Contrast-Enhanced CT Features for Identifying Primary Origin and Differentiation Grade of Neuroendocrine Liver...

Accurate identification of the primary tumor origin and differentiation grade of neuroendocrine liver metastases (NELMs) is critical for guiding treatment. This study aimed to evaluate contrast-enhanced CT (CECT) features of NELMs to differentiate pancreatic from non-pancreatic origins and neuroendocrine carcinoma (NEC) from neuroendocrine tumor (NET).

This single-center retrospective study (July 2019 - December 2022) included consecutive patients with pathologically proven NELM who underwent CECT prior to surgery or biopsy. CT features, including tumor burden, basic characteristics, enhancement patterns, and malignancy-related features, were analyzed. The enhancement pattern was categorized as follows: (A) hypoenhancement (hypodensity in both the arterial phase and portal venous phase); (B) arterial phase hyperenhancement (APHE) and washout; (C) APHE and fade. Univariate and multivariate analyses were performed to identify CT features that differentiated pancreatic from non-pancreatic origins and NEC from NET.

Among 83 patients (median age, 52 years; 34 females), 49 patients had pancreatic NELM and 25 patients had NEC. In univariate analyses, hypoenhancement was significantly more frequent in non-pancreatic NELM compared to pancreatic NELM (32.4% vs. 8.2%; p = 0.01). This association was independent of age, sex, tumor size, and differentiation grade (p = 0.03). In addition, NEC was associated with ill-defined margins and targetoid appearances compared to NET, independent of age, sex, tumor size, and tumor origin (p = 0.045 and 0.003, respectively).

The hypoenhancement of NELM facilitates identification of non-pancreatic primaries, and the presence of an ill-defined margin and a targetoid appearance are indicative of NEC. These features can aid in optimizing management strategies in patients with NELM.