Hepatic reticuloendothelial distribution on sulfur colloid single-photon emission computed tomography/computed tomography is discordant with biochemical liver function in patients undergoing preradioembolization evaluation

OBJECTIVE: To determine whether qualitative technetium-99m sulfur colloid (99mTc-SC) single-photon emission computed tomography/computed tomography (SPECT/CT) grading is discordant with conventional liver function assessment in patients undergoing preradioembolization evaluation. METHODS: This single-center retrospective study included 96 consecutive patients who underwent dual-tracer 99mTc-macroaggregated albumin and 99mTc-SC SPECT/CT for yttrium-90 transarterial radioembolization planning. Sulfur colloid uptake was graded visually on a three-tier ordinal scale: grade I, normal; grade II, intermediate; and grade III, colloid shift. Contemporaneous laboratory values, Child-Pugh class, and model for end-stage liver disease score were recorded. Concordance was assessed using weighted kappa. Associations were evaluated with Spearman correlation, receiver operating characteristic analysis, and ordinal logistic regression. RESULTS: Abnormal sulfur colloid findings, defined as grade II/III uptake, were present in 19 of 96 patients (19.8%), including eight patients (8.3%) with grade III colloid shift. Among 85 Child-Pugh A patients, 15 (17.6%) had abnormal sulfur colloid uptake; among 70 lab-normal patients, 11 (15.7%) had abnormal sulfur colloid uptake. Agreement between sulfur colloid grade and Child-Pugh class was poor (weighted kappa: 0.142). Higher sulfur colloid grade correlated modestly with albumin, total bilirubin, international normalized ratio, aspartate aminotransferase, and creatinine, but no variable remained independently associated after adjustment. Albumin best discriminated grade III shift [area under the curve (AUC): 0.732], whereas Child-Pugh class performed near chance (AUC: 0.511). CONCLUSION: Sulfur colloid SPECT/CT demonstrates reticuloendothelial distribution abnormalities in approximately one-fifth of preradioembolization patients, including some with preserved biochemical function. These discordant findings support further outcome-anchored evaluation of sulfur colloid SPECT/CT as a complementary tool before Y-90 radioembolization.