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Optical Methods for Diabetic Foot Ulcer Screening
Published in Andrey V. Dunaev, Valery V. Tuchin, Biomedical Photonics for Diabetes Research, 2023
Robert Bartlett, Gennadi Saiko, Alexandre Yu. Douplik
An original method described by Tromberg et al. [74] is a development of a rapid, noncontact imaging for quantitative, wide-field characterization of optical absorption and scattering properties of turbid media based on spatial frequency domain imaging (SFDI). This group experimentally demonstrated that by projecting sinusoidal patterns of light onto tissue, one can determine the tissue’s optical properties by measuring the relative decay of spatial patterns of differing frequencies. An algorithm was proposed for reconstructing three-dimensional images directly from measurements made by illuminating tissue with sinusoidal patterns [75] and experimentally proven as a quantitative optical tomography of subsurface heterogeneities (e.g., blood vessels) using spatially modulated structured light [76] and collecting images separated in terms of absorption and reduced scattering coefficients [77]. SFDI has been demonstrated preclinically to track wound healing in a diabetes model [78]. A clinical study has been conducted applying SFDI to measure perfusion in lower extremities for the prediction of both healing and formation of DFU [79,80].
Brain Monitoring Using Optical Imaging and Optical Spectroscopy
Published in Richard A. Jonas, Jane W. Newburger, Joseph J. Volpe, John W. Kirklin, Brain Injury and Pediatric Cardiac Surgery, 2019
Although the power to make good optical tomographic images is only now becoming a reality, light has long been used as a diagnostic imaging tool in vivo. Just as dairy farmers used light to candle eggs, light has also been used to transilluminate the body. Curling, an English physician, reported the use of a flare lantern to transilluminate the scrotum of his patients to screen for tumors in 1843.55 This technique culminated over a century later with the development of a visible light system for detecting breast tumors, known as diaphanography. Unfortunately, this device fell short of its promise, merely generating shadowgrams of superficial structures such as veins while deep structures such as tumors remained lost in a diffuse background glow. These devices failed because they did not take into account the path of photon travel.
Introduction to optical imaging
Published in Ahmad Fadzil Mohamad Hani, Dileep Kumar, Optical Imaging for Biomedical and Clinical Applications, 2017
Dileep Kumar, Ahmad Fadzil Mohamad Hani
At present, various imaging modalities are available that use principles of biomedical optics. The most commonly used biomedical optical imaging techniques are optical coherence tomography (OCT), endoscopy, multispectral endoscopy photoacoustic imaging, diffuse optical tomography (DOT), diffuse reflectance imaging and microscopic techniques such as fluorescence microscopy, stimulated emission depletion (STED), confocal microscopy and multiphoton microscopy. These modalities are portable, cost-effective, and are being used for in vivo and noninvasive imaging of tissues, spanning from molecular and cellular levels. Example images of these optical imaging techniques are shown in Figure 1.3a–d. A brief discussion of each modality is given below and in the following section. The detailed discussion on microscopic optical imaging modalities is given in Section 1.4.
Selective laser sintering 3D printing – an overview of the technology and pharmaceutical applications
Published in Drug Development and Industrial Pharmacy, 2020
Naseem A. Charoo, Sogra F. Barakh Ali, Eman M. Mohamed, Mathew A. Kuttolamadom, Tanil Ozkan, Mansoor A. Khan, Ziyaur Rahman
Usually, 3D objects have higher surface roughness resulting from limited resolution. Therefore, the final esthetic appeal of the product requires an additional mechanical or chemical post-processing step. This is important for reducing staircase effect and deformations. The esthetic appeal can be improved using a bimodal powder with finer powder appearing on the upper surface. Varying powder density may also be a useful strategy to improve the surface appeal of the product. An on-line process monitoring technique called optical tomography has been developed for detecting defects such as lack of fusion. The usefulness of optical coherence tomography in assessing surface and sub-surface features has been demonstrated. Areas of sintering non-uniformity and areas of excessive heat error were identified using tomography [42].
A systematic review of diagnostic techniques to determine tissue perfusion in patients with peripheral arterial disease
Published in Expert Review of Medical Devices, 2019
Kirsten F. Ma, Simone F. Kleiss, Richte C.L. Schuurmann, Reinoud P.H. Bokkers, Çagdas Ünlü, Jean-Paul P.M. De Vries
Several techniques have been recently introduced that may enable tissue perfusion measurements in the lower extremity. Studies with non-invasive techniques include hyperspectral imaging (HSI), laser Doppler perfusion imaging (LDPI), laser speckle contrast imaging (LSCI), near-infrared (NIR) spectroscopy (NIRS), spectrophotometry, transcutaneous oxygen measurements (TcPo2) and vascular optical tomography imaging (VOTI). Other diagnostic techniques using endogenous or exogenous contrast agents include magnetic resonance perfusion imaging (MRI perfusion), contrast-enhanced ultrasound (CEUS) and NIR fluorescence imaging with indocyanine green (ICG). All of these techniques focus on assessment of the microcirculation of the skin or muscle in the lower extremity, but act on different mechanisms.
Machine learning approaches to improve disease management of patients with rheumatoid arthritis: review and future directions
Published in Expert Review of Clinical Immunology, 2021
Joanna Kedra, Thomas Davergne, Ben Braithwaite, Hervé Servy, Laure Gossec
ML methods may also be applied to other imaging techniques. A study based on diffuse optical tomography of proximal interphalangeal joints showed that the use of a polynomial SVM classifier helped for diagnosing RA with a sensitivity of 100.0% and a specificity of 97.8% [58]. Other studies developed automated algorithms to detect synovitis on magnetic resonance imaging (MRI), and compared results from the algorithm with the semi-quantitative RAMRIS scoring system [59,60]. The correlation between automated algorithms and RAMRIS was good, with r = 0.70 to 0.90. These results indicate the potential of ML methods applied to MRI for clinical applications in RA.