A clinical study of diffusion-weighted magnetic resonance imaging-based prediction of efficacy of chemoradiotherapy for esophageal carcinoma

Abstract

Objective To investigate the parameters of diffusion-weighted magnetic resonance imaging (DWMRI) for prediction of the efficacy of chemoradiotherapy (CRT) for esophageal squamous cell carcinoma (ESCC), to determine the optimal time point and threshold for prediction, and to provide a basis for clinical practice. Methods From 2010 to 2011, 38 patients with ESCC were consecutively enrolled as subjects. All patients received three-dimensional conformal radiotherapy with 60 Gy in 30 fractions for 6 weeks. They also received concurrent or consolidation chemotherapy (FP or TP scheme) as adjuvant treatment. Patients received DWMRI scans before radiotherapy and at weeks 1-6 during radiotherapy. The apparent diffusion coefficient (ADC) values and tumor lengths obtained from serial DWMRI scans were recorded and analyzed. Comparison was made by paired t test. Repeated measurements were analyzed by analysis of variance (ANOVA) and multivariate ANOVA. The prognosis was predicted by the Logistic model. The effectiveness analysis and threshold screening were performed using the receiver operating characteristic (ROC) curve. Results In all patients, 20(52.6%) had complete response (CR) and 18(47.4%) had partial response (PR). There were no significant differences in the ADC values before radiotherapy and at weeks 1-6 during radiotherapy between patients with CR and PR (1.82 vs. 1.42; 1.92 vs. 1.49; 2.06 vs. 1.67; 2.35 vs. 1.79; 2.62 vs. 2.11; 2.71 vs. 2.18; 2.96 vs. 2.28×10-3 mm2/s; P=0.006, 0.003, 0.012, 0.001, 0.003, 0.008, 0.002). The ADC value at third week during radiotherapy was the only independent prognostic factor for short-term treatment outcomes in patients with ESCC (OR=0.134, P=0.007). These results were also supported by the multivariate ANOVA analyses. The analysis of the ROC curve showed that at the third week during radiotherapy, the area under the ADC curve was the largest (Az=0.857) and the diagnostic effectiveness was the best; the threshold value, sensitivity, and specificity were 2.02×10-3 mm2/s, 80.0%, and 92.9%, respectively. Eight patients who had tumor out of control or recurrence within 1 year after treatment had the ADC curve fall down at the end of the fifth week and the reduction of tumor length substantially slow down from the fifth week. Conclusions DWMRI is an effective imaging approach for monitoring tumor response to CRT in patients with ESCC. The ADC value at the end of the third week during radiotherapy may be the optimal time point for prediction of treatment outcomes. The reduction in the ADC value or non-reduction in tumor length at the end of the treatment indicates a high risk of recurrence. Key words: Diffusion-weighted magnetic resonance imaging; Apparent diffusion coefficient; Predic therapeutic effect; Esophageal neoplasms/radiotherapy