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Open accessJournal ArticleDOI: 10.3390/S21051776

In Vivo Quantitative Vasculature Segmentation and Assessment for Photodynamic Therapy Process Monitoring Using Photoacoustic Microscopy

04 Mar 2021-Sensors (Multidisciplinary Digital Publishing Institute)-Vol. 21, Iss: 5, pp 1776
Abstract: Vascular damage is one of the therapeutic mechanisms of photodynamic therapy (PDT). In particular, short-term PDT treatments can effectively destroy malignant lesions while minimizing damage to nonmalignant tissue. In this study, we investigate the feasibility of label-free quantitative photoacoustic microscopy (PAM) for monitoring the vasculature changes under the effect of PDT in mouse ear melanoma tumors. In particular, quantitative vasculature evaluation was conducted based on Hessian filter segmentation. Three-dimensional morphological PAM and depth-resolved images before and after PDT treatment were acquired. In addition, five quantitative vasculature parameters, including the PA signal, vessel diameter, vessel density, perfused vessel density, and vessel complexity, were analyzed to evaluate the influence of PDT on four different areas: Two melanoma tumors, and control and normal vessel areas. The quantitative and qualitative results successfully demonstrated the potential of the proposed PAM-based quantitative approach to evaluate the effectiveness of the PDT method.

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5 results found


Open accessJournal ArticleDOI: 10.3390/APP11083626
17 Apr 2021-Applied Sciences
Abstract: The healing power of light has attracted interest for thousands of years. Scientific discoveries and technological advancements in the field have eventually led to the emergence of photodynamic therapy, which soon became a promising approach in treating a broad range of diseases. Based on the interaction between light, molecular oxygen, and various photosensitizers, photodynamic therapy represents a non-invasive, non-toxic, repeatable procedure for tumor treatment, wound healing, and pathogens inactivation. However, classic photosensitizing compounds impose limitations on their clinical applications. Aiming to overcome these drawbacks, nanotechnology came as a solution for improving targeting efficiency, release control, and solubility of traditional photosensitizers. This paper proposes a comprehensive path, starting with the photodynamic therapy mechanism, evolution over the years, integration of nanotechnology, and ending with a detailed review of the most important applications of this therapeutic approach.

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15 Citations


Open accessJournal ArticleDOI: 10.3390/MA14195643
Songah Jeong1, Su Woong Yoo1, Hea Ji Kim1, Jieun Park1  +3 moreInstitutions (1)
28 Sep 2021-Materials
Abstract: For biomedical imaging, the interest in noninvasive imaging methods is ever increasing. Among many modalities, photoacoustic imaging (PAI), which is a combination of optical and ultrasound imaging techniques, has received attention because of its unique advantages such as high spatial resolution, deep penetration, and safety. Incorporation of exogenous imaging agents further amplifies the effective value of PAI, since they can deliver other specified functions in addition to imaging. For these agents, carbon-based materials can show a large specific surface area and interesting optoelectronic properties, which increase their effectiveness and have proved their potential in providing a theragnostic platform (diagnosis + therapy) that is essential for clinical use. In this review, we introduce the current state of the PAI modality, address recent progress on PAI imaging that takes advantage of carbon-based agents, and offer a future perspective on advanced PAI systems using carbon-based agents.

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Topics: Molecular imaging (51%)

Journal ArticleDOI: 10.1016/J.APACOUST.2021.108441
Xinkai Wu1, Zhi-Tao Luo1, Sheng Wang1, Zhang Hui1Institutions (1)
15 Jan 2022-Applied Acoustics
Abstract: The convolutional beamforming algorithm (COBA) which can be easily implemented by fast Fourier transform (FFT) and is suitable for real-time photoacoustic tomography (PAT) is introduced. In order to reveal the imaging effects of COBA, the photoacoustic images reconstructed by COBA, delay-and-sum algorithm (DAS), and minimum variance (MV) are investigated. The results demonstrate that the COBA significantly improves the lateral resolution and the contrast of the photoacoustic images. Moreover, the coherence factor (CF) as an adaptive weighting is used in COBA, the combined method shows that better lateral resolution and contrast of photoacoustic images can be obtained, which can be a potential imaging method for linear-array PAT.

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Open accessJournal ArticleDOI: 10.1016/J.PACS.2021.100310
Cao Duong Ly1, Van Tu Nguyen1, Tan Hung Vo1, Sudip Mondal1  +5 moreInstitutions (2)
01 Mar 2022-Photoacoustics
Abstract: Photoacoustic (PA) microscopy allows imaging of the soft biological tissue based on optical absorption contrast and spatial ultrasound resolution. One of the major applications of PA imaging is its characterization of microvasculature. However, the strong PA signal from skin layer overshadowed the subcutaneous blood vessels leading to indirectly reconstruct the PA images in human study. Addressing the present situation, we examined a deep learning (DL) automatic algorithm to achieve high-resolution and high-contrast segmentation for widening PA imaging applications. In this research, we propose a DL model based on modified U-Net for extracting the relationship features between amplitudes of the generated PA signal from skin and underlying vessels. This study illustrates the broader potential of hybrid complex network as an automatic segmentation tool for the in vivo PA imaging. With DL-infused solution, our result outperforms the previous studies with achieved real-time semantic segmentation on large-size high-resolution PA images.

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Open accessJournal ArticleDOI: 10.3390/PHOTONICS8090352
25 Aug 2021-Photonics
Abstract: Mosaic imaging is a computer vision process that is used for merging multiple overlapping imaging patches into a wide-field-of-view image. To achieve a wide-field-of-view photoacoustic microscopy (PAM) image, the limitations of the scan range of PAM require a merging process, such as marking the location of patches or merging overlapping areas between adjacent images. By using the mosaic imaging process, PAM shows a larger field view of targets and preserves the quality of the spatial resolution. As an essential process in mosaic imaging, various feature generation methods have been used to estimate pairs of image locations. In this study, various feature generation algorithms were applied and analyzed using a high-resolution mouse ear PAM image dataset to achieve and optimize a mosaic imaging process for wide-field PAM imaging. We compared the performance of traditional and deep learning feature generation algorithms by estimating the processing time, the number of matches, good matching ratio, and matching efficiency. The analytic results indicate the successful implementation of wide-field PAM images, realized by applying suitable methods to the mosaic PAM imaging process.

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Topics: Image resolution (51%)
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58 results found


Journal ArticleDOI: 10.1038/NRC1071
Abstract: The therapeutic properties of light have been known for thousands of years, but it was only in the last century that photodynamic therapy (PDT) was developed. At present, PDT is being tested in the clinic for use in oncology--to treat cancers of the head and neck, brain, lung, pancreas, intraperitoneal cavity, breast, prostate and skin. How does PDT work, and how can it be used to treat cancer and other diseases?

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Topics: Cancer (53%), Photodynamic therapy (52%)

4,555 Citations


Open accessJournal ArticleDOI: 10.1126/SCIENCE.1216210
Lihong V. Wang1, Song Hu1Institutions (1)
23 Mar 2012-Science
Abstract: Photoacoustic tomography (PAT) can create multiscale multicontrast images of living biological structures ranging from organelles to organs. This emerging technology overcomes the high degree of scattering of optical photons in biological tissue by making use of the photoacoustic effect. Light absorption by molecules creates a thermally induced pressure jump that launches ultrasonic waves, which are received by acoustic detectors to form images. Different implementations of PAT allow the spatial resolution to be scaled with the desired imaging depth in tissue while a high depth-to-resolution ratio is maintained. As a rule of thumb, the achievable spatial resolution is on the order of 1/200 of the desired imaging depth, which can reach up to 7 centimeters. PAT provides anatomical, functional, metabolic, molecular, and genetic contrasts of vasculature, hemodynamics, oxygen metabolism, biomarkers, and gene expression. We review the state of the art of PAT for both biological and clinical studies and discuss future prospects.

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Topics: Photoacoustic Techniques (59%), Photoacoustic Doppler effect (57%), Photoacoustic effect (56%) ... show more

3,002 Citations


Open accessJournal ArticleDOI: 10.1063/1.2195024
Abstract: Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) has the potential to image animal or human organs, such as the breast and the brain, with simultaneous high contrast and high spatial resolution. This article provides an overview of the rapidly expanding field of photoacoustic imaging for biomedical applications. Imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography with unfocused transducers, are introduced. Special emphasis is placed on computed tomography, including reconstruction algorithms, spatial resolution, and related recent experiments. Promising biomedical applications are discussed throughout the text, including (1) tomographic imaging of the skin and other superficial organs by laser-induced photoacoustic microscopy, which offers the critical advantages, over current high-resolution optical imaging modalities, of deeper imaging depth and higher absorptioncontrasts, (2) breast cancerdetection by near-infrared light or radio-frequency–wave-induced photoacoustic imaging, which has important potential for early detection, and (3) small animal imaging by laser-induced photoacoustic imaging, which measures unique optical absorptioncontrasts related to important biochemical information and provides better resolution in deep tissues than optical imaging.

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2,080 Citations


Open accessJournal ArticleDOI: 10.1021/CR900300P
Jonathan P. Celli1, Bryan Q. Spring2, Imran Rizvi2, Conor L. Evans2  +4 moreInstitutions (2)
12 May 2010-Chemical Reviews
Abstract: 1.1 Photodynamic Therapy and Imaging The purpose of this review is to present the current state of the role of imaging in photodynamic therapy (PDT). In order for the reader to fully appreciate the context of the discussions embodied in this article we begin with an overview of the PDT process, starting with a brief historical perspective followed by detailed discussions of specific applications of imaging in PDT. Each section starts with an overview of the specific topic and, where appropriate, ends with summary and future directions. The review closes with the authors’ perspective of the areas of future emphasis and promise. The basic premise of this review is that a combination of imaging and PDT will provide improved research and therapeutic strategies. PDT is a photochemistry-based approach that uses a light-activatable chemical, termed a photosensitizer (PS), and light of an appropriate wavelength, to impart cytotoxicity via the generation of reactive molecular species (Figure 1a). In clinical settings, the PS is typically administered intravenously or topically, followed by illumination using a light delivery system suitable for the anatomical site being treated (Figure 1b). The time delay, often referred to as drug-light interval, between PS administration and the start of illumination with currently used PSs varies from 5 minutes to 24 hours or more depending on the specific PS and the target disease. Strictly speaking, this should be referred to as the PS-light interval, as at the concentrations typically used the PS is not a drug, but the drug-light interval terminology seems to be used fairly frequently. Typically, the useful range of wavelengths for therapeutic activation of the PS is 600 to 800 nm, to avoid interference by endogenous chromophores within the body, and yet maintain the energetics necessary for the generation of cytotoxic species (as discussed below) such as singlet oxygen (1O2). However, it is important to note that photosensitizers can also serve as fluorescence imaging agents for which activation with light in the 400nm range is often used and has been extremely useful in diagnostic imaging applications as described extensively in Section 2 of this review. The obvious limitation of short wavelength excitation is the lack of tissue penetration so that the volumes that are probed under these conditions are relatively shallow. Open in a separate window Figure 1 (A) A schematic representation of PDT where PS is a photoactivatable multifunctional agent, which, upon light activation can serve as both an imaging agent and a therapeutic agent. (B) A schematic representation of the sequence of administration, localization and light activation of the PS for PDT or fluorescence imaging. Typically the PS is delivered systemically and allowed to circulate for an appropriate time interval (the “drug-light interval”), during which the PS accumulates preferentially in the target lesion(s) prior to light activation. In the idealized depiction here the PS is accumulation is shown to be entirely in the target tissue, however, even if this is not the case, light delivery confers a second layer of selectivity so that the cytotoxic effect will be generated only in regions where both drug and light are present. Upon localization of the PS, light activation will result in fluorescence emission which can be implemented for imaging applications, as well as generation cytotoxic species for therapy. In the former case light activation is achieved with a low fluence rate to generate fluorescence emission with little or no cytotoxic effect, while in the latter case a high fluence rate is used to generate a sufficient concentration of cytotoxic species to achieve biological effects.

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Topics: Imaging agent (53%)

1,631 Citations


Journal ArticleDOI: 10.1016/S1470-2045(04)01529-3
01 Aug 2004-Lancet Oncology
Abstract: It is more than 25 years since photodynamic therapy (PDT) was proposed as a useful tool in oncology, but the approach is only now being used more widely in the clinic. The understanding of the biology of PDT has advanced, and efficient, convenient, and inexpensive systems of light delivery are now available. Results from well-controlled, randomised phase III trials are also becoming available, especially for treatment of non-melanoma skin cancer and Barrett's oesophagus, and improved photosensitising drugs are in development. PDT has several potential advantages over surgery and radiotherapy: it is comparatively non-invasive, it can be targeted accurately, repeated doses can be given without the total-dose limitations associated with radiotherapy, and the healing process results in little or no scarring. PDT can usually be done in an outpatient or day-case setting, is convenient for the patient, and has no side-effects. Two photosensitising drugs, porfirmer sodium and temoporfin, have now been approved for systemic administration, and aminolevulinic acid and methyl aminolevulinate have been approved for topical use. Here, we review current use of PDT in oncology and look at its future potential as more selective photosensitising drugs become available.

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Topics: Methyl aminolevulinate (51%)

1,524 Citations


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