Flash echo gray scale imaging with subtraction in assessment of small hepatocellular carcinoma treated with percutaneous ethanol injection: Preliminary report

Objective. To assess the therapeutic effect of percutaneous ethanol injection on small hepatocellular carcinoma by using a flash echo imaging system, a newly developed technique for detecting echoes from microbubble contrast agents more efficiently. Methods. Six patients with 7 small nodular hepatocellular carcinomas, proved by fine-needle aspiration cytologic or pathologic examination, were included. Percutaneous ethanol injection was performed until there was no intratumoral color signal on conventional color and power Doppler ultrasonography. A bubble contrast agent was then injected, and flash echo imaging in the subtraction mode was performed for assessment of the therapeutic effect. Dynamic computed tomography, magnetic resonance imaging, and hepatic angiography were also used for evaluation of the therapeutic effect. Results. Five tumors had perfusion defects that were equal in size to or larger than the tumors. No tumor stain was shown on hepatic angiography. Two tumors had partial perfusion defects. Viable tumors were confirmed by tumor resection in 1 case and cytologic examination in the other. Conclusions. Our preliminary results show that flash echo imaging with subtraction has potential value in evaluation of the therapeutic effect of percutaneous ethanol injection on small hepatocellular carcinoma.