Table 1.
Pulsed focused ultrasound exposure parameters for different treatment groups
| Treatment type | p+ (MPa) | p− (MPa) | PRF (Hz) | ISPPA (W/cm2) | ISPTA(W/cm2) | ΔT(°C) | Δx (µm) |
|---|---|---|---|---|---|---|---|
| Low20 | 19 | 7 | 20 | 1886 | 0.2 | 0.0005 | 0.09 |
| High20 | 31 | 9 | 20 | 3554 | 0.38 | 0.001 | 0.18 |
| Low80 | 19 | 7 | 80 | 1886 | 0.8 | 0.0005 | 0.09 |
| High80 | 31 | 9 | 80 | 3554 | 1.5 | 0.001 | 0.18 |
| Low1k* | 3 | 2.6 | 1000 | 125 | 0.8 | 4e-5 | 0.006 |
| High1k* | 5 | 3.5 | 1000 | 283 | 1.5 | 9e-5 | 0.014 |
p+ and p− = peak positive and peak negative pressures in the waveform, respectively; PRF = pulse repetition frequency; ISPPA = spatial peak, pulse average intensity;ISPTA= spatial peak, time averaged intensity; ΔT = estimated maximum temperature elevation in muscle resulting from a single ultrasound pulse; Δx = estimated muscle tissue displacement resulting from radiation force exerted by a single ultrasound pulse.
The Low1k and Highlk exposures were designed to mimic the PRF used in low-intensity pulsed ultrasound (LIPUS) treatments (1 kHz), and have the same ISPTA values as Low80 and High80 exposures. In comparison, the LIPUS treatments typically operate at ISATA of 5–100 mW/cm2 and 20% duty factor. LIPUS intensity of 100 mW/cm2 was found to be the minimum intensity that mitigated bone loss in osteopenic animals (Ferreri et al. 2011).