Atherosclerosis is characterised by the buildup of plaque in the inner lining of vessels. Unstable atherosclerotic plaques are prone to rupture, which can lead to heart attacks or strokes. Current clinically available imaging techniques cannot accurately identify unstable plaques based on their structural features. It has been previously reported that unstable plaques may emit autofluorescence. Therefore, our team has developed a dual modality optical coherence tomography and fluorescence intravascular imaging system, and a miniaturised fibre-optic probe incorporating a 3D printed lens. The 3D printed lens is designed to correct the astigmatism that arises from the intravascular catheter, and to reduce stray light. Although the 3D printed lens is made by a polymer photoresist, it has low background fluorescence. We are using our novel fibre probe to explore the autofluorescence present in unstable human plaques.
Atherosclerosis is a leading cause of global mortality. Current clinically available imaging techniques suffer from limited spatial resolution and lack the ability to identify biomolecular features of atherosclerotic plaques. To address this, our team has developed a bimodal imaging system which consists of optical coherence tomography (OCT) and fluorescence. In addition, a nanoparticle named porphysomes is used as a fluorescence contrast agent to target macrophages in the plaques of diseased mice. Results suggest that our intravascular imaging system is capable of detecting the fluorescence from nanoparticles which provides complementary biological information to the structural information obtained from simultaneously-acquired OCT images.
Modern noninvasive imaging techniques are used in many areas of medical research, particularly where an additional modality is required to support close monitoring during pre- or post-care. In oral medicine, the combination of an experienced clinician and supporting noninvasive optical devices for oral imaging, such as optical coherence tomography (OCT), may ensure improved diagnosis. In this study, the pathological features of lichenoid oral mucosa were noninvasively imaged with our miniaturized pen-like OCT probe and compared to adjacent healthy areas. The non-homogeneous epithelial (EP) layer, increased cornification of the EP surface and unidentifiable basement membrane are the most important features recorded.
Preclinical studies and clinical diagnostics increasingly rely on optical techniques to visualize internal organs. Miniaturised catheters or endoscopes are necessary for imaging small and/or delicate arteries. However, current lens fabrication methods limit the performance of these ultrathin devices, resulting in a poor combination of resolution, depth of focus and multimodal imaging capability. This talk will introduce our latest research to address these combined challenges. In particular, we have utilized 3D micro-printing technology to fabricate freeform optics directly onto an optical fiber to achieve freeform designs for aberration-corrected optical coherence tomography (OCT) and to enable highly-sensitive multimodal fluorescence+OCT imaging in vivo.
3D micro-printing enables the formation of complex shapes at a print resolution of tens of nanometers using two-photon lithography. Our team have explored the use of 3D micro-printing to fabricate complex optical geometries directly on the end of a fiber. In this work, we have developed a lens-in-lens design that enables in-vivo high-sensitivity fluorescence and OCT imaging through a single-fiber-based probe, with a diameter <550 microns including a protective catheter sheath. In a parallel work, we have also fabricated a side-facing OCT fiber probe (<300 microns diameter) creating an elongated Bessel beam and simultaneously correct for aberrations.
The fabrication of a stable, reproducible optical imaging phantom is critical to the assessment and optimization of optical imaging systems. In this study, we present a novel design of optical phantom based on metal-doped glass-ceramics. The matrix was doped with nickel ions to imitate the absorption of haemoglobin, and scattering levels representative of tissue were induced through controlled crystallisation in the glass-based phantom at elevated temperature. Our glass-based optical phantom can provide controlled levels of optical scattering and absorption to mimic the optical properties of human tissues with excellent optical homogeneity, and potentially long-term stability and reproducibility.
Significance: Imaging needles consist of highly miniaturized focusing optics encased within a hypodermic needle. The needles may be inserted tens of millimeters into tissue and have the potential to visualize diseased cells well beyond the penetration depth of optical techniques applied externally. Multimodal imaging needles acquire multiple types of optical signals to differentiate cell types. However, their use has not previously been demonstrated with live cells.
Aim: We demonstrate the ability of a multimodal imaging needle to differentiate cell types through simultaneous optical coherence tomography (OCT) and fluorescence imaging.
Approach: We characterize the performance of a multimodal imaging needle. This is paired with a fluorescent analog of the therapeutic drug, tamoxifen, which enables cell-specific fluorescent labeling of estrogen receptor-positive (ER+) breast cancer cells. We perform simultaneous OCT and fluorescence in situ imaging on MCF-7 ER+ breast cancer cells and MDA-MB-231 ER− cells. Images are compared against unlabeled control samples and correlated with standard confocal microscopy images.
Results: We establish the feasibility of imaging live cells with these miniaturized imaging probes by showing clear differentiation between cancerous cells.
Conclusions: Imaging needles have the potential to aid in the detection of specific cancer cells within solid tissue.
Common-path probes provide considerable advantages for fiber-based OCT due to intrinsic length and phase matching. However, the polarization state of the reference light is usually arbitrary and variable due to stress-induced birefringence in single-mode fibers, which complicates implementing polarization-sensitive OCT. Here, we present depth-resolved retardation measurements with a single-mode fiber-based common-path probe by utilizing the constrained polarization evolution and the mirror state phenomenon for reconstruction of the round-trip measurements in the case of arbitrary reference states. Thus, a compact and flexible polarization-sensitive OCT implementation is demonstrated.
We present a miniaturized handheld OCT probe (9 grams weight), approximately the size of a small pen (10 mm x 140 mm), developed for use inside a patient’s mouth for examination of the oral mucosa. The probe operates in common-path mode and uses a magnetic scanning system to actuate a lensed fibre, achieving 50 B-scans per second. The system is demonstrated with OCT imaging of the buccal and alveolar mucosa of six patients with oral lichen planus (OLP) during clinical routine examination, and showed pathological changes in the tissue microarchitecture.
Depth-resolved retardation measurements with a single-mode fiber-based common-path probe by using polarization-sensitive optical coherence tomography are presented, utilizing the constrained polarization evolution and the mirror state phenomenon for reconstruction of the round-trip measurements.
We demonstrate in-vivo chemical sensing using silk-coated exposed-core microstructured optical fibers (ECFs). The ECF provides advantages in sensitivity due to the direct access of the fiber core to the surrounding environment with integrated measurement along the entire fiber length, rather than simply the fiber tip as is common in other probes. The silk coating provides an encapsulation of the sensor molecules, and is well known as a biocompatible material. This deployable fiber sensor is fabricated with simple splicing and coating techniques, making it practical to be used in a range of biomedical sensing applications, which we demonstrate through pH sensing in a mouse model.
Transbronchial needle aspiration (TBNA) of small lesions or lymph nodes in the lung may result in nondiagnostic tissue samples. We demonstrate the integration of an optical coherence tomography (OCT) probe into a 19-gauge flexible needle for lung tissue aspiration. This probe allows simultaneous visualization and aspiration of the tissue. By eliminating the need for insertion and withdrawal of a separate imaging probe, this integrated design minimizes the risk of dislodging the needle from the lesion prior to aspiration and may facilitate more accurate placement of the needle. Results from in situ imaging in a sheep lung show clear distinction between solid tissue and two typical constituents of nondiagnostic samples (adipose and lung parenchyma). Clinical translation of this OCT-guided aspiration needle holds promise for improving the diagnostic yield of TBNA.
Acute cardiovascular events are mostly due to a blood clot or thrombus induced by the sudden rupture of vulnerable atherosclerotic plaques within coronary artery walls. Based on the high optical absorption contrast of the lipid rich plaques within the vessel wall, intravascular photoacoustic (IVPA) imaging at 1.7 μm spectral band has shown promising capabilities for detecting of lipid composition, but the translation of the technology for in vivo application is limited by the slow imaging speed. In this work, we will present a high speed integrated IVPA/US imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm (5 nm linewidth). A miniature catheter with 1.0 mm outer diameter was designed with a polished 200 μm multimode fiber and an ultrasound transducer with 45 MHz center frequency. Two optical illumination methods by gradient-index (GRIN) lens and ball lens are introduced and compared for higher spatial resolution. At 1725 nm, atherosclerotic rabbit abdominal aorta was imaged at two frame per second, which is more than one order of magnitude faster than previous reported IVPA imaging. Furthermore, by wide tuning range of the laser wavelength from 1680 nm to 1770 nm, spectroscopic photoacoustic analysis of lipid-mimicking phantom and an human atherosclerotic artery was performed ex vivo.
Cardiovascular disease is the leading cause of death in the industrialized nations. Accurate quantification of both the morphology and composition of lipid-rich vulnerable atherosclerotic plaque are essential for early detection and optimal treatment in clinics. In previous works, intravascular photoacoustic (IVPA) imaging for detection of lipid-rich plaque within coronary artery walls has been demonstrated in ex vivo, but the imaging speed is still limited. In order to increase the imaging speed, a high repetition rate laser is needed. In this work, we present a high speed integrated IVPA/US imaging system with a 500 Hz optical parametric oscillator laser at 1725 nm. A miniature catheter with 1.0 mm outer diameter was designed with a 200 μm multimode fiber and an ultrasound transducer with 45 MHz center frequency. The fiber was polished at 38 degree and enclosed in a glass capillary for total internal reflection. An optical/electrical rotary junction and pull-back mechanism was applied for rotating and linearly scanning the catheter to obtain three-dimensional imaging. Atherosclerotic rabbit abdominal aorta was imaged as two frame/second at 1725 nm. Furthermore, by wide tuning range of the laser wavelength from 1680 nm to 1770 nm, spectroscopic photoacoustic analysis of lipid-mimicking phantom and an human atherosclerotic artery was performed ex vivo. The results demonstrated that the developed IVPA/US imaging system is capable for high speed intravascular imaging for plaque detection.
Recently, annular beams have been developed to rapidly fabricate microscope tubular structures via two-photon polymerization, but the distribution of the light field is limited to a ring pattern. Here a Fresnel lens is designed and applied to modulate the light field into a uniform quadrangle or hexagon shape with controllable diameters. By applying a spatial light modulator to load the phase information of the Fresnel lens, quadrangle and hexagon structures are achieved through single exposure of a femtosecond laser. A 3×6 array of structures is made within 9 s. Comparing with the conventional holographic processing, this method shows higher uniformity, high efficiency, better flexibility, and easy operation. The approach exhibited a promising prospect in rapidly fabricating structures such as tissue engineering scaffolds and variously shaped tubular arrays.
An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging.
KEYWORDS: Optical coherence tomography, Cancer, Simulation of CCA and DLA aggregates, Tumors, Pancreatic cancer, Imaging systems, Lens design, Visualization, Reflection, Lymphatic system
Gastrointestinal tract cancer, the most common type of cancer, has a very low survival rate, especially for pancreatic cancer (five year survival rate of 5%) and bile duct cancer (five year survival rate of 12%). Here, we propose to use an integrated OCT-US catheter for cancer detection. OCT is targeted to acquire detailed information, such as dysplasia and neoplasia, for early detection of tumors. US is used for staging cancers according to the size of the primary tumor and whether or not it has invaded lymph nodes and other parts of the body. Considering the lumen size of the GI tract, an OCT system with a long image range (>10mm) and a US imaging system with a center frequency at 40MHz (penetration depth > 5mm) were used. The OCT probe was also designed for long-range imaging. The side-view OCT and US probes were sealed inside one probe cap piece and one torque coil and became an integrated probe. This probe was then inserted into a catheter sheath which fits in the channel of a duodenoscope and is able to be navigated smoothly into the bile duct by the elevator of the duodenoscope. We have imaged 5 healthy and 2 diseased bile ducts. In the OCT images, disorganized layer structures and heterogeneous regions demonstrated the existence of tumors. Micro-calcification can be observed in the corresponding US images.
An increased number of integrated optical acoustic intravascular imaging systems have been researched and hold great hope for accurate diagnosing of vulnerable plaques and for guiding atherosclerosis treatment. However, in any intravascular environment, vascular lumen is filled with blood, which is a high-scattering source for optical and high frequency ultrasound signals. Blood must be flushed away to make images clear. To our knowledge, no research has been performed to find the ideal flushing agent that works for both optical and acoustic imaging techniques. We selected three solutions, mannitol, dextran and iohexol, as flushing agents because of their image-enhancing effects and low toxicities. Quantitative testing of these flushing agents was performed in a closed loop circulation model and in vivo on rabbits.
A method for holographic femtosecond laser parallel processing is proposed, which can suppress the interference of zero-order light effectively and improve the energy utilization rate. In order to blaze the target pattern to the peak position of zero-order interference, a phase-only hologram containing a digital blazed grating is designed and generated, and the energy of the target pattern can be increased by 3.793 times in theory. In addition, by subsequently increasing the phase of the divergent spherical wave, the focal plane of the target pattern and the plane of the multiorder diffraction beam resulting from the pixelated structure of the spatial light modulator (SLM) can be separated. Both a high-pass filter and aperture are used to simultaneously eliminate the influences of zero-order light and multiorder interferential patterns. A system based on the phase-only SLM (with resolution of 1920×1080) is set up to validate the proposed method. The experimental results indicate that the proposed method can achieve high-quality holographic femtosecond laser parallel processing with a significantly improved energy utilization rate.
The surface induced flow in micro groove has attracted much attention because it can be used as a passive power source
in microfluidic devices. In recent years, some researchers have used the surface induced force to deliver liquids in micro
groove. The flow speed should be controlled accurately in order to displace liquids with desirable volumes. In this paper,
we investigated the feasibility to control the flow speed by constructing microstructure on surface groove using
femtosecond laser. Firstly, we used femtosecond laser to fabricate different microstructures on alumina surfaces with
different laser scanning speed. It was found that the flow speed in groove increased when the femtosecond laser scanning
speed decreased. And the liquid spread distance was linear to the square of spread time. Then we investigated the
dynamics of the liquid flow which was influenced by the surface chemical composition property. Some metal materials
with different surface energies were sputtered on the irradiated surface. The coated metal film can also change the liquid
spread speed in groove. This work provides a method to obtain the expected controllable spread speed by constructing
the microstructure using femtosecond laser.
A novel method for holographic femtosecond laser parallel processing is proposed, which can suppress the interference
of zero order light effectively and improve the energy utilization rate. In order to blaze the target pattern to the peak
position of zero-order interference, a phase-only hologram containing digital blazed grating are designed and generated,
The energy of the target pattern can be increased to 5.297 times in theory. In addition, by subsequently increasing the
phase of divergent spherical wave, the focal plane of the target pattern and the plane of multi-order diffraction beam
resulted from pixelated structure of the spatial light modulator (SLM) can be separated. Both the high pass filter and
aperture are used to eliminate the influences of zero-order light and multi-order interferential patterns simultaneously. A
system based on the phase-only SLM (with resolution of 1920*1080) is set up to validate the proposed method. The
experimental results indicate that the proposed method can achieve high quality holographic femtosecond laser parallel
processing with a significantly improved energy utilization rate.
Long range optical coherence tomography (OCT), with its high speed, high resolution, non-ionized properties and cross-sectional imaging capability, is suitable for upper airway lumen imaging. To render 2D OCT datasets to true 3D anatomy, additional tools are usually applied, such as X-ray guidance or a magnetic sensor. X-ray increases ionizing radiation. A magnetic sensor either increases probe size or requires an additional pull-back of the tracking sensor through the body cavity. In order to overcome these limitations, we present a novel tracking method using a 1.5 mm×1.5mm, 90/10-ratio micro-beamsplitter: 10% light through the beam-splitter is used for motion tracking and 90% light is used for regular OCT imaging and motion tracking. Two signals corresponding to these two split-beams that pass through different optical path length delays are obtained by the detector simultaneously. Using the two split beams’ returned signals from the same marker line, the 2D inclination angle of each step is computed. By calculating the 2D inclination angle of each step and then connecting the translational displacements of each step, we can obtain the 2D motion trajectory of the probe. With two marker lines on the probe sheath, 3D inclination angles can be determined and then used for 3D trajectory reconstruction. We tested the accuracy of trajectory reconstruction using the probe and demonstrated the feasibility of the design for structure reconstruction of a biological sample using a porcine trachea specimen. This optical-tracking probe has the potential to be made as small as an outer diameter of 1.0mm, which is ideal for upper airway imaging.
We have developed a novel integrated optical coherence tomography (OCT)-intravascular ultrasound (IVUS) probe, with a 1.5 mm-long rigid-part and 0.9 mm outer diameter, for real-time intracoronary imaging of atherosclerotic plaques and guiding interventional procedures. By placing the OCT ball lens and IVUS 45MHz single element transducer back-to-back at the same axial position, this probe can provide automatically co-registered, co-axial OCT-IVUS imaging. To demonstrate its capability, 3D OCT-IVUS imaging of a pig’s coronary artery in real-time displayed in polar coordinates, as well as images of two major types of advanced plaques in human cadaver coronary segments, was obtained using this probe and our upgraded system. Histology validation is also presented.
Intravascular ultrasound (IVUS) imaging and optical coherence tomography (OCT), two commonly used intracoronary imaging modalities, play important roles in plaque evaluation. The combined use of IVUS (to visualize the entire plaque volume) and OCT (to quantify the thickness of the plaque cap, if any) is hypothesized to increase plaque diagnostic accuracy. Our group has developed a fully-integrated dual-modality IVUS-OCT imaging system and 3.6F catheter for simultaneous IVUS-OCT imaging with a high resolution and deep penetration depth. However, the diagnostic accuracy of an integrated IVUS-OCT system has not been investigated. In this study, we imaged 175 coronary artery sites (241 regions of interest) from 20 cadavers using our previous reported integrated IVUS-OCT system. IVUS-OCT images were read by two skilled interventional cardiologists. Each region of interest was classified as either calcification, lipid pool or fibrosis. Comparing the diagnosis by cardiologists using IVUSOCT images with the diagnosis by the pathologist, we calculated the sensitivity and specificity for characterization of calcification, lipid pool or fibrosis with this integrated system. In vitro imaging of cadaver coronary specimens demonstrated the complementary nature of these two modalities for plaques classification. A higher accuracy was shown than using a single modality alone.
We have developed a novel miniature integrated optical coherence tomography (OCT)-intravascular ultrasound (IVUS) probe, with a 1.5-mm-long rigid part and 0.9-mm outer diameter, for real-time intracoronary imaging of atherosclerotic plaques and guiding of interventional procedures. By placing the OCT ball lens and IVUS transducer back-to-back at the same axial position, this probe can provide automatically coregistered, coaxial OCT-IVUS imaging. To demonstrate its real-time capability, three-dimensional OCT-IVUS imaging of a pig’s coronary artery displaying in polar coordinates, as well as images of three major types of atherosclerotic plaques in human cadaver coronary segments, were obtained using this probe and our upgraded system. Histology validation is also presented.
Two-photon polymerization is a powerful technique in the area of functional micro/nano device fabrication. The greatest limiting factor in widespread use of this technique is the low efficiency because the structure is fabricated by point-by-point scanning. In recent years, computer generated hologram is used for parallel fabrication via multi foci. In this paper, we proposed a new rapid fabrication method which use desirable multi-focus pattern as scanning cell instead of single focus point or foci array to polymerize. We establish a femtosecond laser experimental setup involved in a liquid crystal spatial light modulator. The computer generated hologram pattern on spatial light modulator is used to produce desirable foci array. The position and intensity of each focus in the pattern can be controlled well by optimal design. We use multi foci in a line as scanning cell to fabricate some revolving structure and the Fresnel lens can be expected. This work provides a new method to greatly improve the efficiency of two-photon polymerization production in fabricating revolving structures.
This paper reports on the evolution of femtosecond laser induced periodic surface structures (LIPSSs) on titanium surface irradiated with different wavelengths. By SEM observations, it is noted that different nanostructures with respective surface features depend highly on the laser wavelength and the laser fluence. The period of LIPSSs formed at the laser fluence just above the ablation threshold is shorter than the laser wavelength, as well as dependence on the incident wavelength. Experiments using wavelength of 600 and 1500 nm, studies are performed in more detail. The period and the depth of the grooves of LIPSSs are increased with the increase of laser fluence at wavelength of 600nm. The created structures on the surface at the laser fluence of 0.42 J/cm2 would significantly influence the field intensity distribution on the surface. The redistribution of the electric field intensity plays a crucial role in the creation of the HSFLs formed on the ridges of the LIPSSs, and the period decreases to half. Another kind of HSFLs whose orientation is perpendicular to the sidewalls of LIPSSs is created at wavelength of 1500nm. These HSFLs lie at the bottom of the valleys between both the LIPSSs and new formed grooves. As compared with the surface nanostructures formed at wavelength of 600 nm, the formation of identical HSFLs is induced with smaller laser fluence at wavelength of 1500 nm.
Porous anodic alumina (PAA), with highly ordered microstructures, has attracted much attention due to some unique
physical and optical characteristics. In recent years, PAA is also used to obtain different colors by methods such as
growing nanowires, tuning pore depth, or sputtering metal on PAA surface. In this paper, we report a simple and
precisely controllable method to tune color by changing the pore diameter of PAA. In order to obtain PPA with different
pore diameter, we first prepare the PPA membrane by two step anodization of high purity aluminium foil in acidic
solutions and then immerse the fabricated PPA membrane into phosphoric acid to enlarge pore diameter. The different
pore diameters of PAA are controlled by immersed time in phosphoric acid. After sputtering metal on surface of PAA,
the brilliant color can be seen on the surface of PAA. Different colors of PAA film with metal-coated are obtained using
this method and colorful patterns are successfully fabricated. The physical model of the PAA is constructed and the
mechanism of tuning color is analyzed. It is concluded that the color can be tuned by changing pore diameter of the PAA
membrane. This method will be of potential use in decoration, color displays and anti-counterfeiting technology.
We developed a multimodality fluorescence and optical coherence tomography probe based on a double-clad fiber (DCF) combiner. The probe is composed of a DCF combiner, grin lens, and micromotor in the distal end. An integrated swept-source optical coherence tomography and fluorescence intensity imaging system was developed based on the combined probe for the early diagnoses of atherosclerosis. This system is capable of real-time data acquisition and processing as well as image display. For fluorescence imaging, the inflammation of atherosclerosis and necrotic core formed with the annexin V-conjugated Cy5.5 were imaged. Ex vivo imaging of New Zealand white rabbit arteries demonstrated the capability of the combined system.
Intracoronary optical coherence tomography (OCT) and intravascular ultrasound (IVUS) are two popular
techniques for the detection and determination of atherosclerosis. IVUS allows visualization of plaques while also
providing a large penetration depth to determine plaque volume. Intracoronary OCT provides the ability to capture
microscopic features associated with high risk plaque. Traditionally to utilize the benefits of both modalities, separate
probes and systems had to be used one at a time to image a vessel. We present work required to create a combined OCT
IVUS system capable of simultaneous imaging to detect atherosclerotic plaques. A novel integrated probe of size 0.69
mm OD featuring sequential placement of components was created to acquire co-registered images within small
coronary vessels. By utilizing commercial graphics processing units (GPUs) real time visualization of acquired data is
possible up to a maximum 48 frames per second per channel. In vitro studies on human coronary artery samples as well
as in vivo studies in rabbits and pigs show various plaque buildups in both OCT and IVUS images which match
histology results, demonstrating the capabilities of the system.
A miniature integrated optical coherence tomography (OCT) - ultrasound (US) probing system for real-time
intravascular imaging has been developed. The outer diameter of the integrated probe is 0.69 mm, which is small enough
for imaging in human coronary arteries. This probe, which has high resolution and deep tissue penetration, is designed to
identify vulnerable atherosclerotic plaques in coronary arteries. The first in vivo images of a rabbit abdominal aorta
obtained by the integrated OCT-US probe are presented.
KEYWORDS: Optical coherence tomography, Ultrasonography, In vivo imaging, Transducers, Imaging systems, Lithium, Data acquisition, In vitro testing, Arteries, Intravascular ultrasound
We have developed a miniature integrated optical coherence tomography (OCT) ultrasound (US) probing system for intravascular imaging applications. In the OCT probe, the light coming out of a single mode fiber is focused by a gradient-index lens and then reflected by a right-angle prism from the side of the probe into the sample. It was combined with a 35 MHz PMN-PT side-viewing ultrasound transducer to obtain the ultrasound image as well. The OCT and ultrasound probes were integrated as a single probe to obtain OCT and ultrasound images simultaneously. The integrated probe has an outer diameter of 0.69 mm which, to our knowledge, is the smallest integrated OCT-US probe reported. Fast data acquisition and processing was implemented for real-time imaging. In vitro OCT and US images of human coronary artery with pathology, as well as in vivo images of normal rabbit abdominal aorta, were obtained using the integrated OCT-US probe to demonstrate its capability.
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