KEYWORDS: Sensors, Signal detection, Optoacoustics, Ultrasonography, Capacitance, Signal to noise ratio, In vivo imaging, Image processing, Objectives, Design and modelling
A wideband sensitive needle ultrasound sensor based on a polarized PVDF-TrFE copolymer piezoelectric film has been developed, which is capable of providing a noise equivalent pressure of 14 Pa and a uniform frequency response ranging from 1 to 25 MHz. Its high sensitivity (1.6 μV / Pa) and compact size were achieved by capitalizing on the large electromechanical coupling coefficient of PVDF-TrFE and minimizing parasitic capacitance in a two-stage amplifier structure. The detection sensitivity of the newly designed sensor outperformed commercially available hydrophones with an equivalent sensing element area by a factor of 9. The sensor has been successfully integrated into a light scanning optoacoustic microscopy (OAM) system with a limited working space. Submicrometer resolution images were subsequently attained from living mice without employing signal averaging. The miniature sensor design can readily be integrated into various OAM systems and further facilitate multimodal imaging system implementations.
Using optoacoustic microscopy, a radiation-induced increase in the fragmentation of experimental tumor small vessels, as well as the formation of large hemoglobin-containing structures were revealed within first days after treatment.
The possibilities of optoacoustic microscopy for comparison of vascular network of different tumor models as well as for investigation of tumor vessels response to radiation therapy were demonstrated.
KEYWORDS: Tumors, Tissues, Skin, Algorithm development, 3D image processing, Angiography, 3D image reconstruction, Optoacoustics, Reconstruction algorithms, In vivo imaging
We demonstrate the opportunities of the developed 3D optoacoustic image processing algorithm to characterize numerically the vasculature parameters in different applications including monitoring of tumor angiogenesis and assessing skin aging.
Our work was devoted to the experimental comparison of two ultra-wideband detectors based on PVDF piezofilms of different thickness demonstrating different quality of optoacoustic imaging of vessels in tumor and normal tissues.
We present the results of combined fluorescence and optoacoustic monitoring of tumor treatment using novel photoactivatable multi-inhibitor liposomes with BPD and Irinotecan providing a synergetic effect of PDT and chemotherapeutic impact.
Development of a number of diseases is accompanied by changes in the blood vessels’ structure and the investigation of tissue vascular pattern remains one of the most essential problems in experimental and clinical medicine. Hybrid methods of optoacoustic (OA) imaging enable label-free optical-contrast angiography at optical penetration depths with ultrasonic resolution. We used OA to study vascular network of experimental tumor during growth and after treatment as well as to study the dynamics of blood content of human skin during functional tests. Optoacoustic angiography was performed using raster-scan system in reflection mode with 532 nm laser source and wideband PVDF detector. The sensitivity of the system allowed to visualize 50 µm blood vessels at up to 2.1 mm depth. Minimally detected diameter of blood vessel located at the surface of a soft tissue was 15 µm. Imaging of colon tumor models CT26 and HT-29 revealed peculiarities of vascular system development. Irradiation-induced increase of small tumor vessels segments number and parallel decrease in the number of large hemoglobin-containing structures were demonstrated. The fraction of blood-filled vessels of the human skin was assessed during cuff occlusion and temporarily filling with blood became clearly visible on OA images. To study the effects of local mechanical compression on human skin vasculature we varied external pressure and revealed the gradual drop in OA signal from blood vessels. We demonstrated the possibilities of raster-scan angiography for in vivo analysis of vessels structure, for monitoring of neoangiogenesis and for dynamical investigation of blood content under external actions.
Cerebrovascular imaging of rodents is one of the trending applications of optoacoustics aimed at studying brain activity and pathology. Imaging of deep brain structures is often hindered by sub-optimal arrangement of the light delivery and acoustic detection systems. In our work we revisit the physics behind opto-acoustic signal generation and perform theoretical evaluation of optimal laser wavelengths with an aim of enabling whole brain cerebrovascular optoacoustic angiography in small rodents. A comprehensive model based on diffusion approximation was developed to simulate optoacoustic signal generation using optical and acoustic parameters closely mimicking a typical murine brain and surrounding tissues. The model revealed three characteristic wavelength ranges in the visible and near-infrared spectra optimally suited for imaging cerebral vasculature of different size and depth. The theoretical conclusions are confirmed by numerical simulations while in vivo imaging experiments further validated the capacity for accurately resolving brain vasculature at depths ranging between 0.7 and 7 mm.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.