“…Recently, second generation contrast agents for ultrasonography have been developed and contrast-enhanced harmonic imaging with EUS (CH-EUS) is now possible [18,19]. These agents can produce harmonic signals at low acoustic power [20][21][22][23], and therefore, be available even for EUS imaging [18,19]. Sonazoid, a second generation contrast agent, has been reported to be useful in the diagnosis of hepatocellular carcinoma by highlighting tumor microvasculature [24,25].…”