The Value Of Diffusion-Weighted 3.0 T MR Imaging For Detecting The Early Response To Chemo-radiotherapy In Esophageal Squamous Cell Carcinoma

Objective: The purpose of this study was to investigate the utility of Diffusion Weighted Imaging(DWI) derived apparent diffusion coefficient(ADC) value for early detection of treatment response in patient with advanced esophageal carcinoma treated with chemo-radiotherapy(CRT).Materials and Methods: DWI was performed in 31 patients with pathologically confirmed esophageal squamous cell carcinoma. DWI was performed with b value set at 800s/mm2 in patients undergoing chemo-radiotherapy before as well as, after 11 and 32 times of radiotherapy. CRT response was assessed at the end of total 32 times of radiotherapy using response evaluation criteria in solid tumors(RECIST) measuring tumor maximum diameter(Φ). Complete response(CR) and partial response(PR) patient were defined as responder group while stable disease(SD) and progressive disease(PD) classified as non-responder group. ADC value before treatment(ADC0), after receiving 11 and 32 times of radiotherapy(ADC11 and ADC32 respectively) as well as change of ADC value before and after treatment(△ADC) were compared between responders and non-responder group.Results : According to treatment response criteria, 21 cases(68%) were defined as responders while remaining 10 cases(32%) as non-responder group. Average tumor diameter on axial T2 WI was(31.1±4.23) mm where maximum tumor diameter in response group was(30.03±3.21) mm and that of non-responders was 32.03±4.21 mm; no significant differences was observed between the two group(p>0.05). Before the treatment the ADC value of responder and non-responder group were not found significant(1.431±0.046)×10-3 mm2/s,(1.461±0.015)×10-3mm2/s, p >0.05). After 11 doses of radiotherapy, ADC values were found to be significantly higher in responders compared to non-responders(1.874±0.313)×10-3mm2/s 、(1.5±0.324)×10-3mm2/s, p <0.05). The increased rate of ADC after 11 times of radiotherapy(△ADC11) was also significantly high in responders as compared to non-responders(31.54±15.573)% and(1.919±1.443)% respectively,p <0.05. While the increased rate of the ADC after 32 times of radiotherapy(△ADC32) was also significantly higher in responders compared to non-responders(34.91±15.305)%,(18.86±9.774)% respectively,(p >0.05). Increased rate of ADC after 11 times of radiotherapy(△ADC11) was the best indicator for predicting early response. An ADC cut-off value for △ADC11 of 11.593% predicted the responders with a sensitivity and specificity of 83.3% and 76.9%, respectively. The area under the ROC curve was 0.838. Influence of clinical factors(gender, age, T stage, △ADC11 and △ADC32) on sensitivity of esophageal cancer chemo-radiotherapy were assessed using logistic regression analysis. The analysis showed △ADC11 to be an independent prognostic factor and its relative risk was found to be 1.108, p <0.05.Conclusion: DWI plays an important role in the evaluation of esophageal chemo-radiotherapy treatment response. While ADC values(ADC0) before treatment were not found to be effective to predict the prognosis of patients with early esophageal carcinoma, ADC11 predicted the early chemo-radiotherapy treatment response in esophageal cancer with higher sensitivity which can be used as an independent prognostic factor.