Imaging Assessment of Interventional Therapies in Lung and Liver

As minimally invasive oncologic therapies become more commonplace in the management of many types of cancer, intraprocedural and postprocedural imaging plays a critical role in the assessment of treatment success and efficacy. Most imaging is performed with ultrasound, CT, or MRI, but can sometimes be supplemented with other imaging modalities such as PET/CT. Knowing the mechanisms of action and expected posttreatment imaging findings is imperative for accurate assessment of treatment response. For example, with stereotactic body radiotherapy (SBRT) and transarterial radioembolization (TARE), radiation-induced necrosis is the major mechanism of action and therefore mild tumoral enhancement may persist for months after therapy. In contrast, after transcatheter arterial chemoembolization (TACE) or energy-based ablations, a completely treated lesion usually demonstrates nonenhancement. Because of variability in posttreatment changes such as inflammation and edema and depending on the treatment method and time since the procedure, distinguishing between treatment effects and residual disease can be challenging. Energy-based ablation offers advantages of intraprocedural monitoring and assessment, even allowing for immediate modifications of treatment zones to optimize the therapeutic effect. This chapter will focus on intraprocedural and postprocedural imaging assessments of lung and liver tumors following locoregional therapies, including SBRT, TACE, TARE, and percutaneous image-guided ablation.