Analysis of neuroendocrine tumour metastases in the liver using contrast enhanced ultrasonography

Imaging of liver tumours might be improved by contrast-enhanced ultrasonography, which allows much better demonstration of the microvascular system. The aim of this study was to assess the sonographic morphology and vascularity of neuroendocrine liver metastases.

Forty-eight patients with histologically proven neuroendocrine tumours (NET) and suspected liver metastases--as well as 50 consecutive patients with liver metastases of other origins--were included in a prospective study to evaluate tumour characteristics using B-mode, colour Doppler (CDI) and contrast-enhanced ultrasound (CEUS).

In 4/48 patients with NET, liver biopsy revealed hemangiomas. The typical B-mode appearance was that of both echo-rich and echo-poor combined, also inhomogeneous depending on the size, and often centrally cystic. With CDI, neuroendocrine metastases appeared hypervascular (66%) or isovascular (34%). Metastases of another origin were hypovascular in 82%. With CEUS, neuroendocrine metastases showed increased arterial enhancement in 38 patients and hypoechoic appearance in the portalvenous phase in 39 patients. In liver metastases of another origin, the sensitivity for malignancy due to a hypoechoic appearance during the portalvenous phase was 100%. In liver metastases of NET origin the sensitivity for malignancy was 39/48 (82%).

Neuroendocrine tumour metastases might show characteristics which are similar to hemangiomas. In patients with liver cirrhosis and severe fatty liver disease the identification of NET with CEUS as a malignant lesion is more difficult. The sensitivity of CEUS in identifying malignancy based on the lack of portalvenous enhancement is higher for metastases of other origin.