Contrast-Enhanced Tissue Harmonic Imaging versus Phase Inversion Harmonic Sonographic Imaging for the Delineation of Hepatocellular Carcinomas

Objective: To compare contrast tissue harmonic imaging (THI) with low mechanical index (MI) and conventional contrast harmonic imaging (CHI) with respect to lesion visibility of hepatocellular carcinoma (HCC). Methods: One hundred and twenty-five patients (84 men and 41 women, age range 39-94 years, mean age 74 years) with 100 naïve HCCs and 30 lesions after radiofrequency ablation (RFA) for HCC were evaluated. One hundred and four patients had liver cirrhosis of Child-Pugh class A, and the remaining 21 had Child-Pugh class B cirrhosis. The lesion conspicuity and intratumoral echogenicity during the postvascular phase were compared using conventional CHI and contrast THI with low MI. Results: The MI values ranged from 0.20 to 0.30 on conventional CHI and from 0.30 to 0.35 on contrast THI. Regarding HCC lesion conspicuity, contrast THI with low MI was clearer in 79 lesions (60.8%), equal in 34 lesions (26.2%), and less clear in 17 lesions (13.1%) when compared with conventional CHI. The lesion conspicuity with contrast THI was significantly better than that with conventional CHI (p < 0.01). All of the postablative lesions were well delineated in patients who received RFA. Conclusion: Low-MI contrast THI was superior to conventional CHI with respect to lesion visibility of HCCs and might offer good imaging for the guiding of RFA.