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. Author manuscript; available in PMC: 2018 Feb 1.
Published in final edited form as: Ultrasound Med Biol. 2016 Oct 24;43(2):469–475. doi: 10.1016/j.ultrasmedbio.2016.09.019

Figure 3.

Figure 3

Comparison of harmonic emissions strength and MRI contrast enhancement in animals breathing oxygen and medical air. (A) Plot showing the average harmonic emission strength (relative to recordings obtained without microbubbles) as a function of time after microbubble injection for all 0.34-0.36 MPa sonications. Shaded areas show the standard deviation, and the dotted lines are linear regressions of the signal decay. Times when the signals recorded in animals breathing medical air were significantly higher (P<0.05) are indicated by asterisks. (B) Average MRI signal enhancement plotted as a function of time after Gd-DTPA contrast administration for sonications at 0.34-0.36 MPa (mean ± SD shown). The enhancement was significantly (P<0.001) larger for isoflurane and medical air at each time point. (C) For each sonication, the relative harmonic signal vs. time curves were integrated to give a single score. A good correlation (R2: 0.46) was observed in an exponential fit of the MRI signal enhancement as a function of this score, but substantial variability was observed.