Journal•
Biomedical optics
About: Biomedical optics is an academic journal. The journal publishes majorly in the area(s): Optical coherence tomography & Laser. Over the lifetime, 4659 publications have been published receiving 18904 citations.
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TL;DR: The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage has been known for almost forty years since the invention of lasers.
Abstract: The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage has been known for almost forty years since the invention of lasers Originally thought to be a peculiar property of laser light (soft or cold lasers), the subject has now broadened to include photobiomodulation and photobiostimulation using non-coherent light Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial This likely is due to two main reasons; firstly the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones In particular a biphasic dose response has been frequently observed where low levels of light have a much better effect than higher levels This introductory review will cover some of the proposed cellular chromophores responsible for the effect of visible light on mammalian cells, including cytochrome c oxidase (with absorption peaks in the near infrared) and photoactive porphyrins Mitochondria are thought to be a likely site for the initial effects of light, leading to increased ATP production, modulation of reactive oxygen species and induction of transcription factors These effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increased tissue oxygenation The results of these biochemical and cellular changes in animals and patients include such benefits as increased healing in chronic wounds, improvements in sports injuries and carpal tunnel syndrome, pain reduction in arthritis and neuropathies, and amelioration of damage after heart attacks, stroke, nerve injury and retinal toxicity
431 citations
TL;DR: A universal back-projection formula for three-dimensional photoacoustic computed tomography in three types of imaging geometries: planar, spherical, and cylindrical surfaces is reported.
Abstract: We report a universal back-projection formula for three-dimensional photoacoustic computed tomography in three types of imaging geometries: planar, spherical, and cylindrical surfaces. A solid-angle weighting factor is introduced in the back-projection formula to compensate for the variations of detection views. Numerical simulation demonstrates the performance of the algorithm.
356 citations
TL;DR: The characteristics of fixational eye movements and the distortions they produce during retinal imaging are described, examples of images with particular distortions are shown, and eye movement records are shown obtained during the correction of these distortions.
Abstract: The newest generation of confocal scanning laser ophthalmoscopes with adaptive optics correction of ocular aberrations provides retinal images of unprecedented resolution, allowing for real-time imaging of photoreceptors in the living human eye. Natural fixational eye movements made by the subject/patient during recording produce distortions that are unique in each frame. Correction for these distortions is necessary before multiple frames can be added together to achieve noise reduction or to build a mosaic image from different retinal areas. Here we describe the characteristics of fixational eye movements and the distortions they produce during retinal imaging, we show examples of images with particular distortions, and show eye movement records obtained during the correction of these distortions.
128 citations
TL;DR: This work focuses on improving the spatial resolution and the quantitative accuracy of Diffuse Optical Tomography by using a priori anatomical information specific to unknown image, which leads to improved spatial resolution, quantitative accuracy and faster convergence than standard least squares approach.
Abstract: Diffuse optical imaging is an emerging modality that uses Near Infrared (NIR) light to reveal structural and functional information of deep biological tissue. It provides contrast mechanisms for molecular, chemical, and anatomical imaging that is not available from other imaging modalities. Diffuse Optical Tomography (DOT) deals with 3D reconstruction of optical properties of tissue given the measurements and a forward model of photon propagation. DOT has inherently low spatial resolution due to diffuse nature of photons. In this work, we focus to improve the spatial resolution and the quantitative accuracy of DOT by using a priori anatomical information specific to unknown image. Such specific a priori information can be obtained from a secondary high-resolution imaging modality such as Magnetic Resonance (MR) or X-ray. Image reconstruction is formulated within a Bayesian framework to determine the spatial distribution of the absorption coefficients of the medium. A spatially varying a priori probability density function is designed based on the segmented anatomical information. Conjugate gradient method is utilized to solve the resulting optimization problem. Proposed method is evaluated using simulation and phantom measurements collected with a novel time-resolved optical imaging system. Results demonstrate that the proposed method leads to improved spatial resolution, quantitative accuracy and faster convergence than standard least squares approach.
123 citations
TL;DR: The result shows that CAD is able to achieve a higher accuracy than humans for identification of dysplasia in EOCT images, and may be of assistance in the EO CT surveillance of large surface areas of Barrett’s mucosa for Dysplasia.
Abstract: Barrett's esophagus (BE) has become a major health care burden because of its association with adenocarcinoma of the esophagus. We have shown that endoscopic optical coherence tomography (EOCT) has a 70% accuracy in the diagnosis of dysplasia (Gastrointest Endosc 2003; 57:AB77). To demonstrate the feasiblity of computer aided diagnosis (CAD) of dysplasia in BE using EOCT digital images, to quantitate/standardize the diagnosis of dysplasia, and to develop algorithms suitable for EOCT surveillance of large areas of Barrett’s mucosa, 106 EOCT images were selected (13 patients from 28 cases) from the clinical study including 68 of non-dysplastic and 38 of dysplastic mucosa. From the digital image stream, the 3 frames immediately preceding impact of the forceps on the tissue were selected to insure close correlation between histology/EOCT image pairs. Computer aided diagnosis by center symmetric autocorrelation (CENS) and principal component analysis (PCA) were used for feature parameter extraction and analysis based on the segmented ROI. Leave-one-out cross-validation was used for classification and finally receiver operating characteristic (ROC) curve was used to evaluate the performance of CAD and the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated. The result shows that CAD is able to achieve a higher accuracy than humans for identification of dysplasia in EOCT images. CAD may be of assistance in the EOCT surveillance of large surface areas of Barrett’s mucosa for dysplasia.
110 citations