Clinical evaluation of angiotensin II perfused Tc-99m RBC imaging on hepatoma after transcatheter arterial embolization therapy

Transcatheter arterial embolization therapy (TAE) has been the main treatment for hepatoma recently in Japan because it is as effective as surgical therapy. But only one therapy of TAE is not sufficient because it will soon get a recanalization or collateral blood flow. So it is important to repeat TAE when the tumor recovers the high vascularity. However, it is very difficult to know exactly when it does. On the other hand, Angiotensin II (AT-II) is known to decrease the blood flow in normal liver tissue and increase the blood flow in hepatoma relatively much by circulatory autoregulation. This investigation was undertaken to evaluate if AT-II perfused Tc-99m RBC imaging is useful as a monitoring procedure of hepatoma after TAE. Ten AT-II perfused Tc-99m RBC imagings were obtained out of 7 patients with hepatoma after TAE therapy. The efficacy of Tc-99m RBC imaging in estimating the vascularity of hepatoma was evaluated by comparison with a hepatic angiogram which was performed a few days later. The blood flow images of tumors on Tc-99m RBC imaging were undoubtedly enhanced with AT-II in comparison with conventional Tc-99m RBC imaging. In 9 out of 10 images, of which 6 were hypervascular and 4 were hypovascular with a hepatic angiogram, the vascularity was correctly estimated with Tc-99m RBC imaging(90%). The authors conclude that enhanced Tc-99m RBC imaging with AT-II is very useful to judge the recurrence of hepatoma after TAE non-invasively and easily