1. Articles from Qifa Zhou

    1-24 of 29 1 2 »
    1. In vivo evaluation of posterior eye elasticity using shaker-based optical coherence elastography

      In vivo evaluation of posterior eye elasticity using shaker-based optical coherence elastography

      Age-related macular degeneration (AMD) is a progressive retinal disease and becomes the leading cause of blindness. It is well established that early detection is the key to preservation of functional vision. However, it is very difficult to diagnose AMD in very early stages, before structural changes are evident. Consequently, investigating the biomechanical properties of the retina maybe essential for understanding its physiological function. In this study, we present a shear wave-based quantitative method for estimating the elasticity of the posterior eye using shaker-based optical coherence elastography. This technique has been developed and validated on both a homogeneous phantom and a ...

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    2. Acoustic Radiation Force Optical Coherence Elastography

      Acoustic Radiation Force Optical Coherence Elastography

      Mechanical properties, such as the elasticity and viscosity, are often major indicators of diseases. Over the years, tissue mechanical properties have been demonstrated to be an early indicator for cardiovascular disease. Mechanical imaging technologies have been quickly evolving with a goal to effectively diagnose coronary artery disease and atherosclerosis in their early stages. By combining the advantages of acoustic and optical properties, acoustic radiation force optical coherence elastography (ARF-OCE) has become an imaging tool with a high potential for translation into clinics. In this chapter, we review the principles of OCE and describe the development of ARF-OCE systems for imaging ...

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    3. Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Cardiovascular diseases are the leading cause of fatalities in the United States. Atherosclerotic plaques are one of the primary complications that can lead to strokes and heart attacks if left untreated. It is essential to diagnose the disease early and distinguish vulnerable plaques from harmless ones. Many methods focus on the structural or molecular properties of plaques. Mechanical properties have been shown to change drastically when abnormalities develop in arterial tissue. We report the development of an acoustic radiation force optical coherence elastography (ARF-OCE) system that uses an integrated miniature ultrasound and optical coherence tomography (OCT) probe to map the ...

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    4. Fully integrated optical coherence tomography, ultrasound, and indocyanine green-based fluorescence tri-modality system for intravascular imaging

      Fully integrated optical coherence tomography, ultrasound, and indocyanine green-based fluorescence tri-modality system for intravascular imaging

      We present a tri-modality imaging system and fully integrated tri-modality probe for intravascular imaging. The tri-modality imaging system is able to simultaneously acquire optical coherence tomography (OCT), ultrasound (US), and fluorescence imaging. Moreover, for fluorescence imaging, we used the FDA-approved indocyanine green (ICG) dye as the contrast agent to target lipid-loaded macrophages. We conducted imaging from a male New Zealand white rabbit to evaluate the performance of the tri-modality system. In addition, tri-modality images of rabbit aortas were correlated with hematoxylin and eosin (H&E) histology to check the measurement accuracy. The fully integrated miniature tri-modality probe, together with the ...

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    5. In Vivo Near Infrared Virtual Intraoperative Surgical Photoacoustic Optical Coherence Tomography

      In Vivo Near Infrared Virtual Intraoperative Surgical Photoacoustic Optical Coherence Tomography

      Since its first implementation in otolaryngological surgery nearly a century ago, the surgical microscope has improved the accuracy and the safety of microsurgeries. However, the microscope shows only a magnified surface view of the surgical region. To overcome this limitation, either optical coherence tomography (OCT) or photoacoustic microscopy (PAM) has been independently combined with conventional surgical microscope. Herein, we present a near-infrared virtual intraoperative photoacoustic optical coherence tomography (NIR-VISPAOCT) system that combines both PAM and OCT with a conventional surgical microscope. Using optical scattering and absorption, the NIR-VISPAOCT system simultaneously provides surgeons with real-time comprehensive biological information such as tumor ...

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    6. 3D mapping of elastic modulus using shear wave optical micro-elastography

      3D mapping of elastic modulus using shear wave optical micro-elastography

      lastography provides a powerful tool for histopathological identification and clinical diagnosis based on information from tissue stiffness. Benefiting from high resolution, three-dimensional (3D), and noninvasive optical coherence tomography (OCT), optical micro-elastography has the ability to determine elastic properties with a resolution of ~10 μm in a 3D specimen. The shear wave velocity measurement can be used to quantify the elastic modulus. However, in current methods, shear waves are measured near the surface with an interference of surface waves. In this study, we developed acoustic radiation force (ARF) orthogonal excitation optical coherence elastography (ARFOE-OCE) to visualize shear waves in 3D. This ...

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    7. Acoustic Radiation Force Optical Coherence Elastography of Corneal Tissue

      Acoustic Radiation Force Optical Coherence Elastography of Corneal Tissue

      We report on a real-time acoustic radiation force optical coherence elastography (ARF-OCE) system to map the relative elasticity of corneal tissue. A modulated ARF is used as excitation to vibrate the cornea, while OCE serves as detection of tissue response. To show feasibility of detecting mechanical contrast using this method, we performed tissue-equivalent agarose phantom studies with inclusions of a different stiffness. We obtained 3-D elastograms of a healthy cornea and a highly cross-linked cornea. Finally, we induced a stiffness change on a small portion of a cornea and observed the differences in displacement.

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    8. Ultrafast optical-ultrasonic system and miniaturized catheter for imaging and characterizing atherosclerotic plaques in vivo

      Ultrafast optical-ultrasonic system and miniaturized catheter for imaging and characterizing atherosclerotic plaques in vivo

      Atherosclerotic coronary artery disease (CAD) is the number one cause of death worldwide. The majority of CAD-induced deaths are due to the rupture of vulnerable plaques. Accurate assessment of plaques is crucial to optimize treatment and prevent death in patients with CAD. Current diagnostic techniques are often limited by either spatial resolution or penetration depth. Several studies have proved that the combined use of optical and ultrasonic imaging techniques increase diagnostic accuracy of vulnerable plaques. Here, we introduce an ultrafast optical-ultrasonic dual-modality imaging system and flexible miniaturized catheter, which enables the translation of this technology into clinical practice. This system ...

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    9. Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method

      Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method

      We report on a novel acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) technique for imaging shear wave and quantifying shear modulus under orthogonal acoustic radiation force (ARF) excitation using the optical coherence tomography (OCT) Doppler variance method. The ARF perpendicular to the OCT beam is produced by a remote ultrasonic transducer. A shear wave induced by ARF excitation propagates parallel to the OCT beam. The OCT Doppler variance method, which is sensitive to the transverse vibration, is used to measure the ARF-induced vibration. For analysis of the shear modulus, the Doppler variance method is utilized to visualize shear ...

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    10. Integrated Ultrasound, OCT, PA AND/OR Florescence Imaging Endoscope For Diagnosing Cancers In Gastrointestinal, Respiratory, And Urogenital Tracts

      Integrated Ultrasound, OCT, PA AND/OR Florescence Imaging Endoscope For Diagnosing Cancers In Gastrointestinal, Respiratory, And Urogenital Tracts

      A multimodality imaging system including ultrasound, optical coherence tomography (OCT), photoacoustic (PA) imaging, florescence imaging and endoscopic catheter for imaging inside the gastrointestinal tract with real-time automatic image co-registration capability, including: an ultrasound subsystem for imaging; an optical coherence tomography (OCT) subsystem for imaging, a PA microscopy or tomography subsystem for imaging and a florescence imaging subsystem for imaging. An invasive interventional imaging device is included with an instrumentality to take a tissue biopsy from a location visible on the ultrasound subsystem for imaging, on the optical coherence tomography (OCT) subsystem for imaging, photoacoustic (PA) subsystem for imaging and florescence ...

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    11. Integrated OCT-US catheter for detection of cancer in gastrointestinal tract

      Integrated OCT-US catheter for detection of cancer in gastrointestinal tract

      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 ...

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    12. Trimodality imaging system and intravascular endoscopic probe: combined optical coherence tomography, fluorescence imaging and ultrasound imaging

      Trimodality imaging system and intravascular endoscopic probe: combined optical coherence tomography, fluorescence imaging and ultrasound imaging

      In this Letter, we present a trimodality imaging system and an intravascular endoscopic probe for the detection of early-stage atherosclerotic plaques. The integrated system is able to acquire optical coherence tomography (OCT), fluorescence, and ultrasound images and simultaneously display them in real time. A trimodality intravascular endoscopic probe of 1.2 mm in diameter and 7 mm in length was fabricated based on a dual-modality optical probe that integrates OCT and fluorescence imaging functions and a miniature ultrasound transducer. The probe is capable of rotating at up to 600 rpm. Ex vivo images from rabbit aorta and human coronary arteries ...

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    13. Confocal acoustic radiation force optical coherence elastography using a ring ultrasonic transducer

      Confocal acoustic radiation force optical coherence elastography using a ring ultrasonic transducer

      We designed and developed a confocal acoustic radiation force optical coherence elastography system. A ring ultrasound transducer was used to achieve reflection mode excitation and generate an oscillating acoustic radiation force in order to generate displacements within the tissue, which were detected using the phase-resolved optical coherence elastography method. Both phantom and human tissue tests indicate that this system is able to sense the stiffness difference of samples and quantitatively map the elastic property of materials. Our confocal setup promises a great potential for point by point elastic imaging in vivo and differentiation of diseased tissues from normal tissue.

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    14. Resonant Acoustic Radiation Force Optical Coherence Elastography

      Resonant Acoustic Radiation Force Optical Coherence Elastography

      We reported on the development of a resonant acoustic radiation force optical coherence elastography (ARF-OCE) technique that uses mechanical resonant frequency to characterize and identify tissues of different types. The results of resonant ARF-OCE imaging of a post-mortem human coronary artery with atherosclerosis demonstrate the potential of resonant ARF-OCE as a non-invasive method for imaging and characterizing vulnerable plaques. Knowledge of tissue mechanical properties provides valuable medical information in disease diagnosis and prognosis. There is a close correlation between tissue elasticity and pathology. For example, in atherosclerosis, measurement of tissue biomechanical properties has the potential to differentiate between various plaque ...

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    15. Integrated IVUS-OCT for Real-Time Imaging of Coronary Atherosclerosis

      Integrated IVUS-OCT for Real-Time Imaging of Coronary Atherosclerosis

      Accurate assessment of atherosclerotic plaque characteristics and the subsequent tailoring of optimal therapy holds great promise for preventing acute coronary syndromes (ACS) and life-threatening sequelae 1 . Combined use of optical coherence tomography (OCT) and intravascular ultrasound (IVUS) was proposed as a potential method for accurate assessment of plaque characteristics and vulnerability ( 2 , ). However, significant challenges remain in trying to adapt an integrated OCT-IVUS system for clinical applications. We report here a fully integrated intracoronary OCT-IVUS imaging technique to visualize atherosclerotic plaque in living animals and human coronary arteries from cadavers with high resolution and deep penetration capability simultaneously.

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    16. Feature Of The Week 11/24/13 : Miniature OCT/IVUS probe for automatically co-registered three-dimensional intracoronary imaging with real-time display

      Feature Of The Week 11/24/13 : Miniature OCT/IVUS probe for automatically co-registered three-dimensional intracoronary imaging with real-time display

      Combined use of intravascular ultrasound (IVUS) and optical coherence tomography (OCT) holds the potential of combining the strengths of both imaging modalities and improving the diagnostic accuracy of atherosclerotic plaque vulnerability. In this manuscript, we reported a co-registered intracoronary OCT-IVUS system and catheter with real-time imaging and polar-coordinate displaying capability, well-suited for clinical utilization in guiding interventional cardiologists. With an eventual goal of clinical use in humans, this novel catheter design and modified software are poised to strengthen the ability to diagnose vulnerable plaques in patients in real-time. We upgraded our old designs in the following aspects. 1) This novel ...

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    17. Miniature optical coherence tomography-ultrasound probe for automatically coregistered three-dimensional intracoronary imaging with real-time display

      Miniature optical coherence tomography-ultrasound probe for automatically coregistered three-dimensional intracoronary imaging with real-time display

      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 ...

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    18. Phase-resolved acoustic radiation force optical coherence elastography

      Phase-resolved acoustic radiation force optical coherence elastography

      Many diseases involve changes in the biomechanical properties of tissue, and there is a close correlation between tissue elasticity and pathology. We report on the development of a phase-resolved acoustic radiation force optical coherence elastography method (ARF-OCE) to evaluate the elastic properties of tissue. This method utilizes chirped acoustic radiation force to produce excitation along the sample’s axial direction, and it uses phase-resolved optical coherence tomography (OCT) to measure the vibration of the sample. Under 500-Hz square wave modulated ARF signal excitation, phase change maps of tissue mimicking phantoms are generated by the ARF-OCE method, and the resulting Young ...

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    19. A 2.5-mm diameter probe for photoacoustic and ultrasonic endoscopy

      A 2.5-mm diameter probe for photoacoustic and ultrasonic endoscopy

      We have created a 2.5-mm outer diameter integrated photo-acoustic and ultrasonic mini-probe which can be inserted into a standard video endoscope’s instrument channel. A small-diameter focused ultrasonic transducer made of PMN-PT provides adequate signal sensitivity, and enables miniaturization of the probe. Additionally, this new endoscopic probe utilizes the same scanning mirror and micromotor-based built-in actuator described in our previous reports; however, the length of the rigid distal section of the new probe has been further reduced to ~35 mm. This paper describes the technical details of the mini-probe and presents experimental results that both quantify the imaging performance ...

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    20. Advances in a fully integrated intravascular OCT-ultrasound system for cardiovascular imaging

      Advances in a fully integrated intravascular OCT-ultrasound system for cardiovascular imaging

      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 ...

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    21. Integrated optical coherence tomography, ultrasound and photoacoustic imaging for ovarian tissue characterization

      Integrated optical coherence tomography, ultrasound and photoacoustic imaging for ovarian tissue characterization
      Ovarian cancer has the lowest survival rate of the gynecologic cancers because it is predominantly diagnosed in Stages III or IV due to the lack of reliable symptoms, as well as the lack of efficacious screening techniques. Detection before the malignancy spreads or at the early stage would greatly improve the survival and benefit patient health. In this report, we present an integrated optical coherence tomography (OCT), ultrasound (US) and photoacoustic imaging (PAI) prototype endoscopy system for ovarian tissue characterization. The overall diameter of the prototype endoscope is 5 mm which is suitable for insertion through a standard 5-12.5mm ...
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    22. Novel combined miniature optical coherence tomography ultrasound probe for in vivo intravascular imaging

      Novel combined miniature optical coherence tomography ultrasound probe for in vivo intravascular imaging

      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 ...

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    23. Integrated optical coherence tomography - ultrasound system and miniaturized probes for intravascular imaging

      Integrated optical coherence tomography - ultrasound system and miniaturized probes for intravascular imaging

      We report on the development of a multimodal optical coherence tomography (OCT) - ultrasound (US) system and miniaturized OCT-US probe for intravascular imaging. Both OCT optical components and a US transducer were integrated into a single probe, enabling both OCT and US imaging at the same time. A miniaturized OCT-US probe using a single element transducer was designed with a maximum outer diameter of 0.8 mm, which is suitable for in vivo intravascular imaging. The integrated OCT-US imaging system adopted a two-channel data acquisition card to digitize both OCT and US signals. Simultaneous OCT and US data processing and image ...

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    24. Feature Of The Week 1/30/11: Development of Dual-Mode OCT and IVUS for Intravascular Imaging - A look at recent work from University of Southern California and UC Irvine

      Feature Of The Week 1/30/11: Development of Dual-Mode OCT and IVUS for Intravascular Imaging - A look at recent work from University of Southern California and UC Irvine
      Feature Of The Week 1/30/11: Multimodality imaging with OCT is a hot topic in general and at Photonics West in particular. This week’s “Feature Of The Week” is about integrated OCT and IVUS imaging. Below is a summary of work by researchers from the Viterbi School of Engineering at the University of Southern California and the Beckman Laser Institute and Department of Biomedical Engineering at the University of California, Irvine.The USC and UC Irvine researchers developed a dual-mode biomedical imaging probe utilizing intravascular ultrasound (IVUS) and optical coherence tomography (OCT). It consists of an OCT probe ...
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    1-24 of 29 1 2 »
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  2. Topics in the News

    1. (28 articles) Qifa Zhou
    2. (25 articles) Zhongping Chen
    3. (23 articles) UC Irvine
    4. (22 articles) K. Kirk Shung
    5. (21 articles) University of Southern California
    6. (10 articles) Jun Zhang
    7. (10 articles) Xiang Li
    8. (9 articles) Jiawen Li
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    Photoacoustic ophthalmoscopy for in vivo retinal imaging Integrated intravascular optical coherence tomography ultrasound imaging system Integrated intravascular optical coherence tomography (OCT) - ultrasound (US) imaging system High-resolution coregistered intravascular imaging with integrated ultrasound and optical coherence tomography probe A dual-modality probe utilizing intravascular ultrasound and optical coherence tomography for intravascular imaging applications Feature Of The Week 1/30/11: Development of Dual-Mode OCT and IVUS for Intravascular Imaging - A look at recent work from University of Southern California and UC Irvine Integrated optical coherence tomography - ultrasound system and miniaturized probes for intravascular imaging Novel combined miniature optical coherence tomography ultrasound probe for in vivo intravascular imaging Integrated optical coherence tomography, ultrasound and photoacoustic imaging for ovarian tissue characterization Feature Of The Week 11/24/13 : Miniature OCT/IVUS probe for automatically co-registered three-dimensional intracoronary imaging with real-time display High space-bandwidth in quantitative phase imaging using partially spatially coherent optical coherence microscopy and deep neural network Optical coherence tomography assessment of macrophages accumulation in non-ST-segment elevation acute coronary syndromes