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

Abstract

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. Key words: Esophageal neoplasms; Radiotherapy; Diffusion-weighted magnetic resonance imaging; Apparent diffusion coefficient; Therapeutic effect