This Editorial Comment discusses the following AJR article: Comparison of Polyvinyl Alcohol Versus Combination of Lipiodol-Bleomycin Emulsion and NBCA-Lipiodol Emulsion for Renal Angiomyolipoma Embolization: A Prospective Randomized Study.

Patients with large (> 4 cm), symptomatic, or acutely bleeding renal angiomyolipomas (AMLs) are often referred to interventional radiology for management with transcatheter arterial embolization (TAE). The authors of this article performed a clinically relevant randomized prospective trial to compare the safety and efficacy of two different embolic agents for TAE of renal AMLs. Before this evaluation, scant quality evidence was available to guide embolic selection for TAE of renal AMLs. Physicians were thus left to guess and theorize which embolic agent would be most efficacious on the basis of past clinical experience. For example, it is assumed that liquid-based agents, including alcohol and N-butyl cyanoacrylate (NBCA), penetrate more deeply into the vascular system than particle-based agents. This penetration should result in more ischemia and necrosis of the target tissue [1], a desirable effect when treating tumors such as renal AMLs. Moreover, we are starting to understand how embolic agent selection affects the local tumor environment [2], theoretically altering clinical outcomes.

To this end, the authors randomized 78 patients with large (> 4 cm) or symptomatic renal AMLs to TAE with either polyvinyl alcohol particles alone or a Lipiodol-bleomycin emulsion followed by a Lipiodol-NBCA emulsion. The authors found that TAE using the combination of Lipiodol-bleomycin emulsion and Lipiodol-NBCA emulsion resulted in higher rates of hematuria resolution, higher frequency of pain resolution, greater reduction in AML volume, and lower rates of repeat TAE. The inclusion criteria are broad and mimic real-world clinical scenarios, which improves the study’s applicability to everyday practice. One criticism is that the combination of Lipiodol-bleomycin emulsion and Lipiodol-NBCA emulsion is not familiar to most interventional radiologists in the United States, which could limit its adoption. Regardless, the article provides solid evidence that the use of a liquid-based embolic regimen improved the outcomes of TAE for renal AMLs compared with a particle-based regimen.