[CT and MRI findings of primary hepatic neuroendocrine neoplasm]

Objective: To study imaging features of primary hepatic neuroendocrine neoplasm (PHNEN) with CT and MRI. Methods: CT/MRI findings of ten patients with pathologically confirmed PHNEN were retrospectively analyzed. The result was compared with pathologic features classified by the 2010 WHO classification of gastro-entero-pancreatic neuroendocrine tumor which was also compared with the conventional method. Results: Six cases of neuroendocrine tumor (NET), all of which were classified as grade 2 (G2), consisted of 5 cases of carcinoid and 1 case of atypical carcinoid. Four cases of neuroendocrine carcinoma (NEC) classified as grade 3 (G3) were composed of 1 case of atypical carcinoid and 3 cases of small cell carcinoma. On the basis of conventional classification method, CT/MRI features were as follows: (1) Carcinoid: For 5 carcinoid cases, two with solitary mass, two with dominant masses and satellite nodules, and one with diffused nodules. Four cases were cystic-solid and one was solid. Four showed low density on plain CT and moderate to obvious enhancement in arterial phase. Three showed consistent enhancement in portal and delayed phase while one showed rapid washout in portal phase. Four showed low density in delayed phase. One case with cystic degeneration showed hypo-intensity on T1W, hyper-intensity on T2W and halo like hyper-intensity on DWI. In dynamic MRI, the solid part of tumor showed obvious enhancement in arterial phase, consistent enhancement in portal phase with slight washout and homogeneous or slight hypo-geneous signal density in delayed phase. (2) Atypical carcinoid: Two cases presented with cystic-solid mass. They were all dominant masses with satellite nodules. They showed low density on plain CT and mild to moderate enhancement in arterial phase. One case showed rapid washout in portal and delayed phase with embolus in portal vein. The other case showed consistent enhancement in portal phase and hypo-density in delayed phase without enhancement of satellite nodules. (3) Small cell neuroendocrine carcinoma: Three cases of small cell carcinoma were composed of one cystic-solid tumor, one solid tumor and one dominant mass with satellite nodules. Two cases showed low density in CT plain scan while one with cystic degeneration presented hypo-intensity on T1W, hype-rintensity on T2W and halo like hyper-intensity on DWI. Dynamic CT and MRI showed mild to moderate enhancement in arterial phase, consistent enhancement in portal phase and low density or hypo-intensity in delayed phase. Conclusion: PHNEN has specific features on CT and MRI which are valuable in diagnosis and differential diagnosis.