MRI Findings of Liver Parenchyma Peripheral to Colorectal Liver Metastasis: A Potential Predictor of Long-term Prognosis

Background: Gadoxetic acid (Gd-EOB-DTPA)-enhanced MRI is superior to CT in the detection of colorectal liver metastases (CRLMs) smaller than 10 mm. However, few studies have used MRI findings to predict patients' long-term prognosis. Purpose: To investigate the relationship between Gd-EOB-DTPA-enhanced MRI findings in the liver parenchyma peripheral to CRLM and both pathologic vessel invasion and long-term prognosis. Materials and Methods: This retrospective study included patients who underwent Gd-EOB-DTPA-enhanced MRI before curative surgery for CRLM, without neoadjuvant chemotherapy, between July 2008 and June 2015. Early enhancement, reduced Gd-EOB-DTPA uptake, and bile duct dilatation peripheral to the CRLM at MRI were evaluated by three abdominal radiologists. All tumor specimens were reevaluated for the presence or absence of portal vein, hepatic vein, and bile duct invasion. Predictors of recurrencefree survival (RFS) and overall survival (OS) after surgery were identified with Cox proportional hazard model with the Bayesian information criterion. Previously reported prognosticators were selected for multivariable analyses. The median follow-up period was 60 months (range, 9-127 months). Results: Overall, 106 patients (mean age, 65 years +/- 12 [standard deviation]; 68 men) with 148 CRLMs were evaluated. Bile duct dilatation peripheral to the tumor was associated with pathologic portal vein invasion (sensitivity, 12 of 50 [24%]; specificity, 89 of 98 [91%]; P = .02), bile duct invasion (sensitivity, eight of 19 [42%]; specificity, 116 of 129 [90%]; P = .001), poor RFS (P = .03; hazard ratio [HR] = 2.4 [95% confidence interval {CI}: 1.3, 4.2]), and poor OS (P = .01; HR = 2.4 [95% CI: 1.2, 4.9]). For RFS and OS, early enhancement and reduced Gd-EOB-DTPA uptake peripheral to the CRLM were eliminated by means of variable selection in the multivariable analysis, but the combination of these findings with bile duct dilatation provided a predictor of poor OS (P = .001; HR = 3.3 [95% CI: 1.6, 6.8]). Conclusion: MRI signal intensity changes peripheral to the colorectal liver metastasis were predictors of long-term prognosis after curative surgery without neoadjuvant chemotherapy. (C) RSNA, 2020