Hepatobiliary phase enhancement of liver metastases on gadoxetic acid MRI: assessment of frequency and patterns

Objectives To assess for and characterize patterns of hepatobiliary phase (HBP) enhancement in hepatic metastases of various malignancies on gadoxetic acid-enhanced MRI. Methods Eighty gadoxetic acid-enhanced MRI studies performed between July 2012 and November 2019 in patients with hepatic metastases from 13 different primary malignancies were assessed. Most (n = 60) were from colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), or neuroendocrine tumor (NET) primaries. Two radiologists quantitatively evaluated the dominant lesion on each MRI. A lesion was considered enhancing when HBP enhancement relative to muscle exceeded 20%. Lesions were classified by pattern of enhancement. Quantitative enhancement metrics and patterns of enhancement were compared between CRC, PDAC, and NET using non-parametric statistical tests. Results Most dominant metastatic lesions > 1 cm (77%, 54/70) demonstrated HBP enhancement. HBP enhancement was identified in hepatic metastases from 10 different primary malignancies, including CRC, PDAC, and NET. PDAC metastases demonstrated a lower degree of HBP enhancement (26%) than CRC (44%,p(adj) = 0.04) and NET (51%,p(adj) = 0.01) metastases. Three discrete enhancement patterns were identified: peripheral, central (target), and diffuse heterogeneous. Patterns of HBP enhancement varied between CRC, PDAC, and NET, with secondary analysis demonstrating that PDAC had the highest proportion of peripheral pattern (73%,p(adj) < 0.001), CRC the highest proportion of diffuse heterogeneous pattern (32%,p(adj) < 0.01), and NET the highest proportion of central pattern (89%,p(adj) < 0.001). Conclusion Liver metastases from several primary malignancies, including PDAC, demonstrate mild HBP enhancement in variable patterns. Correlation with OATP1B3 expression and prognosis is required.