A morphable model for the synthesis of 3D faces

During the last years, computer-vision-based diagnosis systems have been used in several hospitals and dermatology clinics, aiming mostly at the early detection of skin cancer, and more specifically, the recognition of malignant melanoma tumour. In this paper, we review the state of the art in such systems by first presenting the installation, the visual features used for skin lesion classification, and the methods for defining them. Then, we describe how to extract these features through digital image processing methods, i.e., segmentation, border detection, and color and texture processing, and we present the most prominent techniques for skin lesion classification. The paper reports the statistics and the results of the most important implementations that exist in the literature, while it compares the performance of several classifiers on the specific skin lesion diagnostic problem and discusses the corresponding findings.

Overview of Advanced Computer Vision Systems for Skin Lesions Characterization

Cellular structures with highly controlled micro-architectures are promising materials for orthopedic applications that require bone-substituting biomaterials or implants The availability of additive manufacturing techniques has enabled manufacturing of biomaterials made of one or multiple types of unit cells The diamond lattice unit cell is one of the relatively new types of unit cells that are used in manufacturing of regular porous biomaterials As opposed to many other types of unit cells, there is currently no analytical solution that could be used for prediction of the mechanical properties of cellular structures made of the diamond lattice unit cells In this paper, we present new analytical solutions and closed-form relationships for predicting the elastic modulus, Poisson׳s ratio, critical buckling load, and yield (plateau) stress of cellular structures made of the diamond lattice unit cell The mechanical properties predicted using the analytical solutions are compared with those obtained using finite element models A number of solid and porous titanium (Ti6Al4V) specimens were manufactured using selective laser melting A series of experiments were then performed to determine the mechanical properties of the matrix material and cellular structures The experimentally measured mechanical properties were compared with those obtained using analytical solutions and finite element (FE) models It has been shown that, for small apparent density values, the mechanical properties obtained using analytical and numerical solutions are in agreement with each other and with experimental observations The properties estimated using an analytical solution based on the Euler–Bernoulli theory markedly deviated from experimental results for large apparent density values The mechanical properties estimated using FE models and another analytical solution based on the Timoshenko beam theory better matched the experimental observations

Mechanical behavior of regular open-cell porous biomaterials made of diamond lattice unit cells

Introduction and Aims: There is a relationship between the anatomy of the hip joint and the development of arthritis. A common cause of hip pain in the young adult that can lead to arthritis is acetabular dysplasia. More recently, femoroacetabular impingement has been described as another cause of hip pain. The purpose of our study was to evaluate the applicability of pelvic computed tomography (CT) with three-dimensional surface rendering to evaluate femoro-acetabular impingement. Method Thirty-six hips (30 patients; 17 males; 13 females) with persistent hip pain, mean age 41 (37–52), underwent three-dimensional CT of the pelvis, as well as MRI arthrography with gadolinium enhancement. On 3D CT, the concavity of the femoral head-neck junction (offset), alpha angle as described by Notzli was calculated to depict the anterior femoral neck contour. The concavity of the posterior aspect of the head neck junction was measured as the beta angle. The same measurements were made in 20 hips, consisting of randomly selected patients with no prior history of hip pathology or pain (mean age 37; 13 males; eight females). Results The mean alpha angle for the symptomatic group was 66.4 (39–94) and 43.8 (39.3–48.3) for the control group (p=0.001). All symptomatic hips had abnormal findings on MRA: labral tears in all; cartilage delamination/ulceration in 14 hips; herniation pits in six hips. The majority of labral tears and delamination were located in the antero-superior quadrant. In the surgical treated group, all MRA findings were confirmed. The mean beta angle was significantly smaller (increase concavity) in the symptomatic versus the controls: 40.2 versus 43.8 (p=0.011). Interestingly in the symptomatic group the beta angle was significantly lower than the alpha angle (p Conclusion: 3D CT with surface rendering and multiplanar reformation is useful to determine degree of bone buttressing of the anterior femoral head-neck junction quantitatively assessed by alpha angle measurement, which is elevated in patients with femoro-acetabular impingement. With a greater posterior concavity i.e. small beta angle in the symptomatic group versus the control, subclinical slipped femoral epiphysis remains a plausible cause of this deformity.

Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement

Background: Statistical shape models are widely used in biomedical research. They are routinely implemented for automatic image segmentation or object identification in medical images. In these fields, however, the acquisition of the large training datasets, required to develop these models, is usually a time-consuming process. Even after this effort, the collections of datasets are often lost or mishandled resulting in replication of work. Objective: To solve these problems, the Virtual Skeleton Database (VSD) is proposed as a centralized storage system where the data necessary to build statistical shape models can be stored and shared. Methods: The VSD provides an online repository system tailored to the needs of the medical research community. The processing of the most common image file types, a statistical shape model framework, and an ontology-based search provide the generic tools to store, exchange, and retrieve digital medical datasets. The hosted data are accessible to the community, and collaborative research catalyzes their productivity. Results: To illustrate the need for an online repository for medical research, three exemplary projects of the VSD are presented: (1) an international collaboration to achieve improvement in cochlear surgery and implant optimization, (2) a population-based analysis of femoral fracture risk between genders, and (3) an online application developed for the evaluation and comparison of the segmentation of brain tumors. Conclusions: The VSD is a novel system for scientific collaboration for the medical image community with a data-centric concept and semantically driven search option for anatomical structures. The repository has been proven to be a useful tool for collaborative model building, as a resource for biomechanical population studies, or to enhance segmentation algorithms. [J Med Internet Res 2013;15(11):e245]

The Virtual Skeleton Database: An Open Access Repository for Biomedical Research and Collaboration

A 2D/3D correspondence building method for reconstruction of a patient-specific 3D bone surface model using point distribution models and calibrated X-ray images.

Annually 133.000 people world-wide get sick on malign melanoma, tendency increasing. The purpose of this study is the early diagnosis of malignant skin cancer. At the moment the dermatologists are screening for anomalies at the relevant lesion by examining the skin area with a microscope. To determine changes, another scan has to be taken in a follow- up session after a time period of about 15-20 weeks. Today's visual diagnostic decision is based on the pragmatic ABCD- approach (Asymmetry, Border, Colour, and Diameter). However, there is no adequate and sound non-invasive way to find out, if a skin spot is either malign or benign. If the visual approach corroborates a suspicion of skin cancer, histology is needed to make explicit diagnosis. To avoid unnecessary surgeries (on false positive alarm) and to initiate necessary surgeries in early stages a new diagnostic screening approach is presented here. Based on the fact that malign melanoma have higher metabolism as well as increased blood flow, it has been conjectured that malign melanoma have slightly higher temperature compared to the healthy skin that can be measured by high resolution functional infrared imaging. an invasive histological examination. To avoid redundant excise of tissue and to detect malignant melanoma in an early stage, a new method is proposed here. Thanks to the facts that malignant melanoma have higher consumption of glucose caused by a higher level of metabolism and an augmented branching of blood vessels, the so called angiogenesis, the temperature should be different to its environment, e.g. the surrounding healthy tissue. Associated with the increased demand of energy, it is conjectured that malignant melanoma shows a higher temperature (2-4 K) than its surrounding skin (4). Infrared imaging has a high potential to detect the beginnings of angiogenesis, when cancer cells first try to develop their own blood supply, which is a necessary step before they can grow rapidly and metastasize. To substantiate the conjecture an infrared imaging devices of the latest generation is used. II. PHYSICS AND INSTRUMENTATION Thermographic imaging makes use of the infrared spectral band. The physical formulas describing this topic are Planck's law, Wien's displacement law and the Stefan- Boltzmann law.

Functional infrared imaging for skin-cancer screening.

Twenty-three femurs (one plastic bone and twenty-two cadaver bones) with both nonpathologic and pathologic cases were considered to validate a statistical shape model based technique for three-dimensional (3D) reconstruction of a patient-specific surface model from calibrated x-ray radiographs. The 3D reconstruction technique is based on an iterative nonrigid registration of the features extracted from a statistically instantiated 3D surface model to those interactively identified from the radiographs. The surface models reconstructed from the radiographs were compared to the associated ground truths derived either from a 3D CT-scan reconstruction method or from a 3D laser-scan reconstruction method and an average error distance of 0.95 mm were found. Compared to the existing works, our approach has the advantage of seamlessly handling both nonpathologic and pathologic cases even when the statistical shape model that we used was constructed from surface models of nonpathologic bones.

3D reconstruction of a patient-specific surface model of the proximal femur from calibrated x-ray radiographs: a validation study.

Validation of statistical shape model based reconstruction of the proximal femur--A morphology study.

Femoroacetabular impingement (FAI) before or after Periacetabular Osteotomy (PAO) is surprisingly frequent and surgeons need to be aware of the risk preoperatively and be able to avoid it intraoperatively. In this paper we present a novel computer assisted planning and navigation system for PAO with impingement analysis and range of motion (ROM) optimization. Our system starts with a fully automatic detection of the acetabular rim, which allows for quantifying the acetabular morphology with parameters such as acetabular version, inclination and femoral head coverage ratio for a computer assisted diagnosis and planning. The planned situation was optimized with impingement simulation by balancing acetabuar coverage with ROM. Intra-operatively navigation was conducted until the optimized planning situation was achieved. Our experimental results demonstrated: 1) The fully automated acetabular rim detection was validated with accuracy 1.1 ± 0.7mm; 2) The optimized PAO planning improved ROM significantly compared to that without ROM optimization; 3) By comparing the pre-operatively planned situation and the intra-operatively achieved situation, sub-degree accuracy was achieved for all directions.

Steffen Schumann

Papers

A 2D/3D correspondence building method for reconstruction of a patient-specific 3D bone surface model using point distribution models and calibrated X-ray images.

Functional infrared imaging for skin-cancer screening.

3D reconstruction of a patient-specific surface model of the proximal femur from calibrated x-ray radiographs: a validation study.

Validation of statistical shape model based reconstruction of the proximal femur--A morphology study.

Computer Assisted Planning and Navigation of Periacetabular Osteotomy with Range of Motion Optimization