The experimental setup used for radio-frequency measurements conducted to characterize the subharmonic response of the agent sizes.
(a) The number-weighted, and (b) volume-weighted size distribution of native Targestar-P®, measured with a Casy™ counter. The legend shows the median diameter of the agent.
The spectral response of (a) the 20 MHz transmitting transducer, and (b) the 10 MHz receiving transducer, that was measured with a calibrated broadband hydrophone.
The (a) “baseline” spectral response obtained without contrast agent in the plexiglass chamber, and (b) the spectral response of native Targestar-P® computed for a pressure amplitude of 398 kPa. The subharmonic response of native agent was over 20 dB higher than the baseline spectral power at 10 MHz.
The estimated (a) number-weighted, and (b) volume-weighted size distribution of size-manipulated agent samples. The size distributions were normalized to the maximum in each case for comparison.
The spectral response of the size-manipulated agent populations with median diameters (a) 1.35, (b) 1.44, (c) 1.63, (d) 1.89, (e) 2.15, and (f) 2.99 μm, computed at 398 kPa. The noise floor in each case is denoted with the dotted curve.
The subharmonic response of the agent relative to the baseline signal at 10 MHz, computed for different agent sizes when the peak negative pressure was increased progressively from 190 to 398 kPa.
The peak subharmonic response relative to baseline plotted against the median diameter of (a) number-weighted and (b) volume-weighted agent population. The linear regression was computed for the range of sizes over which the subharmonic response demonstrated a monotonic increase (1.35–2.15 μm).
Size distribution estimates of agents size distributions created from Targestar-P®.
Article metrics loading...
Full text loading...