ⊥in the post-RT group significantly differed compared with those in the pre-RT group (P<0.05). The values of FA, MD, λ‖ and λ⊥were 0.455±0.016,(9.893±0.403)×10-4,(13.441±0.412)×10-4 and (8.231±0.429)×10-4, respectively. Subgroup analysis showed that the extent and degree of λ‖ and λ⊥ changes were exacerbated with the increase of the average dose of temporal lobe after RT. Particularly in high-dose group, the average dose range was 25-35Gy and the extent of regions with significant changes was significantly larger than those in the medium-dose (15-25Gy) and low-dose groups (5-15Gy)(P<0.05). Conclusions DTI can be utilized to detect"normal" brain tissue microdamage in NPC patients at early stage after RT. The average radiation dose of temporal lobe may be one of the reasons for the severity of cerebral microdamage. In the future, DTI technique may be useful for guiding exposure dose of organs at risk during RT planning and to evaluate the cohort with a high risk of cerebral microdamage at early stage after RT, thereby protecting normal cerebral tissues to the maximum extent.
Ren Wenting,Sun Chao,Wu Runye et al. The microdamage of "morphologically normal white matter" in patients with nasopharyngeal carcinoma after radiotherapy and its correlation with the irradiation dose[J]. Chinese Journal of Radiation Oncology, 2019, 28(11): 843-848.
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2019, Vol. 28 
