Low-energy trauma and fragility fractures represent a major public health problem. The societal cost of the fragility fractures that occurred in Sweden 2010 has been estimated at €4 billion. In rheumatoid arthritis (RA), patient outcomes have improved greatly in recent years. However, the therapeutic decision making is still hampered by a lack of effective validated biomarkers. The cost of RA in Sweden 2010 has been estimated at €600 million, of which biologic drugs was €180 million. Digital X-ray radiogrammetry (DXR) is a method to measure bone mineral density (BMD) in the metacarpals of the hand. It can be applied opportunistically in several workflows where a person is already at an X-ray machine, including fracture repositioning follow up, mammography screening and hand imaging in RA. This thesis explored DXR-BMD as a marker to identify individuals who would benefit from anti-osteoporotic treatment, change rate of DXR-BMD as a biomarker in RA and under what conditions historical X-ray images can be used to estimate DXR-BMD. An automated method for measurement of joint space width in metacarpophalangeal and interphalangeal joints was also developed and evaluated as a biomarker in RA. Low DXR-BMD was predictive for hip fractures and predicted fragility fractures to a comparable degree as other BMD measurement sites. Rapid decrease of DXR-BMD was a strong and independent predictor for progression of radiographic damage in RA when manual radiographic progression scores were not available. Change of metacarpal joint space width was a statistically significant but weak predictor of joint space narrowing score progression. Guidelines and considerations for use of historical X-ray radiographs for DXR-BMD measurements in clinical trials have been developed and published.

L'arthrose est une maladie dégénérative de l'articulation qui provoque des douleurs, une raideur et une diminution de mobilité. La quantification de l’interligne articulaire est la mesure qui permet de diagnostiquer la maladie et de suivre son évolution. A ce jour, la radiographie conventionnelle est la méthode de référence pour ce diagnostic et ce suivi. Néanmoins, l'articulation du genou et ses modifications structurales sont trop complexes pour permettre un diagnostic à un stade précoce à partir de simples images 2D. Une des pistes prometteuses de la recherche sur le diagnostic précoce est l’exploitation de l’information 3D de l’interligne. C’est dans ce contexte que s’inscrit cette thèse qui a pour but la segmentation et la quantification 3D de l’interligne articulaire afin d’atteindre l’objectif du diagnostic précoce de l’arthrose de genou. Au cours de cette thèse nous avons développé une méthode de quantification semi-automatique de l’interligne articulaire. La cartographie 3D des distances générée a permis de caractériser la morphologie de l’espace articulaire sur des images haute résolution 3D. Pour atteindre l’objectif de quantification à basse dose, deux approches ont été explorées. La première consistait à proposer une approche de segmentation 3D du volume osseux à partir d’un faible nombre de projections. La deuxième approche consiste à réaliser la quantification 3D de l’interligne sur des images issus d’un scanner basse dose obtenue à l’aide d’autres algorithmes mis en œuvre par les partenaires du projet VOXELO. La segmentation de l’interligne a été dans ce cas utilisée comme un critère de qualité de la reconstruction selon ces différents algorithmes.Afin de tester la robustesse de notre approche, nous avons utilisé des images haute résolution selon 2 types de géométrie du faisceau ou des images à faible dose et également sur des images scanner clinique in vivo. Ceci nous permet de conclure que la méthode de quantification de l’interligne que nous avons développé en 3D est potentiellement applicable sur des images provenant de différents appareils de scanner. Cet outil sera potentiellement utile pour détecter les stades précoces et suivre la progression de l'arthrose en clinique. / Osteoarthritis (OA) is a degenerative joint disease that causes pain, stiffness and decrease mobility. Knee OA presents the greatest morbidity. The main characteristic of OA is the cartilage loss inducing joint space narrowing. Usually, the diagnosis and progression of OA is monitored by the joint space measurement. Actually, conventional radiography is the reference method for the diagnosis and monitoring. However, the knee joint and structural changes are too complex to be assessed from simple 2D images especially at early stage. A promising research into early diagnosis is the use of 3D. The objective of our thesis is to provide a tool for a 3D quantification of joint space in order to achieve the goal of early diagnosis of knee osteoarthritis. In this thesis we have developed a semi-automatic method for the quantification of joint space. The 3D map generated allowed us to characterize the morphology of the joint space widths on 3D high resolution images.To achieve the goal of low-dose quantification, two approaches have been explored. The first was to provide a 3D segmentation method for bone extraction from a limited number of projections. The second approach is to perform the 3D quantification from a low dose scan obtained using other algorithms implemented by our partners of VOXELO project. The segmentation of the joint space was used as a quality criterion according to these different algorithms.To test the robustness of our approach, we used high-resolution images with different geometry acquisition types and low-dose images. We have also done a test on clinical CT images in vivo. This allows us to conclude that the method we developed is potentially applicable to images from different scanner devices. This tool can be used for detecting the early stages and track the progress of the clinical osteoarthritis

Department of Veterans Affairs (VA) audiologists were surveyed regarding their perceptions and evaluations of hearing aid (HA) brands on seven factors previously published in peer-reviewed research as important to the HA brand preference decision of audiologists. One of the seven factors formed a distinct dimension of brand differentiation based on Contract Pricing (dimension 1). Brand perceptions for the other six factors were highly correlated with one another; this dimension of correlated perceptions was labeled Propensity to Dispense Based on a Gestalt Percept (dimension 2). That is, a direct relation exists between the collective perception of HA brand and its likelihood of being dispensed. These two dimensions accounted for 93.1% of the variance in the perceived differences among the HA brands surveyed. Joint-space mapping was used to model the effect of altering perceptions on VA HA brand dispensing. Results indicate that few VA audiologists (7.7%) dispense HA brands in majority association with contract pricing. Instead, the vast majority (77%) form brand preferences in majority association with their individualized perceptions.