Emmanuel PERRIN | Université Claude Bernard Lyon 1 (original) (raw)
Papers by Emmanuel PERRIN
Proceedings of SPIE, Sep 16, 2005
Optical imaging is a non invasive way to characterise turbid media, which is of real interest for... more Optical imaging is a non invasive way to characterise turbid media, which is of real interest for investigating biological tissues for diagnosis purposes. A method called Integral Reflectance (IR) has already been developed [1]. The media being illuminated by a laser beam (670 nm, <1 mW), the backscattered light is captured by a 2D CCD camera. The reduced scattering coefficient μ's and the absorption coefficient μa are determined from the image. Having μ's and μa, the objective is to improve the characterization by estimating the anisotropy factor g, using polarized light. Different patterns depending on g are produced in these images, presenting some lobes, centred in the entry point of the laser beam, whose number and shape vary with g. To assess a simple description of these patterns, a circular outline of the image, at a given radius, is studied by Fourier series decomposition, namely Fourier descriptors, whose indices, modulus and phase provide the number, the size and the orientation of the lobes, respectively. Backscattered images of turbid media with g in the range [0.006 ; 0.93] (μ's = 10, 20, 40 cm-1 ; μa = 0.01, 1, 5 cm-1), were simulated using a Monte Carlo code for polarized light. Tables of Fourier descriptors were obtained as function of g, μ's and μa. Five reference solutions made of polystyrene spheres in liquid, with g varying from 0.71 to 0.919 (tissue phantoms) were tested. The Fourier descriptors were compared to simulations, and g could be retrieved with a maximum error of 10%.
Medical & Biological Engineering & Computing, Jul 1, 1997
The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental ... more The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental frequency and the first three formants are considered. The recognition strategy is based on comparison with normal ranges calculated over 200 ordinary voices, grouped in ten age classes ranging from 20 to 70 years, for males and females. 220 test voices are studied divided into four groups: normal voices, functional dysphonia, nodules and recurrent nerve palsy. Each subject is marked according to his/her normal range. Parameters (or items) are calculated on the interactive Laboratory System workstation. The vocalic material is composed of 11 vowels taken from a sentence. Results are given in terms of the number of values out of the normal ranges. Statistical analysis considers both parameter ability and error rates in pathology recognition. Pathology recognition shows the following error percentages: 23% for dysphonia, 14% for nodules and 33% for recurrent nerve palsy. Parameters do not show the same e~ciency for voice pathology characterisation. Formants appear to be better than the fundamental frequency.
Hearing Research, May 1, 1996
In 28 normal-hearing human subjects, the medial olivocochlear efferent system was activated by co... more In 28 normal-hearing human subjects, the medial olivocochlear efferent system was activated by contralateral acoustic stimulation which is able to mimic the inhibitory effects of electrical stimulation of the crossed olivocochlear bundle. A first experiment on 16 subjects demonstrated that a contralateral white noise of 35 dB SL was able to induce temporal changes on transiently evoked otoacoustic emissions in response to clicks of 63 dB SPL. These temporal changes consisted of an advance of click-evoked otoacoustic signals in 87% of cases and is referred to as phase-shift effect. The phase advance, quantified using two signal processing methods in both time and frequency domains, was found to be mainly associated with lower frequencies, with a maximal effect at 1.5 kHz and minimal effects around 3.5 and 4 kHz. In a second experiment, carried out on 12 subjects, a negative relationship was found to exist between the ipsilateral stimulation level (level of clicks ranging from 57 to 69 dB SPL) and the phase-shift effect (PSE). Specifically in the range of levels tested (25-45 dB SL), a linear relationship presenting no obvious saturation effect was observed between the contralateral level and the PSE. The PSE was examined in 6 additional subjects exhibiting pathological symptoms; 2 of 3 individuals, who had no contralateral stapedial reflexes unilaterally, showed the PSE whereas this response was reduced or absent in 3 other subjects in the ear with severed efferents associated with a vestibular neurotomy. The integrity of olivocochlear efferents was, therefore, necessary to obtain a full effect, but the absence of stapedial reflex did not prevent the effect from occurring.
Magnetic Resonance in Medicine, Feb 28, 2011
ABSTRACT Heat produced by a magnetic resonance (MR) imaging sequence in the vicinity of a conduct... more ABSTRACT Heat produced by a magnetic resonance (MR) imaging sequence in the vicinity of a conductive wire (pacemaker, electrodes, or catheter), is a subject of interest for the assessment of patient safety during imaging. For this purpose, the measurement of temperature rises during an MR imaging sequence using MR T1-based thermometry provides several advantages, mainly in its ability to retrieve in situ real-time thermal maps. Recent studies investigated the heat produced by an independent radiofrequency pulse, assessing MR imaging sequence heating using a specific MR thermometry sequence. This study focuses on self-heating for which the radiofrequency pulses used for measuring temperature create the heat. An experimental design was set up to evaluate T1-based thermometry self-heating using a coupled/decoupled wire and to compare it with a reference temperature gathered by an optical fiber device. For the tested experimental set up, T1-based thermometry is in fairly good agreement with optical fiber reference temperature.
Irbm, Sep 1, 2008
Optical characterization of biological tissues is of real interest to improve medical diagnosis a... more Optical characterization of biological tissues is of real interest to improve medical diagnosis and in particular in the detection of precancerous tissues. The reduced scattering coefficient μ′s and the absorption coefficient μa are the most commonly retrieved coefficients. Some methods also allow to obtain the anisotropy factor g, but only few of them are noninvasive. We propose a new noninvasive
Conference proceedings, Aug 1, 2007
The presence of metallic conductors (implants, wires or catheters) is prohibited in MR imaging fo... more The presence of metallic conductors (implants, wires or catheters) is prohibited in MR imaging for safety purpose with respect to radiofrequency (RF) power deposition caused by RF excitation B1 field. This work describes the use of T1-weigthed MR imaging for estimating a thermal map around a metallic (copper) wire located in the center of a MR imaging unit during an imaging sequence. The experimental set up and the methodology used for capturing the elevation of temperature created by radiofrequency power deposition around the wire is presented. A proof of its efficiency to followup temperature elevation about 0,5 degrees C in a milimetric region of interest (pixel size: 1 x 1 mm2, slice thickness 5 mm) located around the wire is given, leading to further developments of MR imaging in presence of metallic implants, coils or catheters.
... Aurélie Laidevant, Anabela da Silva, Michel Berger, Jean-Marc Dinten CEA-LETI Recherche Techn... more ... Aurélie Laidevant, Anabela da Silva, Michel Berger, Jean-Marc Dinten CEA-LETI Recherche Technologique, Département des micro Technologies pour la Biologie et la Santé, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France e-mail: aurelie.laidevant@cea.fr ...
Medical & Biological Engineering & Computing, Sep 1, 1999
The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental ... more The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental frequency and the first three formants are considered. The recognition strategy is based on comparison with normal ranges calculated over 200 ordinary voices, grouped in ten age classes ranging from 20 to 70 years, for males and females. 220 test voices are studied divided into four groups: normal voices, functional dysphonia, nodules and recurrent nerve palsy. Each subject is marked according to his/her normal range. Parameters (or items) are calculated on the Interactive Laboratory System workstation. The vocalic material is composed of 11 vowels taken from a sentence. Results are given in terms of the number of values out of the normal ranges. Statistical analysis considers both parameter ability and error rates in pathology recognition. Pathology recognition shows the following error percentages: 23% for dysphonia, 14% for nodules and 33% for recurrent nerve palsy. Parameters do not show the same efficiency for voice pathology characterisation. Formants appear to be better than the fundamental frequency.
Applied optics, Oct 24, 2008
Optical characterization of biological tissues is of real interest to improve medical diagnosis, ... more Optical characterization of biological tissues is of real interest to improve medical diagnosis, in particular in the detection of precancerous tissues. We propose a new, noninvasive method allowing the estimation of the anisotropy factor. This method is based on the image analysis of the Q element of the Stokes vector backscattered from the turbid medium. These Q-element images show specific patterns depending on g. Therefore the use of Fourier descriptors (FDs) on simulated data to discriminate the specific geometrical features of the Q element enabled us to determine a linear relation between the anisotropy factor and six FDs. This method was applied on experimental data obtained with calibrated solutions. The anisotropy factor was estimated with a maximum relative error of 13%.
International Journal of Pediatric Otorhinolaryngology, Feb 1, 1999
Cochlear implant (CI) is a good means in developing communication in deaf children. Nevertheless,... more Cochlear implant (CI) is a good means in developing communication in deaf children. Nevertheless, compared to children with the same age, CI patients' voices are far from being similar. In this work, the voice of CI children has been compared with the voice of corresponding normal children (same age, same sex) included in the main stream. Six girls and two boys participated to the experiment. The phonetic material was a paragraph of the French standard text La bise et le soleil (The North Wind and the Sun). An objective and a subjective analysis of the voice were done and parameters were compared between both groups of people (implantees and control). Studied parameters were voice pitch, intensity, fluency, pauses, articulation and pleasantness in the objective analysis, and voice pitch, formants, and duration for the objective study. It appeared that intensity variations were different between control and implanted subjects. Also voice formants were not situated in the same region regarding the normal ranges, but differences were difficult to assess. Globally, the main change was in the speaking duration. This method is open for further studies and points out some relevant items for an efficient use in rehabilitation sessions.
Synopsis Heating of biological tissues along metallic wires placed in MRI scanner has become an i... more Synopsis Heating of biological tissues along metallic wires placed in MRI scanner has become an important question with the development of interventional MRI. This paper presents results about temperature variation due to RF heating along a wire with two different lengths during a MRI examination. Measured values are compared with simulation results. Study shows that the temperature elevation may be important and does not appear only at wire tips.
Acta Acustica united with Acustica
In this paper, the authors investigate the short-term influence of wearing conventional hearing a... more In this paper, the authors investigate the short-term influence of wearing conventional hearing aids (HA) on the spectrum of the sustained vowel [a]. 80 hearing impaired subjects with a binaural HA were included in the study. Their hearing losses were higher than 50 dB SPL above 500 Hz. The subjects were divided into two paired groups. The first group was recorded first without, then with, and finally without hearing aids. The second group was recorded without, then without, and finally with hearing aids. Two kinds of comparison were made between the two groups: (1) the comparison of the two first recordings of the groups gave indications on the influence of fitting HA, and (2) the comparison of the last two recordings of the groups tested the difference of fitting vs. removing HA. The acoustical material was a sustained [a] studied globally and in three segments (beginning, middle and end). The vowel spectrum was studied from 0 to 8 kHz. Each frequency band was 500 Hz wide. Results...
- L'objectif de cette étude est de proposer, à partir du mouvement brownien fractionnaire (fB... more - L'objectif de cette étude est de proposer, à partir du mouvement brownien fractionnaire (fBm) de paramètre H, un modèle plus général qui puisse englober des phénomènes présentant un caractère fractal par morceaux lors d'une analyse en fréquence. Ce nouveau modèle est appelé pfBm de paramètres Ho en basse fréquence, Hi en haute fréquence, ces deux régimes étant séparés par une fréquence de coupure γ. Pour Ho=Hi=H, le pfBm se réduit au fBm, lui même étant le mouvement brownien pour H=0.5. Nous pensons que le pfBm fournit ainsi un outil plus flexible que le fBm pour l'expérimentateur. Nous avons montré que ce processus a des incréments stationnaires et qu'il est autosimilaire de paramètre Ho pour les basses fréquences et de paramètre Hi pour les hautes fréquences. Nous avons alors étudié des radiographies trabéculaires osseuses qui présentent ce caractère bifractal. Les résultats montrent que l'analyse fractale par morceaux est plus efficace que l'analyse frac...
- L'objectif de cette communication est de déterminer la résolution optimale (efficace et de ... more - L'objectif de cette communication est de déterminer la résolution optimale (efficace et de faible coût) d'un système de radiographie numérique permettant une aide au diagnostic précoce de l'ostéoporose par quantification de la qualité du tissu osseux. Pour ce faire, un prototype haute résolution a été développé. Il est l'association d'une source X mini foyer et d'un capteur matriciel dont les pixels carrés sont de 16 microns de côté. La résolution a été artificiellement dégradée en moyennant les pixels adjacents. Deux méthodes d'analyse de la texture de telles images ont été mises en oeuvre : la première est basée sur une étude morphologique des travées après binarisation des images et une autre sur une mesure fractale de la rugosité des mêmes images en niveaux de gris. Les résultats montrent sur des échantillons de têtes de fémur que pour détecter les modifications de l'architecture trabéculaire, une résolution proche de 20 microns serait adaptée.
Advances in Modelling and Analysis B
2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
Biomedical diploma degrees have a long tradition at Lyon 1, Claude Bernard University. Since 2004... more Biomedical diploma degrees have a long tradition at Lyon 1, Claude Bernard University. Since 2004, the transition towards the LMD system leaded to a unified Bachelor and Master Degree in Biomedical Engineering. A next evolution plans the creation of a Biomedical Engineering Department in the future Polytechnic School of Claude Bernard University. This department will form professionals in Biomedical Engineering, Medical Physics and for academic employment in Universities and research structures.
Revue de stomatologie et de chirurgie maxillo-faciale, 1995
The following study concerns the acoustic parameters marking the difference between the phonation... more The following study concerns the acoustic parameters marking the difference between the phonation of children with velar incompetency and a corresponding control group. Population is made of 64 children aged 5 and 6; 32 are in the control group and 32 in the pathological group. Each child was required to repeat several words; 10 vowels and 9 consonants were taken from those words. Acoustic signal was recorded and studied using a standard speech assessment work station. 63 parameters for the vowels and 6 for the consonants were studied. Results showed that the best parameters concerned the vowels and that cepstrum coefficients were an efficient tool to perform the separation of the two groups. On the contrary, formants, voice pitch and jitter did not appear to be efficient enough to do this task. It was, then, deduced a check form for velopharyngeal incompetency, form which will be tested in future work.
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439)
Heating of biological tissues along metallic wires placed in MRI scanner has become an important ... more Heating of biological tissues along metallic wires placed in MRI scanner has become an important question with the development of interventional MRI. In order to assess thermal response to RF exposure during MR procedures, the temperature elevation was studied near metallic non-magnetic wires. All tests have been performed on a 1.5 T clinical scanner. The major issue is to insure
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439)
Feasibility of gastrointestinal walls imaging using endoluminal coils is described. A single-loop... more Feasibility of gastrointestinal walls imaging using endoluminal coils is described. A single-loop coil was built to be inserted into a gastric tube. Endoluminal coil performance was evaluated on a 1.5 T clinical scanner and in vivo high-resolution Magnetic Resonance Imaging (MRI) of rabbit gastrointestinal walls was performed. Images allow visualization and identification of rabbit gastrointestinal walls. Tuning/matching circuit and decoupling
Proceedings of SPIE, Sep 16, 2005
Optical imaging is a non invasive way to characterise turbid media, which is of real interest for... more Optical imaging is a non invasive way to characterise turbid media, which is of real interest for investigating biological tissues for diagnosis purposes. A method called Integral Reflectance (IR) has already been developed [1]. The media being illuminated by a laser beam (670 nm, <1 mW), the backscattered light is captured by a 2D CCD camera. The reduced scattering coefficient μ's and the absorption coefficient μa are determined from the image. Having μ's and μa, the objective is to improve the characterization by estimating the anisotropy factor g, using polarized light. Different patterns depending on g are produced in these images, presenting some lobes, centred in the entry point of the laser beam, whose number and shape vary with g. To assess a simple description of these patterns, a circular outline of the image, at a given radius, is studied by Fourier series decomposition, namely Fourier descriptors, whose indices, modulus and phase provide the number, the size and the orientation of the lobes, respectively. Backscattered images of turbid media with g in the range [0.006 ; 0.93] (μ's = 10, 20, 40 cm-1 ; μa = 0.01, 1, 5 cm-1), were simulated using a Monte Carlo code for polarized light. Tables of Fourier descriptors were obtained as function of g, μ's and μa. Five reference solutions made of polystyrene spheres in liquid, with g varying from 0.71 to 0.919 (tissue phantoms) were tested. The Fourier descriptors were compared to simulations, and g could be retrieved with a maximum error of 10%.
Medical & Biological Engineering & Computing, Jul 1, 1997
The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental ... more The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental frequency and the first three formants are considered. The recognition strategy is based on comparison with normal ranges calculated over 200 ordinary voices, grouped in ten age classes ranging from 20 to 70 years, for males and females. 220 test voices are studied divided into four groups: normal voices, functional dysphonia, nodules and recurrent nerve palsy. Each subject is marked according to his/her normal range. Parameters (or items) are calculated on the interactive Laboratory System workstation. The vocalic material is composed of 11 vowels taken from a sentence. Results are given in terms of the number of values out of the normal ranges. Statistical analysis considers both parameter ability and error rates in pathology recognition. Pathology recognition shows the following error percentages: 23% for dysphonia, 14% for nodules and 33% for recurrent nerve palsy. Parameters do not show the same e~ciency for voice pathology characterisation. Formants appear to be better than the fundamental frequency.
Hearing Research, May 1, 1996
In 28 normal-hearing human subjects, the medial olivocochlear efferent system was activated by co... more In 28 normal-hearing human subjects, the medial olivocochlear efferent system was activated by contralateral acoustic stimulation which is able to mimic the inhibitory effects of electrical stimulation of the crossed olivocochlear bundle. A first experiment on 16 subjects demonstrated that a contralateral white noise of 35 dB SL was able to induce temporal changes on transiently evoked otoacoustic emissions in response to clicks of 63 dB SPL. These temporal changes consisted of an advance of click-evoked otoacoustic signals in 87% of cases and is referred to as phase-shift effect. The phase advance, quantified using two signal processing methods in both time and frequency domains, was found to be mainly associated with lower frequencies, with a maximal effect at 1.5 kHz and minimal effects around 3.5 and 4 kHz. In a second experiment, carried out on 12 subjects, a negative relationship was found to exist between the ipsilateral stimulation level (level of clicks ranging from 57 to 69 dB SPL) and the phase-shift effect (PSE). Specifically in the range of levels tested (25-45 dB SL), a linear relationship presenting no obvious saturation effect was observed between the contralateral level and the PSE. The PSE was examined in 6 additional subjects exhibiting pathological symptoms; 2 of 3 individuals, who had no contralateral stapedial reflexes unilaterally, showed the PSE whereas this response was reduced or absent in 3 other subjects in the ear with severed efferents associated with a vestibular neurotomy. The integrity of olivocochlear efferents was, therefore, necessary to obtain a full effect, but the absence of stapedial reflex did not prevent the effect from occurring.
Magnetic Resonance in Medicine, Feb 28, 2011
ABSTRACT Heat produced by a magnetic resonance (MR) imaging sequence in the vicinity of a conduct... more ABSTRACT Heat produced by a magnetic resonance (MR) imaging sequence in the vicinity of a conductive wire (pacemaker, electrodes, or catheter), is a subject of interest for the assessment of patient safety during imaging. For this purpose, the measurement of temperature rises during an MR imaging sequence using MR T1-based thermometry provides several advantages, mainly in its ability to retrieve in situ real-time thermal maps. Recent studies investigated the heat produced by an independent radiofrequency pulse, assessing MR imaging sequence heating using a specific MR thermometry sequence. This study focuses on self-heating for which the radiofrequency pulses used for measuring temperature create the heat. An experimental design was set up to evaluate T1-based thermometry self-heating using a coupled/decoupled wire and to compare it with a reference temperature gathered by an optical fiber device. For the tested experimental set up, T1-based thermometry is in fairly good agreement with optical fiber reference temperature.
Irbm, Sep 1, 2008
Optical characterization of biological tissues is of real interest to improve medical diagnosis a... more Optical characterization of biological tissues is of real interest to improve medical diagnosis and in particular in the detection of precancerous tissues. The reduced scattering coefficient μ′s and the absorption coefficient μa are the most commonly retrieved coefficients. Some methods also allow to obtain the anisotropy factor g, but only few of them are noninvasive. We propose a new noninvasive
Conference proceedings, Aug 1, 2007
The presence of metallic conductors (implants, wires or catheters) is prohibited in MR imaging fo... more The presence of metallic conductors (implants, wires or catheters) is prohibited in MR imaging for safety purpose with respect to radiofrequency (RF) power deposition caused by RF excitation B1 field. This work describes the use of T1-weigthed MR imaging for estimating a thermal map around a metallic (copper) wire located in the center of a MR imaging unit during an imaging sequence. The experimental set up and the methodology used for capturing the elevation of temperature created by radiofrequency power deposition around the wire is presented. A proof of its efficiency to followup temperature elevation about 0,5 degrees C in a milimetric region of interest (pixel size: 1 x 1 mm2, slice thickness 5 mm) located around the wire is given, leading to further developments of MR imaging in presence of metallic implants, coils or catheters.
... Aurélie Laidevant, Anabela da Silva, Michel Berger, Jean-Marc Dinten CEA-LETI Recherche Techn... more ... Aurélie Laidevant, Anabela da Silva, Michel Berger, Jean-Marc Dinten CEA-LETI Recherche Technologique, Département des micro Technologies pour la Biologie et la Santé, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France e-mail: aurelie.laidevant@cea.fr ...
Medical & Biological Engineering & Computing, Sep 1, 1999
The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental ... more The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental frequency and the first three formants are considered. The recognition strategy is based on comparison with normal ranges calculated over 200 ordinary voices, grouped in ten age classes ranging from 20 to 70 years, for males and females. 220 test voices are studied divided into four groups: normal voices, functional dysphonia, nodules and recurrent nerve palsy. Each subject is marked according to his/her normal range. Parameters (or items) are calculated on the Interactive Laboratory System workstation. The vocalic material is composed of 11 vowels taken from a sentence. Results are given in terms of the number of values out of the normal ranges. Statistical analysis considers both parameter ability and error rates in pathology recognition. Pathology recognition shows the following error percentages: 23% for dysphonia, 14% for nodules and 33% for recurrent nerve palsy. Parameters do not show the same efficiency for voice pathology characterisation. Formants appear to be better than the fundamental frequency.
Applied optics, Oct 24, 2008
Optical characterization of biological tissues is of real interest to improve medical diagnosis, ... more Optical characterization of biological tissues is of real interest to improve medical diagnosis, in particular in the detection of precancerous tissues. We propose a new, noninvasive method allowing the estimation of the anisotropy factor. This method is based on the image analysis of the Q element of the Stokes vector backscattered from the turbid medium. These Q-element images show specific patterns depending on g. Therefore the use of Fourier descriptors (FDs) on simulated data to discriminate the specific geometrical features of the Q element enabled us to determine a linear relation between the anisotropy factor and six FDs. This method was applied on experimental data obtained with calibrated solutions. The anisotropy factor was estimated with a maximum relative error of 13%.
International Journal of Pediatric Otorhinolaryngology, Feb 1, 1999
Cochlear implant (CI) is a good means in developing communication in deaf children. Nevertheless,... more Cochlear implant (CI) is a good means in developing communication in deaf children. Nevertheless, compared to children with the same age, CI patients' voices are far from being similar. In this work, the voice of CI children has been compared with the voice of corresponding normal children (same age, same sex) included in the main stream. Six girls and two boys participated to the experiment. The phonetic material was a paragraph of the French standard text La bise et le soleil (The North Wind and the Sun). An objective and a subjective analysis of the voice were done and parameters were compared between both groups of people (implantees and control). Studied parameters were voice pitch, intensity, fluency, pauses, articulation and pleasantness in the objective analysis, and voice pitch, formants, and duration for the objective study. It appeared that intensity variations were different between control and implanted subjects. Also voice formants were not situated in the same region regarding the normal ranges, but differences were difficult to assess. Globally, the main change was in the speaking duration. This method is open for further studies and points out some relevant items for an efficient use in rehabilitation sessions.
Synopsis Heating of biological tissues along metallic wires placed in MRI scanner has become an i... more Synopsis Heating of biological tissues along metallic wires placed in MRI scanner has become an important question with the development of interventional MRI. This paper presents results about temperature variation due to RF heating along a wire with two different lengths during a MRI examination. Measured values are compared with simulation results. Study shows that the temperature elevation may be important and does not appear only at wire tips.
Acta Acustica united with Acustica
In this paper, the authors investigate the short-term influence of wearing conventional hearing a... more In this paper, the authors investigate the short-term influence of wearing conventional hearing aids (HA) on the spectrum of the sustained vowel [a]. 80 hearing impaired subjects with a binaural HA were included in the study. Their hearing losses were higher than 50 dB SPL above 500 Hz. The subjects were divided into two paired groups. The first group was recorded first without, then with, and finally without hearing aids. The second group was recorded without, then without, and finally with hearing aids. Two kinds of comparison were made between the two groups: (1) the comparison of the two first recordings of the groups gave indications on the influence of fitting HA, and (2) the comparison of the last two recordings of the groups tested the difference of fitting vs. removing HA. The acoustical material was a sustained [a] studied globally and in three segments (beginning, middle and end). The vowel spectrum was studied from 0 to 8 kHz. Each frequency band was 500 Hz wide. Results...
- L'objectif de cette étude est de proposer, à partir du mouvement brownien fractionnaire (fB... more - L'objectif de cette étude est de proposer, à partir du mouvement brownien fractionnaire (fBm) de paramètre H, un modèle plus général qui puisse englober des phénomènes présentant un caractère fractal par morceaux lors d'une analyse en fréquence. Ce nouveau modèle est appelé pfBm de paramètres Ho en basse fréquence, Hi en haute fréquence, ces deux régimes étant séparés par une fréquence de coupure γ. Pour Ho=Hi=H, le pfBm se réduit au fBm, lui même étant le mouvement brownien pour H=0.5. Nous pensons que le pfBm fournit ainsi un outil plus flexible que le fBm pour l'expérimentateur. Nous avons montré que ce processus a des incréments stationnaires et qu'il est autosimilaire de paramètre Ho pour les basses fréquences et de paramètre Hi pour les hautes fréquences. Nous avons alors étudié des radiographies trabéculaires osseuses qui présentent ce caractère bifractal. Les résultats montrent que l'analyse fractale par morceaux est plus efficace que l'analyse frac...
- L'objectif de cette communication est de déterminer la résolution optimale (efficace et de ... more - L'objectif de cette communication est de déterminer la résolution optimale (efficace et de faible coût) d'un système de radiographie numérique permettant une aide au diagnostic précoce de l'ostéoporose par quantification de la qualité du tissu osseux. Pour ce faire, un prototype haute résolution a été développé. Il est l'association d'une source X mini foyer et d'un capteur matriciel dont les pixels carrés sont de 16 microns de côté. La résolution a été artificiellement dégradée en moyennant les pixels adjacents. Deux méthodes d'analyse de la texture de telles images ont été mises en oeuvre : la première est basée sur une étude morphologique des travées après binarisation des images et une autre sur une mesure fractale de la rugosité des mêmes images en niveaux de gris. Les résultats montrent sur des échantillons de têtes de fémur que pour détecter les modifications de l'architecture trabéculaire, une résolution proche de 20 microns serait adaptée.
Advances in Modelling and Analysis B
2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
Biomedical diploma degrees have a long tradition at Lyon 1, Claude Bernard University. Since 2004... more Biomedical diploma degrees have a long tradition at Lyon 1, Claude Bernard University. Since 2004, the transition towards the LMD system leaded to a unified Bachelor and Master Degree in Biomedical Engineering. A next evolution plans the creation of a Biomedical Engineering Department in the future Polytechnic School of Claude Bernard University. This department will form professionals in Biomedical Engineering, Medical Physics and for academic employment in Universities and research structures.
Revue de stomatologie et de chirurgie maxillo-faciale, 1995
The following study concerns the acoustic parameters marking the difference between the phonation... more The following study concerns the acoustic parameters marking the difference between the phonation of children with velar incompetency and a corresponding control group. Population is made of 64 children aged 5 and 6; 32 are in the control group and 32 in the pathological group. Each child was required to repeat several words; 10 vowels and 9 consonants were taken from those words. Acoustic signal was recorded and studied using a standard speech assessment work station. 63 parameters for the vowels and 6 for the consonants were studied. Results showed that the best parameters concerned the vowels and that cepstrum coefficients were an efficient tool to perform the separation of the two groups. On the contrary, formants, voice pitch and jitter did not appear to be efficient enough to do this task. It was, then, deduced a check form for velopharyngeal incompetency, form which will be tested in future work.
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439)
Heating of biological tissues along metallic wires placed in MRI scanner has become an important ... more Heating of biological tissues along metallic wires placed in MRI scanner has become an important question with the development of interventional MRI. In order to assess thermal response to RF exposure during MR procedures, the temperature elevation was studied near metallic non-magnetic wires. All tests have been performed on a 1.5 T clinical scanner. The major issue is to insure
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439)
Feasibility of gastrointestinal walls imaging using endoluminal coils is described. A single-loop... more Feasibility of gastrointestinal walls imaging using endoluminal coils is described. A single-loop coil was built to be inserted into a gastric tube. Endoluminal coil performance was evaluated on a 1.5 T clinical scanner and in vivo high-resolution Magnetic Resonance Imaging (MRI) of rabbit gastrointestinal walls was performed. Images allow visualization and identification of rabbit gastrointestinal walls. Tuning/matching circuit and decoupling