Correlation of Technetium-99m Macroaggregated Albumin and Yttrium-90 Glass Microsphere Biodistribution in Hepatocellular Carcinoma: A Retrospective Review of Pretreatment Single Photon Emission CT and Posttreatment Positron Emission Tomography/CT.

PURPOSE: To evaluate whether technetium-99 (99m Tc)-labeled macroaggregated albumin (MAA) can predict subsequent yttrium-90 (90 Y) distribution and imaging response in patients with hepatocellular carcinoma (HCC).

MATERIALS: Retrospective review was performed of records of 83 patients with HCC who underwent 90 Y glass microsphere radioembolization with 99m Tc-MAA single photon emission computed tomography (SPECT) and 90 Y positron emission tomography (PET)/CT between January 2013 and December 2014. Images were fused to segment the whole liver normal tissue (WLNT) and the largest tumors. Fused images were reviewed and analyzed for comparison of absorbed dose (AD) to tumors and WLNT as calculated from 99m Tc-MAA SPECT and from 90 Y PET/CT, subjective imaging comparison of 99m Tc-MAA SPECT and 90 Y PET for tumors and WLNT, and correlation of tumoral AD with response on follow-up CT.

RESULTS: Final analysis included 73 and 63 patients for WLNT and tumor 99m Tc-MAA/90 Y correlation, respectively, and 62 patients for AD vs response. 99m Tc-MAA/90 Y limit of agreement for each reviewer was viewed as clinically acceptable only for WLNT (-15 to 15 Gy). AD interreviewer variability was clinically acceptable for WLNT but was too broad for tumor. Mean tumor AD for objective response (78%) was 313 Gy vs 234 Gy for nonresponders. No threshold was found between tumor AD and response (P > .1). Catheter mismatch between 99m Tc-MAA and 90 Y had a direct impact on AD mismatch between the 2 image sets.

CONCLUSIONS: 99m Tc-MAA was found to be a poor surrogate to quantitatively predict subsequent 90 Y AD to hepatocellular tumors. 99m Tc-MAA distribution correlated with 90 Y distribution in the normal hepatic parenchyma.