Comparative analysis of hepatopulmonary shunt obtained from pretherapy 99mTc MAA scintigraphy and post-therapy 90Y Bremsstrahlung imaging in 90Y microsphere therapy

INTRODUCTION Tc macroaggregate albumin (MAA) scintigraphy is routinely used to estimate the hepatopulmonary shunt (HPS) of Y microspheres because of their comparable average particle sizes (20–30 µm). However, the MAA particle size can vary from 10 to 90 µm. Therefore, HPS computed from Tc MAA scintigraphy may not accurately represent the HPS of Y microspheres. In view of this, the present study was undertaken to investigate the accuracy of Tc MAA scintigraphy in estimating the HPS of Y microspheres. MATERIALS AND METHODSNineteen sessions of transarterial radioembolization using Y therasphere were carried out in 17 patients for hepatic malignancies (both primary and secondary). For each session of therapy, a pretherapeutic Tc MAA scintigraphy and post-therapeutic Y Bremsstrahlung scintigraphy were performed. The HPSs obtained from these images were compared. RESULTSThe mean HPS fractions calculated from the pretherapeutic Tc MAA study and the post-therapeutic Y Bremsstrahlung images were 4.77±2.81 and 4.52±2.5%, respectively. The coefficient of correlation (r) was 0.96. CONCLUSIONTc MAA scintigraphy accurately predicts the HPS of Y microspheres.