Prediction of Therapeutic Effect to Treatment in Patients with Colorectal Liver Metastases Using Functional Magnetic Resonance Imaging and RECIST Criteria: A Pilot Study in Comparison between Bevacizumab-Containing Chemotherapy and Standard Chemotherapy

Background Response Evaluation Criteria in Solid Tumors (RECIST) criteria are widely used for evaluating the therapeutic effect of colorectal liver metastases (CRLM) patients, but showed undesirable accuracy. Objective This study aimed to evaluate the value of functional MRI compared with RECIST criteria in predicting the therapeutic effect in CRLM patients receiving neoadjuvant chemotherapy with and without bevacizumab. Methods Overall, 137 patients with CRLM who received neoadjuvant chemotherapy followed by hepatic resection between January 2013 and November 2018 were included and were divided into the bevacizumab and non-bevacizumab groups. Apparent diffusion coefficient (ADC) values of pre- and post-treatment diffusion-weighted imaging (DWI) were generated on the whole-volume (ADC mean ), periphery (ADC peri ), and isocenter (ADC central ) of the tumor at the maximum slice. Overall survival (OS) and relapse-free survival (RFS) were used as prognostic indicators. Results Post-treatment ADC mean was significantly associated with OS ( p = 0.001) and RFS ( p = 0.008) in the bevacizumab group, while RECIST-defined response was found to be only significantly associated with RFS in the non-bevacizumab group ( p = 0.042). When categorizing the bevacizumab group by the post-treatment ADC mean cut-off value of 1.15 ×10 -3 mm 2 /s, patients in the ADC response group showed significantly better OS than the non-response group (3-year OS: 91.5% vs. 64.5%, p = 0.001). However, no significant difference was found between RECIST-defined response and non-response in either OS (3-year OS: 60.2% vs. 44.0%, p = 0.104) or RFS (3-year RFS: 26.2% vs. 17.4%, p = 0.129) in the bevacizumab group. Conclusions DWI-related parameters such as post-treatment ADC mean could accurately reflect the therapeutic effectiveness and predicting survival in patients treated with bevacizumab, which is superior to the RECIST criteria.