Value of introvoxel incoherent motion imaging on evaluating concurrent chemoradiotherapy response in patients with advanced uterine cervix cancer

Abstract

Objective To investigate the value of introvoxel incoherent motion (IVIM) using 3.0 T MRI to evaluate response to concurrent chemoradiotherapy (CCRT) in patients with advanced uterine cervix cancer. Methods From July 2015 to December 2016, 63 patients with advanced (≥ⅡB) cervical cancer diagnosed by clinical and imaging study, who had completed CCRT plan in Henan Cancer Hospital, were prospectively enrolled. Pelvic MRI protocol including T1WI, T2WI, IVIM and dynamic contrasted enhanced scans were performed in each patient before CCRT and 3 weeks after starting therapy (total dose of 30 Gy), and at the end of therapy (total dose of 90 Gy, 8 weeks after therapy). The mean values of ADC, true molecular diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) in each tumor at pre-therapy, in the middle of therapy and post-therapy were measured and recorded as ADC-pre, D-pre, D*-pre, f-pre;ADC-mid, D-mid, D*-mid, f-mid and ADC-post, D-post, D*-post, f-post, respectively;the change rates of these parameters during and after therapy (recorded as ΔADC-mid, ΔD-mid, ΔD*-mid, Δf-mid; ΔADC-post, ΔD-post, ΔD*-post, Δf-post) were also calculated. Patients were classified into response group and non-response group, according to response evaluation criteria in solid tumors after CCRT. MRI imaging study was performed in each patient within 1 month after CCRT to follow up, and tumor regression rate was calculated. The Mann-Whitney U test was used to compare differences of parameters and their change rates between response group and non-response group. Spearman correlation analysis was performed to assess relationships between parameters, parameter change rates and tumor regression rate. Logistic regression model was applied to find potential ADC values for predicting therapeutic response. ROC was used to analyze efficacy of ADC values for evaluating therapeutic response in advanced uterine cervix cancer after CCRT. Results The mean value of tumor maximum diameter before and after therapy was (47.5 ± 12.9) and (12.8 ± 10.0) mm, tumor regression rate was (66.7 ± 33.6)%. Forty-eight patients were in the response group and 15 in the non-response group. The mean value of ADC-pre, D-pre, D*-pre and f-pre was 0.74(0.43, 1.14)×10-3, 0.58(0.33, 0.91)×10-3, 12.12(2.30, 21.4)×10-3mm2/s, 9.65%(4.45%, 13.89%), respectively. Tumor regression rate had positive correlation with ADC-pre and D-pre (r=0.773, 0.840;P<0.05). Responders had increased ADC-pre, D-pre values than non-responders, which had statistically significant difference (P<0.05). Responders had increased ADC-mid, D-mid and f-mid values than non-responders, which had statistically significant difference (P<0.05), tumor regression rate had positive correlation with ADC-mid, D-mid and f-mid (r=0.808, 0.834, 0.563;P<0.05). Responders had increased ADC-post, D-post and f-post values than non-responders, which had statistically significant difference (P<0.05), tumor regression rate had positive correlation with ADC-post and D-post (r=0.799, 0.829;P<0.05).Tumor regression rate had positive correlation with ΔADC-mid, ΔD-mid, Δf-mid(r=0.526, 0.573, 0.454;P<0.05) and with ΔADC-post, ΔD-post, Δf-post (r=0.541, 0.555, 0.388;P<0.05). Responders had increased ΔADC-mid, ΔD-mid, Δf-mid and ΔADC-post, ΔD-post, Δf-post, which had statistically significant difference (P<0.05). Logistic regression analysis revealed only ADC-pre and D-post could be independent factors to predict therapeutic response in advanced uterine cervix cancer after CCRT, values of B, Wald, odds ratio and P was 22.488, 8.431, 1.429, 0.004 and 16.542, 8.517, 1.779, 0.004. ROC analysis showed the area under the curve (AUC) of ADC-pre, D-pre, ΔADC-mid, ΔD-mid, Δf-mid, ΔADC-post, ΔD-post and Δf-post for predicting therapeutic response in advanced uterine cervix cancer after CCRT were 0.890, 0.926, 0.942, 0.851, 0.803, 0.929, 0.951 and 0.906, respectively. Conclusion The IVIM parameters before and during CCRT process and their changes are valuable for predicting and evaluating therapeutic response in advanced uterine cervix cancer after CCRT, with high clinical practice value. Key words: Uterine cervical neoplasms; Magnetic resonance imaging; Introvoxel incoherent motion; Efficacy evaluation; Concurrent chemoradiotherapy