Table 1.

Summary statistics for MDA-MB-231 (n = 6 at MI = 1.0, n = 6 at MI = 1.5) and MCF-7 (n = 6 at MI = 1.0, n = 6 at MI = 1.5) imaging experiments. (i) % Internalization = percentage of cells with at least 1 intracellular microbubble. (ii) # MB per cell = mean number of microbubbles per cell, for all cells with at least 1 intracellular microbubble. (iii) Ultrasound Activation Ratio = number of intracellular microbubbles per cell post-ultrasound / number of intracellular microbubbles per cell pre-ultrasound, including those cells with 0 intracellular PCCAs. (iv) FR-α Targeting Ratio = number of FR-targeted intracellular microbubbles per cell / number of untargeted intracellular microbubbles per cell, including those cells with 0 intracellular PCCAs.

Cell Line	MDA-MB-231		MCF-7
Mechanical Index	MI = 1.0	MI = 1.5	MI = 1.0	MI = 1.5
i) % Internalization (± SE)	93.0% ± 2.7%	79.5% ± 6.8%	42.4% ± 5.0%	35.7% ± 6.8%
ii) # MB per cell (± SE)	4.38 ± 0.98	3.63 ± 0.67	1.72 ± 0.07	2.32 ± 0.27
iii) Ultrasound Activation Ratio (± SD)	1.90 ± 0.32 (p < 0.01)	1.97 ± 0.22 (p < 0.01)	1.81 ± 0.35 (p < 0.01)	1.37 ± 0.33 (p = 0.164)
iv) FR-α Targeting Ratio	44.8 (p < 0.0001)	48.5 (p < 0.0001)	8.27 (p < 0.001)	5.54 (p < 0.001)