MRI-based radiomics predicts the pathologic response of colorectal liver metastases to systemic therapy: A multicenter study

Background: Tumor response to preoperative chemotherapy is a key prognostic factor for colorectal liver metastases (CRLM), but an accurate non-invasive assessment remains an unmet need. Objective: To assess the contribution of radiomic analysis of preoperative, post-chemotherapy, gadoxetic acid (Gd-EOB-DTPA)-enhanced MRI to the non-invasive prediction of the pathologic response to systemic therapy of CRLM. Methods: This retrospective bi-institutional study included all consecutive patients undergoing resection for CRLM (2018-2021) after preoperative oxaliplatin/irinotecan-based chemotherapy. We selected patients with stable disease or partial response at the last restaging, and with post-chemotherapy MRI performed <= 60 days before surgery. The largest CRLM (>= 10 mm) was analyzed. Pathologic response was evaluated according to the TRG. The tumor (Tumor-VOI) was manually segmented on the portal venous phase (PVP) and hepatobiliary phase (HBP) sequences; a 5-mm ring of peritumoral tissue was automatically generated (Margin-VOI) and manually corrected. The predictive models underwent internal validation. Results: Overall, 162 patients (median age 62.5 years, 102 men) were evaluated. Of the 131 patients with a radiologic partial response, 59 (45 %) had no tumor regression at pathology (TRG4-5). The model including both clinical variables and radiomic features extracted from the Tumor-VOI/Margin-VOI of PVP and HBP achieved the best performances: at validation, Accuracy = 0.773, Sensitivity = 0.724, Specificity = 0.812, and ROC-AUC = 0.860. The combined clinical-radiomic model outperformed the pure clinical one (p < 0.001). The features extracted from the Tumor-VOI in PVP and Margin-VOI in HBP had the highest impact. Conclusion: The addition of radiomic features extracted from the PVP and HBP of post-chemotherapy Gd-EOB-DTPA-enhanced MRI enhanced standard radiologic and clinical assessment of CRLM response to chemotherapy, providing a reliable non-invasive assessment of TRG.