High-resolution imaging of microvasculature in human skin in-vivo with optical coherence tomography

Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA.
Optics Express (Impact Factor: 3.49). 03/2012; 20(7):7694-705. DOI: 10.1364/OE.20.007694
Source: PubMed


In this paper, the features of the intensity-based Doppler variance (IBDV) method were analyzed systemically with a flow phantom. The effects of beam scanning density, flow rate and the time interval between neighboring A-lines on the performance of this method were investigated. The IBDV method can be used to quantify the flow rate and its sensitivity can be improved by increasing the time interval between the neighboring A-lines. A higher sensitivity IBDV method that applies the algorithm along the slower scan direction was proposed. In comparison to laser speckle imaging maps of blood flow, we demonstrated the ability of the method to identify vessels with altered blood flow. In clinical measurements, we demonstrated the ability of the method to image vascular networks with exquisite spatial resolution and at depths up to 1.2 mm in human skin. These results collectively demonstrated the potential of the method to monitor the microvasculature during disease progression and in response to therapeutic intervention.

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    • "The intensity-based methods are based on the speckle effect and are capable of characterizing the transverse component (perpendicular to the OCT beam) of the flow velocity. Intensity-based Doppler variance algorithm [30], amplitude speckle [31], intensity threshold binarization-based method [32], split-spectrum amplitude-decorrelation angiography method [33], logarithmic intensity-based motion contrast methods [34] and amplitude autocorrelation (AAC) method [35] are among the intensity-based methods. "
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    ABSTRACT: In this paper, we propose a super-resolution spectral estimation technique to quantify microvascular hemodynamics using optical microangiography (OMAG) based on optical coherence tomography (OCT). The proposed OMAG technique uses both amplitude and phase information of the OCT signals which makes it sensitive to the axial and transverse flows. The scanning protocol for the proposed method is identical to three-dimensional ultrahigh sensitive OMAG, and is applicable for in vivo measurements. In contrast to the existing capillary flow quantification methods, the proposed method is less sensitive to tissue motion and does not have aliasing problems due fast flow within large blood vessels. This method is analogous to power Doppler in ultrasonography and estimates the number of red blood cells passing through the beam as opposed to the velocity of the particles. The technique is tested both qualitatively and quantitatively by using OMAG to image microcirculation within mouse ear flap in vivo.
    Biomedical Optics Express 07/2013; 4(7):1214-1228. DOI:10.1364/BOE.4.001214 · 3.65 Impact Factor
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    • "The development of Fourier domain OCT brought a dramatic increase in sensitivity which made in vivo full volume measurement with short acquisition time possible [7–10]. Human skin microcirculation imaging based on Fourier domain OCT was demonstrated by calculating the intensity-based Doppler variance [11]. An enhanced field of view (FOV) of up to 8 × 7 mm was shown by correlation mapping OCT [12]. "
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    ABSTRACT: We demonstrate noninvasive structural and microvascular contrast imaging of different human skin diseases in vivo using an intensity difference analysis of OCT tomograms. The high-speed swept source OCT system operates at 1310 nm with 220 kHz A-scan rate. It provides an extended focus by employing a Bessel beam. The studied lesions were two cases of dermatitis and two cases of basal cell carcinoma. The lesions show characteristic vascular patterns that are significantly different from healthy skin. In case of inflammation, vessels are dilated and perfusion is increased. In case of basal cell carcinoma, the angiogram shows a denser network of unorganized vessels with large vessels close to the skin surface. Those results indicate that assessing vascular changes yields complementary information with important insight into the metabolic demand.
    Biomedical Optics Express 10/2012; 3(10):2636-46. DOI:10.1364/BOE.3.002636 · 3.65 Impact Factor
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    • ". The characteristics of IBDV and PRDV are quite similar: the variance value increases proportionally with the increase of the time interval until the variance values reach saturation at large time intervals. One efficient way to obtain high velocity sensitivity is to apply the algorithms along the slow scanning direction [8,12,16,20,30,31]. This inter-frame (IF) algorithm method can improve the velocity sensitivity without modification of the OCT hardware or software. "
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    ABSTRACT: We compare, in detail, the phase-resolved color Doppler (PRCD), phase-resolved Doppler variance (PRDV) and intensity-based Doppler variance (IBDV) methods. All the methods are able to quantify flow speed when the flow rate is within a certain range, which is dependent on the adjacent A-line time interval. While PRCD is most sensitive when the flow direction is along the probing beam, PRDV and IBDV can be used to measure the flow when the flow direction is near perpendicular to the probing beam. However, the values of PRDV and IBDV are Doppler angle-dependent when the Doppler angle is above a certain threshold. The sensitivity of all the methods can be improved by increasing the adjacent A-line time interval while still maintaining a high sampling density level. We also demonstrate for the first time, to the best of our knowledge, high resolution inter-frame PRDV method. In applications where mapping vascular network such as angiogram is more important than flow velocity quantification, IBDV and PRDV images show better contrast than PRCD images. The IBDV and PRDV show very similar characteristics and demonstrate comparable results for vasculature mapping. However, the IBDV is less sensitive to bulk motion and with less post-processing steps, which is preferred for fast data processing situations. In vivo imaging of mouse brain with intact skull and human skin with the three methods were demonstrated and the results were compared. The IBDV method was found to be able to obtain high resolution image with a relative simple processing procedure.
    Biomedical Optics Express 10/2012; 3(10):2669-80. DOI:10.1364/BOE.3.002669 · 3.65 Impact Factor
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