ASO Visual Abstract: Prediction of Therapeutic Effect of Treatment on Patients with Colorectal Liver Metastases Using Functional Magnetic Resonance Imaging and RECIST Criteria: A Pilot Study Comparing Bevacizumab-Containing Chemotherapy and Standard Chemotherapy

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. 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. 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 (ADCmean), periphery (ADCperi), and isocenter (ADCcentral) of the tumor at the maximum slice. Overall survival (OS) and relapse-free survival (RFS) were used as prognostic indicators. Post-treatment ADCmean 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 ADCmean cut-off value of 1.15 ×10-3 mm2/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. DWI-related parameters such as post-treatment ADCmean could accurately reflect the therapeutic effectiveness and predicting survival in patients treated with bevacizumab, which is superior to the RECIST criteria.