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Optoacoustic (OA) imaging utilizes short laser pulses to create acoustic sources in tissue and time resolved detection of generated pressure profiles for image reconstruction. The ultrasonic transients provide information on the distribution of optical absorption coefficient that can be useful for early cancer diagnostics. In this work a new design of wide-band array transducer is developed and tested. The array consists of 32 focused piezo-elements made of PVDF slabs imposed on a cylindrical surface. A single array element response to an OA signal coming from arbitrarily located point source is investigated theoretically and experimentally. The measured signals correspond well to numerically calculated ones. Focal zone maps of the elements with aperture angles 30 degrees and 60 degrees are presented and discussed; the resolution in direction perpendicular to the imaging plane is determined. Point spread function of the whole array is calculated using experimentally obtained signals from the sources located at different distances from the array. Backprojection algorithm is employed for reconstruction of the optoacoustic images. It is shown that the spatial resolution of the images yielded by the proposed array increases significantly compared to previous transducer designs.

The goal of this work was to investigate numerically the dependence of the resolution and the imaging window size, provided by a cylindrically focused wideband piezoelectric detector in optoacoustic tomography, on the detector dimensions and frequency bandwidth. Analytical expressions found by O’Neil for a continuous spherically focused ultrasonic radiator were found to fit the numerical data accurately to within a constant factor. The range of application and limitations of these expressions were investigated.

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The applicability of the optoacoustic (OA) method for monitoring temperature during thermal impact on biological tissues is studied experimentally. Tissues under study were chicken breast (as a model of muscle), porcine lard (as a model of fatty tissue) and porcine liver (as a model of richly perfused tissue). The temperature dependences of the amplitude of the OA signals excited in biologi cal tissues were measured in-vitro in the temperature range of 20 -80 °C under the narrow laser beam conditions. Measurements were performed in two regimes: during heating and cooling. Simi larities and differences in the behaviour of the dependences in dif ferent temperature ranges associated with different structural com position of the samples were obtained. The accuracy of temperature reconstruction from experimental data for the investigated tissue types was evaluated. It is shown that during tissue coagulation its temperature can be determined with an accuracy of about 1 °C.

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This article reviews the most current methods and technological aspects of highintensity focused ultrasound (HIFU), which is termed histotripsy. The rationale for focal therapy for prostate carcinoma rather than prostatectomy, which is being used extensively throughout Europe and Asia, is presented, and an argument for why HIFU is the modality of choice for primary therapy and recurrent disease is offered. The article presents a review of the technical advances including higher ultrasound beam energy than current thermal HIFU which allows for more accurate tissue targeting, less collateral tissue damage, and faster treatment times. Finally, the article presents a discussion about the advantage of ultrasound guidance for histotripsy in preference to magnetic resonance imaging guidance primarily based on cost, ease of application, and portability.

Current clinical treatment regimens, including many emergent immune strategies (e.g. checkpoint inhibitors) have done little to affect the devastating course of pancreatic ductal adenocarcinoma (PDA). Clinical trials for PDA often employ multi-modal treatment, and have started to incorporate stromal-targeted therapies, which have shown promising results in early reports. Focused ultrasound (FUS) is one such therapy that is uniquely equipped to address local and systemic limitations of conventional cancer therapies as well as emergent immune therapies for PDA. FUS methods can non-invasively generate mechanical and/or thermal effects that capitalize on the unique oncogenomic/proteomic signature of a tumor. Potential benefits of FUS therapy for PDA include: 1) emulsification of targeted tumor into undenatured antigens in situ, increasing dendritic cell maturation, and increasing intra-tumoral CD8+/ T regulatory cell ratio and CD8+ T cell activity; 2) reduction in intra-tumoral hypoxic stress; 3) modulation of tumor cell membrane protein localization to enhance immunogenicity; 4) modulation of the local cytokine milieu toward a Th1-type inflammatory profile; 5) up-regulation of local chemoattractants; 6) remodeling the tumor stroma; 7) localized delivery of exogenously packaged immune-stimulating antigens, genes and therapeutic drugs. While not all of these results have been studied in experimental PDA models to date, the principles garnered from other solid tumor and disease models have direct relevance to the design of optimal FUS protocols for PDA. In this review, we address the pertinent limitations in current and emergent immune therapies that can be improved with FUS therapy for PDA.