Objectives In this study, Ultrasound Needle—an improved minimally invasive ultrasonic horn device was used to explore its potential of synergizing with urokinase in enhancing clots lysis in an in vitro intracranial hematoma model. Materials and methods Ten milliliter bovine blood was incubated for 3 h at 37℃, and coagulated into clot to mimic intracranial hematoma in vitro. Ultrasound Needle was an improved ultrasonic horn with a fine tip (1.80 mm) and metallic sheath, and had a frequency of 29.62 kHz. The 10,000 IU urokinase was injected through the metallic sheath during the vibration of Ultrasound Needle tip to lyse the clots for 8 min under different working parameter settings (n = 8) to explore the influence of parameters Amplitude (%) and Duty (%) on clot lysis weight (W0). The maximum temperatures were measured by an infrared thermometer during the treatment process. The W0 of different treatment groups (US (Ultrasound Needle), US + NS (normal saline), UK (urokinase), US + UK, n = 8) were compared to verify the synergistic lysis effect of Ultrasound Needle combined with urokinase at optimal working parameters (40% Amplitude, 20% Duty; input power 4.20 W; axial tip‐vibration amplitude 69.17 μm). Clots samples after treatment were fixed overnight for macroscopic examination. And fluorescent frozen sections and scanning electron microscopy examination were performed to show microscopic changes in clots and evaluate the cavitation effect of Ultrasound Needle on promoting drug diffusion within the clots. Results The clot lysis weight W0 increased with the parameters Amplitude (%) and Duty (%), reached a peak (2.435 ± 0.137 g) at 40% Amplitude and 20% Duty (input power 4.20 W), and then decreased. Higher Amplitude (%) and Duty (%) led to higher maximum temperature, and W0 was negatively correlated with the maximum temperature after the peak (r = −0.958). At the optimal parameter setting, the maximum temperature was 33.8 ± 0.9℃, and the W0 of the US + UK group was more than four times of UK alone group (2.435 ± 0.137 g vs. 0.607 ± 0.185 g). Fluorescent frozen sections confirmed that the ultrasound energy of Ultrasound Needle could mechanically damage the clot tissues and promote the intra‐clots drug diffusion. Macroscopic examination showed that US + UK group caused larger clots lysis area than UK alone group (2.08 cm2 vs. 0.65 cm2). In addition, electron microscopy examination exhibited that the fibrin filaments of the clots in US + UK group were lysed more thoroughly compared to single treatment groups. Conclusions Ultrasound Needle, an improved ultrasonic horn device, can mechanically damage the clot tissues and exhibit an excellent synergistic lysis effect with thrombolytic drugs. Therefore, Ultrasound Needle has great potential in providing a new minimally invasive strategy for rapid intracranial hematoma evacuation.

Background Hypoperfusion or resultant hypoxia in solid tumours is a main reason for therapeutic resistance. Augmenting the blood perfusion of hypovascular tumours might improve both hypoxia and drug delivery. Cavitation is known to result in microstreaming and sonoporation and to enhance drug diffusion into tumours. Here, we report the ability to enhance both tumour blood perfusion and doxorubicin (Dox) delivery using a new sononeoperfusion effect causing a cavitation effect on tumour perfusion in subcutaneous Walker-256 tumours of rats using ultrasound stimulated microbubble (USMB). Methods To induce the sononeoperfusion effect, USMB treatment was performed with a modified diagnostic ultrasound (DUS) system and SonoVue® microbubbles. The therapeutic pulse was operated with a peak negative pressure of 0.26 to 0.32 MPa and a pulse repetition frequency (PRF) of 50 Hz to 2 kHz. Contrast-enhanced ultrasound (CEUS) was used for tumour perfusion assessment. Results The USMB treatment of 0.26 MPa and 1 kHz could significantly enhance tumour perfusion with a 20.29% increase in the CEUS peak intensity and a 21.42% increment in the perfusion area for more than 4 hours (P < 0.05). The treatment also increased Dox delivery to tumours by approximately 3.12-fold more than that of the control (P < 0.05). Furthermore, ELISAs showed that vasodilators and inflammatory factors increased 4 hours after treatment (P < 0.05), suggesting that the inflammatory response plays an important role in the sononeoperfusion effect. Conclusion The USMB-induced sononeoperfusion effect could significantly enhance the blood perfusion of Walker-256 tumours and promote drug delivery. It might be a novel physical method for overcoming the therapeutic resistance of hypoperfused or hypoxic tumours.

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