Gray scale second harmonic imaging of acoustic emission signals improves detection of liver tumors in rabbits

This study evaluates a new reticuloendothelium specific sonographic contrast agent NC100100 (Sonazoid) for detection of liver VX‐2 tumors in rabbits. Gray scale imaging of five groups of three rabbits, with hepatic VX‐2 tumors implanted 7, 10, 12, 14, and 18 days previously, was performed prior to injection of Sonazoid (dosages, 0.01‐0.5 ml/kg). Sonazoid produces induced acoustic emission after uptake in the liver. Therefore, harmonic gray scale images were obtained immediately after injection as well as delayed (by up to 2(1/2) h). Five rabbits (one from each group) also had angiography performed, while all animals were evaluated by pathologic examination. Non‐contrast enhanced sonography detected 17 of 61 tumors (29%), as well as three false‐positives, while the addition of Sonazoid detected 57 tumors (93%) and one false‐positive (P