Contrast-enhanced and targeted ultrasound

Figure 4 Nonlinear phenomena and the regimes for their occurrence. Microbubble shell classes: (I) free or released gas; (II) thin shells < 10 nm; (III) thick shells < 500 nm; (IV) very thick shells > 500 nm. Acoustic regimes: low (L) for mechanical index (MI) < 0.3; medium (M) for 0.3 < MI < 0.7; high (H) for MI > 0.7. The figure has been based on Postema[12].