The MRI Signature of Neuroendocrine Liver Metastases: Toward a Radiologic Identikit

Background: Neuroendocrine neoplasms are frequently diagnosed after the detection of liver metastases, often when the primary tumor remains occult. Accurate non-invasive differentiation of neuroendocrine liver metastases (NELMs) from other focal hepatic lesions is therefore crucial. This study aimed to characterize the magnetic resonance imaging (MRI) features of NELMs using hepatocyte-specific contrast agents and to identify a potential radiologic “signature” that may suggest a neuroendocrine origin. Methods: This retrospective study included three cohorts: patients with histologically confirmed NELMs (n = 51; 146 lesions), patients with colorectal cancer liver metastases (n = 18; 46 lesions), and patients with benign hepatic hemangiomas (n = 28; 51 lesions). All subjects underwent standardized liver MRI with Gd-EOB-DTPA. Lesions were evaluated for size, diffusion-weighted imaging characteristics, apparent diffusion coefficient values, arterial-phase enhancement, T2-weighted signal, hepatobiliary-phase appearance, and hemorrhagic components. Statistical analyses included univariate and multivariate testing and receiver operating characteristic curve analysis. Results: NELMs commonly demonstrated arterial hyperenhancement, diffusion restriction, and variable T2 and hepatobiliary-phase signal heterogeneity. Compared with colorectal metastases and hemangiomas, NELMs showed distinctive patterns, particularly higher rates of hepatobiliary-phase heterogeneity and arterial enhancement. Lesion size, ADC metrics, T2 heterogeneity, and hemorrhage were significant discriminators. Conclusions: Hepatocyte-specific MRI enables identification of characteristic imaging features of NELMs. An integrated assessment of morphologic, diffusion, and hepatobiliary-phase findings may facilitate early recognition of neuroendocrine metastases, even when the primary tumor is unknown, improving diagnostic confidence and clinical management.