1H-MR spectroscopy study on radiation-induced injury of the temporal lobes in the elderly patients with nasopharyngeal carcinoma / 中华放射学杂志

ABSTRACT

Objective To study the metabolic characteristics of neuronal injury in the temporal lobes during the radiotherapy in the elderly patients with nasopharyngeal carcinoma by 1H-MR spectroscopy.Methods Conventional MRI and 1H-MRS were performed in 21 elderly (age ≥60 years) and 33 young (age ≤ 45 years) patients who were historically confirmed with nasopharyngeal carcinoma and received radiotherapy for the first time.MR data were collected before and during the therapy at the radiation dosages of 20,40 and 60 Gy,respectively.Student t test was used to compare the NAA/Cr,Cho/Cr and NAA/Cho ratios of 1H-MRS in the temporal lobes between the two groups.Results The ratios of NAA/Cr,Cho/Cr before radiotherapy were 1.94 ± 0.15,1.86 + 0.20 in the elderly group,and 2.12 + 0.25,1.82 ± 0.24 in the young group respectively,but the difference was not statistically significant ( t =1.417,1.070,P ＞ 0.05 ).At the radiation with dosages of 20,40,and 60 Gy,the ratios of NAA/Cr were 1.81 ± 0.14,1.53 + 0.16,1.06 ±0.08 in the elderly group respectively,and were 2.03 ±0.16,1.92 ±0.21,1.77 ±0.18 in the young group respectively.There were statistical differences between two groups ( t =8.386,9.113,13.729,respectively,P＜0.05,＜0.05,＜0.01).The ratios of Cho/Cr were 1.82 +0.16,1.61 +0.29,1.37 +0.13 in the elderly group respectively,and were 1.77 + 0.19,1.48 + 0.17,1.06 + 0.14 in the young group respectively.There were statistical differences between the two groups at dosages of 40 and 60 Gy ( t =5.230,9.322 respectively,P ＜ 0.05 ).The ratios of NAA/Cho were 1.17 + 0.15,1.10 ± 0.08,0.83 ±0.05 in the elderly group respectively,and were 1.52 ±0.13,1.36 +0.15,1.10 +0.17 in the young group respectively.There were statistical differences between two groups ( t =5.862,2.560,9.754 respectively,P ＜0.05,＜0.05,＜0.01 ).At the dosages of 20,40 and 60 Gy,the decreases of NAA/Cr in the elderly group (6.70％,14.43％,24.23％ respectively) were more significantly higher than those in the young group(4.25％,5.19％,7.08％ respectively).The decrease of Cho/Cr in the elderly group (2.15％,11.29％,12.90％ respectively) were lower than those in the young group ( 3.30％,15.93％,17.58％ respectively).And the decrease of NAA/Cho in the elderly group (8.59％,5.47％,21.09％ respectively) were higher than those in the young group (2.56％,10.26％,16.67％ respectively).Conclusion Under the same radiotherapy pattern and radiation dosage,the injury to the neurons in the temporal lobes is significantly greater in the elderly patients than in young patients.Since the injury is smallest at the dose of 20 Gy among the doses evaluated,the intervention conducted in the elderly patients at this dose may help to minimize the injury to the neurons.