Optical Coherence Tomography and Autofluorescence Imaging of Human Tonsil

For the first time, we present co-registered autofluorescence imaging and optical coherence tomography (AF/OCT) of excised human palatine tonsils to evaluate the capabilities of OCT to visualize tonsil tissue components. Despite limited penetration depth, OCT can provide detailed structural information about tonsil tissue with much higher resolution than that of computed tomography, magnetic resonance imaging, and Ultrasound. Different tonsil tissue components such as epithelium, dense connective tissue, lymphoid nodules, and crypts can be visualized by OCT. The co-registered AF imaging can provide matching biochemical information. AF/OCT scans may provide a non-invasive tool for detecting tonsillar cancers and for studying the natural history of their development.     

GPU-Accelerated Framework for Intracoronary Optical Coherence Tomography Imaging at the Push of a Button

Frequency domain optical coherence tomography (FD-OCT) has become one of the important clinical tools for intracoronary imaging to diagnose and monitor coronary artery disease, which has been one of the leading causes of death. To help more accurate diagnosis and monitoring of the disease, many researchers have recently worked on visualization of various coronary microscopic features including stent struts by constructing three-dimensional (3D) volumetric rendering from series of cross-sectional intracoronary FD-OCT images. In this paper, we present the first, to our knowledge, "push-of-a-button" graphics processing unit (GPU)-accelerated framework for intracoronary OCT imaging. Our framework visualizes 3D microstructures of the vessel wall with stent struts from raw binary OCT data acquired by the system digitizer as one seamless process. The framework reports the state-of-the-art performance; from raw OCT data, it takes 4.7 seconds to provide 3D visualization of a 5-cm-long coronary artery (of size 1600 samples x 1024 A-lines x 260 frames) with stent struts and detection of malapposition automatically at the single push of a button.     

Noninvasive Imaging of Ethanol‐Induced Developmental Defects in Zebrafish Embryos Using Optical Coherence Tomography

In this article, we report the use of optical coherence tomography for noninvasive cross‐sectional real‐time imaging of ethanol‐induced developmental defects in zebrafish embryos larvae. For ethanol concentration of over 300 mM, developmental defects of eye (shrinkage and retinal abnormalities), malformation of the notochord and ataxia arising due to the toxic effects of ethanol were observed in OCT images from 3 days post fertilization onwards. The results suggest that OCT could be a valuable tool for noninvasive assessment of birth defects in small animal systems.     

位相分辨偏振灵敏光学相干层析术:组织双折射特性的成像与定量分析

我们研制了一种基于光纤的位相分辨偏振灵敏光学相干层析成像系统。该系统中的偏振状态控制设量在参考臂而非光源臂上,因而使得光抵达样品的传输效率大大提高。鉴于光源的部分偏振性,入射于样品上的光含有任意偏振状态的分量,通过对参考光偏振状态的调制,就可相干地提取对应于入射光四种正交偏振状态并经样品后向散射的光信号。基于斯托克斯矢量夹角在无损光纤系统传输的变换不变性,我们能利用测量臂中光信号的斯托克斯参数来确定双折射样品深度分辨的位相延迟信息。利用所研制的偏振灵敏光学相干层析成像系统,不仅确认了韧带和软骨的双折射性质,而且定量分析了不同条件下韧带的双折射变化．研究结果表明：韧带松弛可使其双折射特性明显减弱,而韧带经拉伸后,其双折射特性的变化却不明显。     

基于光学相干层析图像的离体牙三维重建

利用shear-warp算法对离体牙的光学相干层析图像进行三维重建,通过不透明度传递函数的合理设置及光照模型的引入实现牙齿内部组织结构的可视化,便于医生在早期龋齿诊断中定位病变.介绍了shear-warp算法的原理、用于龋齿检测的全光纤光学相干层析成像系统及其二维层析图,以及利用离体牙牙冠的二维层析图重建获得三维结构图.     

Measurement of Myopia and Normal Human Choroidal Thickness Using Spectral Domain Optical Coherence Tomography

Myopia is a common ophthalmic deficiency. The structure and function of choroid layer is assumed to be associated with myopia. In this study, a laboratory developed spectral domain optical coherence tomography scanning system is used to image human eyes. The axial resolution of the system is about 7 μm, and the acquisition rate is 100 kHz. Firstly, a cross-sectional image was acquired by averaging 100 images from imaging posterior segment of each eye. The choroid thickness was measured by 11 discrete points. The average thickness of normal human eyes was (0.296 ± 0.126) mm, whereas the average choroid thickness of myopic eyes was (0.220 ± 0.095) mm. Afterwards, the T test is used to calculate the data statistically. The analysis of the final result is based on the average thickness measured and the thickness of each measuring point. There was a significant difference in choroid thickness between myopia and normal eyes (P value < 0.01), which indicates that the choroid thickness of myopia was significantly thinner than that of normal eyes. Besides, there are findings that the choroidal thickness in nasal side is thinner than that in the fovea and temporal side in each eye. The choroidal thickness on temporal side in myopia eye has the most significant difference comparing with that in normal eye. The comprehensive evaluation of myopia and normal choroidal thickness using spectral domain optical coherence tomography may provide an important reference for the development of medical methods for diagnosis and treatment of myopia.     

Feasibility of the Assessment of Cholesterol Crystals in Human Macrophages Using Micro Optical Coherence Tomography

The presence of cholesterol crystals is a hallmark of atherosclerosis, but until recently, such crystals have been considered to be passive components of necrotic plaque cores. Recent studies have demonstrated that phagocytosis of cholesterol crystals by macrophages may actively precipitate plaque progression via an inflammatory pathway, emphasizing the need for methods to study the interaction between macrophages and crystalline cholesterol. In this study, we demonstrate the feasibility of detecting cholesterol in macrophages in situ using Micro-Optical Coherence Tomography (µOCT), an imaging modality we have recently developed with 1-µm resolution. Macrophages containing cholesterol crystals frequently demonstrated highly scattering constituents in their cytoplasm on µOCT imaging, and µOCT was able to evaluate cholesterol crystals in cultured macrophage cells. Our results suggest that µOCT may be useful for the detection and characterization of inflammatory activity associated with cholesterol crystals in the coronary artery.     

Study of the Morphological and Functional State of Higher Plant Tissues by Optical Coherence Microscopy and Optical Coherence Tomography

Comparative analysis of two optical methods—optical coherence tomography (OCT) and optical coherence microscopy (OCM)—was made for vital visualization of plant tissues in tomato (Lycopersicon esculentum Mill), spiderwort (Tradescantia pallida (Rose) D. Hunt), orach (Atriplex sp.), and leaves and seeds of medium starwort (Stellaria media L.). The obtained OCT- and OCM-images allowed the morphological and functional state of plant tissues to be assessed in vivo. A higher spatial resolution of the OCM method, as compared to OCT method, allowed plant morphological structures to be identified with greater confidence. The morphological and functional state of tissues can be monitored with a time resolution of 1–4 s in intact plants, without removing them from the habitat.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 628–634.Original Russian Text Copyright © 2005 by Kutis, Sapozhnikova, Kuranov, Kamenskii.     

Assessment of Choroidal Thickness in Healthy and Glaucomatous Eyes Using Swept Source Optical Coherence Tomography

Purpose

To evaluate choroidal thickness (CT) in healthy and glaucomatous eyes using Swept Source Optical Coherence Tomography (SS-OCT).

Methods

A cross-sectional observational study of 216 eyes of 140 subjects with glaucoma and 106 eyes of 67 healthy subjects enrolled in the Diagnostic Innovations in Glaucoma Study. CT was assessed from wide-field (12×9 mm) SS-OCT scans. The association between CT and potential confounding variables including age, gender, axial length, intraocular pressure, central corneal thickness and ocular perfusion pressure was examined using univariable and multivariable regression analyses.

Results

Overall CT was thinner in glaucomatous eyes with a mean (± standard deviation) of 157.7±48.5 µm in glaucoma compared to 179.9±36.1 µm in healthy eyes (P<0.001). The choroid was thinner in both the peripapillary and macular regions in glaucoma compared to controls. Mean peripapillary CT was 154.1±44.1 µm and 134.0±56.9 µm (P<0.001) and macular CT 199.3±46.1 µm and 176.2±57.5 µm (P<0.001) for healthy and glaucomatous eyes respectively. However, older age (P<0.001) and longer axial length (P<0.001) were also associated with thinner choroid and when differences in age and axial length between glaucomatous and healthy subjects were accounted for, glaucoma was not significantly associated with CT. There was also no association between glaucoma severity and CT.

Conclusions

Glaucoma was not associated with CT measured using SS-OCT; however, older age and longer axial length were associated with thinner choroid so should be considered when interpreting CT measurements.     

3D Evaluation of the Lamina Cribrosa with Swept-Source Optical Coherence Tomography in Normal Tension Glaucoma

Purpose

Although the lamina cribrosa (LC) is the primary site of axonal damage in glaucoma, adequate methods to image and measure it are currently lacking. Here, we describe a noninvasive, in vivo method of evaluating the LC, based on swept-source optical coherence tomography (SS-OCT), and determine this method’s ability to quantify LC thickness.

Methods

This study comprised 54 eyes, including normal (n = 18), preperimetric glaucoma (PPG; n = 18), and normal tension glaucoma (NTG; n = 18) eyes. We used SS-OCT to obtain 3 x 3 mm cube scans of an area centered on the optic disc, and then synchronized reconstructed B- and en-face images from this data. We identified the LC in these B-scan images by marking the visible borders of the LC pores. We marked points on the anterior and posterior borders of the LC in 12 B-scan images in order to create a skeleton model of the LC. Finally, we used B-spline interpolation to form a 3D model of the LC, including only reliably measured scan areas. We calculated the average LC thickness (avgLCT) in this model and used Spearman''s rank correlation coefficient to compare it with circumpapillary retinal nerve fiber layer thickness (cpRNFLT).

Results

We found that the correlation coefficient of avgLCT and cpRNFLT was 0.64 (p < 0.01). The coefficient of variation for avgLCT was 5.1%. AvgLCT differed significantly in the groups (normal: 282.6 ± 20.6 μm, PPG: 261.4 ± 15.8 μm, NTG: 232.6 ± 33.3 μm). The normal, PPG and NTG groups did not significantly differ in age, sex, refractive error or intraocular pressure (IOP), although the normal and NTG groups differed significantly in cpRNFLT and Humphrey field analyzer measurements of mean deviation.

Conclusion

Thus, our results indicate that the parameters of our newly developed method of measuring LC thickness with SS-OCT may provide useful and important data for glaucoma diagnosis and research.     

The Correlation Between Texture Features and Fibrous Cap Thickness of Lipid-Rich Atheroma Based on Optical Coherence Tomography Imaging

Fibrous cap thickness (FCT) is seen as critical to plaque vulnerability. Therefore, the development of automatic algorithms for the quantification of FCT is for estimating cardiovascular risk of patients. Intravascular optical coherence tomography (IVOCT) is currently the only in vivo imaging modality with which FCT, the critical component of plaque vulnerability, can be assessed accurately. This study was aimed to discussion the correlation between the texture features of OCT images and the FCT in lipid-rich atheroma. Methods: Firstly, a full automatic segmentation algorithm based on unsupervised fuzzy c means (FCM) clustering with geometric constrains was developed to segment the ROIs of IVOCT images. Then, 32 features, which are associated with the structural and biochemical changes of tissue, were carried out to describe the properties of ROIs. The FCT in grayscale IVOCT images were manually measured by two independent observers. In order to analysis the correlation between IVOCT image features and manual FCT measurements, linear regression approach was performed. Results: Inter-observer agreement of the twice manual FCT measurements was excellent with an intraclass correlation coefficient (ICC) of 0.99. The correlation coefficient between each individual feature set and mean FCT of OCT images were 0.68 for FOS, 0.80 for GLCM, 0.74 for NGTDM, 0.72 for FD, 0.62 for IM and 0.58 for SP. The fusion image features of automatic segmented ROIs and FCT measurements improved the results significantly with a high correlation coefficient (r= 0.91, p<0.001). Conclusion The OCT images features demonstrated the perfect performances and could be used for automatic qualitative analysis and the identification of high-risk plaques instead manual FCT measurements.     

Longitudinal Study of Mammary Epithelial and Fibroblast Co-Cultures Using Optical Coherence Tomography Reveals Morphological Hallmarks of Pre-Malignancy

The human mammary gland is a complex and heterogeneous organ, where the interactions between mammary epithelial cells (MEC) and stromal fibroblasts are known to regulate normal biology and tumorigenesis. We aimed to longitudinally evaluate morphology and size of organoids in 3D co-cultures of normal (MCF10A) or pre-malignant (MCF10DCIS.com) MEC and hTERT-immortalized fibroblasts from reduction mammoplasty (RMF). This co-culture model, based on an isogenic panel of cell lines, can yield insights to understand breast cancer progression. However, 3D cultures pose challenges for quantitative assessment and imaging, especially when the goal is to measure the same organoid structures over time. Using optical coherence tomography (OCT) as a non-invasive method to longitudinally quantify morphological changes, we found that OCT provides excellent visualization of MEC-fibroblast co-cultures as they form ductal acini and remodel over time. Different concentrations of fibroblasts and MEC reflecting reported physiological ratios [1] were evaluated, and we found that larger, hollower, and more aspherical acini were formed only by pre-malignant MEC (MCF10DCIS.com) in the presence of fibroblasts, whereas in comparable conditions, normal MEC (MCF10A) acini remained smaller and less aspherical. The ratio of fibroblast to MEC was also influential in determining organoid phenotypes, with higher concentrations of fibroblasts producing more aspherical structures in MCF10DCIS.com. These findings suggest that stromal-epithelial interactions between fibroblasts and MEC can be modeled in vitro, with OCT imaging as a convenient means of assaying time dependent changes, with the potential for yielding important biological insights about the differences between benign and pre-malignant cells.     

维生素C对光化学法诱导皮肤光损伤的光保护作用:OCT定量研究

8-甲氧补骨脂素(8-MOP)联合UVA辐射(即光化学疗法PUVA)因诱导皮肤光损伤的副作用,常被用于实验动物皮肤光损伤模型的构建。为研究维生素C(Vc)对皮肤光损伤的保护效应,本研究在Balb/c小鼠背部皮肤涂抹0.1%8-MOP溶液1h后进行UVA辐照(10 J/cn2)。然后分别涂抹7.5%、15%和30%浓度的Vc溶液的进行光保护治疗,利用光学相干层析成像分析皮肤厚度和光信号衰减的变化,从而评估Vc对皮肤的光保护作用。结果显示,相对于溶媒组,Vc治疗组皮肤厚度减小,光衰减系数增加,其中15%效果尤为明显结果表明,局部涂抹Vc溶液具有一定的光损伤保护效应。     

Structure-Function Modeling of Optical Coherence Tomography and Standard Automated Perimetry in the Retina of Patients with Autosomal Dominant Retinitis Pigmentosa

Purpose

To assess relationships between structural and functional biomarkers, including new topographic measures of visual field sensitivity, in patients with autosomal dominant retinitis pigmentosa.

Methods

Spectral domain optical coherence tomography line scans and hill of vision (HOV) sensitivity surfaces from full-field standard automated perimetry were semi-automatically aligned for 60 eyes of 35 patients. Structural biomarkers were extracted from outer retina b-scans along horizontal and vertical midlines. Functional biomarkers were extracted from local sensitivity profiles along the b-scans and from the full visual field. These included topographic measures of functional transition such as the contour of most rapid sensitivity decline around the HOV, herein called HOV slope for convenience. Biomarker relationships were assessed pairwise by coefficients of determination (R²) from mixed-effects analysis with automatic model selection.

Results

Structure-function relationships were accurately modeled (conditional R²>0.8 in most cases). The best-fit relationship models and correlation patterns for horizontally oriented biomarkers were different than vertically oriented ones. The structural biomarker with the largest number of significant functional correlates was the ellipsoid zone (EZ) width, followed by the total photoreceptor layer thickness. The strongest correlation observed was between EZ width and HOV slope distance (marginal R² = 0.85, p<10⁻¹⁰). The mean sensitivity defect at the EZ edge was 7.6 dB. Among all functional biomarkers, the HOV slope mean value, HOV slope mean distance, and maximum sensitivity along the b-scan had the largest number of significant structural correlates.

Conclusions

Topographic slope metrics show promise as functional biomarkers relevant to the transition zone. EZ width is strongly associated with the location of most rapid HOV decline.     

Analytic 3D Imaging of Mammalian Nucleus at Nanoscale Using Coherent X-Rays and Optical Fluorescence Microscopy

Despite the notable progress that has been made with nano-bio imaging probes, quantitative nanoscale imaging of multistructured specimens such as mammalian cells remains challenging due to their inherent structural complexity. Here, we successfully performed three-dimensional (3D) imaging of mammalian nuclei by combining coherent x-ray diffraction microscopy, explicitly visualizing nuclear substructures at several tens of nanometer resolution, and optical fluorescence microscopy, cross confirming the substructures with immunostaining. This demonstrates the successful application of coherent x-rays to obtain the 3D ultrastructure of mammalian nuclei and establishes a solid route to nanoscale imaging of complex specimens.     

Analytic 3D Imaging of Mammalian Nucleus at Nanoscale Using Coherent X-Rays and Optical Fluorescence Microscopy

Despite the notable progress that has been made with nano-bio imaging probes, quantitative nanoscale imaging of multistructured specimens such as mammalian cells remains challenging due to their inherent structural complexity. Here, we successfully performed three-dimensional (3D) imaging of mammalian nuclei by combining coherent x-ray diffraction microscopy, explicitly visualizing nuclear substructures at several tens of nanometer resolution, and optical fluorescence microscopy, cross confirming the substructures with immunostaining. This demonstrates the successful application of coherent x-rays to obtain the 3D ultrastructure of mammalian nuclei and establishes a solid route to nanoscale imaging of complex specimens.     

Aortic and Cardiac Structure and Function Using High-Resolution Echocardiography and Optical Coherence Tomography in a Mouse Model of Marfan Syndrome

Marfan syndrome (MFS) is an autosomal-dominant disorder of connective tissue caused by mutations in the fibrillin-1 (FBN1) gene. Mortality is often due to aortic dissection and rupture. We investigated the structural and functional properties of the heart and aorta in a [Fbn1^C1039G/+] MFS mouse using high-resolution ultrasound (echo) and optical coherence tomography (OCT). Echo was performed on 6- and 12-month old wild type (WT) and MFS mice (n = 8). In vivo pulse wave velocity (PWV), aortic root diameter, ejection fraction, stroke volume, left ventricular (LV) wall thickness, LV mass and mitral valve early and atrial velocities (E/A) ratio were measured by high resolution echocardiography. OCT was performed on 12-month old WT and MFS fixed mouse hearts to measure ventricular volume and mass. The PWV was significantly increased in 6-mo MFS vs. WT (366.6 ± 19.9 vs. 205.2 ± 18.1 cm/s; p = 0.003) and 12-mo MFS vs. WT (459.5 ± 42.3 vs. 205.3 ± 30.3 cm/s; p< 0.0001). PWV increased with age in MFS mice only. We also found a significantly enlarged aortic root and decreased E/A ratio in MFS mice compared with WT for both age groups. The [Fbn1^C1039G/+] mouse model of MFS replicates many of the anomalies of Marfan patients including significant aortic dilation, central aortic stiffness, LV systolic and diastolic dysfunction. This is the first demonstration of the direct measurement in vivo of pulse wave velocity non-invasively in the aortic arch of MFS mice, a robust measure of aortic stiffness and a critical clinical parameter for the assessment of pathology in the Marfan syndrome.     

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Stroke is the third leading cause of death among Americans 65 years of age or older¹. The quality of life for patients who suffer from a stroke fails to return to normal in a large majority of patients², which is mainly due to current lack of clinical treatment for acute stroke. This necessitates understanding the physiological effects of cerebral ischemia on brain tissue over time and is a major area of active research. Towards this end, experimental progress has been made using rats as a preclinical model for stroke, particularly, using non-invasive methods such as ¹⁸F-fluorodeoxyglucose (FDG) coupled with Positron Emission Tomography (PET) imaging^3,10,17. Here we present a strategy for inducing cerebral ischemia in rats by middle cerebral artery occlusion (MCAO) that mimics focal cerebral ischemia in humans, and imaging its effects over 24 hr using FDG-PET coupled with X-ray computed tomography (CT) with an Albira PET-CT instrument. A VOI template atlas was subsequently fused to the cerebral rat data to enable a unbiased analysis of the brain and its sub-regions⁴. In addition, a method for 3D visualization of the FDG-PET-CT time course is presented. In summary, we present a detailed protocol for initiating, quantifying, and visualizing an induced ischemic stroke event in a living Sprague-Dawley rat in three dimensions using FDG-PET.     

基于光学相干层析成像技术的鼠皮肤II度烫伤及其修复过程监控

建立小鼠皮肤的Ⅱ度烫伤的模型,分别于烫伤前、烫伤后1 min、8 h、1 d、3 d、5 d、7 d、9 d、11 d、13 d、15 d、17 d,用光学相干层析成像技术(OCT)对烫伤的创面进行动态的监测,同时对创面进行组织病理学的检测,对结果进行分析。利用OCT单次散射模型获得皮肤在烫伤前后光衰减系数的变化情况,结果显示光衰减系数的值在烫伤后是呈先减小后增大的趋势,待修复完全后又恢复到烫伤前相近的值。该结果与组织病理学的结果相吻合,这表明OCT技术可以用于实时诊断烫伤的皮肤。     

Diagnostic Ability of Macular Ganglion Cell Inner Plexiform Layer Measurements in Glaucoma Using Swept Source and Spectral Domain Optical Coherence Tomography

PurposeTo evaluate the diagnostic ability of macular ganglion cell and inner plexiform layer measurements in glaucoma, obtained using swept source (SS) and spectral domain (SD) optical coherence tomography (OCT) and to compare to circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements.MethodsThe study included 106 glaucomatous eyes of 80 subjects and 41 eyes of 22 healthy subjects from the Diagnostic Innovations in Glaucoma Study. Macular ganglion cell and inner plexiform layer (mGCIPL), macular ganglion cell complex (mGCC) and cpRNFL thickness were assessed using SS-OCT and SD-OCT, and area under the receiver operating characteristic curves (AUCs) were calculated to determine ability to differentiate glaucomatous and healthy eyes and between early glaucomatous and healthy eyes.ResultsMean (± standard deviation) mGCIPL and mGCC thickness were thinner in both healthy and glaucomatous eyes using SS-OCT compared to using SD-OCT. Fixed and proportional biases were detected between SS-OCT and SD-OCT measures. Diagnostic accuracy (AUCs) for differentiating between healthy and glaucomatous eyes for average and sectoral mGCIPL was similar in SS-OCT (0.65 to 0.81) and SD-OCT (0.63 to 0.83). AUCs for average cpRNFL acquired using SS-OCT and SD-OCT tended to be higher (0.83 and 0.85, respectively) than for average mGCC (0.82 and 0.78, respectively), and mGCIPL (0.73 and 0.75, respectively) but these differences did not consistently reach statistical significance. Minimum SD-OCT mGCIPL and mGCC thickness (unavailable in SS-OCT) had the highest AUC (0.86) among macular measurements.ConclusionAssessment of mGCIPL thickness using SS-OCT or SD-OCT is useful for detecting glaucomatous damage, but measurements are not interchangeable for patient management decisions. Diagnostic accuracies of mGCIPL and mGCC from both SS-OCT and SD-OCT were similar to that of cpRNFL for glaucoma detection.