磁共振弥散加权成像在食管癌放疗疗效评价中的应用价值探讨

Application of diffusion-weighted magnetic resonance imaging for evaluating the therapeutic effect of esophageal carcinoma

目的 探讨磁共振弥散加权成像（DWI）在食管癌放疗疗效评价中的应用价值.方法 74例食管鳞癌患者接受三维适形放疗或调强放疗,处方剂量56 ～ 61.2 Gy,单次1.8 ～2 Gy.放疗前、放疗末及放疗后1～3个月行DWI检查,用食管钡餐造影、DWI高信号消失情况、表面弥散系数（ADC）对放疗疗效进行评价,并与预后相结合进行生存分析.结果 中位随访时间22个月,随访率98.7％.放疗末DWI高信号消失组23例,1、2年生存率分别为82.6％、68.5％；放疗后1～3个月消失组40例,1、2年生存率分别为74.5％、49.2％；始终未消失组11例,1年生存率9.1％,生存期最长17个月（x2=39.78,P＜0.05）.造影评价完全缓解47例中,20例放疗末DWI高信号消失；23例放疗后1～3个月消失,其1、2年生存率分别为80％、64.3％和86.7％、66.1％；高信号始终未消失4例,生存期4～7个月（x2=37.80,P＜0.05）.造影评价为部分缓解的26例中,3例放疗末高信号消失；17例放疗后1～3个月高信号消失,1、2年生存率为58.8％、19.3％、高信号始终未消失6例,生存期4 ～17个月（x2=11.72,P＜0.05）.患者正常食管组织的ADC0、食管肿瘤放疗前的ADC1及放疗末的ADC2值分别为（3.12±0.53）、（1.64±0.48）、（2.65±0.58） s/mm2,疗末ADC2/ADC0≤90％组（40例）与＞90％组（34例）1、2年生存率分别为56.4％、28.2％和83.1％、75.7％（x2=10.35,P＜0.05）.放疗末肿瘤区域ADC值为独立预后影响因素（OR=0.060,P＜0.05）.结论 利用磁共振弥散加权成像检查对食管癌放疗疗效进行评价可以较好地提示预后,弥补食管钡餐造影在疗效评价中的不足,疗后肿瘤区域ADC值大小为独立预后影响因素.

Objective To investigate the application value of diffusion-weighted magnetic resonance imaging（DWI） in the evaluation of therapeutic effect of esophageal carcinoma treatment with 3-dimensional conformal radiotherapy（3D-CRT）or intensity-modulated radiation therapy （IMRT）.Methods Seventy-four patients with advanced esophageal carcinoma received 3D-CRT or IMRT with the median dose of 60 Gy （56-61.2 Gy） given at conventional fractions,and followed up for a median follow-up time of 22 months.DWI was conducted before,at the end of,and 1-3 months after the radiotherapy.Therapeutic effect was evaluated by esophagography,status of hyperintense expression in DWI,and value of apparent diffusion coefficient （ADC）.The prognosis analysis was performed associated with the above factors.Results Seventy-three patients were followed up with a follow-up rate of 98.7％.The hyperintense disappeared immediately after radiation in 23 of the 74 patients,disappeared 1-3 months after radiation in 40 patients,and never disappeared in 11 patients.The 1-,and 2-year survival rates of the immediate disappearance group were 82.6％ and 68.5％ respectively,and the 1-,and 2-year survival rates of the second and the third groups were 74.5％,42.9％ and 9.1％.There was significant difference among the three groups （x2 =39.78,P ＜ 0.05）.Of the 47 patients who achieved complete remission according to esophagogram,hyperintense disappeared immediately after radiation in 20 patients,disappeared 1-3 months after radiation in 23 patients,and never disappeared in 4 patients.The 1-,and 2-year survival rates of the immediate disappearance group were 80％ and 64.3％ respectively,those of the disappearance 1-3 months later group were 86.7％,66.1％ respectively,and the survival time of the non-disappearance group ranged from 4 to 7 months （x2 =37.80,P ＜ 0.05）.Of the 26 patients who achieved partial remission according to esophagogram,hyperintense disappeared immediately after radiotherapy in 3 patients who survived without tumor till the end of follow-up,disappeared 1-3 months after radiotherapy in 17 patients with the 1-,and 2-year survival rates of 58.8％ and 19.3％ respectively,and never disappeared in 6 patients who all died with the survival times of 4 to 17 months respectively （x2 =11.72,P ＜ 0.05）.The ADC values of the normal esophageal tissue （ADC0）,esophageal tumor before radiotherapy （ADC1）,and tumor tissue after radiotherapy（ADC2） were （3.12 ± 0.53）,（1.64 ±0.48）,and（2.65 ± 0.58）,respectively.The 1-,and 2-year survival rates of the patients with the ADC2/ADC0 ≤90％ （n =40） were 56.4％ and 28.2％ respectively,significantly lower than those with ADC2/ADC0 ＞90％ （n =34） （83.1％ and 75.7％ respectively,x2 =10.35,both P ＜ 0.05）.Multivariate analysis of Cox regression showed that the ADC value of the tumor region after radiotherapy increased with the improvement of the prognosis for the normal esophageal tissue.Conclusions Examination of DWI can be used to evaluate the therapeutic effect of esophageal carcinoma treatment with 3D-CRT or IMRT accurately and make up the deficiency of esophagography.The ADC value of tumor region after radiotherapy can be an independent prognosis factor.