A patient with unresectable hepatocellular carcinoma is planned for yttrium-90 (Y-90) radioembolization. Before treatment, technetium-99m macroaggregated albumin (MAA) is injected into the hepatic artery. What is the purpose of this pre-treatment MAA scan?

• A To assess hepatopulmonary shunting and calculate the lung radiation dose ✓
• B To measure the tumour uptake of lipiodol
• C To confirm patency of the portal vein
• D To map the arterial supply of the gallbladder

Explanation

Tc-99m MAA particles are similar in size to Y-90 microspheres and lodge in the same vascular bed. Scintigraphy after MAA injection quantifies shunting to the lungs and gut, allowing calculation of the absorbed lung dose and identification of gastrointestinal flow that would cause radiation ulcers. If lung shunt fraction is excessive, the Y-90 activity is reduced or treatment abandoned. Portal vein patency is assessed by Doppler or CT, not by MAA scintigraphy.

Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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