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<0.001). Acoustic emission made 2 x 2 mm
tumors (invisible in conventional B-mode sonography) clearly perceivable in harmonic gray scale. In the subgroup that received angiography, 12 of 36
tumors (33%) were detected with conventional sonography compared to 22
tumors (61%) seen with angiography (P = 0.002). After injection of
Sonazoid the ultrasonographic detection rate increased to 97% (35 of 36
tumors), which was a significant improvement over angiography (P = 0.00024). Improved detection of hepatic VX-2
tumors with second harmonic gray scale imaging of
Sonazoid is possible because of this agent's acoustic emission capabilities.