Quantification of Global Tortuosity in Retinal Blood Vessels

Tortuosity is a parameter that indicates the tendency of a blood vessel segment to contain multiple twists and turns. Chronic hemodynamic changes in the body due to diabetes and hypertension will manifest as increased retinal vascular tortuosity, rendering tortuosity as a suitable indicator for diabetic and hypertensive retinopathy. Retinal tortuosity may be evaluated locally on a single segment or globally in the complete vascular network. Global tortuosity quantification consists of automated segmentation and partition of retinal vessel network, local tortuosity measurement, and global tortuosity index derivation from weighted combination of local tortuosity values. This paper proposes several weighting schemes and evaluates their performance when combined with different local tortuosity indexes. We perform rank correlation analysis to find the global tortuosity quantification that is most consistent with the ophthalmologists. Our results show that local tortuosity indexes that are robust to variations in scale and number of sampling points provide the best performance. Furthermore, weighting scheme based on chord length yields better results than the one based on arc length. The combination of Tortuosity Density (TD) local index and Tortuosity Density Global (TDG) weighting scheme provides the highest consistency with ophthalmologists, with the average rank correlation coefficient of 0.98 (p-value < 0.03)

Deep learning in ophthalmology: The technical and clinical considerations

The advent of computer graphic processing units, improvement in mathematical models and availability of big data has allowed artificial intelligence (AI) using machine learning (ML) and deep learning (DL) techniques to achieve robust performance for broad applications in social-media, the internet of things, the automotive industry and healthcare. DL systems in particular provide improved capability in image, speech and motion recognition as well as in natural language processing. In medicine, significant progress of AI and DL systems has been demonstrated in image-centric specialties such as radiology, dermatology, pathology and ophthalmology. New studies, including pre-registered prospective clinical trials, have shown DL systems are accurate and effective in detecting diabetic retinopathy (DR), glaucoma, age-related macular degeneration (AMD), retinopathy of prematurity, refractive error and in identifying cardiovascular risk factors and diseases, from digital fundus photographs. There is also increasing attention on the use of AI and DL systems in identifying disease features, progression and treatment response for retinal diseases such as neovascular AMD and diabetic macular edema using optical coherence tomography (OCT). Additionally, the application of ML to visual fields may be useful in detecting glaucoma progression. There are limited studies that incorporate clinical data including electronic health records, in AL and DL algorithms, and no prospective studies to demonstrate that AI and DL algorithms can predict the development of clinical eye disease. This article describes global eye disease burden, unmet needs and common conditions of public health importance for which AI and DL systems may be applicable. Technical and clinical aspects to build a DL system to address those needs, and the potential challenges for clinical adoption are discussed. AI, ML and DL will likely play a crucial role in clinical ophthalmology practice, with implications for screening, diagnosis and follow up of the major causes of vision impairment in the setting of ageing populations globally

Automatic computation of the arteriovenous ratio and assessment of its effectiveness as a prognostic indicator in hypertension

[Resumen] La retina es la única parte del cuerpo humano en donde se pueden observar los vasos sanguíneos directamente de una forma no invasiva mediante un examen de fondo de ojo. De esta manera, la imagen de la retina mediante las técnicas de procesamiento de imágenes se convirtió en un campo de clave para el diagnóstico precoz de varias enfermedades sistémicas que provocan alteraciones visibles en dicha imagen. Así, alteraciones en el ancho de los vasos retinianos se asocian con patologías tales como diabetes o hipertensión. De hecho, el estrechamiento de las arterias constituye un indicio precoz de la hipertensión arterial sistémica, siendo una característica del grado I de la retinopatía hipertensiva de acuerdo con la clasificación de Keith-Wagener-Barker. En este sentido, se han realizado esfuerzos para desarrollar programas asistidos por ordenador para medir con precisión los cambios en el ancho de los vasos a través del índice arteriovenoso (IAV), es decir, la relación entre los calibres de las arterias y las venas. Sin embargo, aunque estos sistemas se han usado en muchos estudios con fines de investigación, su aplicabilidad en la práctica clínica diaria es todavía discutida. En este trabajo, se propone una nueva metodología para el cálculo del IAV con el fin de estratificar el riesgo cardiovascular de los hipertensos. Por un lado, se ha desarrollado un método completamente automático para estimar el IAV en una imagen de fondo de ojo de un paciente. Por otro lado, se propone un sistema para monitorizar el IAV del paciente a lo largo del tiempo. Para este fin, las mediciones del IAV en las diferentes imágenes adquiridas sobre el mismo ojo del paciente en diferentes fechas se estiman usando el mismo conjunto de vasos medidos en las mismas áreas. Por lo tanto, la mediciones obtenidos de esta manera son comparables y precisas, debido a que son independientes en el conjunto de vasos seleccionados para el cálculo. Las dos técnicas se han integrado en SIRIUS, un sistema web destinado a incluir diferentes servicios en el campo del análisis de la imagen retiniana. El sistema incluye también gestión de pacientes y revisiones, lo que facilita el análisis de las lesiones retinianas causadas por diferentes patologías y su evolución después de un determinado tratamiento. Además al ser una aplicación distribuída a través de la web, proporciona un entorno de colaboración entre diferentes médicos, investigadores y centros.[Resumo] A retina é a única parte do corpo humano onde se poden observar os vasos sanguíneos directamente dunha maneira non invasiva mediante un examen do fondo do ollo. Desta maneira, a imaxe da retina mediante as técnicas de procesamento de imáxenes converteuse nun campo chave para o diagnóstico precoz de varias enfermidades sistémicas que provocan alteracións visibles en dita imaxe. Así, cambios no ancho dos vasos retinianos asócianse con patoloxías tales como a diabetes ou a hipertensión. De feito, o estreitamento das arterias constitúe un indicio prematuro da hipertensión arterial sistémica, sendo unha característica do grado I da retinopatía hipertensiva dacordo coa clasificación de Keith- Wagener-Barker. Neste sentido, fixerónse moitos esforzos para desenvolver programas asistidos por ordenador para medir con precisión os cambios no ancho dos vasos a través do índice arteriovenoso (IAV), é dicir, a relación entre os calibres das arterias e das veas. Nembargantes, aínda que estes sistemas foron usados en moitos estudios con fins investigadores, a sua aplicabilidade na práctica clínica diaria aínda é discutida. Neste traballo, proponse unha nova metodoloxía para o cálculo do IAV co fin de estratificar o risco cardiovascular dos hipertensos. Por un lado, desenvolveuse un método completamente automático para estimar o IAV nunha imaxe de fondo de ollo dun doente. Por outra banda, proponse un sistema para monitorizar o IAV dun doente a lo longo do tempo. Para isto, as medicións do IAV nas diferentes imaxes adquiridas sobre o mesmo ollo do doente en diferentes datas fanse usando o mesmo conxunto de vasos medidos nas mesmas áreas. Polo tanto, as medicións obtidas desta maneira son comparables e precisas, debido a que son independentes do conxunto de vasos seleccionados para o cálculo. As dúas técnicas foron integradas no SIRIUS, un sistema web destinado a incluir diferentes servicios no campo da análise da imaxe retiniana. O sistema inclúe tamén xestión de doentes e revisións, facilitando a análise e estudo das lesións retinianas causadas por diferentes patoloxías e a súa evolución despois dun determinado tratamento. Ademais ao ser unha aplicación distribuída a través da web, proporciona un entorno de colaboración entre diferentes médicos, investigadores e centros.[Abstract] Retina is the only part in the human body where blood vessels can be directly observed in a non-invasive way through an eye fundus examination. In this manner, the retinal imaging assisted by image processing techniques became a key field for the early diagnosis of several systemic diseases which cause visible alterations in the fundus image. Thus, changes in the retinal vessel widths are associated with pathologies such as diabetes or hypertension. In fact, arteriolar narrowing constitutes an early sign of systemic hypertension, being a feature for the grade I of hypertension retinopathy according to Keith-Wagener-Barker classification. In this sense, some efforts have been made to develop computer-assisted programs to measure accurately abnormalities in the vessel widths through the arteriovenous ratio (AVR), that is, the relation between arteriolar and venular vessel widths. However, although these systems have been used in many studies for research purposes, their applicability to daily clinical practice is yet discussed. In this work, a new methodology for the AVR computation is proposed in order to stratify the cardiovascular risk of hypertension. On one hand, a fully automatic method to estimate the AVR in a sample patient's image is developed. On the other hand, an AVR monitoring system to compute the patient's AVR over time was implemented. To this end, the AVR measurements computed in the different patient's images acquired from the same eye at different dates, uses the same set of vessels measured at the same areas. Thus, the measurements achieved in this manner are comparable and precise due to they are independent on the set of vessels selected for the calculus. The two approaches have been integrated in SIRIUS, a web-based system aimed to include different services in the field of retinal image analysis. It includes patient and checkup management, making easier to analyze the retinal lesions caused by different pathologies and their evolution after a specific treatment. Moreover, being a application distributed via the web, it provides a collaborative environment among different physicians, researchers and medical centers

Characterising pattern asymmetry in pigmented skin lesions

Abstract. In clinical diagnosis of pigmented skin lesions asymmetric pigmentation is often indicative of melanoma. This paper describes a method and measures for characterizing lesion symmetry. The estimate of mirror symmetry is computed first for a number of axes at different degrees of rotation with respect to the lesion centre. The statistics of these estimates are the used to assess the overall symmetry. The method is applied to three different lesion representations showing the overall pigmentation, the pigmentation pattern, and the pattern of dermal melanin. The best measure is a 100% sensitive and 96% specific indicator of melanoma on a test set of 33 lesions, with a separate training set consisting of 66 lesions

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference

Telemedicine

Telemedicine is a rapidly evolving field as new technologies are implemented for example for the development of wireless sensors, quality data transmission. Using the Internet applications such as counseling, clinical consultation support and home care monitoring and management are more and more realized, which improves access to high level medical care in underserved areas. The 23 chapters of this book present manifold examples of telemedicine treating both theoretical and practical foundations and application scenarios

Imaging Sensors and Applications

In past decades, various sensor technologies have been used in all areas of our lives, thus improving our quality of life. In particular, imaging sensors have been widely applied in the development of various imaging approaches such as optical imaging, ultrasound imaging, X-ray imaging, and nuclear imaging, and contributed to achieve high sensitivity, miniaturization, and real-time imaging. These advanced image sensing technologies play an important role not only in the medical field but also in the industrial field. This Special Issue covers broad topics on imaging sensors and applications. The scope range of imaging sensors can be extended to novel imaging sensors and diverse imaging systems, including hardware and software advancements. Additionally, biomedical and nondestructive sensing applications are welcome

Case series of breast fillers and how things may go wrong: radiology point of view

INTRODUCTION: Breast augmentation is a procedure opted by women to overcome sagging breast due to breastfeeding or aging as well as small breast size. Recent years have shown the emergence of a variety of injectable materials on market as breast fillers. These injectable breast fillers have swiftly gained popularity among women, considering the minimal invasiveness of the procedure, nullifying the need for terrifying surgery. Little do they know that the procedure may pose detrimental complications, while visualization of breast parenchyma infiltrated by these fillers is also deemed substandard; posing diagnostic challenges. We present a case series of three patients with prior history of hyaluronic acid and collagen breast injections. REPORT: The first patient is a 37-year-old lady who presented to casualty with worsening shortness of breath, non-productive cough, central chest pain; associated with fever and chills for 2-weeks duration. The second patient is a 34-year-old lady who complained of cough, fever and haemoptysis; associated with shortness of breath for 1-week duration. CT in these cases revealed non thrombotic wedge-shaped peripheral air-space densities. The third patient is a 37‐year‐old female with right breast pain, swelling and redness for 2- weeks duration. Previous collagen breast injection performed 1 year ago had impeded sonographic visualization of the breast parenchyma. MRI breasts showed multiple non- enhancing round and oval shaped lesions exhibiting fat intensity. CONCLUSION: Radiologists should be familiar with the potential risks and hazards as well as limitations of imaging posed by breast fillers such that MRI is required as problem-solving tool

Characterization of alar ligament on 3.0T MRI: a cross-sectional study in IIUM Medical Centre, Kuantan

INTRODUCTION: The main purpose of the study is to compare the normal anatomy of alar ligament on MRI between male and female. The specific objectives are to assess the prevalence of alar ligament visualized on MRI, to describe its characteristics in term of its course, shape and signal homogeneity and to find differences in alar ligament signal intensity between male and female. This study also aims to determine the association between the heights of respondents with alar ligament signal intensity and dimensions. MATERIALS & METHODS: 50 healthy volunteers were studied on 3.0T MR scanner Siemens Magnetom Spectra using 2-mm proton density, T2 and fat-suppression sequences. Alar ligament is depicted in 3 planes and the visualization and variability of the ligament courses, shapes and signal intensity characteristics were determined. The alar ligament dimensions were also measured. RESULTS: Alar ligament was best depicted in coronal plane, followed by sagittal and axial planes. The orientations were laterally ascending in most of the subjects (60%), predominantly oval in shaped (54%) and 67% showed inhomogenous signal. No significant difference of alar ligament signal intensity between male and female respondents. No significant association was found between the heights of the respondents with alar ligament signal intensity and dimensions. CONCLUSION: Employing a 3.0T MR scanner, the alar ligament is best portrayed on coronal plane, followed by sagittal and axial planes. However, tremendous variability of alar ligament as depicted in our data shows that caution needs to be exercised when evaluating alar ligament, especially during circumstances of injury