Automated Analysis of Metacarpal Cortical Thickness in Serial Hand Radiographs

To understand the roles of various genes that influence skeletal bone accumulation and loss, accurate measurement of bone mineralization is needed. However, it is a challenging task to accurately assess bone growth over a person\u27s lifetime. Traditionally, manual analysis of hand radiographs has been used to quantify bone growth, but these measurements are tedious and may be impractical for a large-scale growth study. The aim of this project was to develop a tool to automate the measurement of metacarpal cortical bone thickness in standard hand-wrist radiographs of humans aged 3 months to 70+ years that would be more accurate, precise and efficient than manual radiograph analysis. The task was divided into two parts: development of automatic analysis software and the implementation of the routines in a Graphical User Interface (GUI). The automatic analysis was to ideally execute without user intervention, but we anticipated that not all images would be successfully analyzed. The GUI, therefore, provides the interface for the user to execute the program, review results of the automated routines, make semi-automated and manual corrections, view the quantitative results and growth trend of the participant and save the results of all analyses. The project objectives were attained. Of a test set of about 350 images from participants in a large research study, automatic analysis was successful in approximately 75% of the reasonable quality images and manual intervention allowed the remaining 25% of these images to be successfully analyzed. For images of poorer quality, including many that the Lifespan Health Research Center (LHRC) clients would not expect to be analyzed successfully, the inputs provided by the user allowed approximately 80% to be analyzed, but the remaining 20% could not be analyzed with the software. The developed software tool provides results that are more accurate and precise than those from manual analyses. Measurement accuracy, as assessed by phantom measurements, was approximately 0.5% and interobserver and intraobserver agreement were 92.1% and 96.7%, respectively. Interobserver and intraobserver correlation values for automated analysis were 0.9674 and 0.9929, respectively, versus 0.7000 and 0.7820 for manual analysis. The automated analysis process is also approximately 87.5% more efficient than manual image analysis and automatically generates an output file containing over 160 variables of interest. The software is currently being used successfully to analyze over 17,000 images in a study of human bone growth

Automated Bone Age Assessment: Motivation, Taxonomies, and Challenges

Bone age assessment (BAA) of unknown people is one of the most important topics in clinical procedure for evaluation of biological maturity of children. BAA is performed usually by comparing an X-ray of left hand wrist with an atlas of known sample bones. Recently, BAA has gained remarkable ground from academia and medicine. Manual methods of BAA are time-consuming and prone to observer variability. This is a motivation for developing automated methods of BAA. However, there is considerable research on the automated assessment, much of which are still in the experimental stage. This survey provides taxonomy of automated BAA approaches and discusses the challenges. Finally, we present suggestions for future research

Hand X-ray absorptiometry for measurement of bone mineral density on a slot-scanning X-ray imaging system

Includes bibliographical references.Bone mineral density (BMD) is an indicator of bone strength. While femoral and spinal BMDs are traditionally used in the management of osteoporosis, BMD at peripheral sites such as the hand has been shown to be useful in evaluating fracture risk for axial sites. These peripheral locations have been suggested as alternatives to the traditional sites for BMD measurement. Dual-energy X-ray absorptiometry (DXA) is the gold standard for measuring BMD due to low radiation dose, high accuracy and proven ability to evaluate fracture risk. Computed digital absorptiometry (CDA) has also been shown to be very effective at measuring the bone mass in hand bones using an aluminium step wedge as a calibration reference. In this project, the aim was to develop algorithm s for accurate measurement of BMD in hand bones on a slot - scanning digital radiography system. The project assess e d the feasibility of measuring bone mineral mass in hand bones using CDA on the current system. Images for CDA - based measurement were acquired using the default settings on the system for a medium sized patient. A method for automatic processing of the hand images to detect the aluminium step wedge, included in the scan for calibration, was developed and the calibration accuracy of the step wedge was evaluated. The CDA method was used for computation of bone mass with units of equivalent aluminium thickness (mmA1). The precision of the method was determined by taking three measurements in each of 1 6 volunteering subjects and computing the root - mean - square coefficient of variation (CV) of the measurements. The utility of the method was assessed by taking measurements of excised bones and assessing the correlation between the measured bone mass and ash weight obtained by incinerating the bones. The project also assessed the feasibility of implementing a DXA technique using two detectors in a slot-scanning digital radiography system to acquire dual-energy X-ray images for measuring areal and volumetric BMD of the middle phalanx of the middle finger. The dual-energy images were captured in two consecutive scans. The first scan captured the low- energy image using the detector in its normal set-up. The second scan captured the high- energy image with the detector modified to include an additional scintillator to simulate the presence of a second detector that would capture the low-energy image in a two-detector system. Scan parameters for acquisition of the dual-energy images were chosen to optimise spectral separation, entrance dose and image quality. Simulations were carried out to evaluate the spectral separation of the low- and high-energy spectra

In vivo morphometric and mechanical characterization of trabecular bone from high resolution magnetic resonance imaging

La osteoporosis es una enfermedad ósea que se manifiesta con una menor densidad ósea y el deterioro de la arquitectura del hueso esponjoso. Ambos factores aumentan la fragilidad ósea y el riesgo de sufrir fracturas óseas, especialmente en mujeres, donde existe una alta prevalencia. El diagnóstico actual de la osteoporosis se basa en la cuantificación de la densidad mineral ósea (DMO) mediante la técnica de absorciometría dual de rayos X (DXA). Sin embargo, la DMO no puede considerarse de manera aislada para la evaluación del riesgo de fractura o los efectos terapéuticos. Existen otros factores, tales como la disposición microestructural de las trabéculas y sus características que es necesario tener en cuenta para determinar la calidad del hueso y evaluar de manera más directa el riesgo de fractura. Los avances técnicos de las modalidades de imagen médica, como la tomografía computarizada multidetector (MDCT), la tomografía computarizada periférica cuantitativa (HR-pQCT) y la resonancia magnética (RM) han permitido la adquisición in vivo con resoluciones espaciales elevadas. La estructura del hueso trabecular puede observarse con un buen detalle empleando estas técnicas. En particular, el uso de los equipos de RM de 3 Teslas (T) ha permitido la adquisición con resoluciones espaciales muy altas. Además, el buen contraste entre hueso y médula que proporcionan las imágenes de RM, así como la utilización de radiaciones no ionizantes sitúan a la RM como una técnica muy adecuada para la caracterización in vivo de hueso trabecular en la enfermedad de la osteoporosis. En la presente tesis se proponen nuevos desarrollos metodológicos para la caracterización morfométrica y mecánica del hueso trabecular en tres dimensiones (3D) y se aplican a adquisiciones de RM de 3T con alta resolución espacial. El análisis morfométrico está compuesto por diferentes algoritmos diseñados para cuantificar la morfología, la complejidad, la topología y los parámetros de anisotropía del tejido trabecular. En cuanto a la caracterización mecánica, se desarrollaron nuevos métodos que permiten la simulación automatizada de la estructura del hueso trabecular en condiciones de compresión y el cálculo del módulo de elasticidad. La metodología desarrollada se ha aplicado a una población de sujetos sanos con el fin de obtener los valores de normalidad del hueso esponjoso. Los algoritmos se han aplicado también a una población de pacientes con osteoporosis con el fin de cuantificar las variaciones de los parámetros en la enfermedad y evaluar las diferencias con los resultados obtenidos en un grupo de sujetos sanos con edad similar.Los desarrollos metodológicos propuestos y las aplicaciones clínicas proporcionan resultados satisfactorios, presentando los parámetros una alta sensibilidad a variaciones de la estructura trabecular principalmente influenciadas por el sexo y el estado de enfermedad. Por otra parte, los métodos presentan elevada reproducibilidad y precisión en la cuantificación de los valores morfométricos y mecánicos. Estos resultados refuerzan el uso de los parámetros presentados como posibles biomarcadores de imagen en la enfermedad de la osteoporosis.Alberich Bayarri, Á. (2010). In vivo morphometric and mechanical characterization of trabecular bone from high resolution magnetic resonance imaging [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8981Palanci

Biplanar Fluoroscopic Analysis of in vivo Hindfoot Kinematics During Ambulation

The overall goal of this project was to develop and validate a biplanar fluoroscopic system and integrated software to assess hindfoot kinematics. Understanding the motion of the foot and ankle joints may lead to improved treatment methods in persons with foot and ankle pathologies. During gait analysis, skin markers are placed on the lower extremities, which are defined as four rigid-body segments with three joints representing the hip, knee and ankle. This method introduces gross assumptions on the foot and severely limits the analysis of in depth foot mechanics. Multi-segmental models have been developed, but are susceptible to skin motion artifact error. Intra-cortical bone pins studies provide higher accuracy, but are invasive. This dissertation developed and validated a noninvasive biplane fluoroscopy system to overcome the skin motion artifacts and rigid-body assumptions of conventional foot motion analysis. The custom-built biplane fluoroscopy system was constructed from two fluoroscopes separated by 60°, attached to a custom walkway with an embedded force plate. Open source software was incorporated to correct the image distortion and calibrate the capture volume. This study was the first that quantified the cross-scatter contamination in a biplane fluoroscopic system and its effects on the accuracy of marker-based tracking. A cadaver foot study determined the static and dynamic error of the biplane fluoroscopic system using both marker-based and model-based tracking algorithms. The study also developed in vivo 3D kinematic models of the talocrural and subtalar joints during the stance phase of gait. Cross-scatter degradation showed negligible effects in the smallest phantom, suggesting negligible motion tracking error due to cross scatter for distal extremities. Marker-based tracking error had a maximum absolute mean error of 0.21 (± 0.15) in dynamic trials. Model-based tracking results compared to marker-based had an overall dynamic RMS average error of 0.59 mm. Models were developed using custom algorithms to determine talocrural and subtalar joint 3D kinematics. The models offer a viable, noninvasive method suitable for quantifying hindfoot kinematics. Patients with a variety of adult and pediatric conditions which affect foot and ankle dynamics during walking may benefit from this work

An Improved 2DOF Elastokinematic Surrogate Model for Continuous Motion Prediction and Visualisation of Forearm Pro-and Supination for Surgical Planning

Forearm rotation (pro-/supination) involves a non-trivial combination of rotation and translation of two bones, namely, radius and ulna, relatively to each other. Early works regarded this relative motion as a rotation about a fixed (skew) axis. However, this assumption turns out not to be exact. This thesis regards a spatial-loop surrogate mechanism involving two degrees of freedom with an elastic coupling for better forearm motion prediction. In addition, the influence of the bone morphology and position of elbow on kinematics are also considered. The model parameters are not measured directly from the anatomical components, but are fitted by reducing the errors between predicted and measured values in an optimization loop. For non-invasive measurement of bone position, magnetic resonance imaging (MRI) is employed. We present a method to self-calibrate the arm position in the MRI scanning tube and to fit the model parameters from a few, coarse MRI scans. Results show a good concordance between measurement and simulation. Moreover, the minimum distance changing between bones during forearm rotation is elucidated, which is not yet proved in anatomical and clinical literatures. The minimum distance is calculated by searching for the global shortest distance between bone contours on ulna and radius by a two-level selection and a following multidimensional Newton-Raphson algorithm. To this end, the methodology is extended from healthy bones to deformed arms and an angulated forearm model is developed. The 3D angulated bone geometry is obtained by manually separating the bone structure at the broken position, and the minimum distance and the range of motion of fractured forearms are analyzed. As shown for a single case validation, simulated results show very small deviations from anatomical data. Furthermore, the simulations discussed above are visualized using interactive interfaces, which facilitates the application of the model in clinical planning.Die Unterarmrotation beinhaltet eine nicht triviale Kombination einer Rotation und Translokation zweier Knochen, Radius und Ulna relativ zu einander. Frühere Arbeiten betrachteten diese relative Bewegung als eine Rotation um eine fixierte Achse. Allerdings scheint diese Annahme ungenau zu sein. Diese Arbeit betrachtet ein Spatial-Loop Surrogat Mechanismus unter Berücksichtigung von zwei Freiheitsgraden mit einer elastischen Gelenkverbindung für eine bessere Prognose der Unterarm-Bewegung. Zusätzlich wird der Einfluss der Knochenmorphologie und die Position des Ellenbogens auf die Kinematik berücksichtig. Die Modellparameter werden nicht direkt von den anatomischen Komponenten bestimmt, sondern unter Berücksichtigung der Abweichung von Annahme und Messung. Zur nicht invasiven Messung der Knochenposition wird die Methode der Magnetresonanztomographie (MRT) angewendet. Wir stellen hier eine Methode um die Arm-Position in das MRI Scan-Rohr selbst zu kalibrieren und die Modellparameter aus einige grobe MRT-Aufnahmen zu passen. Die simulierten Ergebnisse zeigen sehr kleine Abweichungen von anatomischen Daten. Eine minimale Änderung der Distanz zwischen den Knochen während der Unterarmrotation wird beleuchte, die bisher nicht in der anatomischen und klinischen Literatur beschrieben ist. Die Berechnung der minimalen Distanz erfolgt über die Ermittlung der gesamt kürzesten Distanz. Zu diesem Zweck wird die Methodik von gesunden Knochen auf deformiere Arme und ein angewinkeltes Unterarmmodel entwickelt. Die 3D gewinkelte Knochen-Geometrie ergibt sich aus der Knochenstruktur an der gebrochener Position manuell zu trennen, und darauf werden der Mindestabstand und der Bereich der Bewegung von dem gebrochenen Unterarm analysiert. Wie dies bei einer einzelnen Fall Validierung, zeigen die simulierten Ergebnisse sehr kleine Abweichungen von anatomischen Daten. Darüber hinaus werden die oben beschrieben Simulationen mit interaktiven Benutzeroberflächen visualisiert, welche die Anwendung des Modells in der klinischen Planung erleichtert

Investigation of in-vivo hindfoot and orthotic interactions using bi-planar x-ray fluoroscopy

A markerless RSA method was used to determine the effect of orthotics on the normal, pes planus and pes cavus populations. Computed tomography (CT) was used to create bone models that were imported into the virtual environment. Joint coordinate systems were developed to measure kinematic changes in the hindfoot during weight-bearing gait and quiet standing. The objectives of this thesis were to (1) implement a fluoroscopy-based markerless RSA system on the foot, (2) determine the effect of various orthotics at midstance of fully weight-bearing dynamic gait, and (3) determine the effect of orthotics as measured using three different techniques. Every individual in this study reacted differently depending on the footwear condition tested. Despite the change in alignment caused by orthotics lacking statistical significance it appears the change may be significant with more subjects. Fluoroscopy should enable substantial improvements in orthotic design for optimal results in the future

The Impact of Scaphoid Malunion on Wrist Kinematics & Kinetics: A Biomechanical Investigation

Scaphoid fractures are very common injuries that can have serious sequelae if pathologic healing ensues. Although there is consensus regarding the importance of a non-united scaphoid, the impact of a malunited scaphoid is less clear. This is based on a paucity in the literature and understanding of the natural history of scaphoid malunion. This study aims to elucidate this study but investigating the impact of scaphoid malunion and joint kinetics, as well as the impact of scaphoid malunion on carpal bone kinematics. This was accomplished using a combination of in-silico, as well as in-vivo modelling based of cadaveric results derived from an active motion. Our results showed that increasing scaphoid malunion was associated with increasing joint contact at the radioscaphoid joint. There was no significant relationship between scaphoid motion and scaphoid malunion severity, however, there was a significant change in lunate motion, as well as motion between the scaphoid and lunate. This work serves as the framework for understanding the complex motion of the carpus and emphasizes the potential importance of establishing a good reduction of the scaphoid following fracture. The clinical importance of this finding has yet to be elucidated, but by understanding this relationship future clinical studies can be target at identifying feature of patients who may benefit from therapy

Recent Advances in Forensic Anthropological Methods and Research

Forensic anthropology, while still relatively in its infancy compared to other forensic science disciplines, adopts a wide array of methods from many disciplines for human skeletal identification in medico-legal and humanitarian contexts. The human skeleton is a dynamic tissue that can withstand the ravages of time given the right environment and may be the only remaining evidence left in a forensic case whether a week or decades old. Improved understanding of the intrinsic and extrinsic factors that modulate skeletal tissues allows researchers and practitioners to improve the accuracy and precision of identification methods ranging from establishing a biological profile such as estimating age-at-death, and population affinity, estimating time-since-death, using isotopes for geolocation of unidentified decedents, radiology for personal identification, histology to assess a live birth, to assessing traumatic injuries and so much more

Eye Tracking Methods for Analysis of Visuo-Cognitive Behavior in Medical Imaging

Predictive modeling of human visual search behavior and the underlying metacognitive processes is now possible thanks to significant advances in bio-sensing device technology and machine intelligence. Eye tracking bio-sensors, for example, can measure psycho-physiological response through change events in configuration of the human eye. These events include positional changes such as visual fixation, saccadic movements, and scanpath, and non-positional changes such as blinks and pupil dilation and constriction. Using data from eye-tracking sensors, we can model human perception, cognitive processes, and responses to external stimuli. In this study, we investigated the visuo-cognitive behavior of clinicians during the diagnostic decision process for breast cancer screening under clinically equivalent experimental conditions involving multiple monitors and breast projection views. Using a head-mounted eye tracking device and a customized user interface, we recorded eye change events and diagnostic decisions from 10 clinicians (three breast-imaging radiologists and seven Radiology residents) for a corpus of 100 screening mammograms (comprising cases of varied pathology and breast parenchyma density). We proposed novel features and gaze analysis techniques, which help to encode discriminative pattern changes in positional and non-positional measures of eye events. These changes were shown to correlate with individual image readers' identity and experience level, mammographic case pathology and breast parenchyma density, and diagnostic decision. Furthermore, our results suggest that a combination of machine intelligence and bio-sensing modalities can provide adequate predictive capability for the characterization of a mammographic case and image readers diagnostic performance. Lastly, features characterizing eye movements can be utilized for biometric identification purposes. These findings are impactful in real-time performance monitoring and personalized intelligent training and evaluation systems in screening mammography. Further, the developed algorithms are applicable in other application domains involving high-risk visual tasks