A 62-year-old man with an unresectable liver tumour is being planned for yttrium-90 radioembolization. Before treatment, a planning angiogram is performed and technetium-99m macroaggregated albumin (MAA) is injected into the tumour-supplying artery followed by scintigraphy. What is the primary purpose of this MAA study?

• A To document baseline liver function before dosimetry
• B To confirm the arterial vascularity of the tumour before treatment
• C To measure residual portal venous perfusion to the treated lobe
• D To quantify hepatopulmonary shunting and detect extrahepatic gastrointestinal deposition ✓

Explanation

MAA particles are similar in size to yttrium-90 microspheres and lodge in the same locations, so the scan simulates the treatment distribution. It quantifies the fraction of activity shunted to the lungs, which dictates whether the prescribed activity must be reduced or the procedure abandoned, and it reveals unintended deposition in gut vessels so that these can be coil-protected. Tumour vascularity and liver function are assessed separately on conventional angiography and biochemical testing respectively.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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