鼻咽癌放疗后放射性脑损伤的MRI扩散加权成像研究

MR diffusion-weighted imaging of temporal lobe injury following radiotherapy for nasopharyngeal carcinoma

目的探讨鼻咽癌放疗后颞叶放射性损伤的MRI扩散加权成像的改变。方法选取60例志愿者作为正常对照组、30例鼻咽癌放疗后正常表现患者作为放疗后无损伤组和30例鼻咽癌放疗后出现颞叶损伤患者作为颞叶损伤组。进行常规MRIT1WI、T2WI成像和弥散加权成像(DWI),分别测量颞叶的表观扩散系数(ADC)值,然后进行比较。结果正常对照组、鼻咽癌放疗后无损伤组和放射性颞叶损伤组的平均ADC值(ADCav)分别为(0·82±0·08)×10-3、(0·76±0·12)×10-3和(2·08±0·33)×10-3mm2/s。放疗后无损伤组的ADCav值小于正常对照组,差异有统计学意义(P<0·05);颞叶放射性损伤组的ADCav值分别大于正常对照组和放疗后无损伤组,差异有显著统计学意义(P<0·01)。结论鼻咽癌放疗后,尽管MRIT1WI、T2WI显示颞叶正常,但ADCav值减小,反映受照区域水分子的弥散能力降低,可能与细胞毒性水肿有关。当出现放射性脑损伤后,ADCav值明显升高,反映损伤组织水分子的弥散能力增加。DWI为放射性脑病的早期发现和提前干预性治疗提供了可能。

Objective To evaluate the changes of diffusion in temporal lobe injury following radiotherapy for nasopharyngeal carcinoma. Methods Selected 60 healthy volunteers as contrast group, 30 cases of post-radiotherapy with nasopharyngeal carcinoma （NPC） but no temporal lobe injury as no injury group and 30 cases of temporal lobe injury following radiotherapy for nasopharyngeal carcinoma as injury group. All of them were examined with routine MRI and diffusion weighted imaging （ DWI ） and measured the ADC values of temporal lobe. Their average of ADC value （ ADCav ） between groups were compared. Results The ADCav values of contrast group,no injury group and injury group were （0. 82 ±0.08 ） × 10^-3, （0.76 ±0.12） × 10^-3, （2.08 ±0.33）× 10^-3 mm^2/s respectively. The ADCav value in no injury group decrease than in contrast group and has statistical significance between them（ P 〈 0.05 ）. The ADCav value in injury group increase than in no injury group and contrast group respectively and have statistical significance between of both them （ P 〈 0. 0001 ）. Conclusions Post-radiotherapy of nasopbaryngeal carcinoma, the ADCav value of temporal lobe decreased and reflecting the water molecule diffusion reduction. It is may related to cellular toxicity edema. After radiation injury appear, the ADCav values increased. It reflected the water molecule diffusion reinforcement. Diffusion weighted imaging can sensitively display radiation injury of temporal lobe, but can quantitively analysis damage degree by the means of measurement ADC values. It is provide a opportunity that radiation injuries are detected in earlier period and management in time.