Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shapememory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel pre-clinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

May-Thurner syndrome (MTS) is the pathologic compression of the left common iliac vein by the right common iliac artery, resulting in left lower extremity pain, swelling, and deep venous thrombosis. Though this syndrome was first described in 1851, there are currently no standardized criteria to establish the diagnosis of MTS. Since MTS is treated by a wide array of specialties, including interventional radiology, vascular surgery, cardiology, and vascular medicine, the need for an established diagnostic criterion is imperative in order to reduce misdiagnosis and inappropriate treatment. Although MTS has historically been diagnosed by the presence of pathologic features, the use of dynamic imaging techniques has led to a more radiologic based diagnosis. Thus, imaging plays an integral part in screening patients for MTS, and the utility of a wide array of imaging modalities has been evaluated. Here, we summarize the historical aspects of the clinical features of this syndrome. We then provide a comprehensive assessment of the literature on the efficacy of imaging tools available to diagnose MTS. Lastly, we provide clinical pearls and recommendations to aid physicians in diagnosing the syndrome through the use of provocative measures.

Intravascular tumor extension, also known as tumor thrombus, can occur in many different types of cancer. Those with the highest proclivity include Wilm's tumor, renal cell carcinoma (RCC), adrenal cortical carcinoma (ACC) and hepatocellular carcinoma (HCC). The presence of tumor thrombus markedly worsens prognosis and impacts treatment approach. Imaging plays a key role in its diagnosis. Endovascular methods also play a large role in treatment.

Background. Conflicting data exist regarding the prognostic impact of the isocitrate dehydrogenase (IDH) mutation in intrahepatic cholangiocarcinoma (ICC), and limited data exist in patients with advanced-stage disease. Similarly, the clinical phenotype of patients with advanced IDH mutant (IDHm) ICC has not been characterized. In this study, we report the correlation of IDH mutation status with prognosis and clinicopathologic features in patients with advanced ICC. Methods. Patients with histologically confirmed advanced ICC who underwent tumor mutational profiling as a routine part of their care between 2009 and 2014 were evaluated. Clinical and pathological data were collected by retrospective chart review for patients with IDHm versus IDH wild-type (IDHwt) ICC. Pretreatment tumor volume was calculated on computed tomography or magnetic resonance imaging.

• RAS and ablation margins are predictors of local tumour progression-free survival. • Ablation margin >10 mm, always desirable, is crucial for mutant RAS metastases. • Interventional radiologists should be aware of RAS status to optimize LTPFS.

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer and affects millions worldwide. Due to the lack of effective systemic therapies for HCC, researchers have been investigating the use of locoregional tumor control with Yttrium-90 (Y90) radioembolization since the 1960s. Following the development of glass and resin Y90 microspheres in the early 1990s, Y90 radioembolization has been shown to be a safe and efficacious treatment for patients with HCC across Barcelona Clinic Liver Cancer (BCLC) stages. By demonstrating durable local control, good long term outcomes, and equivalent if not superior tumor responses and tolerability when compared to alternative therapies including transarterial chemoembolization (TACE) and sorafenib, Y90 radioembolization is being increasingly used in HCC treatment. More recently, investigations into variations in Y90 radioembolization technique including radiation segmentectomy and radiation lobectomy have further expanded its clinical utility. Here, we discuss the history and evolution of Y90 use in HCC. We outline key clinical trials that have established the safety and efficacy of Y90 radioembolization, and also summarize trials comparing its efficacy to existing HCC treatments. We conclude by reviewing the techniques of radiation segmentectomy and lobectomy, and by discussing dosimetry.

Percutaneous image-guided ablation is an increasingly common treatment for a multitude of solid organ malignancies. While historically these techniques have been restricted to the management of small, unresectable tumors, there is an expanding appreciation for the systemic effects these locoregional interventions can cause. In this review, we summarize the mechanisms of action for the most common thermal ablation modalities and highlight the key advances in knowledge regarding the interactions between thermal ablation and the immune system.

Minimally invasive techniques to occlude flow within blood vessels, initially pioneered in the 1970s with autologous materials and subsequently advanced with increasingly sophisticated engineered biomaterials, are routinely performed for a variety of medical conditions. Contemporary interventional radiologists have at their disposal a wide armamentarium of occlusive agents to treat a range of disease processes through a small incision in the skin. In this review, we provide a historical perspective on endovascular embolization tools, summarize the current state-of-the-art, and highlight burgeoning technologies that promise to advance the field in the near future.