Embolization for the treatment of hypervascularized tumors

Hypervascular liver tumors include both hepatocellular carcinoma (HCC) and metastatic lesions from neuroendocrine tumors (NETs). Conspicuity of hepatic tumors on diagnostic imaging studies depends on adequate contrast with normal liver parenchyma. As well demonstrated previously, the hepatic artery has long been considered the predominant source of blood supply for liver tumors. HCC is one of the most vascular solid tumors in which angiogenesis plays an important role. The status of angiogenesis in HCC correlates with the disease progression and prognosis and, thus, provides a potential therapeutic target. Transarterial embolization (TAE) is a palliative treatment for patients with liver metastases from NETs, reducing hormonal symptoms and improving patients' survival. The rationale for transarterial treatments is based on the observations that both HCC and liver metastases from NETs are typically hypervascular deriving the majority of their blood supply from the hepatic artery. The TAE with microparticles should result in terminal vessel occlusion and blood flow obstruction. Microparticles should be very small, precisely and tightly calibrated just to be delivered into smaller peripheral arteries, and cause permanent ischemia. When using very small embolic agents two complications may occur: pulmonary embolism and nontarget embolization with reflux of embolization material. This article gives an overview on how to manage hypervascular liver tumors.