Tissue elasticity is an important biomarker for early prediction of diseases, and elastography methods have been developed for several modalities. In practice, photoacoustic imaging (PAI) provides information about the optical properties of deep-seated tissue based on an ultrasonic readout. In this study, we demonstrate the use of PAI to measure tissue elasticity through high frequency acquisitions. The method was tested using tissue mimicking agar phantoms and transducers of different frequencies. The results show that elastic contrast can be recovered from PA signals only using high-frequency transducers, given significant differences of elasticity between the imaging target and background.
Photoacoutic imaging of biological tissues is characterized by depth dependent optical fluence loss and acoustic variations. Here, we aim to correct for these inaccuracies aided by extrinsic imaging priors obtained through concurrent high-frequency ultrasound (US) imaging of tissue samples. We segmented the skin line and characterized tissue components using deformable model-based segmentation from the ultrasound images. The prior information from co-registered US images and tissue temperature was used to accurately model light fluence and speed of sound respectively. Methods applied here show significant improvement in beamforming performance, enhanced visual image quality and a higher PSNR.
Determination of ovarian status and follicle monitoring are common methods of diagnosing female infertility. We
evaluated the suitability of selective plane illumination microscopy (SPIM) for the study of ovarian follicles. Owing to
the large field of view and fast acquisition speed of our newly developed SPIM system, volumetric image stacks from
entire intact samples of pig ovaries have been rendered demonstrating clearly discernible follicular features like follicle
diameters (70 μm - 2.5 mm), size of developing Cumulus oophorus complexes (COC ) (40 μm - 110 μm), and follicular
wall thicknesses (90 μm-120 μm). The observation of clearly distinguishable COCs protruding into the follicular antrum
was also shown possible, and correlation with the developmental stage of the follicles was determined. Follicles of all
developmental stages were identified, and even the small primordial follicle clusters forming the egg nest could be
observed. The ability of the system to non-destructively generate sub-cellular resolution 3D images of developing
follicles, with excellent image contrast and high throughput capacity compared to conventional histology, suggests that it
can be used to monitor follicular development and identify structural abnormalities indicative of ovarian ailments.
Accurate folliculometric measurements provided by SPIM images can immensely help the understanding of ovarian
physiology and provide important information for the proper management of ovarian diseases.
In this article we propose a point-of-care screening device for the detection and identification of malaria parasite, plasmodium vivax, plasmodium malaria, plasmodium oval and plasmodium falciparum with a time frame of 15-20 minute. In our device we can provide 97-98% sensitivity for each species as we are using traditional staining methods for detecting the parasites. In addition, as we are also quantifying the parasites, it is possible to provide an accurate estimate about the malarial stage of the patient. The image processing approach increases the total numbers of samples screened by reducing interventions of trained pathologists. This helps in reducing the delays in screening process arising from increased number of potential cases based on seasonal and local variations. The same reduces mortality rate by faster diagnosis and reduced false negative detections (i.e. increased sensitivity). The system can also be integrated with telemedicine platform to obtain inputs from medical practitioners at tertiary healthcare units for diagnostic decision making. Through this paper, we present the functional prototype of this device containing all the integrated parts.
The prototype incorporates image acquisition, image processing, storage, multimedia transmission and reporting
environment for a low cost PDA device. It is a portable device capable of scanning slides. The acquired image will be preprocessed and processed to get desired output. The device is capable of transmitting and storing pathological information to database placed in a distant pathological center for further consultation.
Imaging plays an increasingly important role in clinical management and preclinical studies of cancer. Application of optical molecular imaging technologies, in combination with highly specific contrast agent approaches, eminently contributed to understanding of functional and histological properties of tumors and anticancer therapies. Yet, optical imaging exhibits deterioration in spatial resolution and other performance metrics due to light scattering in deep living tissues. High resolution molecular imaging at the whole-organ or whole-body scale may therefore bring additional understanding of vascular networks, blood perfusion and microenvironment gradients of malignancies.
In this work, we constructed a volumetric multispectral optoacoustic tomography (vMSOT) scanner for cancer imaging in preclinical models and explored its capacity for real-time 3D intravital imaging of whole breast cancer allografts in mice. Intrinsic tissue properties, such as blood oxygenation gradients, along with the distribution of externally administered liposomes carrying clinically-approved indocyanine green dye (lipo-ICG) were visualized in order to study vascularization, probe penetration and extravasation kinetics in different regions of interest within solid tumors.
The use of v-MSOT along with the application of volumetric image analysis and perfusion tracking tools for studies of pathophysiological processes within microenvironment gradients of solid tumors demonstrated superior volumetric imaging system performance with sustained competitive resolution and imaging depth suitable for investigations in preclinical cancer models.
In optoacoustic imaging, the resolution and image quality in a certain imaging position usually cannot be enhanced without changing the imaging configuration. Post-reconstruction image processing methods offer a new possibility to improve image quality and resolution. We have developed a geometrical super-resolution (GSR) method which uses information from spatially separated frames to enhance resolution and contrast in optoacoustic images. The proposed method acquires several low resolution images from the same object located at different positions inside the imaging plane. Thereafter, it applies an iterative registration algorithm to integrate the information in the acquired set of images to generate a single high resolution image. Herein, we present the method and evaluate its performance in simulation and phantom experiments, and results show that geometrical super-resolution techniques can be a promising alternative to enhance resolution in optoacoustic imaging.
The speed of sound (SoS) in the imaged sample and in the coupling medium is an important parameter in optoacoustic tomography that must be specified in order to accurately restore maps of local optical absorbance. In this work, several hybrid focusing functions are described that successfully determine the most suitable SoS based on post-reconstruction images. The SoS in the coupling medium (water) can be determined from temperature readings. Thereby, this value is suggested to be used as an initial guess for faster SoS calibration in the reconstruction of tissues having a different SoS than water.
KEYWORDS: Calibration, Reconstruction algorithms, Wavelets, Tomography, Image quality, Temperature metrology, Signal to noise ratio, Real time imaging, Visualization, Image restoration
Reconstruction in multispectral optoacoustic tomography has become an critical area of importance, given the development of real-time imaging and visualization techniques. Speed of sound calibration is an intrinsic problem associated with the reconstruction process. Traditionally, the calibration has been user mediated, making it a tedious and offline affair. In this manuscript, we aim to introduce autofocusing and wavelet based measures to automatically calibrate the speed of sound. Further, it is observed that the temperature of the coupling medium (water) often drift during the signal acquisition, severely straining the image quality. The measures address these problems by iteratively determining the speeds with the changing boundary conditions with time.
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