High-speed optical coherence tomography by circular interferometric ranging.

Existing three-dimensional optical imaging methods excel in controlled environments but are difficult to deploy over large, irregular and dynamic fields. This has limited imaging in areas such as material inspection and medicine. To better address these applications, we developed methods in optical coherence tomography (OCT) to efficiently interrogate sparse scattering fields, i.

Phase-stable Doppler OCT at 19 MHz using a stretched-pulse mode-locked laser.

We present a swept-wavelength optical coherence tomography (OCT) system with a 19 MHz laser source and electronic phase-locking of the source, acquisition clock, and beam scanning mirrors. The laser is based on stretched-pulse active mode-locking using an electro-optic modulator. Beam scanning in the fast axis uses a resonant micro-electromechanical systems (MEMS) -based mirror at ~23.

Lymphatic function measurements influenced by contrast agent volume and body position.

Several imaging modalities have been used to assess lymphatic function, including fluorescence microscopy, near-infrared fluorescence (NIRF) imaging, and Doppler optical coherence tomography (DOCT). They vary in how the mouse is positioned, the invasiveness of the experimental setup, and the volume of contrast agent injected. Here, we present how each of these experimental parameters affects functional measurements of collecting lymphatic vessels.

Methicillin-resistant causes sustained collecting lymphatic vessel dysfunction.

Methicillin-resistant (MRSA) is a major cause of morbidity and mortality worldwide and is a frequent cause of skin and soft tissue infections (SSTIs). Lymphedema-fluid accumulation in tissue caused by impaired lymphatic vessel function-is a strong risk factor for SSTIs. SSTIs also frequently recur in patients and sometimes lead to acquired lymphedema.

Simultaneous measurements of lymphatic vessel contraction, flow and valve dynamics in multiple lymphangions using optical coherence tomography.

Lymphatic dysfunction is involved in many diseases including lymphedema, hypertension, autoimmune responses, graft rejection, atherosclerosis, microbial infections, cancer and cancer metastasis. Expanding our knowledge of lymphatic system function can lead to a better understanding of these disease processes and improve treatment options. Here, optical coherence tomography (OCT) methods were used to reveal intraluminal valve dynamics in 3 dimensions, and measure lymph flow and vessel contraction simultaneously in 3 neighboring lymphangions of the afferent collecting lymphatic vessels to the popliteal lymph node in mice.

Murine chronic lymph node window for longitudinal intravital lymph node imaging.

Chronic imaging windows in mice have been developed to allow intravital microscopy of many different organs and have proven to be of paramount importance in advancing our knowledge of normal and disease processes. A model system that allows long-term intravital imaging of lymph nodes would facilitate the study of cell behavior in lymph nodes during the generation of immune responses in a variety of disease settings and during the formation of metastatic lesions in cancer-bearing mice. We describe a chronic lymph node window (CLNW) surgical preparation that allows intravital imaging of the inguinal lymph node in mice.

Lymph node effective vascular permeability and chemotherapy uptake.

Objective: Lymph node metastases are a poor prognostic factor. Additionally, responses of lymph node metastasis to therapy can be different from the primary tumor. Investigating the physiologic lymph node blood vasculature might give insight into the ability of systemic drugs to penetrate the lymph node, and thus into the differential effect of therapy between lymph node metastasis and primary tumors.

In vivo label-free measurement of lymph flow velocity and volumetric flow rates using Doppler optical coherence tomography.

Direct in vivo imaging of lymph flow is key to understanding lymphatic system function in normal and disease states. Optical microscopy techniques provide the resolution required for these measurements, but existing optical techniques for measuring lymph flow require complex protocols and provide limited temporal resolution. Here, we describe a Doppler optical coherence tomography platform that allows direct, label-free quantification of lymph velocity and volumetric flow rates.

Line-field parallel swept source MHz OCT for structural and functional retinal imaging.

We demonstrate three-dimensional structural and functional retinal imaging with line-field parallel swept source imaging (LPSI) at acquisition speeds of up to 1 MHz equivalent A-scan rate with sensitivity better than 93.5 dB at a central wavelength of 840 nm. The results demonstrate competitive sensitivity, speed, image contrast and penetration depth when compared to conventional point scanning OCT.

Doppler optical coherence tomography.

Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology.

Angle independent flow assessment with bidirectional Doppler optical coherence tomography.

Bidirectional Doppler optical coherence tomography is a stable and accurate method to extract the absolute velocity of vessels close to perpendicular to the optical axis by illuminating the sample under two different angles. However it requires knowledge of the vessel angle in the en face plane. In this Letter, we demonstrate that a direct calculation of the flow out of bidirectional Doppler cross sections perpendicular to the illumination plane is independent of that angle and of the Doppler angle, thereby improving the accuracy and flexibility of that technique.

Dove prism based rotating dual beam bidirectional Doppler OCT.

Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism.

Intrasweep phase-sensitive optical coherence tomography for noncontact optical photoacoustic imaging.

We introduce a method to extract the photoacoustic (PA) signal from the phase time evolution of an optical coherence tomography (OCT) swept source spectral sweep. This all-optical detection is achieved in a noncontact fashion directly on the sample surface by using its specular reflection. High-speed measurement and referencing allow for close to shot noise limited phase-sensitive detection.

In situ structural and microangiographic assessment of human skin lesions with high-speed OCT.

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.

Ultrahigh-speed non-invasive widefield angiography.

Retinal and choroidal vascular imaging is an important diagnostic benefit for ocular diseases such as age-related macular degeneration. The current gold standard for vessel visualization is fluorescence angiography. We present a potential non-invasive alternative to image blood vessels based on functional Fourier domain optical coherence tomography (OCT).

Extended focus high-speed swept source OCT with self-reconstructive illumination.

We present a Bessel beam illumination FDOCT setup using a FDML Swept Source at 1300 nm with up to 440 kHz A-scan rate, and discuss its advantages for structural and functional imaging of highly scattering samples. An extended focus is achieved due to the Bessel beam that preserves its lateral extend over a large depth range. Furthermore, Bessel beams exhibit a self-reconstruction property that allows imaging even behind obstacles such as hairs on skin.

Imaging of the parafoveal capillary network and its integrity analysis using fractal dimension.

Using a spectral domain OCT system, equipped with a broadband Ti:sapphire laser, we imaged the human retina with 5 µm x 1.3 µm transverse and axial resolution at acquisition rate of 100 kHz. Such imaging speed significantly reduces motion artifacts.

Vectorial reconstruction of retinal blood flow in three dimensions measured with high resolution resonant Doppler Fourier domain optical coherence tomography.

Resonant Doppler Fourier domain optical coherence tomography (FDOCT) is a functional imaging tool for extracting tissue flow. The method is based on the effect of interference fringe blurring in spectrometer-based FDOCT, where the path difference between structure and reference changes during camera integration. If the reference path length is changed in resonance with the Doppler frequency of the sample flow, the signals of resting structures will be suppressed, whereas the signals of blood flow are enhanced.

Resonant Doppler flow imaging and optical vivisection of retinal blood vessels.

For Fourier domain optical coherence tomography any sample movement during camera integration causes blurring of interference fringes and as such reduction of sensitivity for flow detection. The proposed method overcomes this problem by phase-matching a reference signal to the sample motion. The interference fringes corresponding to flow signal will appear frozen across the detector whereas those of static sample structures will be blurred resulting in enhanced contrast for blood vessels.