29 results on '"J. Vautier"'
Search Results
2. Impact dosimétrique de la pose d’un espaceur rectal dans le traitement de cancer de la prostate localisé par irradiation en conditions stéréotaxiques
- Author
-
V. Anthonipillai, L Abbassi, M. Ung, Alberto Bossi, J. Vautier, Pierre Blanchard, and M. Cheve
- Subjects
business.industry ,medicine.medical_treatment ,Rectum ,Mean age ,medicine.disease ,Radiation therapy ,03 medical and health sciences ,Prostate cancer ,0302 clinical medicine ,medicine.anatomical_structure ,Oncology ,Rectal wall ,030220 oncology & carcinogenesis ,medicine ,High doses ,Radiology, Nuclear Medicine and imaging ,Local anesthesia ,Nuclear medicine ,business ,Stereotactic body radiotherapy - Abstract
Purpose Stereotactic body radiotherapy (SBRT) of prostate cancer is associated with rectal toxicities, which can be reduced by using a hydrogel spacer. The object of this retrospective study was to show the feasibility of spacer placement under local anesthesia and utility of hydrogel spacer to reduce the dose to the rectal wall. Material and methods We collected data from all patients with localised prostate cancer treated with SBRT (40Gy in 5 fractions) between 2018 and 2020. A hydrogel spacer (SpaceOAR®) was placed depending on the availability of the product. We collected dosimetric data for target volumes and organs at risk. We calculated mean values, which were compared using non-parametric tests. Results Among 35 patients, mean age was 75 years. Seventeen had a spacer placed, with a mean space created of 10mm. No complication was reported during the intervention. High doses to the rectal wall were significantly lower in spacer group (V38: 0.39 cm3 vs. 0.72 cm3; P=0.02). PTV were better covered in spacer group (P=0.07). Doses to the bladder wall were similar in both groups. Conclusion Spacer procedure under local anesthesia was well tolerated. Hydrogel spacer allowed to reduce doses to the rectum while improving PTV coverage.
- Published
- 2021
3. [Dosimetric impact of hydrogel spacer use for stereotactic body radiotherapy of localised prostate cancer]
- Author
-
M, Ung, A, Bossi, L, Abbassi, J, Vautier, V, Anthonipillai, M, Chevé, and P, Blanchard
- Subjects
Aged, 80 and over ,Male ,Organs at Risk ,Urinary Bladder ,Rectum ,Prostatic Neoplasms ,Hydrogels ,Radiotherapy Dosage ,Middle Aged ,Radiosurgery ,Statistics, Nonparametric ,Feasibility Studies ,Humans ,Radiation Injuries ,Aged ,Anesthesia, Local ,Retrospective Studies - Abstract
Stereotactic body radiotherapy (SBRT) of prostate cancer is associated with rectal toxicities, which can be reduced by using a hydrogel spacer. The object of this retrospective study was to show the feasibility of spacer placement under local anesthesia and utility of hydrogel spacer to reduce the dose to the rectal wall.We collected data from all patients with localised prostate cancer treated with SBRT (40Gy in 5 fractions) between 2018 and 2020. A hydrogel spacer (SpaceOAR®) was placed depending on the availability of the product. We collected dosimetric data for target volumes and organs at risk. We calculated mean values, which were compared using non-parametric tests.Among 35 patients, mean age was 75 years. Seventeen had a spacer placed, with a mean space created of 10mm. No complication was reported during the intervention. High doses to the rectal wall were significantly lower in spacer group (V38: 0.39 cmSpacer procedure under local anesthesia was well tolerated. Hydrogel spacer allowed to reduce doses to the rectum while improving PTV coverage.
- Published
- 2020
4. Impact dosimétrique et clinique de la pose d’un espaceur rectal dans le traitement de cancer de prostate localisé par irradiation en conditions stéréotaxiques
- Author
-
V. Anthonipillai, L.M. Abbassi, Alberto Bossi, Pierre Blanchard, M. Cheve, J. Vautier, and M. Ung
- Subjects
Gynecology ,03 medical and health sciences ,medicine.medical_specialty ,0302 clinical medicine ,Oncology ,business.industry ,030220 oncology & carcinogenesis ,medicine ,Radiology, Nuclear Medicine and imaging ,business - Abstract
Introduction et but de l’etude La radiotherapie stereotaxique du cancer de prostate localise est pourvoyeuse de toxicite rectale, qui peut etre reduite en utilisant un espaceur rectal. L’objectif de cette etude retrospective etait de demontrer la faisabilite d’une implantation sous anesthesie locale et l’utilite d’un espaceur dans la reduction de la dose dans la paroi rectale. Materiel et methodes Nous avons recueilli les donnees de l’ensemble des patients atteints d’un adenocarcinome de prostate localise traite par irradiation stereotaxique de 40 Gy en cinq fractions entre 2018 et 2020. Un espaceur (SpaceOAR®) a ete mis en place en fonction de la disponibilite du dispositif. Nous avons releve des indicateurs dosimetriques concernant le volume cible et les organes a risque. Les valeurs continues ont ete representees par leurs moyennes et comparees avec un test de Mann–Whitney. Resultats et analyse statistique Parmi les 35 patients, 17 ont beneficie de la pose d’un espaceur rectal, sans complication lors de l’implantation, permettant un espacement moyen de 10 mm. Les fortes doses dans la paroi rectale etaient significativement plus basses dans le groupe beneficiant de l’espaceur (volume recevant 38 Gy : 0,39 cm3 contre 0,72 cm3 ; p = 0,02). Il y avait une tendance a une meilleure couverture du volume cible previsionnel dans le groupe beneficiant de l’espaceur (p = 0,07). Les doses recues dans la paroi vesicale etaient similaires entre les deux groupes. Conclusion L’implantation sous anesthesie locale d’un espaceur rectal est faisable, et s’accompagne d’une diminution de la dose dans le rectum. L’espaceur semble permettre une meilleure couverture du volume cible previsionnel.
- Published
- 2020
5. Exactitude des logiciels commerciaux de délinéation automatique en stéréotaxie cérébrale
- Author
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J. Vautier, S. Kreps, Catherine Durdux, H. Tournat, C. Daveau-Bergerault, P. Giraud, Jean-Emmanuel Bibault, and N. Meillan
- Subjects
Oncology ,Radiology, Nuclear Medicine and imaging - Abstract
Objectif de l’etude La radiotherapie hypofractionnee en conditions stereotaxiques est un traitement efficace et reconnu pour les patients oligometastatiques cerebraux. Sa planification est par contre longue du fait des nombreux organes ou structures a delineer. Cette etude compare la performance de deux logiciels commerciaux de segmentation automatique. Materiel et methode Une tomodensitometrie a ete acquise en position de traitement et fusionnee avec une IRM diagnostique. Les volumes ont ete delinees manuellement par un clinicien (yeux, cristallins, nerfs optiques, chiasma, tronc cerebral). Deux segmentations automatiques de ces memes structures ont ete realisees (iPlan© et Smart Segmentation©). Les fichiers RTSTRUCT ont ete compares avec le module de comparaison Artistruct© d’Aquilab. Notre critere de jugement principal etait le pourcentage de volume delinee commun defini comme (A ∩ B)/A avec A le volume delinee manuellement et B le volume obtenu par segmentation automatique. Les criteres secondaires etaient le coefficient de Dice–Sorensen : 2 (A ∩ B)/(A + B), l’overlap ratio : (A ∩ B)/(A U B) et le volume delinee additionnel : (B − A)/B. Resultats Nous avons inclus 20 patients consecutifs. L’accord entre les volumes delinees manuellement et automatiquement etait faible. Les pourcentages de volumes communs etaient compris entre 7,71 % et 82,54 %, les coefficients de Dice–Sorensen entre 0,0745 et 0,8398, l’overlap ratio entre 0,0414 et 0,7275 et les pourcentages de volume additionnels entre 9,80 % et 92,25 % sans superiorite claire de l’un ou l’autre logiciel. Conclusion La precision de la segmentation automatique reste bien trop faible pour une utilisation en routine clinique. Le role du clinicien reste essentiel dans la definition des volumes et ce meme dans une situation aussi reproductible que le crâne.
- Published
- 2017
6. Conservation Biology for Seven Palm Species from Diverse Genera
- Author
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Laurent G. Rakotondranony, Wen Bin, Christopher B. Wood, Helen J. Vautier, and Hugh W. Pritchard
- Subjects
Ravenea rivularis ,Caryota urens ,biology ,Trachycarpus latisectus ,Germination ,Botany ,General Earth and Planetary Sciences ,Arecaceae ,Conservation biology ,Sabal ,Adonidia merrillii ,biology.organism_classification ,General Environmental Science - Abstract
Arecaceae are a relatively large family with a considerable number of species of local and global socioeconomic importance. Many species are also under threat of impending extinction, indicating an urgent need to improve their conservation prospects. Here we present studies on seven palm species (Adonidia merrillii, Caryota urens, Livistona muelleri, Ravenea rivularis, Sabal [minor via. louisiana], Trachycarpus latisectus, and Wallichia disticha) from diverse genera in relation to various seed traits, including germination, desiccation tolerance, and weight. Germination varied from ca. 12-100% and mean time to germinate ranged from four days to four and one-half weeks at 30°C. Six of the species were newly screened for seed conservation biology and of these two were found to possess desiccation-tolerant seeds, indicating opportunities for longer-term storage and improved use.
- Published
- 2006
7. Acute rheumatic peritonitis
- Author
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L, GRAS and J, VAUTIER
- Subjects
Rheumatic Diseases ,Humans ,Peritonitis ,Rheumatic Fever - Published
- 2010
8. Retraction of a cavity ballooned by intravenous injections of atropine during a pneumothorax complicated by pleurisy
- Author
-
L, GRAS and J, VAUTIER
- Subjects
Atropine ,Pneumothorax, Artificial ,Tuberculosis ,Tuberculosis, Pulmonary - Published
- 2010
9. Vesiculo-edematous arsenical erythroderma cured by sulfamidotherapy
- Author
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L, GRAS and J, VAUTIER
- Subjects
Arsenic Poisoning ,Humans ,Dermatitis, Exfoliative ,Arsenic - Published
- 2010
10. Bolus-tracking MRI with a simultaneous T1- and T2*-measurement
- Author
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S, Sourbron, M, Heilmann, A, Biffar, C, Walczak, J, Vautier, A, Volk, and M, Peller
- Subjects
Contrast Media ,Mice, Nude ,Reproducibility of Results ,Image Enhancement ,Models, Biological ,Sensitivity and Specificity ,Mice ,Diffusion Magnetic Resonance Imaging ,Meglumine ,Cell Line, Tumor ,Image Interpretation, Computer-Assisted ,Organometallic Compounds ,Animals ,Humans ,Computer Simulation ,Colorectal Neoplasms ,Algorithms - Abstract
The aim of this study was to propose and evaluate a methodology to analyze simultaneously acquired T2*-weighted dynamic susceptibility contrast (DSC) MRI and T(1)-weighted dynamic contrast enhanced (DCE) MRI data. Two generalized models of T2*-relaxation are proposed to account for tracer leakage, and a two-compartment exchange model is used to separate tracer in intra- and extravascular spaces. The methods are evaluated using data extracted from ROIs in three mice with subcutaneously implanted human colorectal tumors. Comparing plasma flow values obtained from DCE-MRI and DSC-MRI data defines a practical experimental paradigm to measure T2*-relaxivities, and reveals a factor of 15 between values in tissue and blood. Comparing mean transit time values obtained from DCE-MRI and DSC-MRI without leakage correction, indicates a significant reduction of susceptibility weighting in DSC-MRI during tracer leakage. A one-parameter gradient correction model provides a good approximation for this susceptibility loss, but redundancy of the parameter limits the practical potential of this model for DSC-MRI. Susceptibility loss is modeled more accurately with a variable T2*-relaxivity, which allows to extract new parameters that cannot be derived from DSC-MRI or DCE-MRI alone. They reflect the cellular and vessel geometry, and thus may lead to a more complete characterization of tissue structure.
- Published
- 2009
11. Gestion et embauche de personnel à long terme par programmation linéaire et simulation
- Author
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J. Vautier and J. Agard
- Subjects
Geography ,General Medicine - Published
- 1968
12. [Functioning of a sheltered apartment and role of the nursing team]
- Author
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M B, Diligent, J, Vautier, E, Mazur, and L, Heip
- Subjects
Adult ,Male ,Patient Care Team ,Mental Disorders ,Chronic Disease ,Humans ,Female ,France ,Residential Facilities - Published
- 1985
13. [The spleen in Besnier-Boeck-Schaumann disease]
- Author
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B, DUPERRAT and J, VAUTIER
- Subjects
Sarcoidosis ,Spleen - Published
- 1952
14. Breakwater Man, The – A Biography of Napier Pioneer John Helier Vautier
- Author
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Noel J Vautier
15. Prostate radiotherapy may cause fertility issues: a retrospective analysis of testicular dose following modern radiotherapy techniques.
- Author
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Kissel M, Terlizzi M, Giraud N, Alexis A, Cheve M, Vautier J, Bossi A, Morice P, and Blanchard P
- Subjects
- Humans, Male, Retrospective Studies, Middle Aged, Organs at Risk radiation effects, Aged, Adult, Radiation Injuries etiology, Fertility radiation effects, Prostatic Neoplasms radiotherapy, Testis radiation effects, Radiotherapy Dosage, Radiotherapy, Intensity-Modulated adverse effects, Radiotherapy, Intensity-Modulated methods, Radiotherapy Planning, Computer-Assisted methods
- Abstract
Background: Prostate cancer in younger men is rare but not exceptional. Radiotherapy is a cornerstone of prostate cancer treatment and yet, its impact on fertility is scarcely reported in literature. Given the radiosensitivity of testicular tissue, this study aimed to determine the testicular dose using modern radiotherapy techniques for definitive prostate irradiation., Methods: One hundred radiotherapy plans were reviewed. Testicles were contoured retrospectively without dosimetric optimization on testicles., Results: The median testicular dose was 0.58 Gy: 0.18 Gy in stereotactic plans, 0.62 Gy in Volumetric Modulated Arc Therapy plans and 1.50 Gy in Tomotherapy plans (p < 0.001). Pelvic nodal irradiation increased the median testicular dose to 1.18 Gy versus 0.26 Gy without nodal irradiation (p < 0.001). Weight and BMI were inversely associated with testicular dose (p < 0.005). 65% of patients reached the theoretical dose threshold for transient azoospermia, and 10% received more than 2 Gy, likely causing definitive azoospermia., Conclusion: Despite being probably lower than doses from older techniques, the testicular dose delivered with modern prostate radiotherapy is not negligible and is often underestimated because the contribution of daily repositioning imaging is not taken into account and most Treatment Planning Systems underestimate the out of field dose. Radiation oncologists should consider the impact on fertility and gonadal endocrine function, counseling men on sperm preservation if they wish to maintain fertility., Trial Registration: retrospectively registered., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
16. [Dosimetric impact of hydrogel spacer use for stereotactic body radiotherapy of localised prostate cancer].
- Author
-
Ung M, Bossi A, Abbassi L, Vautier J, Anthonipillai V, Chevé M, and Blanchard P
- Subjects
- Aged, Aged, 80 and over, Anesthesia, Local, Feasibility Studies, Humans, Male, Middle Aged, Organs at Risk radiation effects, Prostatic Neoplasms pathology, Radiosurgery adverse effects, Radiotherapy Dosage, Retrospective Studies, Statistics, Nonparametric, Urinary Bladder radiation effects, Hydrogels administration & dosage, Prostatic Neoplasms radiotherapy, Radiation Injuries prevention & control, Radiosurgery methods, Rectum radiation effects
- Abstract
Purpose: Stereotactic body radiotherapy (SBRT) of prostate cancer is associated with rectal toxicities, which can be reduced by using a hydrogel spacer. The object of this retrospective study was to show the feasibility of spacer placement under local anesthesia and utility of hydrogel spacer to reduce the dose to the rectal wall., Material and Methods: We collected data from all patients with localised prostate cancer treated with SBRT (40Gy in 5 fractions) between 2018 and 2020. A hydrogel spacer (SpaceOAR®) was placed depending on the availability of the product. We collected dosimetric data for target volumes and organs at risk. We calculated mean values, which were compared using non-parametric tests., Results: Among 35 patients, mean age was 75 years. Seventeen had a spacer placed, with a mean space created of 10mm. No complication was reported during the intervention. High doses to the rectal wall were significantly lower in spacer group (V38: 0.39 cm
3 vs. 0.72 cm3 ; P=0.02). PTV were better covered in spacer group (P=0.07). Doses to the bladder wall were similar in both groups., Conclusion: Spacer procedure under local anesthesia was well tolerated. Hydrogel spacer allowed to reduce doses to the rectum while improving PTV coverage., (Copyright © 2020 Société française de radiothérapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.)- Published
- 2021
- Full Text
- View/download PDF
17. Automatic Intracranial Segmentation: Is the Clinician Still Needed?
- Author
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Meillan N, Bibault JE, Vautier J, Daveau-Bergerault C, Kreps S, Tournat H, Durdux C, and Giraud P
- Subjects
- Adult, Aged, Aged, 80 and over, Algorithms, Female, Humans, Imaging, Three-Dimensional methods, Male, Middle Aged, Organs at Risk, Radiosurgery methods, Software, Brain Neoplasms pathology, Brain Neoplasms radiotherapy, Image Processing, Computer-Assisted methods, Magnetic Resonance Imaging methods, Radiotherapy Planning, Computer-Assisted methods, Tomography, X-Ray Computed methods
- Abstract
Introduction: Stereotactic hypofractionated radiotherapy is an effective treatment for brain metastases in oligometastatic patients. Its planning is however time-consuming because of the number of organs at risk to be manually segmented. This study evaluates 2 automated segmentation commercial software., Methods: Patients were scanned in the treatment position. The computed tomography scan was registered on a magnetic resonance imaging and volumes were manually segmented by a clinician. Then 2 automated segmentations were performed (with iPlan and Smart Segmentation). RT STRUCT files were compared with Aquilab's Artistruct segment comparison module. We selected common segmented volume ratio as the main judging criterion. Secondary criteria were Dice-Sørensen coefficients, overlap ratio, and additional segmented volume., Results: Twenty consecutive patients were included. Agreement between manual and automated contouring was poor. Common segmented volumes ranged from 7.71% to 82.54%, Dice-Sørensen coefficient ranged from 0.0745 to 0.8398, overlap ratio ranged from 0.0414 to 0.7275, and additional segmented volume ranged from 9.80% to 92.25%. Each software outperformed the other on some organs while performing worse on others., Conclusion: No software seemed clearly better than the other. Common segmented volumes were much too low for routine use in stereotactic hypofractionated brain radiotherapy. Manual editing is still needed.
- Published
- 2018
- Full Text
- View/download PDF
18. Radial multigradient-echo DCE-MRI for 3D K(trans) mapping with individual arterial input function measurement in mouse tumor models.
- Author
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Vautier J, El Tannir El Tayara N, Walczak C, Mispelter J, and Volk A
- Subjects
- Animals, Arteries, Female, Heart Neoplasms blood supply, Mammary Neoplasms, Experimental blood supply, Mice, Pilot Projects, Magnetic Resonance Imaging, Cine methods, Neoplasms, Experimental blood supply
- Abstract
The purpose of this study was to provide proof of concept for a new three-dimensional (3D) radial dynamic contrast enhanced MRI acquisition technique, called "Radial Entire Tumor with Individual Arterial input function dynamic contrast-enhanced MRI" (RETIA dynamic contrast-enhanced MRI), which allows for the simultaneous measurement of an arterial input function in the mouse heart at 2 s temporal resolution and coverage of the whole tumor. Alternating 2D and 3D projections contribute to the 2D heart image or 3D tumor data with a 3-cm field of view. Sixty-four 2D images of the heart are obtained during acquisition of each 3D tumor dataset. In a pilot study, global K(trans) and ve values were measured in four mice, in a respiratory motion-animated subcutaneously implanted breast tumor model. This technique is expected to be most useful for the characterization of microvasculature in motion-animated orthotopic tumors., (Copyright © 2012 Wiley Periodicals, Inc.)
- Published
- 2013
- Full Text
- View/download PDF
19. T2*-relaxivity contrast imaging: first results.
- Author
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Sourbron S, Heilmann M, Walczak C, Vautier J, Schad LR, and Volk A
- Subjects
- Algorithms, Animals, Cell Line, Tumor, Computer Simulation, Contrast Media pharmacokinetics, Image Enhancement methods, Mice, Mice, Nude, Pilot Projects, Reproducibility of Results, Sensitivity and Specificity, Colorectal Neoplasms diagnosis, Colorectal Neoplasms metabolism, Heterocyclic Compounds pharmacokinetics, Image Interpretation, Computer-Assisted methods, Magnetic Resonance Imaging methods, Models, Biological, Organometallic Compounds pharmacokinetics
- Abstract
In this study, T2*- relaxivity contrast imaging (RCI) is proposed for new contrast generation in MRI. The method produces images of relaxivities r*2,vasc and r*2,EES caused by susceptibility gradients across the vessel walls and cell membranes, respectively. The sensitivity to noise was assessed with a simulation study, and initial results are presented for five colorectal tumor xenografts in nude mice. Simulations show that the new relaxivity parameters are at least as accurate and precise as standard parameters such as plasma volume and interstitial volume. Mean values of both relaxivities were significantly different (r*2,vasc=10.9±2.9 mM(-1) s(-1) and r*2,EES=15.6±2.6 mM(-1) s(-1)). r*2,vasc (r=0.67) and r*2,EES (r=0.52) were weakly correlated with plasma volume and interstitial volume, respectively. Images of r*2,vasc and r*2,EES reveal a different tumor structure than plasma volume and interstitial volume maps. These results suggest that relaxivity contrast imaging is practically feasible and might offer supplementary information compared to dynamic contrast-enhanced-MRI., (Copyright © 2012 Wiley Periodicals, Inc.)
- Published
- 2013
- Full Text
- View/download PDF
20. 2D and 3D radial multi-gradient-echo DCE MRI in murine tumor models with dynamic R*2-corrected R1 mapping.
- Author
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Vautier J, Heilmann M, Walczak C, Mispelter J, and Volk A
- Subjects
- Animals, Colorectal Neoplasms diagnostic imaging, Disease Models, Animal, Humans, Mice, Phantoms, Imaging, Radiography, Colorectal Neoplasms diagnosis, Contrast Media, Magnetic Resonance Imaging methods
- Abstract
Dynamic contrast-enhanced MRI is extensively studied to define and evaluate biomarkers for early assessment of vasculature-targeting therapies. In this study, two-dimensional and three-dimensional radial multi-gradient-echo techniques for dynamic R*(2)-corrected R(1) mapping based on the spoiled gradient recalled signal equation were implemented and validated at 4.7 T. The techniques were evaluated on phantoms and on a respiratory motion animated tumor model. R(1) measurements were validated with respect to a standard inversion-recovery spin-echo sequence in a four-compartment phantom covering a range of relaxation rates typically found in tumor tissue. In the range of [0.4, 3] sec(-1), R(1) differences were less than 10% for both two-dimensional and three-dimensional experiments. A dynamic contrast-enhanced MRI pilot study was performed on a colorectal tumor model subcutaneously implanted in mice at the abdominal level. Low motion sensitivity of radial acquisition allowed image recording without respiratory triggering. Three-dimensional K(trans) maps and significantly different mean K(trans) values were obtained for two contrast agents with different molecular weights. The radial multi-gradient-echo approach should be most useful for preclinical experimental conditions where the tissue of interest experiences physiologic motion, like spontaneous extracerebral tumors developed by transgenic mice, and where dynamic contrast-enhanced MRI is performed with high-relaxivity contrast agents., ((c) 2010 Wiley-Liss, Inc.)
- Published
- 2010
- Full Text
- View/download PDF
21. Bolus-tracking MRI with a simultaneous T1- and T2*-measurement.
- Author
-
Sourbron S, Heilmann M, Biffar A, Walczak C, Vautier J, Volk A, and Peller M
- Subjects
- Algorithms, Animals, Cell Line, Tumor, Computer Simulation, Humans, Image Enhancement methods, Mice, Mice, Nude, Models, Biological, Reproducibility of Results, Sensitivity and Specificity, Colorectal Neoplasms diagnosis, Colorectal Neoplasms metabolism, Contrast Media pharmacokinetics, Diffusion Magnetic Resonance Imaging methods, Image Interpretation, Computer-Assisted methods, Meglumine pharmacokinetics, Organometallic Compounds pharmacokinetics
- Abstract
The aim of this study was to propose and evaluate a methodology to analyze simultaneously acquired T2*-weighted dynamic susceptibility contrast (DSC) MRI and T(1)-weighted dynamic contrast enhanced (DCE) MRI data. Two generalized models of T2*-relaxation are proposed to account for tracer leakage, and a two-compartment exchange model is used to separate tracer in intra- and extravascular spaces. The methods are evaluated using data extracted from ROIs in three mice with subcutaneously implanted human colorectal tumors. Comparing plasma flow values obtained from DCE-MRI and DSC-MRI data defines a practical experimental paradigm to measure T2*-relaxivities, and reveals a factor of 15 between values in tissue and blood. Comparing mean transit time values obtained from DCE-MRI and DSC-MRI without leakage correction, indicates a significant reduction of susceptibility weighting in DSC-MRI during tracer leakage. A one-parameter gradient correction model provides a good approximation for this susceptibility loss, but redundancy of the parameter limits the practical potential of this model for DSC-MRI. Susceptibility loss is modeled more accurately with a variable T2*-relaxivity, which allows to extract new parameters that cannot be derived from DSC-MRI or DCE-MRI alone. They reflect the cellular and vessel geometry, and thus may lead to a more complete characterization of tissue structure.
- Published
- 2009
- Full Text
- View/download PDF
22. In vitro setup to study permeability characteristics of contrast agents by MRI.
- Author
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Heilmann M, Vautier J, Robert P, and Volk A
- Subjects
- Models, Molecular, Permeability, Contrast Media chemistry, Magnetic Resonance Imaging methods
- Abstract
An experimental setup consisting of a hollow fiber module (HFM) was developed for the in vitro study of contrast agent (CA) permeability. Controllable flow and known fiber characteristics allowed permeability studies under well-defined conditions with CAs of different molecular weight (MW). In the MRI experiments performed at 4.7 T, the system was perfused at a constant flow rate (5 ml/min) with water and four CA of different MW: Gd-DOTA (MW=0.6 kDa), P846 (3.5 kDa), P792 (6.5 kDa) and P717 (50.5 kDa). R(1) time courses were measured with a saturation-recovery multi-gradient-echo snapshot sequence in the fiber-free HFM input and the fiber-filled center. Concentration time courses were calculated, and CA extravasation was analyzed with a pharmacokinetic model yielding exchange rate constant k(ie). Only Gd-DOTA (k(ie)=2.37+/-0.16 min(-1)) and P846 (k(ie)=0.58+/-0.17 min(-1)) showed quantifiable extravasation. P717 perfusion yielded an intra-capillary volume fraction of 15.6+/-2.7% compared with 12% estimated from the HFM manufacturer's specifications. In conclusion, the experimental setup allowed classification of in vitro permeability characteristics for CAs with different MW and therefore holds potential for systematic comparison of CAs currently under development.
- Published
- 2009
- Full Text
- View/download PDF
23. Simultaneous dynamic T1 and T2* measurement for AIF assessment combined with DCE MRI in a mouse tumor model.
- Author
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Heilmann M, Walczak C, Vautier J, Dimicoli JL, Thomas CD, Lupu M, Mispelter J, and Volk A
- Subjects
- Animals, Disease Models, Animal, Heart anatomy & histology, Humans, Mice, Mice, Nude, Myocardium pathology, Necrosis, Colorectal Neoplasms pathology, Magnetic Resonance Imaging methods
- Abstract
A double-delay SR-MGE-SNAP sequence allowing simultaneous T1 and T2* measurement was developed for integrating arterial input function (AIF) measurement into DCE MRI. Implemented on a 4.7-T animal MR system, this technique was applied to mice with colorectal tumor xenografts. AIF, measured in the mouse heart, was modeled by a bi-exponential function, whereas tumor K(trans) and v(e) parameter maps were obtained from analysis with a two- compartment model using an individually measured AIF. AIF analysis of T2*-corrected data yielded A1 = 9.2 +/- 4.3 kg/l, A(2) = 4.2 +/- 0.8 kg/l, m1 = 2.3 +/- 1.1 min(-1), and m2 = 0.05 +/- 0.02 min(-1). The mean initial plasma concentration C ( p )(t = 0) = 8.0 +/- 2.7 mM was compatible with estimated 8.6 mM. Without T2*-correction distribution phase parameters A1, m1, and C(p)(t = 0) were underestimated. In tumors, neglect of T2* effects yielded mean K(trans) values which were reduced by 14% (P < 0.05), whereas v(e) showed only a slight non-significant reduction. Simultaneous measurement of DeltaR1 and DeltaR2* studied in highly and poorly vascularized and (pre-)necrotic tumor regions revealed complementary behavior of both parameters with respect to vascular properties. In conclusion, the presented measurement technique is a promising tool for dynamic MRI applications studied in animal models at high field strengths and/or with CA of high relaxivities, as it combines classical DCE MRI integrating AIF assessment with dynamic T2* measurement.
- Published
- 2007
- Full Text
- View/download PDF
24. [Functioning of a sheltered apartment and role of the nursing team].
- Author
-
Diligent MB, Vautier J, Mazur E, and Heip L
- Subjects
- Adult, Chronic Disease, Female, France, Humans, Male, Mental Disorders rehabilitation, Patient Care Team, Mental Disorders nursing, Residential Facilities
- Published
- 1985
25. Vesiculo-edematous arsenical erythroderma cured by sulfamidotherapy.
- Author
-
GRAS L and VAUTIER J
- Subjects
- Humans, Arsenic toxicity, Arsenic Poisoning, Dermatitis, Exfoliative therapy
- Published
- 1946
26. [The spleen in Besnier-Boeck-Schaumann disease].
- Author
-
DUPERRAT B and VAUTIER J
- Subjects
- Sarcoidosis, Spleen
- Published
- 1952
27. Retraction of a cavity ballooned by intravenous injections of atropine during a pneumothorax complicated by pleurisy.
- Author
-
GRAS L and VAUTIER J
- Subjects
- Atropine therapy, Pneumothorax, Artificial, Tuberculosis, Tuberculosis, Pulmonary
- Published
- 1945
28. Arsenical vesicular-edematous erythroderma cured by sulfamidotherapy.
- Author
-
GRAS L and VAUTIER J
- Subjects
- Arsenic toxicity, Arsenic Poisoning
- Published
- 1946
29. Acute rheumatic peritonitis.
- Author
-
GRAS L and VAUTIER J
- Subjects
- Humans, Peritonitis etiology, Rheumatic Diseases complications, Rheumatic Fever complications
- Published
- 1946
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