Contrast-enhanced ultrasound for evaluating response to pulsed-wave high-intensity focused ultrasound therapy in advanced pancreatic cancer

OBJECTIVE: To examine whether contrast-enhanced ultrasound (CEUS) parameters in patients with advanced pancreatic cancer could be used to assess response to treatment with pulsed-wave high intensity focused ultrasound (PW-HIFU). METHODS: We prospectively recorded the pretreatment and posttreatment CEUS related parameters, CA19-9, pain scores of 30 patients with advanced pancreatic cancer treated with PW-HIFU treatment. Correlation of clinical parameters, tumor characteristics, and PW-HIFU treatment energy with CEUS parameters were analyzed. RESULTS: Pain score decreased after treatment (from 4.80±2.14 to 3.28±1.93, p = 0.001). CA19-9 dropped in RT decreased group, 4 weeks after one session PW-HIFU, compared with prolonged group (p = 0.013). According to the display of blood vessels in the mass by CEUS, tumors were classified by vessel grade (VG), VG1: no vessel can be seen; VG 2: vessels diameter < 5 mm; VG 3: vessels diameter > 5 mm. VGs were different between increased and decreased relative rise intensity (rRI) groups (p = 0.008). VG1 group shown a decreased rRI after treatment, while VG3 group showed the opposite trend (p = 0.006). CONCLUSIONS: CEUS can evaluating response to PW-HIFU in advanced pancreatic cancer. Quantitative analysis may help to assess the short-term efficacy of patients and help for individualized treatment.

Lessons learned during implementation of MR-guided High-Intensity Focused Ultrasound treatment of uterine fibroids

Background Although promising results have been reported for Magnetic Resonance image-guided High-Intensity Focused Ultrasound (MR-HIFU) treatment of uterine fibroids, this treatment is not yet widely implemented in clinical practice. During the implementation of a new technology, lessons are learned and an institutional learning-curve often has to be completed. The primary aim of our prospective cohort study was to characterize our learning-curve based on our clinical outcomes. Secondary aims included identifying our lessons learned during implementation of MR-HIFU on a technical, patient selection, patient counseling, medical specialists and organizational level. Results Our first seventy patients showed significant symptom reduction and improvement of quality of life at 3, 6 and 12 months after MR-HIFU treatment compared to baseline. After the first 25 cases, a clear plateau phase was reached in terms of failed treatments. The median non-perfused volume percentage of these first 25 treatments was 44.6% (range: 0–99.7), compared to a median of 74.7% (range: 0–120.6) for the subsequent treatments. Conclusions Our findings describe the learning-curve during the implementation of MR-HIFU and include straightforward suggestions to shorten learning-curves for future users. Moreover, the lessons we learned on technique, patient selection, patient counseling, medical specialists and organization, together with the provided supplements, may be of benefit to other institutions aiming to implement MR-HIFU treatment of uterine fibroids. Trial registration ISRCTN14634593. Registered January 12, 2021—Retrospectively registered, https://www.isrctn.com/ISRCTN14634593.

Biological Tissue Damage Monitoring Method Based on IMWPE and PNN during HIFU Treatment

Biological tissue damage monitoring is an indispensable part of high-intensity focused ultrasound (HIFU) treatment. As a nonlinear method, multi-scale permutation entropy (MPE) is widely used in the monitoring of biological tissue. However, the traditional MPE method neglects the amplitude information when calculating the time series complexity, and the stability of MPE is poor due to the defects in the coarse-grained process. In order to solve the above problems, the method of improved coarse-grained multi-scale weighted permutation entropy (IMWPE) is proposed in this paper. Compared with the MPE, the IMWPE method not only includes the amplitude of signal when calculating the signal complexity, but also improves the stability of entropy value. The IMWPE method is applied to the HIFU echo signals during HIFU treatment, and the probabilistic neural network (PNN) is used for monitoring the biological tissue damage. The results show that compared with multi-scale sample entropy (MSE)-PNN and MPE-PNN methods, the proposed IMWPE-PNN method can correctly identify all the normal tissues, and can more effectively identify damaged tissues and denatured tissues. The recognition rate for the three kinds of biological tissues is higher, up to 96.7%. This means that the IMWPE-PNN method can better monitor the status of biological tissue damage during HIFU treatment.

Numerical Study of Bubble Cloud and Thermal Lesion Evolution During Acoustic Droplet Vaporization Enhanced Hifu Treatment

Acoustic droplet vaporization (ADV) has proven to enhance high intensity focused ultrasound (HIFU) thermal ablation of tumor. It has also been demonstrated that triggering droplets before HIFU exposure could be a potential way to control both the size and the shape of the thermal lesion. In this paper, a numerical model is proposed to predict the thermal lesion created in ADV enhanced HIFU treatment. Bubble oscillation was coupled into a viscoelastic medium in the model to more closely represent real applications in tissues. Several physical processes caused by continuous wave ultrasound and elevated temperature during the HIFU exposure were considered, including rectified diffusion, gas solubility variation with temperature in the medium, boiling, etc. Four droplet concentrations spanning two orders of magnitude were calculated. The bubble cloud formed from triggering of the droplets by the pulse wave ultrasound, along with the evolution of the shape and location of the bubble cloud and thermal lesion during the following continuous wave exposure were obtained. The increase of bubble void fraction caused by continuous wave exposure were found to be consistent with the experimental observation. With the increase of droplet concentration, the predicted bubble cloud shapes vary from tadpole to triangular and double triangular, while the thermal lesions move toward the transducer. The results show that the assumptions used in this model increased the accuracy of the results. This model may be used for parametrical study of ADV enhanced HIFU treatment and be further used for treatment planning and optimization in the future.

Phase-changeable nanoparticle-mediated energy conversion promotes highly efficient high-intensity focused ultrasound ablation

: This review describes how phase-changeable nanoparticles enable highly efficient high-intensity focused ultrasound ablation (HIFU). HIFU is effective in the clinical treatment of solid malignant tumors. However, it has intrinsic disadvantages for treating some deep lesions, such as damage to surrounding normal tissues. When phase-changeable nanoparticles are used in HIFU treatment, they could serve as good synergistic agents because they are transported in the blood and permeated and accumulated effectively in tissues. HIFU’s thermal effects can trigger nanoparticles to undergo a special phase transition, thus enhancing HIFU ablation efficiency. Nanoparticles can also carry anticancer agents and release them in the targeted area to achieve chemo-synergistic therapy response. Although the formation of nanoparticles is complicated and HIFU applications are still in an early stage, the potential for their use in synergy with HIFU treatment shows promising results.

An Acoustic Backscatter-Based Method for Estimating Attenuation Towards Monitoring Lesion Formation in High Intensity Focused Ultrasound

This work investigated the transient characteristics of tissue attenuation coefficients before, during and after HIFU treatment at different total acoustic powers in

An Acoustic Backscatter-Based Method for Estimating Attenuation Towards Monitoring Lesion Formation in High Intensity Focused Ultrasound

This work investigated the transient characteristics of tissue attenuation coefficients before, during and after HIFU treatment at different total acoustic powers in