Biomedical subjects

Nadia Magnenat-Thalmann

Publications and source records attributed to Nadia Magnenat-Thalmann.

4 recordsLinked to original sources

PubMed2005

Bone motion analysis from dynamic MRI: acquisition and tracking.

RATIONALE AND OBJECTIVES: For diagnosis, preoperative planning and postoperative guides, an accurate estimate of joint kinematics is required. It is important to acquire joint motion actively with real-time protocols. MATERIALS AND METHODS: We bring together MRI developments and new image processing methods in order to automatically extract active bone kinematics from multi-slice real-time dynamic MRI. We introduce a tracking algorithm based on 2D/3D registration and a procedure to validate the technique by using both dynamic and sequential MRI, providing a gold standard bone position measurement. RESULTS: We present our technique for optimizing jointly the tracking method and the acquisition protocol to overcome the trade-off in acquisition time and tracking accuracy. As a case study, we apply this methodology on a human hip joint. CONCLUSION: The final protocol (bFFE, TR/TE 3.5/1.1 ms, Flip angle 80 degrees , pixel size 4.7 x 2.6 mm, partial Fourier reduction factor of 0.65 in read direction, SENSE acceleration factor of 2, frame rate = 6.7 frames/s) provides sufficient morphological data for bone tracking to be carried out with an accuracy of 3 degrees in terms of joint angle.

Algorithms↗

PubMed2003

A virtual reality system for the training of volunteers involved in health emergency situations.

In order to guarantee an effective and punctual medical intervention to injured people involved in health emergency situations, where usually both professional and non-professional health operators are involved, a fast and accurate treatment has to be carried out. In case of catastrophic or very critical situations, non-professional operators who did not receive proper training (volunteers are among them) could be affected by psychological inhibitions. Their performances could slow down in such way that would affect the quality of the treatment and increase both direct and indirect costs. Our virtual reality system that is currently in use at the health care emergency center of San Martino Hospital in Genoa, Italy, has been designed and developed to check health emergency operators' capabilities to adopt correct decision-making procedures, to make optimal use of new technological equipment and to overcome psychological barriers. Our system is composed of (1) a high-end simulation PC, whose main functions are execution of the main software module, rendering of 3D scenes in stereo mode, rendering of sound, and control of data transmission from/to VR devices; (2) a low-end control PC, which controls the VR simulation running on the simulation PC, manages medical emergency simulation scenarios, introduces unexpected events to the simulation and controls the simulation difficulty level; (3) a magnetic-based motion tracking device used for head and hand tracking; (4) a wireless pair of shutter glasses together with a cathode ray tube wall projector; and (5) a high-end surround sound system. The expected benefits have been verified through the design and implementation of controlled clinical trials.

Clinical Trials as Topic↗

PubMed2002

A computational skin model: fold and wrinkle formation.

This paper presents a computational model for studying the mechanical properties of skin with aging. In particular, attention is given to the folding capacity of skin, which may be manifested as wrinkles. The simulation provides visual results demonstrating the form and density of folds under the various conditions. This can help in the consideration of proper measures for a cosmetic product for the skin.

Aging↗

PubMedDate not supplied

Real-time animation of complex hairstyles.

True real-time animation of complex hairstyles on animated characters is the goal of this work, and the challenge is to build a mechanical model of the hairstyle which is sufficiently fast for real-time performance while preserving the particular behavior of the hair medium and maintaining sufficient versatility for simulating any kind of complex hairstyles. Rather than building a complex mechanical model directly related to the structure of the hair strands, we take advantage of a volume free-form deformation scheme. We detail the construction of an efficient lattice mechanical deformation model which represents the volume behavior of the hair strands. The lattice is deformed as a particle system using state-of-the-art numerical methods, and animates the hairs using quadratic B-Spline interpolation. The hairstyle reacts to the body skin through collisions with a metaball-based approximation. The model is highly scalable and allows hairstyles of any complexity to be simulated in any rendering context with the appropriate trade off between accuracy and computation speed, fitting the need of Level-of-Detail optimization schemes.

Algorithms↗