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OMAG image of cortical brain in mouse with intact skull in vivo (enface view of maximum projection image with volumetric data).
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The microcirculation is a complex system, and the visualization of microcirculation has great significance in improving our understanding of pathophysiological processes in various disease conditions, in both clinical and fundamental studies. A range of techniques are available or emerging for investigating different aspect of the microcirculation...
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... show the advantages of DOMAG in imaging the blood flow velocities over PRDOCT, a 3D comparison of DOMAG and PRDOCT images were evaluated from a scanned tissue volume from the mouse brain cortex with the skull left intact. Figure 8 shows the OMAG image of cortical brain in mouse with intact skull in vivo. ...Citations
... A fotopletismografia (PPG) é uma técnica óptica, não invasiva, de baixo custo e amplamente usada na monitorização de pacientes em cuidados intensivos, anestesia e medicina de emergência (1)(2)(3). Esta técnica detecta alterações no volume sanguíneo periférico em diferentes partes do corpo (4,5), especialmente em extremidades. Para isso, a PPG utiliza luz monocromática aplicada sobre um tecido e a resposta é modulada por mudanças no volume de sangue presente no vaso, permitindo a determinação da frequência cardíaca (FC). ...
A fotopletismografia (PPG) é uma técnica utilizada na monitoração da saturação de oxigênio (SpO2) e frequência cardíaca. A medição da pressão arterial é convencionalmente feita utilizando o esfigmomanômetro (EM). O EM, além de depender da oclusão de um membro não é possível de realizar a medida de forma contínua. Através da Análise da Decomposição do pulso de PPG foi demonstrado que é possível determinar a Pressão Arterial, através da determinação do Tempo de Trânsito do pulso sanguíneo (PTT). Entretanto, a decomposição em pulsos gaussianos, Rayleigh e Log-Normal sugeridas na literatura geram grandes incertezas na determinação de PTT. Para diminuir tais incertezas, sugerimos como hipótese o uso da decomposição da curva de PPG em pulsos do tipo secante hiperbólica. Analisamos 20 curvas de PPG para nove voluntários com idades de 20 a 50 anos. Utilizamos minimização de Qui-quadrado e o critério de Akaike para avaliação dos resultados. A decomposição em pulsos do tipo secante hiperbólica reduziu a incerteza relativa na determinação do PTT em cerca de 50%, em relação ao padrão da literatura que é a decomposição em pulsos gaussianos. Para determinação de pressão arterial através de PPG, essa redução na incerteza permite resposta quatro vezes mais rápida na medida de variações de pressão arterial, para uma dada resolução.Palavras-chave: Pressão Arterial, Pletismografia, Monitoramento não invasivo, Análise de Decomposição de pulso
... Among them, a videocapillaroscope, which provides high magnification, has been used to examine and classify the morphological shape of the capillaries to distinguish the diseases accurately [8,9]. However, the shape of the capillaries is immensely sensitive to external environments, and as a result, the outcomes have been shown to vary [10]. Moreover, the diagnosis using the device can be only realized by dermatologists in a hospital. ...
For appropriate treatment, accurate discrimination between seborrheic dermatitis and psoriasis in a timely manner is crucial to avoid complications. However, when they occur on the scalp, differential diagnosis can be challenging using conventional dermascopes. Thus, we employed smartphone-based multispectral imaging and analysis to discriminate between them with high accuracy. A smartphone-based multispectral imaging system, suited for scalp disease diagnosis, was redesigned. We compared the outcomes obtained using machine learning-based and conventional spectral classification methods to achieve better discrimination. The results demonstrated that smartphone-based multispectral imaging and analysis has great potential for discriminating between these diseases.
... Recently, the functional extension of the OCT technique to image depth-resolved microcirculation has become a very promising area of research. There is a growing interest in the field of development of various types of OCT based angiographic techniques, which aims to visualize the lumens and architecture of blood vessels in many clinical and fundamental areas of research, including cardiology, dermatology, neurology, ophthalmology, small animal imaging studies, and so forth [8]. OCT-based angiography techniques utilize the red blood cell scattering dynamics as contrast mechanism, which exhibits phase or amplitude fluctuations over time, while the static tissue scattering is relatively constant over time. ...
In this paper we demonstrate a novel application of correlation mapping optical coherence tomography (cm-OCT) for volumetric nailfold capillaroscopy (NFC). NFC is a widely used non-invasive diagnostic method to analyze capillary morphology and microvascular abnormalities of nailfold area for a range of disease conditions. However, the conventional NFC is incapable of providing volumetric imaging, when volumetric quantitative microangiopathic parameters such as plexus morphology, capillary density, and morphologic anomalies of the end row loops most critical. cm-OCT is a recently developed well established coherence domain magnitude based angiographic modality, which takes advantage of the time-varying speckle effect, which is normally dominant in the vicinity of vascular regions compared to static tissue region. It utilizes the correlation coefficient as a direct measurement of decorrelation between two adjacent B-frames to enhance the visibility of depth-resolved microcirculation.
... There is a growing interest in the field of development of various types of OCTbased angiographic techniques, which aims to visualize the lumens and architecture of blood vessels in many clinical and fundamental areas of research, including cardiology, dermatology, neurology, ophthalmology, small animal imaging studies, and so forth. 6 OCT-based angiography techniques utilize the red blood cell scattering dynamics as contrast mechanism, which exhibits phase or amplitude fluctuations over time, while the static tissue scattering is relatively constant over time. There are mainly three categories of OCT-based angiography methods, which are essentially based on the utilization of the complex nature of the OCT signal to obtain the microcirculation map: phase-based techniques, 7-11 magnitude-based techniques, [12][13][14][15][16][17] and techniques that use the complex data, [18][19][20][21][22][23] incorporating both magnitude and phase information. ...
Microcirculation imaging is a key parameter for studying the pathophysiological processes of various disease conditions, in both clinical and fundamental research. A full-range spectral-domain correlation mapping optical coherence tomography (cm-OCT) method to obtain a complex-conjugate-free, full-range depth-resolved microcirculation map is presented. The proposed system is based on a high-speed spectrometer at 91 kHz with a modified scanning protocol to achieve higher acquisition speed to render cm-OCT images with high-speed and wide scan range. The mirror image elimination is based on linear phase modulation of B-frames by introducing a slight off-set of the probe beam with respect to the lateral scanning fast mirror's pivot axis. An algorithm that exploits the Hilbert transform to obtain a complex-conjugate-free image in conjunction with the cm-OCT algorithm is used to obtain full-range imaging of microcirculation within tissue beds in vivo. The estimated sensitivity of the system was around 105 dB near the zero-delay line with ∼20 dB roll-off from ±0.5 to ±3 mm imaging-depth position. The estimated axial and lateral resolutions are ∼12 and ∼30 μm, respectively. A direct consequence of this complex conjugate artifact elimination is the enhanced flow imaging sensitivity for deep tissue imaging application by imaging through the most sensitive zero-delay line and doubling the imaging range.
In this review article, we explore the mechanisms of optical coherence tomography (OCT) and its applications in various skin diseases. OCT is a novel real-time imaging modality based on Michelson interferometry of infrared radiation and living tissues. This technique permits the high resolution of 2 and 3-dimensional cross-sectional microvasculature imaging of tissues and surveillance over time. The major purpose of this review article is to explore OCT imaging of skin tumors, oral tumors, tumor angiogenesis, and choroidal tumors with early phase detection.
