Contents Preface Chapter 1 Clinical Applications of Retinal Optical Coherence 1.1 Anatomy of the Eye and Retina 1 1.1.1 Simple Anatomy of the Eye 1 1.1.2 Simple Histology of Retina 2 1.1.3 Normal Macular OCT Image 4 1.2 Vitreomacular Interface Diseases 5 1.2.1 Vitreomacular Adhesion 5 1.2.2 Vitreomacular Traction 6 1.2.3 Full Thickness Macular Hole (FTMH) 7 1.2.4 Epiretinal Membrane 8 1.2.5 Myopic Traction Maculopathy 10 1.3 Glaucoma and Optic Neuropathy 10 1.3.1 Parapapillary Retinal Nerve Fiber Layer Thickness 11 1.3.2 Macular Ganglion Cell Thickness 11 1.3.3 0ptic Nerve Head Morphology 12 1.4 Retinal Vascular Diseases 14 1.4.1 Retinal Artery Occlusion 14 1.4.2 Diabetic Retinopathy 15 1.4.3 Retinal Vein Occlusion 16 1.5 0uter Retinal Degenerative Diseases 19 1.6 Choroidal Neovascularization and Polypoidal Choroidal Chapter 2 Fundamentals of Retinal Optical Coherence Tomography 26 2.1 Introduction 26 2.2 Developments and Principles of Operation of Optical Coherence 2.2.1 Time Domain OCT 27 2.2.2 Fourier Domain OCT 28 2.2.3 0ther Evolving OCT Technologies 30 2.3 Interpretation of the Optical Coherence Tomography Image 32 Chapter 3 Speckle Noise Reduction and Enhancement for OCT Images 38 3.1.2 Speckle Properties 40 3.2 0CT Image Modeling 41 3.3 Statistical Model for OCT Contrast Enhancement 47 3.4 Data Adaptive Transform Models for OCT Denoising 50 3.4.1 Conventional Dictionary Learning 50 3.4.2 Dual Tree Complex Wavelet Transform 51 3.4.3 Dictionary Learning with Wise Selection of Start Dictionary 52 3.5 Non Data Adaptive Transform Models for OCT Denoising 56 3.5.1 Denoising by Minimum Mean Square Error (MMSE) Estimator .58 Chapter 4 Reconstruction of Retinal OCT Images with Sparse 4.1 Introduction 75 4.2 Sparse Representation for Image Reconstruction 77 4.3 Sparsity Based on Methods for the OCT Image Reconstruction 78 4.3.1 Multiscale Sparsity Based on Tomographic Denoising (MSBTD) 78 4.3.2 Sparsity Based on Simultaneous Denoising and Interpolation (SBSDI) 86 4.3.3 3D Adaptive Sparse Representation Based on Compression 4.4 Conclusions 102 References 104 Chapter 5 Segmentation of OCT Scans Using Probabilistic Graphical 5.1 Introduction 109 5.2 A Probabilistic Graphical Model for Retina Segmentation 111 5.2.1 The Graphical Model 111 5.2.2 Variationallnference 114 5.3 Results 117 Contents v 5.3.1 Segmentation Performance 117 5.3.2 Pathology Detection 121 5.4 Segmenting Pathological Scans 125 5.5.1 Conclusion 127 5.5.2 Prospective Work 127 A Appendix 128 A.l Derivation of the Objective (5.16) 128 A.2 0ptimization with Respect to qb 132 References 134 Chapter 6 Diagnostic Capability of Optical Coherence Tomography Based Quantitative Analysis for Various Eye Diseases and Additional Factors Affecting Morphological 6.1 Introduction 137 6.2 0CT Based Retinal Morphological Measurements .140 6.2.1 Quantitative Measurements of Retinal Morphology 140 6.2.2 Quality， Artifacts， and Errors in Optical Coherence Tomography 6.2.3 Effect of Axial Length on Thickness 144 6.3 Capability of Optical Coherence Tomography Based Quantitative Analysis for Various Eye Diseases 147 6.3.1 Diabetic Retinopathy 148 6.3.2 Multiple Sclerosis 150 6.3.3 Amblyopia 156 6.4 Concluding Remarks 163 References 165 Chapter 7 Quantitative Analysis of Retinal Layers' Opticallntensities Based on Optical Coherence Tomography 182 7.1 Introduction 182 7.2 Automatic Layer Segmentation in OCT Images 184 7.3 The Optical Intensity of Retinal Layers of Normal Subjects 185 7.3.1 Data Acquisition 185 7.3.2 Statistical Analysis 185 7.3.3 Results of Quantitative Analysis of Retinal Layer Optical Intensities of Normal Subjects 185 7.3.4 Discussion 188 7.4 Distribution and Determinants of the Opticallntensity of Retinal Layers of Normal Subjects 188 7.4.1 Data Acquisition and Image Processing 189 7.4.2 Statistical Analysis 190 7.4.3 Retinal Optical Intensity Measurement 190 7.4.4 Determinants of Retinal Optical Intensity 194 7.4.5 Discussion 195 7.5 The Opticallntensity Distribution in Central Retinal Artery 7.5.1 Central Retinal Artery Occlusion 195 7.5.2 Subjects and Data Acquisition 196 7.5.3 Image Analysis 197 7.5.5 Discussion 200 References 203 Chapter 8 Segmentation of Optic Disc and Cup to Disc Ratio Quantification Based on OCT Scans 207 8.1 Introduction 207 8.2 0ptic Disc Segmentation 209 8.2.1 0verview of the Method 210 8.2.2 Coarse Disc Margin Location 211 8.2.3 SVM Based Patch Searching 214 8.3 Evaluation of Optic Disc Segmentation and C/D Ratio Quantification 216 8.3.1 Evaluation of Optic Disc Segmentation 216 8.3.2 Evaluation of C/D Ratio Quantification 219 References 222 Chapter 9 Choroidal OCT Analytics 22
摘要
Chapter 1 Clinical Applications of Retinal Optical Coherence Tomography Haoyu Chen， Tingkun Shi and Danny Siu-Chun Ng The developments of medical imaging techniques and medical image analysismethods are always motivated by the needs arising from clinical applications. Thischapter introduces anatomy of the eye and the retina， describes various types of eyediseases that can be visualized with OCT imaging， and therefore presents the must-know background knowledge for readers interested in retinal OCT imageanalysis. 1.1 Anatomy of the Eye and Retina 1.1.1 Simple Anatomy of the Eye The eye is an organ that perceives light and visualinformation. There are five sensesin human body， including vision， hearing， smell， touch and taste. More than 800/o ofinformation we received is obtained through vision perceived by the eyes. The structure of the eye is like a ball， although it is not a perfect sphere. Thereare three layers of coats， enclosing three intraocular components:The front ofthe eyeball is cornea， which is transparent and contribute to most of the refractivepower of the eye; the posterior part of the outermostlayer is sclera， which consists offibrous tissue and protects the inner structures. The middle layer of the eyeballis vascular tunic or uvea， which consists of iris， ciliary body and choroid. Thecenter of iris is open and called pupil. The muscles inside the iris control the sizeof pupil and the amount of light getting into the retina. Ciliary body is responsiblefor the generation of aqueous humor and accommodation. The choroid is locatedjust outside the retina and provides nutrition and oxygen for the outer part of retina.The innermost layer is retina， which is an extension of central nerve system and responsible for the transduction of visual signal into neural signal. The intraocular components include aqueous humor， lens and vitreous body. The lens is connected to ciliary body by the zonules. Aqueous humor and vitreous body locate in front and back of the lens (Fig. 1.1). The eye is a very spe organ. The optical media， including cornea， aqueous humor， lens and vitreous， are transparent. This character allows light getting into the innermost layer， retina， and also allows visualization of retinal structure using various instruments， including optical coherence tomography. 1.1.2 Simple Histology of Retina Retina is the most important structure of the eye. It is a neural tissue and transduces light into neural signal. The histology of the retina consists of ten layers. From inner to outer， they are internal limiting membrane， retinal nerve fiber layer， retinal ganglion cell layer， inner plexiform layer， inner nuclear layer， outer plexiform layer， outer nuclear layer， externallimiting membrane， photoreceptorinner and outer segment， retinal pigment epithelium. Retina is transparent except for the blood vessels and retinal pigment epithelium monolayer (Fig. 1.2). Transparency of retina allows light passing through and reaching the photoreceptors， where the photo-neural transduction occurs. There are two blood supply systems to retina， retinal vascular system and choroidal vascular system. The retinal vascular system rises from optic disc， branches on the retinal nerve fiber layer， and forms three layers of capillary， located in the retinal ganglion cell layer， inner plexiform layer and outer plexiform layer. The retinal vascular system supplies the inner layers of retina. The outer retina is avascular， and oxygen and nutrition is supplied from the choroidal capillary through retinal pigment epithelium. On fundus photography， the optic disc is an important landmark of the retina. It is about l.5 mm diameter， with a cup at the center. It is located about 2.5 0ptic disc diameter nasal to the fovea， which is the center point of the macula. The fovea is spe because it consists of abundant number of cone photoreceptors， which is responsible for fine vision and color vision. There is no inner retinal structure in fovea， hence， there is no blood vessel and allows light to reach the photoreceptors without any disturbance (Fig. 1.3). 1.1.3 Normal Macular OCTlmage OCT provides high resolution imaging for the cross-sectional structure of retina. The reflectivity of tissue is determined by the optical character of tissue itself. Vitreous has the lowest reflectivity in normal subjects. The highest reflective band at the inner retina is retinal nerve fiber layers， which is thickest at the parapapillary region and thinnest just temporal to the fovea. Generally， the nerve fiber layers have higher reflectivity compared with nuclear layers. OCT not only demonstrates the 10 layers of retina， but it is also able to visualize the detail structures of photoreceptor and choroidcl]. There are four hyper-reflective bands at outer retina: externallimiting membrane， inner segment ellipsoid zone， interdigitation zone， and RPE/Bruch's complex. The c
