Flash-Echo Gray-Scale Imaging in the Subtraction Mode for Assessing Perfusion of Small Hepatocellular Carcinoma

Purpose. The aim of this study was to evaluate the effectiveness of using flash-echo imaging (FEI) in the subtraction mode to assess the vascularity of small hepatocellular carcinomas (HCCs) that had been unsatisfactorily assessed with power Doppler sonography. Methods. Between May 2000 and April 2001, we prospectively assessed nodular small HCCs using FEI in the subtraction mode after power Doppler sonography resulted in unsatisfactory images. After microbubble contrast was injected, we used the FEI technique to assess tumor perfusion in the arterial, portal, and delayed phases. Results. Our study population comprised 14 patients (10 men and 4 women) whose ages ranged from 31 to 79 years (mean, 61 ± 13.7 years) and whose tumors ranged in size from 0.8 to 3 cm (mean, 1.8 ± 0.5 cm). Power Doppler sonography was unable to assess tumor vascularity in 6 cases because of interference by heart pulsation, and it failed to detect a color signal in the other 8 cases. All tumors were enhanced with FEI. In the arterial phase, 7 of the 14 tumors (50%) showed hyperperfusion relative to liver parenchyma enhancement, 5 of 14 (36%) showed isoperfusion, and 2 of 14 (14%) showed hypoperfusion. In the portal phase, 3 of the 14 tumors (21%) showed isoperfusion, and the other 11 (79%) showed hypoperfusion. In the delayed phase, all 14 tumors showed hypoperfusion. Conclusions. Despite heart pulsation and slow vascular flow, FEI in the subtraction mode was sensitive and effective in assessing the perfusion of small HCCs.