François Langevin

Three dimensional representation of brain electrical activity

SummaryBrain topography mapping is a useful technique for the representation of electrical activity recorded on the scalp. It clarifies spatial and temporal relationships between different cortical areas. In this work we propose a system which includes several enhancements over those previously proposed, such as an optimised interpolation method and a three dimensional reconstruction of maps. This system is available in a personal computer environment. Results clearly show a superiority of the 3D representation over 2D maps obtained with different projections. The performance of this system in terms of speed and precision is comparable to that of dedicated image processing and image synthesis workstations proposed for brain mapping.

Image fusion by an orthogonal wavelet transform and comparison with other methods

We present a new hierarchical image merging scheme based on an orthogonal wavelet transform. The composite images produced by this scheme preserve those details from the input images that are most relevant to visual perception. Some comparisons of the results of this method with those of other methods, previously proposed, are presented.

A new production method of elastic silicone carotid phantom based on MRI acquisition using rapid prototyping technique

In vitro experimental simulations of blood fluid in carotid artery require ideal phantoms that are as precise as possible. The purpose of this work is to demonstrate a method for carotid phantom fabrication by rapid prototyping technique (RP). By using 3D reconstructed projection of the 3D time-of-flight (TOF) Magnetic Resonance Imaging (MRI) sequence, a 12.5cm multi-dimensional spatial structure of a carotid artery has been set up. Y-shaped and patient specific models have been generated respectively using silicone elastomer, which has a high resilience and a good tensile strength. The final patient specific model has internal carotid artery (ICA) with a highly spiraling siphon and an external carotid artery (ECA). Elastic properties of carotid walls have also been evaluated by Youngs elastic modulus test and dynamic behaviors in optical and echography simulation experiments.

Biomedical Education for Clinical Engineers

Biomedical equipment Masters degree is recognized by the French Ministry of Health, since its creation in 1975 under the denomination of ldquoSpecialization for Hospital Biomedical Engineersrdquo. Since the new national status of technical staff in the public service by decree of September 5th of 1991, it allows to access directly to the level of Chief Hospital Engineer (first category, second class, by ordinance of October 23rd, 1992). Biomedical Engineers jobs in French hospitals are selected after an examination organized by the recruiting hospital. Masters graduates are most often the best qualified.

Clinical Engineers In French Public Hospitals Distribution, Function And Education

In this paper, a brief description of the organization of clinical engineering profession in French public hospitals is given. Their population has grown since 1975 to reach today 150 clinical engineers. Their training is five or six years long, and their task is clearly dependant of the size of the medical institution they belong to. The relatively small population size. and the youth of the engineers lead to a dynamic profession, solving the increasing investments problems, organizing the maintenance and the security. They are also involved in many original experiences in the field of regional structures, expert valuations, applied research organizations. They often become the advisers of hospital managers in slrategic technology choice. surgery, and laboratories. A survey that we realized in 1988 for the French Ministry of Health showed that. at that time, hospital employed a mean of one CE for 9 MF (1.5 M%) of medical investments a year (in the range of 3.5 MF to 36 m. It is re~ogniwl today that maintcnance costs have been reduced after the constitution of inside hospital technical teams. Generalization of training of medical staff helped in reducing the important number of small fahes. Inprovements have also been recorded in the fields of security and immobilization time.

A newly designed MR-compatible guidewire for intracranial aneurysmal interventional therapy: Initial researchs and results

Intracranial aneurysm is one of the most common vascular disorders, as one of its treatments, endovascular coiling is now carried out by means of fluoroscopy and this can bring ionizing radiation to both patients and operators. However, compared with fluoroscopy, Magnetic Resonance Imaging (MRI) has many advantages such as higher contrast of soft tissue and especially, free of radiation during image acquisition. In this study, we have developed a new guidewire which is compatible with MRI, meanwhile, ultra-rapid MRI sequences are used to trace the guidewire in vitro.

Clinical Engineering Education in France Situation in 2007 and Evolution

Compiegnes University of Technology is one of the main contributors in clinical engineering education in France. Knowledge and skills have been acquired since 1974 through professional specialization courses and new programs such as masters degrees, engineering and PhD degrees, and continuing education courses for technicians. To face current hospitals needs, new investments in distance learning have been made. The first results are presented in the following.

A low cost image transfer system for small medical centers

Last years one of the principal felds in radiology communication research has been the study of the PACS (Picture Archiving and Communication Systems) and their interconnexion through long distance nets using the ISDN (Integrated Service Digital Network). For a successful every day use, it is necessary to have a standarization of the methods. High costs systems installed in the biggest hospitals are not well suited for small structures. The CIMA belongs to this last group and we have adopted a system based on low cost standard networks as Ethernet and Numeris (Numeris is a registered trademark of ISDN in France) and protocols, connected with other medical centers of the region.

2D Time-Resolved Phase-Contrast MRI Measurements in Silicone Intracranial Aneurysm Phantoms

Aneurysm is widely believed as a fatal pathology. As one type of aneurysms, an intracranial aneurysm is notably dangerous due to its thin vessel wall and high rate of rupture. The objective of this study in vitro is to analyze the hemodynamics in an intracranial aneurysm using a silicone phantom. The feasibility of the phantom is verified. In order to visualize and quantify the flow in the phantom, time-resolved 2-dimensional phase-contrast MRI sequence is applied. With post-processing of images, velocity profile and 3-dimensional path lines are obtained and analyzed.

Blood velocity estimation feasibility using high resolution time-resolved MR sequences

Blood velocity quantification is a challenge for vascular flow observation and arterial pathogenesis comprehension. In this context, magnetic resonance dynamic sequences could be used for spatial velocity encoding. On one hand, phase contrast techniques use spins phase modification for velocity information extraction. On the other hand, time of flight (TOF) technique has a high temporal resolution, but it is still considered a vascular visualization technique. The aim of this study is to check feasibility to estimate blood velocity from gradient echo TOF-based images. This is advantageous as high temporal resolution (<;10 ms) has the potential to produce more precise exploration of vessel, and blood movements. This work represents an experimental analysis of MR signal behavior as a function of velocity, in fast gradient echo TOF-based sequence. The study of this relationships shape is necessary for later velocity quantification methods design. MR signal behavior is studied for a full scale of velocity, and reproducibility is checked. Imaging parameters influence is also reported. High temporal resolution, blood velocity estimation feasibility are finally discussed.