Figure 2.

Volumetric SPAQ measurements of entire tumors prove the specificity of targeted microbubbles: After injection of unspecific microbubbles, no relevant accumulation was observed within tumor vessels. After administration of RGD-coated microbubbles targeted against α_vβ₃-integrin, more Doppler signals (yellow dots) were visible, representing the bursting of stationary microbubbles at their target. Quantitative analysis indicated significant accumulation compared with unspecific microbubbles. Accumulation of anti-ICAM-1 antibody-coated microbubbles was even more pronounced (*P < .05; **P < .01; n = 8 tumors).