RESUMO
PURPOSE: To determine if baseline patient, tumor, and pretreatment evaluation characteristics could help identify patients who require technetium-99m (99mTc) macroaggregated albumin (99mTc MAA) imaging before selective internal radiation therapy (SIRT). MATERIALS AND METHODS: In this retrospective analysis, 532 consecutive patients with primary (n = 248) or metastatic (n = 284) liver tumors were evaluated between 2006 and 2015. Variables were compared between patients in whom 99mTc MAA imaging results contraindicated/modified SIRT administration with yttrium-90 (90Y) resin microspheres and those who were treated as initially planned. The 99mTc MAA findings that contraindicated/modified SIRT were a lung shunt fraction (LSF) > 20%, gastrointestinal 99mTc MAA uptake, or a mismatch between 99mTc MAA uptake and intrahepatic tumor distribution. RESULTS: LSF > 20% and gastrointestinal MAA uptake were observed in 7.5% and 3.9% of patients, respectively, and 11% presented a mismatch. Presence of a single lesion (odds ratio [OR] = 2.4) and vascular invasion (OR = 5.5) predicted LSF > 20%, and GI MAA uptake was predicted by the presence of liver metastases (OR = 3.7) and 99mTc MAA injection through the common/proper hepatic artery (OR = 4.7). Vascular invasion (OR = 4.1) was the only predictor of LSF > 20% and/or GI MAA uptake (sensitivity = 49.2%, specificity = 80.3%, negative predictive value = 92.4%). Previous antiangiogenic treatment (OR = 2.4) and presence of a single lesion (OR = 2.6) predicted mismatch. CONCLUSIONS: Imaging with 99mTc MAA is essential in SIRT workup because baseline characteristics may not adequately predict 99mTc MAA results. Nevertheless, the absence of vascular invasion potentially identifies a group of patients at low risk of SIRT contraindication/modification in whom performing SIRT in a single session (ie, pretreatment evaluation and SIRT on the same day) should be explored.
