What is the purpose of performing MAA prior to SIRT?

Performing MAA (macroaggregated albumin) imaging prior to SIRT (Selective Internal Radiation Therapy) serves a critical role in ensuring that there are no extra-hepatic shunts present. The primary goal of MAA imaging in this context is to identify any vascular pathways that might divert blood flow from the targeted liver tumors to other organs, such as the lungs. By detecting these shunts, clinicians can prevent potentially harmful radiation therapy from affecting non-target tissues, particularly those that could lead to severe complications, such as radiation pneumonitis if the lungs receive unintended radiation exposure.

This imaging step is essential as it guides the planning and execution of the SIRT procedure, ensuring patient safety and optimizing the treatment's effectiveness. Although the other choices relate to aspects of liver function and treatment response, they do not directly address the specific aim of pre-treatment MAA imaging, which is primarily focused on assessing vascular flow and identifying shunting issues.