Imaging for Selective Internal Radiation Therapy (SIRT) with Intraarterial Infusion of Yttrium-90 (Y-90) Microspheres: Pearls and Pitfalls

1324 Objectives 1. To describe the significance of Tecnetium-99m (Tc-99m)macroaggragated albumin (MAA) imaging prior to treatment. 2. To review the basics of SIRT using Y-90. 3. To demonstrate examples of expected and unexpected imaging patterns after SIRT. SIRT using Y-90 microspheres is an effective and usually well tolerated method for treating nonresectable primary or metastatic liver cancers. However, appropriate treatment planning prior to SIRT is crucial to avoid potentially harmful side effects. Tc-99m labelled MAA is injected into hepatic artery prior to treatment with Y-90 to demonstrate the shunting to the lungs or gastrointestinal tract. Lung shunting of <20% is required to reduce radiation related side effects in the lungs. If unexpected shunting to GI system is detected, angiographic embolization may be needed prior to treatment. A posttreatment bremsstrahlung scan should be obtained to verify the distribution of the Y-90 microspheres. This would also enable detection of unexpected areas of uptake that were not observed on pretreatment scan so that patients can be monitored more closely. SIRT using Y-90 microspheres is safe and efficient treatment modality in salvage therapy of metastatic liver cancers or nonresectable hepatocellular carcinoma. To avoid potentially harmful side effects, pretherapeutic work-up to explore hepatic vasculature and to assess shunting to lungs and GI system allows a better patient selection. Methods - Results - Conclusions -