Rozprawy doktorskie na temat „Non-invasive images”

L'estimation de la profondeur des veines sous-cutanées a été un sujet de recherche important ces dernières années en raison de son importance dans l'optimisation de pose de cathéters, de perfusions et plus généralement de ponctions veineuses. Par le passé, diverses techniques et systèmes de visualisation des veines ont été proposés, cependant le manque d'information sur la profondeur de la veine limite les possibilités pour une automatisation de la ponction veineuse ; le geste clinique restant dans de nombreux cas tributaire des compétences ou de l'expérience des cliniciens. Plusieurs techniques ont été proposées pour estimer la profondeur de la veine en utilisant la réflectance diffuse dont le principe repose sur la mesure de rapport de densité optique (ODR). Le concept de mesure de la profondeur des veines à l'aide de la technique ODR mérite d'être appliqué dans le monde réel en raison de son faible coût, de ses propriétés non invasives et du fait qu'il s'agit d'une technique de mesure sans contact avec la peau. Les travaux initiaux de Nishidate et. Al. [1] ont montré sur fantôme des résultats prometteurs. Cependant, une telle expérience peut ne pas être suffisante pour prouver son application pour la mesure in vivo en raison du manque d'expérience pour les données réelles. Par conséquent, ce travail de thèse a été commencé pour améliorer le modèle proposé par Nishidate et. Al. et l'élargir pour mesurer l'estimation in vivo de la profondeur de la veine sur de vrais patients. Le système proposé intègre de nouveaux composants tels qu'un algorithme de segmentation des veines, une méthode d'estimation plus précise du contenu en mélanine (Cm) et une conception matérielle entièrement nouvelle avec des composants stables. Les résultats obtenus par ODR ont été comparés à des données fournies par une machine Ultrason médicale. Les résultats de l'expérience montrent une corrélation de Pearson forte de 0,843 par rapport aux données échographiques et prouvent que le système développé est fiable pour la mesure in vivo de la profondeur de la veine. En outre, il est proposé d'utiliser un filtre de segmentation de veine optimal (filtre adapté) dans le système d'imagerie pour permettre une segmentation et par la suite une mesure de la profondeur automatique
The estimation of subcutaneous vein depth has been an important research topic in recent years due to its importance in optimizing the intravenous (IV) access of venipuncture. Various techniques and system of vein visualization were proposed to improve the vein viewing, but the lack of vein depth information limits the system performance in assisting the IV access; thus, the IV access in many cases remains dependent on skill or experience of the clinicians. Several techniques were proposed to estimate the vein depth using diffuse reflectance of which the optical density ratio (ODR) technique is the most complete solution. The concept of measuring the veins depth using ODR based technique is deserved to be applied in the real-world due to its low cost, non-invasive properties and from the fact that it is a non-skin contact measurement technique. Nishidate et. al. [1] suggested an optimum conditions to measure the vein depth and thickness by using ODR which was supported by experiment with customized tissue-like agar gel phantom. However, such experiment may not be sufficient to prove its application for in vivo measurement due to the lack of experiment for real data. Therefore, this thesis work was first started to improve the proposed model by Nishidate et. al. and expand it to measure the in vivo estimation of vein depth on real patients. The proposed system incorporates new components such as an autonomous vein segmentation algorithm, a more accurate estimation method for melanin content (Cm) and a fully new hardware design with reliable parts. Importantly, the experiment estimate the vein depth on real patients as well as a through comparison with Ultrasound data. The experiment results show a strong Pearson correlation of 0.843 as compared to Ultrasound data and this evidence that the developed system is works for the in vivo measurement of vein depth. Besides that, an optimum vein filter (matched filter) is proposed to be used in the imaging system to preserve the most accurate vein detection and allow the system to produce the results with least detection error. The selection of the optimum vein filter has laid an important platform from which to obtain the accurate vein segmentation of a NIR image

Les images hyperspectrales suscitent un intérêt croissant depuis une quinzaine d'années. Elles fournissent une information plus détaillée d'une scène et permettent une discrimination plus précise des objets que les images couleur RVB ou multi-spectrales. Bien que les potentialités de la technologie hyperspectrale apparaissent relativement grandes, l'analyse et l'exploitation de ces données restent une tâche difficile et présentent aujourd'hui un défi. Les travaux de cette thèse s'inscrivent dans le cadre de la réduction et de partitionnement des images hyperspectrales de grande dimension spatiale. L'approche proposée se compose de deux étapes : calcul d'attributs et classification des pixels. Une nouvelle approche d'extraction d'attributs à partir des matrices de tri-occurrences définies sur des voisinages cubiques est proposée en tenant compte de l'information spatiale et spectrale. Une étude comparative a été menée afin de tester le pouvoir discriminant de ces nouveaux attributs par rapport aux attributs classiques. Les attributs proposés montrent un large écart discriminant par rapport à ces derniers et par rapport aux signatures spectrales. Concernant la classification, nous nous intéressons ici au partitionnement des images par une approche de classification non supervisée et non paramétrique car elle présente plusieurs avantages: aucune connaissance a priori, partitionnement des images quel que soit le domaine applicatif, adaptabilité au contenu informationnel des images. Une étude comparative des principaux classifieurs semi-supervisés (connaissance du nombre de classes) et non supervisés (C-moyennes, FCM, ISODATA, AP) a montré la supériorité de la méthode de propagation d'affinité (AP). Mais malgré un meilleur taux de classification, cette méthode présente deux inconvénients majeurs: une surestimation du nombre de classes dans sa version non supervisée, et l'impossibilité de l'appliquer sur des images de grande taille (complexité de calcul quadratique). Nous avons proposé une approche qui apporte des solutions à ces deux problèmes. Elle consiste tout d'abord à réduire le nombre d'individus à classer avant l'application de l'AP en agrégeant les pixels à très forte similarité. Pour estimer le nombre de classes, la méthode AP utilise de manière implicite un paramètre de préférence p dont la valeur initiale correspond à la médiane des valeurs de la matrice de similarité. Cette valeur conduisant souvent à une sur-segmentation des images, nous avons introduit une étape permettant d'optimiser ce paramètre en maximisant un critère lié à la variance interclasse. L'approche proposée a été testée avec succès sur des images synthétiques, mono et multi-composantes. Elle a été également appliquée et comparée sur des images hyperspectrales de grande taille spatiale (1000 × 1000 pixels × 62 bandes) avec succès dans le cadre d'une application réelle pour la détection des plantes invasives
The interest in hyperspectral image data has been constantly increasing during the last years. Indeed, hyperspectral images provide more detailed information about the spectral properties of a scene and allow a more precise discrimination of objects than traditional color images or even multispectral images. High spatial and spectral resolutions of hyperspectral images enable to precisely characterize the information pixel content. Though the potentialities of hyperspectral technology appear to be relatively wide, the analysis and the treatment of these data remain complex. In fact, exploiting such large data sets presents a great challenge. In this thesis, we are mainly interested in the reduction and partitioning of hyperspectral images of high spatial dimension. The proposed approach consists essentially of two steps: features extraction and classification of pixels of an image. A new approach for features extraction based on spatial and spectral tri-occurrences matrices defined on cubic neighborhoods is proposed. A comparative study shows the discrimination power of these new features over conventional ones as well as spectral signatures. Concerning the classification step, we are mainly interested in this thesis to the unsupervised and non-parametric classification approach because it has several advantages: no a priori knowledge, image partitioning for any application domain, and adaptability to the image information content. A comparative study of the most well-known semi-supervised (knowledge of number of classes) and unsupervised non-parametric methods (K-means, FCM, ISODATA, AP) showed the superiority of affinity propagation (AP). Despite its high correct classification rate, affinity propagation has two major drawbacks. Firstly, the number of classes is over-estimated when the preference parameter p value is initialized as the median value of the similarity matrix. Secondly, the partitioning of large size hyperspectral images is hampered by its quadratic computational complexity. Therefore, its application to this data type remains impossible. To overcome these two drawbacks, we propose an approach which consists of reducing the number of pixels to be classified before the application of AP by automatically grouping data points with high similarity. We also introduce a step to optimize the preference parameter value by maximizing a criterion related to the interclass variance, in order to correctly estimate the number of classes. The proposed approach was successfully applied on synthetic images, mono-component and multi-component and showed a consistent discrimination of obtained classes. It was also successfully applied and compared on hyperspectral images of high spatial dimension (1000 × 1000 pixels × 62 bands) in the context of a real application for the detection of invasive and non-invasive vegetation species

The development of a method for a reliable quantification of 11C-MP4A PET images without arterial input function at pixel level in order to study acetylcholine esterase activity (AChE) is of clinical interest for the diagnosis of dementia and memory disorders. Two groups of subjects, normal control group (4 subjects - NC group) and Alzheimer disease group (7 subjects - AD group) participated for the study. AChE activity can be quantify by using a reference input function derived from region having a very high metabolism by AChE and a three-rate constant compartmental model. In order to obtain, at pixel level, accurate and precise estimates of model parameters in both low and moderate enzymatic expression regions, a novel method based on the use of the maximum a posteriori probability (MAP) Bayesian estimator has been developed. This method was compared to other approaches already published for quantification of AChE activity: 1) the method based on the use of a linear least squares (RLS) analysis; 2) the RRE method based on a simplification of the model structure; 3) the RRE_BF method which consider a basis function approach for RRE procedure; 4) the method R_NLLS based on a non linear least squares estimator. AChE activity was measured in terms of the rate constant for hydrolysis of 11C-MP4A, k3. Striatum (basal ganglia) was used as reference region based on its very high AChE activity. Parametric images of k3 obtained with MAP from areas with different levels of AChE activity were compared between groups and respect to the k3 estimates obtained with the other mathematical approaches. Despite the small group of subjects, the methods (RLS; RRE, RRE_BF, R_NLLS, MAP,) used to generate k3 parametric image were able to detect a reduction on AChE activity in neocortex of AD patients respect to NC. However, only MAP allows to quantify k3 in region with moderate enzyme expression like thalamus and brainstem. The different performance of the five estimation methods has an impact in the statistical significance of k3 differences. In fact, only the MAP method shows significant differences in thalamus and brainstem that are in good agreement with published study.

The tear film plays an important role preserving the health of the ocular surface and maintaining the optimal refractive power of the cornea. Moreover dry eye syndrome is one of the most commonly reported eye health problems. This syndrome is caused by abnormalities in the properties of the tear film. Current clinical tools to assess the tear film properties have shown certain limitations. The traditional invasive methods for the assessment of tear film quality, which are used by most clinicians, have been criticized for the lack of reliability and/or repeatability. A range of non-invasive methods of tear assessment have been investigated, but also present limitations. Hence no “gold standard” test is currently available to assess the tear film integrity. Therefore, improving techniques for the assessment of the tear film quality is of clinical significance and the main motivation for the work described in this thesis. In this study the tear film surface quality (TFSQ) changes were investigated by means of high-speed videokeratoscopy (HSV). In this technique, a set of concentric rings formed in an illuminated cone or a bowl is projected on the anterior cornea and their reflection from the ocular surface imaged on a charge-coupled device (CCD). The reflection of the light is produced in the outer most layer of the cornea, the tear film. Hence, when the tear film is smooth the reflected image presents a well structure pattern. In contrast, when the tear film surface presents irregularities, the pattern also becomes irregular due to the light scatter and deviation of the reflected light. The videokeratoscope provides an estimate of the corneal topography associated with each Placido disk image. Topographical estimates, which have been used in the past to quantify tear film changes, may not always be suitable for the evaluation of all the dynamic phases of the tear film. However the Placido disk image itself, which contains the reflected pattern, may be more appropriate to assess the tear film dynamics. A set of novel routines have been purposely developed to quantify the changes of the reflected pattern and to extract a time series estimate of the TFSQ from the video recording. The routine extracts from each frame of the video recording a maximized area of analysis. In this area a metric of the TFSQ is calculated. Initially two metrics based on the Gabor filter and Gaussian gradient-based techniques, were used to quantify the consistency of the pattern’s local orientation as a metric of TFSQ. These metrics have helped to demonstrate the applicability of HSV to assess the tear film, and the influence of contact lens wear on TFSQ. The results suggest that the dynamic-area analysis method of HSV was able to distinguish and quantify the subtle, but systematic degradation of tear film surface quality in the inter-blink interval in contact lens wear. It was also able to clearly show a difference between bare eye and contact lens wearing conditions. Thus, the HSV method appears to be a useful technique for quantitatively investigating the effects of contact lens wear on the TFSQ. Subsequently a larger clinical study was conducted to perform a comparison between HSV and two other non-invasive techniques, lateral shearing interferometry (LSI) and dynamic wavefront sensing (DWS). Of these non-invasive techniques, the HSV appeared to be the most precise method for measuring TFSQ, by virtue of its lower coefficient of variation. While the LSI appears to be the most sensitive method for analyzing the tear build-up time (TBUT). The capability of each of the non-invasive methods to discriminate dry eye from normal subjects was also investigated. The receiver operating characteristic (ROC) curves were calculated to assess the ability of each method to predict dry eye syndrome. The LSI technique gave the best results under both natural blinking conditions and in suppressed blinking conditions, which was closely followed by HSV. The DWS did not perform as well as LSI or HSV. The main limitation of the HSV technique, which was identified during the former clinical study, was the lack of the sensitivity to quantify the build-up/formation phase of the tear film cycle. For that reason an extra metric based on image transformation and block processing was proposed. In this metric, the area of analysis was transformed from Cartesian to Polar coordinates, converting the concentric circles pattern into a quasi-straight lines image in which a block statistics value was extracted. This metric has shown better sensitivity under low pattern disturbance as well as has improved the performance of the ROC curves. Additionally a theoretical study, based on ray-tracing techniques and topographical models of the tear film, was proposed to fully comprehend the HSV measurement and the instrument’s potential limitations. Of special interested was the assessment of the instrument’s sensitivity under subtle topographic changes. The theoretical simulations have helped to provide some understanding on the tear film dynamics, for instance the model extracted for the build-up phase has helped to provide some insight into the dynamics during this initial phase. Finally some aspects of the mathematical modeling of TFSQ time series have been reported in this thesis. Over the years, different functions have been used to model the time series as well as to extract the key clinical parameters (i.e., timing). Unfortunately those techniques to model the tear film time series do not simultaneously consider the underlying physiological mechanism and the parameter extraction methods. A set of guidelines are proposed to meet both criteria. Special attention was given to a commonly used fit, the polynomial function, and considerations to select the appropriate model order to ensure the true derivative of the signal is accurately represented. The work described in this thesis has shown the potential of using high-speed videokeratoscopy to assess tear film surface quality. A set of novel image and signal processing techniques have been proposed to quantify different aspects of the tear film assessment, analysis and modeling. The dynamic-area HSV has shown good performance in a broad range of conditions (i.e., contact lens, normal and dry eye subjects). As a result, this technique could be a useful clinical tool to assess tear film surface quality in the future.

Prostate cancer is one of the most common cancer diagnosis in men. This project aimed to help in characterization and treatment planning of prostate cancer by producing a Gleason grading probability based on apparent diffusion coefficient (ADC). In a study, from which this project received the patient data, the patients were first imaged using magnetic resonance imaging (MRI) in a 3T positron emission tomography MRI (PET/MRI) scanner. The prostates were surgically removed and placed in a patient specific mold. While inside the mold, the prostates were imaged using the same scanner, producing ex-vivo images of the prostates. Lastly the prostates were cut in histopathology slices and Gleason graded by a pathologist. To get correlation between ADC and Gleason grade all images needed to be correctly related to each other. This was done by three image registrations, which was the main part of this project. The histopathology slices were first registered to the ex-vivo images of the prostate, and then to the in-vivo T2-weighted images. The in-vivo T2w images were matched to images depicting the diffusion of water in the prostates, known as ADC-maps. The ADC-values were collected and matched to their possible Gleason grade. Information from 149 images were used, which came from 22 different patients. 3D pixels, known as voxels, with a corresponding Gleason grade annotation measured a lower average ADC-value. These voxels also showed more variation with a larger standard deviation. Furthermore, these voxels measured a larger range of ADC-values compared to voxels without a corresponding Gleason grade, but the probability of a Gleason grade was mainly seen for ADC-values below 1200 mm2/s. Filtering the ADC-map before collecting the information showed less spread in measurements, and larger total probability of Gleason grade annotation for lower ADC-values. To test the validity of the result a movement of the Gleason grade map was used to simulate registration errors. No large impact was observed for small movements but more obvious change for large. The results indicate this method as promising in predicting regions with a probability for Gleason grade of 3 or 4, however it was less accurate in separating the two. Gleason 5 showed very low probability, mainly as a result of the low sample size since only two patients had such tumors. Further research with better optimized filtering is recommended in the future.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.
Includes bibliographical references (p. 83-92).
Research on spine biomechanics is critical to understand pathology such as degenerative changes and low back pain. However, current study on in-vivo spine biomechanics is limited by the complex anatomy and invasive methodology. Modem clinical imaging techniques such as magnetic resonance and fluoroscope images, which are widely accessible nowadays, have the potential to study in-vivo spine biomechanics accurately and non-invasively. This research presents a new combined magnetic resonance and fluoroscope imaging matching method to study human lumbar vertebral kinematics and disc deformation during various physiologic functional activities. Validation and application of this method as well as discussion of its performance and applicability are detailed herein.
by Shaobai Wang.
S.M.

This work presents a strategy for detection of abdominal adhesions based on cine-MRI data, image processing and the production of a ‘sheargram’. Abdominal adhesions are a common complication of abdominal surgery and can cause serious morbidity. Diagnosis is difficult and often one of exclusion. A conclusive diagnosis typically requires laparoscopic explorative surgery, which itself may cause further adhesions. A non-invasive means of diagnosis is preferred and likely to aid patient management. Cine-MRI can capture the motion of the abdominal structures during respiration and has shown promise for adhesion detection. However, such images are difficult and time consuming to interpret. A previous PhD considered augmenting cine-MRI by quantifying movement for detection of gross adhesive pathology. This thesis presents a refined image processing approach aimed at detection of more subtle adhesions to the abdominal wall. In the absence of adhesive pathology, the abdominal contents (bowels, kidneys, liver) slide smoothly against the perimeter of the abdominal cavity – a process termed visceral slide. An adhesion is expected to produce a localised resistance that inhibits smooth visceral sliding. In this PhD, development of a 2D technique to quantify sliding around the perimeter of the abdominal cavity (with particular emphasis on the abdominal wall) sought to highlight regions of reduced sliding. Segmentation and image registration were employed to quantify movement and shear, the latter used as an analogue for sliding. The magnitude of shear over all frames in the dynamic MR image sequence was extracted and displayed as a colour plot over the MR image for anatomical context. This final output is termed a ‘sheargram’. Suitability of the technique for diagnosis was assessed through a series of experimental tests and correlation with clinical data. The latter involved a retrospective pilot study incorporating data from 52 patients scanned for suspected adhesions. A total of 141 slices were processed and reported. The validation experiments confirmed the technique had the attributes to accurately and reproducibly report sliding and demonstrated proof of concept for detection of adhered regions. The pilot study confirmed the sheargram matched expert clinical judgement in the vast majority of cases (>84%) and detected >93% of all adhesions. However, the investigation also highlighted limitations, principally structures moving out of the imaging plane creates a fundamental problem and requires a 3D imaging solution. In conclusion, the work has produced encouraging results and merits further development.

Thesis (M.S.)--West Virginia University, 1999.
Title from document title page. Document formatted into pages; contains x, 126 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. [72]-75).

Adherent cell culture is a key experimental method for biological investigations in diverse areas such as developmental biology, drug discovery and biotechnology. Light microscopy-based methods, for example phase contrast microscopy (PCM), are routinely used for visual inspection of adherent cells cultured in transparent polymeric vessels. However, the outcome of such inspections is qualitative and highly subjective. Analytical methods that produce quantitative results can be used but often at the expense of culture integrity or viability. In this work, an imaging-based strategy to adherent cell cultures monitoring was investigated. Automated image processing and analysis of PCM images enabled quantitative measurements of key cell culture characteristics. Two types of segmentation algorithms for the detection of cellular objects on PCM images were evaluated. The first one, based on contrast filters and dynamic programming was quick (<1s per 1280×960 image) and performed well for different cell lines, over a wide range of imaging conditions. The second approach, termed ‘trainable segmentation’, was based on machine learning using a variety of image features such as local structures and symmetries. It accommodated complex segmentation tasks while maintaining low processing times (<5s per 1280×960 image). Based on the output from these segmentation algorithms, imaging-based monitoring of a large palette of cell responses was demonstrated, including proliferation, growth arrest, differentiation, and cell death. This approach is non-invasive and applicable to any transparent culture vessel, including microfabricated culture devices where a lack of suitable analytical methods often limits their applicability. This work was a significant contribution towards the establishment of robust, standardised, and affordable monitoring methods for adherent cell cultures. Finally, automated image processing was combined with computer-controlled cultures in small-scale devices. This provided a first demonstration of how adaptive culture protocols could be established; i.e. culture protocols which are based on cellular response instead of arbitrary time points.

Familial amyloid polyneuropathy (FAP) is a hereditary condition characterized by systemic deposition of transthyretin (TTR), which causes debilitating peripheral polyneuropathy, cardiopathy, nephropathy and usually after a few years, ophtalmopathy. Occasionally the onset can be atypical and the diagnosis of FAP is reliant on identifying ocular amyloid deposition clinically and histopathologically. However, images of TTR derived from the eye, identified using immunolabeling techniques, have so far not been published. In ocular tissues FAP can cause sight-threatening complications such as glaucoma and retinal amyloid angiopathy. Glaucoma in FAP often requires surgical treatment. Nonpenetrating deep sclerectomy (NPDS) is a surgical technique with several advantages over the traditional trabeculectomy. It is successfully performed in primary and many types of secondary open-angle glaucoma, but so far with limited reports in FAP. Retina imaging modalities, such as optic coherence tomography (OCT) and autofluorescence (AF), have significant value in the assessment of retinal pathologies. Fluorescein angiography is the conventional method of evaluating retinal vasculature, but requires injection of fluorescein, which has several side effects and contraindications. Recently a new non-invasive modality, the OCT angiography (OCT-A) has become a useful tool for visualizing posterior pole blood circulation. In patients with FAP the use of OCT-A has so far not been reported and only few cases of AF findings were published. This doctoral thesis, presented as a compendium of publications, is divided into three parts. The first part (Paper 1) aims to present the immunostaining images of TTR amyloid derived from the vitreous of a series of patients with FAP, which demonstrates vitreous biopsy as a valid diagnostic tool, especially in clinically challenging cases. The second part (Paper 2) is a retrospective review of clinical charts of patients with FAP to determine the prevalence and characteristics of open-angle glaucoma secondary to FAP. It reveals the particularly quick progression of glaucoma in FAP and its increased risk in patients with a previous vitrectomy. Surgical management and outcomes of the affected patients are presented, indicating that NPDS is a safe and effective treatment of glaucoma secondary to FAP. The third part (Paper 3) is an observational cross-sectional study of retinal findings in patients with FAP. It gives a descriptive analysis of retinal images in FAP using novel non-invasive techniques: AF, OCT, OCT-A, and ultra-wide-field (UWF) retinography. These modalities can be used to detect perivascular retinal amyloid deposits, as well as microvascular changes including areas of non-perfusion, allowing better understanding of the pathology, complications and prognosis of patients with FAP. It also shows that amyloid retinopathy is more frequent than previously reported. The thesis outcomes emphasize glaucoma and retinopathy as the severe irreversible complications of FAP and need for addressing them promptly. This is especially important in establishing adequate regular eye reviews in patients with FAP and identifying those individuals requiring stricter ophthalmological care to prevent vision loss.
La polineuropatía amiloidótica familiar (PAF) es una enfermedad hereditaria caracterizada por el depósito sistémico de transtiretina (TTR), que resulta en polineuropatía periférica debilitante, cardiopatía, nefropatía y, habitualmente, después de unos años, oftalmopatía. Ocasionalmente, el inicio puede ser atípico y el diagnóstico de PAF depende de la identificación de depósitos de amiloide en tejidos oculares clínicamente e histopatológicamente. Sin embargo, hasta ahora no se han publicado imágenes de TTR derivadas del ojo, identificadas utilizando técnicas de inmunotinción. En los tejidos oculares, la PAF puede causar complicaciones amenazantes para la vista, como el glaucoma y la angiopatía amiloide de la retina. El glaucoma en la PAF frecuentemente requiere tratamiento quirúrgico. La esclerectomía profunda no penetrante (EPNP) es una técnica quirúrgica con varias ventajas sobre la trabeculectomía tradicional. Se realiza con éxito en glaucoma de ángulo abierto primario y muchos tipos de glaucoma secundario, pero hasta ahora con pocos casos descritos en PAF. Las modalidades de imágen de retina, como la tomografía de coherencia óptica (OCT) y la autofluorescencia (AF), tienen un valor importante en la evaluación de las patologías retinianas. La angiografía con fluoresceína es el método convencional para evaluar la vasculatura retiniana, pero requiere la inyección de fluoresceína, que tiene varios efectos secundarios y contraindicaciones. Recientemente, una nueva modalidad no invasiva, la angiografía OCT (OCT-A) se ha convertido en una herramienta útil para visualizar la circulación sanguínea del polo posterior. En pacientes con PAF, el uso de OCT-A no ha sido publicado hasta ahora, y solo se han descrito dos casos de hallazgos de AF. Esta tesis doctoral, presentada como un compendio de publicaciones, se divide en tres partes. La primera parte (Artículo 1) tiene como objetivo presentar las imágenes de inmunotinción de TTR amiloide derivado del vítreo en una serie de pacientes con PAF, lo que demuestra que la biopsia vítrea es una herramienta de diagnóstico válida, especialmente en casos clínicamente atípicos. La segunda parte (Artículo 2) es una revisión retrospectiva de las historias clínicas de pacientes con PAF para determinar la prevalencia y las características del glaucoma de ángulo abierto secundario a la PAF. Revela la progresión particularmente rápida del glaucoma en la PAF y su mayor riesgo en pacientes con vitrectomía previa. Se ha presentado el tratamiento quirúrgico y los resultados de los pacientes afectados, lo que indica que EPNP es un tratamiento seguro y efectivo para el glaucoma secundario a PAF. La tercera parte (Artículo 3) es un estudio transversal observacional de hallazgos retinianos en pacientes con PAF. Se expone un análisis descriptivo de las imágenes de la retina en PAF utilizando nuevas técnicas no invasivas: AF, OCT, OCT-A y retinografía de campo amplio (UWF). Estas modalidades se pueden utilizar para detectar depósitos amiloides perivasculares de la retina, así como cambios microvasculares que incluyen áreas de no perfusión, lo que permite una mejor comprensión de la patología, las complicaciones y el pronóstico de los pacientes con PAF. También se muestra que la retinopatía amiloidea es más frecuente de lo que se publicó anteriormente. Los resultados de la tesis enfatizan el glaucoma y la retinopatía como las complicaciones irreversibles graves de la PAF y la necesidad de abordarlos precozmente. Esto es especialmente importante para establecer revisiones oculares regulares adecuadas en pacientes con PAF e identificar a aquellas personas que requieren atención oftalmológica más estricta para prevenir la pérdida de visión.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.
This thesis was scanned as part of an electronic thesis pilot project.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 183-193).
Image segmentation and classification, the identification and demarcation of regions of interest within an image, is necessary prior to subsequent information extraction, analysis, and inference. Many available segmentation algorithms require manual delineation of initial conditions to achieve acceptable performance, even in cases with high signal to noise and interference ratio that do not necessitate restoration. This weakness impedes application of image analysis to many important fields, such as automated, mass scale cultivation and non-invasive, non-destructive high throughput analysis, monitoring, and screening of pluripotent and differentiated stem cells, whether human embryonic (hESC), induced pluripotent (iPSC), or animal. Motivated by this and other applications, the Bayesian Level Set (BLS) algorithm is developed for automated segmentation and classification that computes smooth, regular segmenting contours in a manner similar to level sets while possessing a simple, probabilistic implementation similar to that of the finite mixture model EM. The BLS is subsequently extended to harness the power of image texture methods by incorporating learned sets of class-specific textural primitives, known as textons, within a three-stage Markov model. The resulting algorithm accurately and automatically classifies and segments images of pluripotent hESC and trophectoderm colonies with 97% and 91% accuracy for high-content screening applications and requires no previous human initialization. While no prior knowledge of colony class is assumed, the framework allows for its incorporation. The BLS is also validated on other applications, including brain MRI, retinal lesions, and wildlife images.
by Nathan Christopher Lowry.
Sc.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
MIT Institute Archives copy: with CD-ROM; divisional library copy with no CD-ROM.
Includes bibliographical references (p. 99-104).
Knowledge of in-vivo glenohumeral joint biomechanics after total shoulder arthroplasty are important for the improvement of patient function, implant longevity and surgical technique. No data has been published on the in-vivo glenohumeral joint contact locations in patients after total shoulder arthroplasty. Therefore, the objectives of this thesis were to determine the in-vivo glenohumeral joint contact locations and humeral head translations in patients after total shoulder arthroplasty. First, a non-invasive three dimensional fluoroscopic image matching method was developed and validated for use in the shoulder joint complex. Next, a group of patients that have undergone clinically successful total shoulder arthroplasty surgeries were recruited for study and imaged by the fluoroscopic imaging technique.The fluoroscopic imaging system was recreated in a virtual environment and the in vivo kinematics that were recorded by the fluoroscopes were recreated with three dimensional models. The contact centroids of the glenohumeral joint and humeral head translations were measured using solid modeling software. In summary, this thesis quantified the in-vivo glenohumeral joint contact locations and humeral head translations after total shoulder arthroplasty. These data provides surgeons and engineers valuable information for developing surgical treatments that may better help recreate 'normal' motion of the shoulder after total shoulder arthroplasty.
by Daniel Frank Massimini.
S.M.

During my PhD I developed two parallel and complementary topics, concerning both works of art and materials. The first one, focused on non-invasive investigations on works of art (ancient and contemporary), was aimed to deepen conservative state, material composition, painting techniques and the early detection of any deterioration. This latter goal also guided the study of pictorial and restoration materials, mainly aimed at their characterization from the optical point of view. Diagnostic activities made use of different methods of investigation. Among image techniques, photography and macrophotography in diffuse, specular and raking light, ultraviolet fluorescent, image spectroscopy, wide band infrared reflectography, digital and differential K-edge radiography. To get as much information as possible, to be properly integrated with other data, punctual diagnostic techniques, such as reflectance spectrophotometry, colorimetry and X Ray fluorescence, were also used.

Une tomographie ultrasonore par reconstruction utilisant le coefficient d'absorption ultrasonore a été réalisé. Le diamètre des transducteurs est de 1. 5 cm, la fréquence ultrasonore est de 1. 5 MHZ. Le système mécanique de rotation incrémente l'angle de mesure de π/4. Un interface électronique détecte l'amplitude maximale du signal reçu. Cette donnée est acquise et traitée au moyen d'un micro ordinateur. Le programme d'exploitation des mesures est écrit en BASIC. La visualisation de la reconstruction d'images est faite à l'aide d'une imprimante, les images peuvent-être de 54 * 54 pixels avec 8 tons de gris. Les reconstructions ont été faites sur des échantillons de duralumin, nylon, cuivre, laiton, glycérine, huile de vazeline. Ce dispositif a permis de relever la topographie interne de milieux hétérogènes. Le coefficient d'absorption ultrasonore étant sensible aux variations de température pour certains milieux, une étude de la faisabilité d'utiliser une telle méthode dans le but de réaliser une thermomètrie non invasive a été faite. Nous avons réalisé la reconstruction d'images représentant la variation de température, en temps différé, de tubes emplis soit de glycérine soit de solutions de glucose.

Diagnostics in the cultural heritage field is an important resource to investigate art history, issues, execution techniques, materials and state of conservation of an artwork. In this field the main concern is preservation and, for this reason, new non-invasive and non-destructive technologies have been developed. At the Department of Physics in Ferrara, imaging for cultural heritage, using electromagnetic radiation, from visible light to X-rays is applied and studied. A diagnostics protocol has been defined to standardize the study approach on paintings considering that each painting is a particular case, and the protocol must be adapted to the needs that the artwork itself requires. This work consists in the development of a scanning devices for wide band infrared Reflectography, to extend the applications of the reflectographic technique, and how it is inserted in the diagnostic protocol. Infrared reflectography use the electromagnetic radiation of Near-IR to investigate the underdrawing in paintings. The success of IR Reflectography to reveal the underdrawing in paintings since XIV up to XVI century depends on the peculiar technique of painters in that period. Thin and uniform pictorial layers, covering high contrast drawings on white priming allow a good detection of underdrawing details. Paintings of late sixteenth century have dark preparations and thick paint layers, so Reflectography doesn’t get the same good results. Extension of the spectral band to longer wavelengths, up to 2,5 μm, is a tool to improve reflectographic capability.

碩士
國立陽明大學
醫學工程研究所
90
The quantitative analysis of [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is able to provide an absolute value of the cerebral metabolic rate of glucose (CMRGlc) for the diagnosis of various brain functions; however, an input function from about 20 arterial blood samples is necessary for such a study. Due to the invasive nature of the blood sampling schedule, FDG-PET quantitative analysis is seldom performed in routine procedures. This study proposes two new techniques for estimating the input function without any blood samples. Methods: The first method proposed in this study is the Simplified Simultaneous Estimation (SSIME), which is based upon the Simultaneous Estimation (SIME) technique, but uses 1-point blood sampling method as the input function model in SSIME in order to simply the simultaneous estimation process. Twenty-three patients were tested with this new approach, and the input functions estimated with SSIME were compared with real input functions deriving from blood samples. In our observations, SSIME method provides improved estimation ability than SIME, although it is restricted by some limitations and only applicable for a group of patients. Therefore, we propose another novel technique that is based on the multiple linear regression analysis. Forty-four patients were included in the development of this new statistic approach. First, we generated the tissue time-activity curves (TTACs) of the gray matter and the whole brain with a segmentation technique for every subject. Summations of different intervals of those two curves were used as a feature vector, including the net injection dose. Multiple linear regression analysis was then applied to find the correlation between the input function and the feature vector. When these regression coefficients were found with a group of patients, they would be used to estimate the input functions for another group of patients, where these estimated input functions were compared to the real ones. After a simulation study with in vivo data was performed to primitively verify the input function estimation ability of this method, 29 patients were then applied for calculating the regression coefficients, which were further used to estimate the input functions of other 15 subjects. Results: For 15 patients with their real and estimated input functions compared, the averaged AUC and CMRGlc error percentage were 12.13±8.85 and 16.60±9.61 respectively. The regression analysis of the CMRGlc values derived from the real and estimated input functions revealed a high correlation with r = 0.913, P<0.0001. Conclusion: The multiple linear regression analysis can be used to find the correlation between the input function and the feature vector. This correlation can be further applied for reliable input function estimation in clinical FDG-PET quantitative analysis.

Yes
Human fall detection systems play an important role in our daily life, because falls are the main obstacle for elderly people to live independently and it is also a major health concern due to aging population. Different approaches are used to develop human fall detection systems for elderly and people with special needs. The three basic approaches include some sort of wearable devices, ambient based devices or non-invasive vision-based devices using live cameras. Most of such systems are either based on wearable or ambient sensor which is very often rejected by users due to the high false alarm and difficulties in carrying them during their daily life activities. This paper proposes a fall detection system based on the height, velocity and position of the subject using depth information from Microsoft Kinect sensor. Classification of human fall from other activities of daily life is accomplished using height and velocity of the subject extracted from the depth information. Finally position of the subject is identified for fall confirmation. From the experimental results, the proposed system was able to achieve an average accuracy of 94.81% with sensitivity of 100% and specificity of 93.33%.
Partly sponsored by Center for Graduate Studies. This work is funded under the project titled “Biomechanics computational modeling using depth maps for improvement on gait analysis”. Universiti Tun Hussein Onn Malaysia for provided lab components and GPPS (Project Vot No. U462) sponsor.

The primary goal of this thesis is to develop a light sheet based microscopy system that provides non-invasive images having high spatial and temporal resolution. The fluorescence microscopy has become an indispensable tool for biologists to understand the underlying mechanisms of various biological processes. The phenomenon of fluorescence offers non-invasive imaging with high speci ficity and single molecule sensitivity which is of interest in the life sciences research. The confocal microscopy has emerged as a potential technique which enables optical sectioning by employing a pinhole in the detector side to eliminate out of focus light. The confocal microscopy has been combined with other techniques such as multi-photon excitation microscopy to tackle scattering and to improve the penetration depth. The super resolution 4Pi microscopy is also combined with confocal detection to improve axial resolution. Past decade has seen the evolution of a large number of super resolution techniques such as STED, fPALM, PALM, STORM, SSIM, RESOLFT and GSDIM. This was a major breakthrough in fluorescence microscopy enabling single molecule resolution. Imaging of dynamical processes such as embryo development is an important and challenging problem in developmental biology. Long period monitoring is required to capture these processes which demand the sample to be kept in its natural environment with minimal interference from the probing light. The photobleaching and photodamage are the real issues when the sample is exposed to probing light for a long time. Imaging at high spatial and temporal resolution with minimal photodamage is a real challenge even for confocal and two photon excitation microscopy. Light sheet microscopy offers multitude of possibilities to the photobleaching problem and has found applications in various domains during the last decade. This thesis introduces an improvised light sheet microscopy technique where the number of images needed to construct 3D volume is greatly reduced by choosing an alternate acquisition strategy. The statistical image reconstruction techniques such as maximum likelihood (ML) approach is used for post-processing and has been shown to improve the image quality for the applications presented in the thesis. The introduction of light sheet illumination on a micro fluidic platform is also studied to enable 3D imaging of uni-cellular and multi-cellular organisms. A brief summary of the work is given below. Chapter 1 gives a brief outline of the developments in the field of fluorescence microscopy. The quest for improved resolution, contrast, penetration depth, speed and minimal damage to the sample has motivated researchers to come up with different microscopy designs which can tackle the aforementioned aspects. The emergence of light sheet microscopy is explained in detail as a promising tool in scenarios where the conventional techniques like confocal and multi-photon excitation microscopy are inadequate to overcome the challenges in various life science research areas. Chapter 2 is dedicated to explain the fundamentals of fluorescence. A brief outline is given to introduce various contrasts existing in optical microscopy, highlighting the advantages of fluorescence. Resolution of an imaging system is discussed in detail and the idea of the point spread function is introduced as it determines the performance of an optical system in terms of resolution. Some of the widely used fluorescence microscopy techniques are explained to provide an overview of developments happening in the fi eld of fluorescence microscopy. Image degradations due to blurring, noise and aberrations are inescapable in an imaging system. In general most of the microscopic samples are 3D objects. But what we acquire is a 2D image and can have ambiguities due to its 3D nature, like presence of out of focus features in the image. Hence the 2D image is a false representation of the 3D object. In order to tackle these issues image deconvolution techniques are usually employed. In chapter 3 we discuss about the state-of-the-art statistical image reconstruction technique maximum likelihood (ML) approach for image deconvolution. Due to its iterative nature ML algorithm is inherently slow. In order to process and view images in real-time, ML algorithm has to be accelerated. A step in this direction has been the incorporation of Biggs-Andrews algorithm into ML framework to accelerate ML. BA approach is based on vector extrapolation method which is a simple method without any derivative calculation and inherits automatic acceleration. We have tested the performance of the algorithm on microscopy images obtained from three techniques wide field, confocal and super-resolution 4Pi microscopy. The convergence is improved by a factor of two for all the tested images. Developmental biology is one of the promising areas which demands fast and high resolution imaging to understand various biological processes during embryo development. Light sheet florescence microscopy was introduced to tackle this highly challenging problem because of its inherent optical sectioning capability which helps in eliminating out of focus illumination. This reduces photobleaching and phototoxicity. We have developed limited view light sheet microscopy (LVLSM) in which the volume of zebra sh embryo is constructed from a very few angular views. Chapter 4 deals with LVLSM. The rotation and translation involved in multi-view microscopy is time consuming and hundreds of images are acquired to construct a 3D volume. In this work we have developed a scheme that uses only rotation to acquire the data. In addition, we have used ML algorithm to improve the contrast of the image and to remove the noise. We have reconstructed a ve day old zebra sh embryo using 18 views which is an order of magnitude less compared to the number of images used in multi-view light sheet microscopy. We study the effect of limited number of views in the 3D image reconstruction in the next chapter in the light of speeding up the imaging process as well as for reducing of photobleaching further. We have done the time-lapse imaging of a ve day old zebra sh embryo to study the effect of photobleaching. The uorescence decay curve is fitted with mono-exponential decay and the parameters are obtained. We have constructed 3D volume from 18, 9 and 6 angular views at 10o; 20o and 30o angular separation respectively and checked the performance in terms of contrast. The image quality with 18 and 9 views were found to be almost the same. However, there is a reduction in contrast for reconstruction with only 6 views. But even with 6 views, it is found that the structural details are retained in volume reconstruction. Intensity line plots are employed to quantitatively check the reconstruction with 18, 9 and 6 views and it is found that there is a good agreement between reconstructions with 18 and 9 views. In chapter 6 we have explored the light sheet illumination for the 3D imaging of organisms during ow on micro fluidic platform. Light sheet illumination can provide optical sectioning and hence it is possible to get 2D cross-sections of the sample during the fllow. The micro fluidic channel is kept at an angle with respect to the illumination axis and the illumination and detection arms are orthogonal. Optimization of the light sheet dimensions, ow parameters and camera settings facilitates 3D imaging without any translation of the sample. The performance of the system is checked by imaging samples of two different sizes, HeLa cells and C: elegans worms. In order to tackle the problem of motion blur, maximum likelihood algorithm is employed in which we have used experimentally measured PSF to deblur the image. PSF is estimated by owing nanobeads through the channel at the same ow rate as that of the sample. The reconstructed images show better contrast and less noise compared to raw images. The proposed system is promising for 3D imaging ow cytometry as well as for 3D imaging of live model organisms for high throughput screening. The conclusion for the thesis is given in chapter 7. Some of the prospects of the work is given as future scope.

碩士
國立交通大學
影像與生醫光電研究所
103
Arteriovenous fistula is an arterial and venous vascular anastomosis surgery, mainly used in hemodialysis patients. In order to make the process of hemodialysis with good efficiency, we must always maintain and monitor arteriovenous fistula function. 80% or more frequent injections of arteriovenous fistula will develop, which led to the phenomenon of vascular stenosis squeeze generated, stenosis due to blood vessel blockage and can’t be dialysis treatment, there will be life-threatening. In order to maintain arteriovenous fistula blood flow, and attention must always keep monitoring whether the produce vascular stenosis phenomenon between hemodialysis patients and doctors important objective. This study use a non-invasive hyperspectral imaging technology, including the use of charge-coupled display different laser wavelengths. Using Matlab to transform image which format is JPEG into 1024*768 – 8bit matrix in order to be used by Labview for image handling, the goal of this research is to develop and apply particular the principle of hyperspectral imaging for early detection and real-time monitoring the status of narrowing blood vessel, which could increase the quality of clinical care.

碩士
長庚大學
機械工程研究所
92
The non-invasive inspection method is one of the development direction of the contemporary medicine. And the functional medical image inspection methods aim at specific tissue, organ or disease majority, rather than the invasive inspection method, always use the digital image processing technology to achieve the inspection purpose. This research manipulate the digital image processing as the core technology, and point to some specific messages of the human body such as saliva crystallization, foot bottom pressure and temperature, and discuss these relations with the health. This investigation is divided into three parts: The first part of this research is "Using the Infrared Thermal Image Technology on the degenerative arthritis", it use an infrared thermal image instrument to quantitatively evaluate the patient of the degenerative arthritis in contrast with the normal people at the knees. The clinical experiment of this research is cooperated with the St. Paul`s Hospital, and the patients who are suitable to execute this clinical experiment is selected by the orthopaedic doctor. Use the thermal distribution diagram measured by the infrared thermal image instrument to do the temperature analysis. The thermal image of the tested of their left and right knee was divided into four areas at first, and then compute the average temperatures of each areas, and use the SPSS statistical software by the means of the independent sample t-test and paired t-test, to analyze the temperature difference between the patient of the degenerative arthritis and the normal people, also the difference between the disease leg and normal leg of the degenerative arthritic patient, and the relationship with the pain index. The second part of this research is「The Development of Digital Optical Saliva Crystallization by Functional medical image inspection System」,first of all a pilot study about the relationship between women menstrual cycle and saliva crystal was carried out to clarify the relationship between the pull strings of saliva in women’s mouth and the ovulate period. After confirmed the mechanism that related in this research, the notion designed of hardware and software were done, the model of the hardware were built by using the CAD designing software, then prototype was made and a testing procedure was carried out. In addition, the evaluate system was developed by using Borland C++ Builder software, each functional component of this system was tested and integrated. This digital optical saliva crystallization by functional medical image inspection system was testing on clinical patient. The third part of this research is「The Development of the Bottom Foot Health-Care’s Functional Medical Image Inspection System」,the task of research included investigated against the foot pressure、temperature of foot、temperature of foot and relation between the human health and clinical problem clarification, then the notion designed of hardware and software were carried out, the model of the hardware were built by using the CAD designing software, after prototype was made a testing procedure was carried out. This bottom foot health-care’s functional medical image inspection system also developed by Borland C++ Builder software. Via the image processing technique, the pressure distribution of foot was calculated by math’s transformation formula by the foot contact on ground was scanned with optical scanner and matched up with subject’s body weight. The superficial temperature of foot was acquired by the liquid crystal temperature slab’s characteristic of detect temperature color. After the hardware and software were integrated, the functional testing and clinical testing was carried out. The first part of research about the infrared thermal image technology on the degenerative arthritis, the clinical experiment proved that the superficial temperature difference have positive correlation with the clinical features, so doctor was suggested to use infrared thermal image system as an objective evaluation device on knee degenerative arthritis patient. In the part of the developed digital optical saliva crystallization by functional medical image inspection system, in this research, the image processing analysis technique to establish correlation index and saliva crystallization image database, it may be can provide women a ovulate period inspection device. And the part of the bottom foot health-care’s functional medical image inspection system was developed, due to the multiple function of this system, it can simultaneously evaluated the body weight、the contours of foot bottom、foot pressure and temperature distribution, it will be a multiple health-care device for self evaluate specific message from foot bottom at home.

Indiana University-Purdue University Indianapolis (IUPUI)
While computed tomographic angiography (CTA) has emerged as a powerful noninvasive option that allows for direct visualization of arterial stenosis(AS), it cant assess the hemodynamic abnormality caused by an AS. Alternatively, trans-stenotic pressure gradient (TSPG) and fractional flow reserve (FFR) are well-validated hemodynamic indices to assess the ischemic severity of an AS. However, they have significant restriction in practice due to invasiveness and high cost. To fill the gap, a new computational modality, called InVascular has been developed for non-invasive quantification TSPG and/or FFR based on patient's CTA, aiming to quantify the hemodynamic abnormality of the stenosis and help to assess the therapeutic/surgical benefits of treatment for the patient. Such a new capability gives rise to a potential of computation aided diagnostics and therapeutics in a patient-specific environment for ASs, which is expected to contribute to precision planning for cardiovascular disease treatment. InVascular integrates a computational modeling of diseases arteries based on CTA and Doppler ultrasonography data, with cutting-edge Graphic Processing Unit (GPU) parallel-computing technology. Revolutionary fast computing speed enables noninvasive quantification of TSPG and/or FFR for an AS within a clinic permissible time frame. In this work, we focus on the implementation of inlet and outlet boundary condition (BC) based on physiological image date and and 3-element Windkessel model as well as lumped parameter network in volumetric lattice Boltzmann method. The application study in real human coronary and renal arterial system demonstrates the reliability of the in vivo pressure quantification through the comparisons of pressure waves between noninvasive computational and invasive measurement. In addition, parametrization of worsening renal arterial stenosis (RAS) and coronary arterial stenosis (CAS) characterized by volumetric lumen reduction (S) enables establishing the correlation between TSPG/FFR and S, from which the ischemic severity of the AS (mild, moderate, or severe) can be identified. In this study, we quantify TSPG and/or FFR for five patient cases with visualized stenosis in coronary and renal arteries and compare the non-invasive computational results with invasive measurement through catheterization. The ischemic severity of each AS is predicted. The results of this study demonstrate the reliability and clinical applicability of InVascular.

While computed tomographic angiography (CTA) has emerged as a powerful noninvasive option that allows for direct visualization of arterial stenosis(AS), it cant assess the hemodynamic abnormality caused by an AS. Alternatively, trans-stenotic pressure gradient (TSPG) and fractional flow reserve (FFR) are well-validated hemodynamic indices to assess the ischemic severity of an AS. However, they have significant restriction in practice due to invasiveness and high cost. To fill the gap, a new computational modality, called InVascular has been developed for non-invasive quantification TSPG and/or FFR based on patient's CTA, aiming to quantify the hemodynamic abnormality of the stenosis and help to assess the therapeutic/surgical benefits of treatment for the patient. Such a new capability gives rise to a potential of computation aided diagnostics and therapeutics in a patient-specific environment for ASs, which is expected to contribute to precision planning for cardiovascular disease treatment. InVascular integrates a computational modeling of diseases arteries based on CTA and Doppler ultrasonography data, with cutting-edge Graphic Processing Unit (GPU) parallel-computing technology. Revolutionary fast computing speed enables noninvasive quantification of TSPG and/or FFR for an AS within a clinic permissible time frame. In this work, we focus on the implementation of inlet and outlet boundary condition (BC) based on physiological image date and and 3-element Windkessel model as well as lumped parameter network in volumetric lattice Boltzmann method. The application study in real human coronary and renal arterial system demonstrates the reliability of the in vivo pressure quantification through the comparisons of pressure waves between noninvasive computational and invasive measurement. In addition, parametrization of worsening renal arterial stenosis (RAS) and coronary arterial stenosis (CAS) characterized by volumetric lumen reduction (S) enables establishing the correlation between TSPG/FFR and S, from which the ischemic severity of the AS (mild, moderate, or severe) can be identified. In this study, we quantify TSPG and/or FFR for five patient cases with visualized stenosis in coronary and renal arteries and compare the non-invasive computational results with invasive measurement through catheterization. The ischemic severity of each AS is predicted. The results of this study demonstrate the reliability and clinical applicability of InVascular.

No
As part of the cancer drug development process, evaluation in experimental subcutaneous tumour transplantation models is a key process. This involves implanting tumour material underneath the mouse skin and measuring tumour growth using calipers. This methodology has been proven to have poor reproducibility and accuracy due to observer variation. Furthermore the physical pressure placed on the tumour using calipers is not only distressing for the mouse but could also lead to tumour damage. Non-invasive digital imaging of the tumour would reduce handling stresses and allow volume determination without any potential tumour damage. This is challenging as the tumours sit under the skin and have the same colour pattern as the mouse body making them hard to differentiate in a 2D image. We used the pre-trained convolutional neural network VGG-16 and extracted multiple layers in an attempt to accurately locate the tumour. When using the layer FC7 after RELU activation for extraction, a recognition rate of 89.85% was achieved.

Many individuals with severe motor impairments are cognitively capable, but because of their physical impairments, unable to express their intention through conventional means of communication. Access technologies are devices that attempt to translate the intention of these individuals into functional activity by harnessing their residual physical or physiological abilities. The primary objective of this thesis was to design and develop a novel non-invasive and non-contact access technology based on infrared thermal imaging. This access technology translates the local temperature change associated with voluntary mouth opening to activation of a binary switch such as a mouse click or key press. To this end, an algorithm based on motion and temperature analyses, and morphological and anthropometric filters was designed to detect mouth opening activity in thermal video in real-time. The secondary objective of this thesis was to introduce a mutual information measure for objective assessment of binary switch users’ performance. A model was suggested, in which combination of cognitive and physical abilities of the human user of a binary access switch constitute a communication channel. The proposed mutual information measure estimates the rate of information transmission in the ‘human communication channel’ during stimulus response tasks. Using this measure, in a study with ten able-bodied participants, the infrared thermal switch was validated against a conventional chin switch. Impairments in body functions and structures that may contraindicate the use of the infrared thermal switch were explored in a study with seven clients, with severe disabilities. Potential hard and soft technological solutions to mitigate the effect of these impairments on infrared thermal switch use were recommended. Finally the infrared thermal switch was tailored to meet the needs of a young man with severe spastic quadriplegic cerebral palsy, who had no other means of physical access.