Pilot Experiment on Non-Invasive Non-Thermal Disintegration of Human Mucinous Breast Carcinoma Ex Vivo Using Boiling Histotripsy.

We present the results of a pilot study demonstrating the feasibility of non-invasive non-thermal disintegration of human mucinous carcinoma of the breast ex vivo using sequences of high-intensity focused ultrasound pulses in boiling histotripsy regimen. The target volume was sonicated by focusing ultrasound pulses (n=20) of 1.5 MHz frequency, 10-msec duration and 1-sec pulse repetition period, 517 W acoustic power within the pulse, and 103 MPa shock front amplitude at the focus into each node of a volumetric grid 4×4×1 mm. Sonication was visualized and controlled using B-mode ultrasound imaging, total time of the treatment was 21 min. Histological hematoxylin and eosin and Masson's trichrome staining revealed the absence of tumor elements in the treated region confirming destruction of cancer cells and their nuclei after boiling histotripsy procedure.

Pilot ex vivo study on non-thermal ablation of human prostate adenocarcinoma tissue using boiling histotripsy.

Focused ultrasound technologies are of growing interest for noninvasive ablation of localized prostate cancer (PCa). Here we present the results of the first case study evaluating the feasibility of non-thermal mechanical ablation of human prostate adenocarcinoma tissue using the boiling histotripsy (BH) method on ex vivo tissue. High intensity focused ultrasound field was generated using a 1.5-MHz custom-made transducer with nominal F#=0.75. A sonication protocol of 734 W acoustic power, 10-ms long BH-pulses, 30 pulses per focal spot, 1 % duty cycle, and 1 mm distance between single foci was tested in an ex vivo human prostate tissue sample containing PCa. The protocol used here has been successfully applied in the previous BH studies for mechanical disintegration of ex vivo prostatic human tissue with benign hyperplasia. BH treatment was monitored using B-mode ultrasound. Post-treatment histologic analysis demonstrated BH produced liquefaction of the targeted tissue volume. BH treated benign prostate parenchyma and PCa had similar tissue fractionation into subcellular fragments. The results of the study demonstrated that PCa tumor tissue can be mechanically ablated using the BH method. Further studies will aim on optimizing protocol parameters to accelerate treatment while maintaining complete destruction of the targeted tissue volume into subcellular debris.

[A novel method for non-invasive mechanical ablation of prostate tumors using pulsed focused ultrasound].

AIM: of the study: demonstrate the feasibility of non-invasive mechanical disintegration of human prostate tissue using pulsed high-intensity focused ultrasound (pHIFU), a method termed boiling histotripsy. MATERIALS AND METHODS: An ultrasound experimental system was developed for producing localized mechanical lesions in ex vivo biological tissue samples under ultrasound guidance. A series of experiments was carried out to create small single-focus lesions (volume < 2 mm3) and one large lesion (volume > 50 mm3) in ex vivo prostate tissue samples. After irradiation, two samples were bisected to visualize the region of destruction; the other tissue samples were examined histologically. RESULTS: During pHIFU irradiation under B-mode ultrasound guidance, a region of increased echogenicity caused by formation of vapor-gas bubbles was visualized in the target region. After exposure, small and large lesions filled with a suspension of liquefied tissue were observed. Histological examination confirmed that the prostate tissue in the focal region was disintegrated into subcellular fragments. CONCLUSION: A pilot study showed the feasibility of using boiling histotripsy as a non-invasive method for treating prostate diseases.