1. Articles from Wei Zhang

    1-15 of 15
    1. High-resolution multimodal photoacoustic microscopy and optical coherence tomography image-guided laser induced branch retinal vein occlusion in living rabbits

      High-resolution multimodal photoacoustic microscopy and optical coherence tomography image-guided laser induced branch retinal vein occlusion in living rabbits

      Joint high-resolution multimodal photoacoustic microscopy (PAM) and optical coherence tomography (OCT) was developed to improve the efficiency for visualizing newly developed retinal neovascularization (RNV) and to monitor the dynamic changes of retinal vein occlusion (RVO) in living rabbits. The RNV and RVO models were created in New Zealand rabbits by Rose Bengal laser-induced RVO. Dual modalities imaging equipment, including color fundus photography, fluorescein angiography (FA), OCT, and PAM, was used to image and assess the changes of retinal vasculature. In vivo experimental results exhibited that not only the treatment boundaries and the position of the occluded vasculature but also the ...

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    2. In Vivo 3D Imaging of Retinal Neovascularization Using Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Imaging

      In Vivo 3D Imaging of Retinal Neovascularization Using Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Imaging

      The pathological process of neovascularization of the retina plays a critical role in causing vision loss in several diseases, including diabetes, retinal vein occlusion, and sickle cell disease. Retinal neovascularization can lead to vitreous hemorrhage and retinal detachment, yet the pathological process of neovascularization is a complex phenomenon under active investigation. Understanding and monitoring retinal neovascularization is critically important in clinical ophthalmology. This study describes a novel multimodal ocular imaging system which combines photoacoustic microscopy (PAM) and a spectral domain optical coherence tomography (SD-OCT) to improve the visualization of retinal neovascularization (RNV), their depth, and the surrounding anatomy in living ...

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    3. High-resolution, in vivo multimodal photoacoustic microscopy, optical coherence tomography, and fluorescence microscopy imaging of rabbit retinal neovascularization

      High-resolution, in vivo multimodal photoacoustic microscopy, optical coherence tomography, and fluorescence microscopy imaging of rabbit retinal neovascularization

      Photoacoustic microscopy (PAM) is an emerging imaging technology that can non-invasively visualize ocular structures in animal eyes. This report describes an integrated multimodality imaging system that combines PAM, optical coherence tomography (OCT), and fluorescence microscopy (FM) to evaluate angiogenesis in larger animal eyes. High-resolution in vivo imaging was performed in live rabbit eyes with vascular endothelial growth factor (VEGF)-induced retinal neovascularization (RNV). The results demonstrate that our multimodality imaging system can non-invasively visualize RNV in both albino and pigmented rabbits to determine retinal pathology using PAM and OCT and verify the leakage of neovascularization using FM and fluorescein dye ...

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    4. Multi-wavelength, en-face photoacoustic microscopy and optical coherence tomography imaging for early and selective detection of laser induced retinal vein occlusion

      Multi-wavelength, en-face photoacoustic microscopy and optical coherence tomography imaging for early and selective detection of laser induced retinal vein occlusion

      Multi-wavelength en face photoacoustic microscopy (PAM) was integrated with a spectral domain optical coherence tomography (SD-OCT) to evaluate optical properties of retinal vein occlusion (RVO) and retinal neovascularization (RNV) in living rabbits. The multi-wavelength PAM of the RVO and RNV were performed at several wavelengths ranging from 510 to 600 nm. Rose Bengal-induced RVO and RNV were performed and evaluated on eight rabbits using color fundus photography, fluorescein angiography, OCT, and spectroscopic en face PAM. In vivo experiment demonstrates that the spectral variation of photoacoustic response was achieved. The location and the treatment margins of the occluded vasculature as well ...

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      Mentions: Wei Zhang
    5. Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample

      Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample

      Compression is one of the typical parameters measured in material mechanics. In this research, the compression displacement fields on the front and rear surfaces of an epoxy sample are measured by using a tilt depth-resolved wavenumber-scanning Michelson interferometer. The light source is a distributed feedback laser diode, the wavenumber of which can be modulated to about 1.017 × 104 m–1 by the temperature without mode hopping. A random-sampling Fourier transform is designed to evaluate the phase differences before and after the applied loads. Experimental results show that the depth-resolved measurement of the compression displacement field is of high accuracy ...

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    6. Novel Photoacoustic Microscopy and Optical Coherence Tomography Dual-modality Chorioretinal Imaging in Living Rabbit Eyes

      Novel Photoacoustic Microscopy and Optical Coherence Tomography Dual-modality Chorioretinal Imaging in Living Rabbit Eyes

      Photoacoustic ocular imaging is an emerging ophthalmic imaging technology that can noninvasively visualize ocular tissue by converting light energy into sound waves and is currently under intensive investigation. However, most reported work to date is focused on the imaging of the posterior segment of the eyes of small animals, such as rats and mice, which poses challenges for clinical human translation due to small eyeball sizes. This manuscript describes a novel photoacoustic microscopy (PAM) and optical coherence tomography (OCT) dual-modality system for posterior segment imaging of the eyes of larger animals, such as rabbits. The system configuration, system alignment, animal ...

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    7. Integrated photoacoustic microscopy, optical coherence tomography, and fluorescence microscopy for multimodal chorioretinal imaging

      Integrated photoacoustic microscopy, optical coherence tomography, and fluorescence microscopy for multimodal chorioretinal imaging

      Current clinical available retinal imaging techniques have limitations, including limited depth of penetration or requirement for the invasive injection of exogenous contrast agents. Here, we developed a novel multimodal imaging system for high-speed, high-resolution retinal imaging of larger animals, such as rabbits. The system integrates three state-of-the-art imaging modalities, including photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescence microscopy (FM). In vivo experimental results of rabbit eyes show that the PAM is able to visualize laser-induced retinal burns and distinguish individual eye blood vessels using a laser exposure dose of ~80 nJ, which is well below the American National ...

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    8. Noninvasive chorioretinal imaging in living rabbits using integrated photoacoustic microscopy and optical coherence tomography

      Noninvasive chorioretinal imaging in living rabbits using integrated photoacoustic microscopy and optical coherence tomography

      Most reported photoacoustic ocular imaging work to date uses small animals, such as mice and rats, the eyeball sizes of which are less than one-third of those of humans, posing challenges for clinical translation. Here we developed a novel integrated photoacoustic microscopy (PAM) and optical coherence tomography (OCT) system for dual-modality chorioretinal imaging of larger animals, such as rabbits. The system has quantified lateral resolutions of 4.1 µm (PAM) and 3.8 µm (OCT), and axial resolutions of 37.0 µm (PAM) and 4.0 µm (OCT) at the focal plane of the objective. Experimental results in living rabbits ...

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    9. Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature

      Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature

      We present the first endoscopic Doppler optical coherence tomography and co-registered autofluorescence imaging (DOCT-AFI) of peripheral pulmonary nodules and vascular networks in vivo using a small 0.9 mm diameter catheter. Using exemplary images from volumetric data sets collected from 31 patients during flexible bronchoscopy, we demonstrate how DOCT and AFI offer complementary information that may increase the ability to locate and characterize pulmonary nodules. AFI offers a sensitive visual presentation for the rapid identification of suspicious airway sites, while co-registered OCT provides detailed structural information to assess the airway morphology. We demonstrate the ability of AFI to visualize vascular ...

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    10. Bronchial thermoplasty in asthma: 2-year follow-up using optical coherence tomography

      Bronchial thermoplasty in asthma: 2-year follow-up using optical coherence tomography

      Bronchial thermoplasty (BT) is a novel, nonpharmacological procedure for treatment of severe asthma. Recently, the Asthma Intervention Research 2 clinical trial demonstrated asthmatics had fewer hospitalisations following BT, which persisted 5 years after therapy [1]. However, it is well recognised that asthma is a heterogeneous disease with distinct asthma phenotypes and, not surprisingly, not all asthmatics in that trial benefited from BT [2].

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    11. Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer

      Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer

      Diagnosis of peripheral lung nodules is challenging because they are rarely visualized endobronchially. Imaging techniques such as endobronchial ultrasound (EBUS) are employed to improve tumor localization. The current EBUS probe provides limited nodule characterization and has an outer diameter of 1.4 mm that restricts access to small peripheral airways. We report a novel co-registered autofluoresence Doppler optical coherence tomography (AF/DOCT) system with a 0.9 mm diameter probe to characterize peripheral lung nodules prior to biopsy in vivo. Method: Patients referred for evaluation of peripheral lung nodules underwent bronchoscopy with examination of standard EBUS and the novel AF ...

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    12. Sex differences in chronic obstructive pulmonary disease evaluated using optical coherence tomography

      Sex differences in chronic obstructive pulmonary disease evaluated using optical coherence tomography

      Although there are more women than men dying of chronic obstructive pulmonary disease (COPD) in the United States and elsewhere, we still do not have a clear understanding of the differences in the pathophysiology of airflow obstruction between the sexes. Optical coherence tomography (OCT) is an emerging imaging technology that has the capability of imaging small bronchioles with resolution approaching histology. Therefore, our objective was to compare OCT-derived airway wall measurements between males and females matched for lung size and in anatomically matched small airways. Subjects 50-80 yrs were enrolled in the British Columbia Lung Health Study and underwent OCT ...

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    13. Localized Retinal Nerve Fiber Layer Defects Detected by Optical Coherence Tomography: The Beijing Eye Study

      Localized Retinal Nerve Fiber Layer Defects Detected by Optical Coherence Tomography: The Beijing Eye Study

      Objective To assess the prevalence of localized retinal nerve fiber layer defects (LRNFLD) and associated factors in adult Chinese. Methods The population-based Beijing Eye Study 2011 included 3468 individuals (mean age: 64.6±9.8 years (range: 50–93 years)). The study participants underwent a detailed ophthalmological examination including spectral-domain optical coherence tomography (Spectralis R -OCT) assisted measurement of the RNFL. A LRNFLD was defined as a sector in which the RNFL contour line dipped into the red zone for a length of <180°. Results Readable OCT images were available for 3242 (93.5%) subjects. LRNFLDs were detected in 640 ...

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    14. Cervical Epithelial Brightness by Optical Coherence Tomography Can Determine Histological Grades of Cervical Neoplasia

      Cervical Epithelial Brightness by Optical Coherence Tomography Can Determine Histological Grades of Cervical Neoplasia

      Objective: The study aimed to determine if the difference in cervical epithelium brightness, as measured by optical coherence tomography (OCT), has potential as a distinguishing characteristic of normal, low-grade, high-grade (cervical intraepithelial neoplasia 2+), and cancer histological findings. Materials and Methods: Information from 476 women was available for analysis. Demographic information was collected through in-person interview. All participants were human papillomavirus positive and/or had abnormal cytological finding and underwent colposcopy or unaided visual inspection and examination by OCT by quadrant. All women had a minimum of 4 OCT-matched cervical biopsies and endocervical curettage. Two sample t tests were used ...

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    15. Study of the Diagnostic Efficacy of Real-Time Optical Coherence Tomography as an Adjunct to Unaided Visual Inspection With Acetic Acid for the Diagnosis of Preinvasive and Invasive Neoplasia of the Uterine Cervix

      Study of the Diagnostic Efficacy of Real-Time Optical Coherence Tomography as an Adjunct to Unaided Visual Inspection With Acetic Acid for the Diagnosis of Preinvasive and Invasive Neoplasia of the Uterine Cervix

      Objectives: To determine the sensitivity and specificity of optical coherence tomography (OCT) as an adjunct to unaided visual inspection using acetic acid (VIA) in the detection of cervical intraepithelial neoplasia 2 (CIN 2) in a real-time clinical evaluation. Background: This clinical study was a prospective cross-sectional comparative trial that screened 1000 patients (aged 30-50 years) in a low-resource setting. Women with abnormal cervical cytology or positive human papillomavirus (HPV) tests were referred for further evaluation including VIA, OCT imaging, colposcopy, and cervical biopsies. Methods: The VIA diagnoses were coded by quadrant. The OCT was then performed in all VIA-positive areas ...

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    1-15 of 15
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  2. Topics in the News

    1. (13 articles) Wei Zhang
    2. (6 articles) University of Michigan
    3. (4 articles) Stephen Lam
    4. (3 articles) Pierre M. Lane
    5. (2 articles) British Columbia Cancer Agency
    6. (2 articles) Nancy J. Tresser
    7. (2 articles) Tawimas Shaipanich
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    Study of the Diagnostic Efficacy of Real-Time Optical Coherence Tomography as an Adjunct to Unaided Visual Inspection With Acetic Acid for the Diagnosis of Preinvasive and Invasive Neoplasia of the Uterine Cervix Cervical Epithelial Brightness by Optical Coherence Tomography Can Determine Histological Grades of Cervical Neoplasia Localized Retinal Nerve Fiber Layer Defects Detected by Optical Coherence Tomography: The Beijing Eye Study Sex differences in chronic obstructive pulmonary disease evaluated using optical coherence tomography Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer Bronchial thermoplasty in asthma: 2-year follow-up using optical coherence tomography Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature Noninvasive chorioretinal imaging in living rabbits using integrated photoacoustic microscopy and optical coherence tomography Novel Photoacoustic Microscopy and Optical Coherence Tomography Dual-modality Chorioretinal Imaging in Living Rabbit Eyes Depth-resolved measurement of the compression displacement fields on the front and rear surfaces of an epoxy sample KU Leuven leads €6 million research project on heart disease and dementia Gabor optical coherence tomographic angiography (GOCTA) (Part II): theoretical basis of sensitivity improvement and optimization for processing speed