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Chrit T. W. Moonen - One of the best experts on this subject based on the ideXlab platform.
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Quantitative magnetic resonance Temperature Mapping for real-time monitoring of radiofrequency ablation of the liver: an ex vivo study.
European radiology, 2006Co-Authors: Olivier Seror, Bruno Quesson, Hervé Trillaud, Matthieu Lepetit-coiffé, Chrit T. W. MoonenAbstract:We evaluated the feasibility and accuracy of real-time magnetic resonance (MR) thermometry for monitoring radiofrequency (RF) ablation in the liver. Continuous MR Temperature Mapping was used to monitor bipolar RF ablations performed in ex vivo livers with and without flow using two parallel electrodes. Macroscopic inspection of ablation zones was compared with thermal dose maps (TDm) and T1-weighted inversion recovery turbo spin echo (IR-TSE) images for their size and shape and the influence of flow. Pearson’s correlation (r), Bland and Altman tests and kappa (χK) tests were performed. The mean differences in ablation zone size between macroscopic and TDm and IR-TSE measurements were +4 mm and −2 mm, respectively. TDm was well correlated with macroscopy (r=0.77 versus r=0.44 for IR-TSE). TDm was found to be more precise for shape recognition (χK=0.73 versus χK=0.55 for IR-TSE) and for detection of an intact ring of liver due to the cooling effect of flow which was impossible with IR-TSE. Simultaneous monitoring of RF ablation by MR thermometry is feasible and reliable for predicting the shape of ablation zones and the impact of the heat-sink effect of flow. Further studies are needed to confirm these results in vivo.
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ICIP (3) - 3D motion estimation for on-line MR Temperature Mapping
IEEE International Conference on Image Processing 2005, 2005Co-Authors: B. D. De Senneville, Pascal Desbarats, Bruno Quesson, Chrit T. W. MoonenAbstract:Magnetic resonance (MR) Temperature Mapping can be used to monitor Temperature changes during minimally invasive thermal therapies during the procedure. Robust 3D estimation of organ displacement during the intervention is hardly feasible due to technical limitations (spatial and temporal resolution are not sufficient to perform classic 3D registration methods on anatomical images). However, organ displacements due to physiological activity (heart and respiration) may induce important artifacts on apparent Temperature maps and prevent the treatment of a tumor with an external heating device. Recent development has allowed increasing external information for 3D motion estimation. This paper presents a new method that exploits image information for robust 3D motion estimation from MR images, in order to make possible the treatment of organs such as the kidney, and to improve the precision of Temperature estimation using the proton resonance frequency (PRF) shift. The motion estimation described in this paper consists of two steps: a reference volume is initially computed in a preparation phase; during the intervention a 3D displacement vector is estimated on-line for each pixel of the acquired images by using this reference volume. This method can be applied to any type of image sequences and thus is not restricted to MR images.
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Intraluminal ultrasound applicator compatible with magnetic resonance imaging "real-time" Temperature Mapping for the treatment of oesophageal tumours: an ex vivo study.
Medical physics, 2004Co-Authors: David Melodelima, Chrit T. W. Moonen, R. Salomir, Charles Mougenot, Frédéric Prat, Y. Theillere, Dominique CathignolAbstract:High intensity ultrasound has shown considerable ability to produce precise and deep thermal coagulation necrosis. Focused, cylindrical, spherical or plane transducers have been used to induce high Temperatures in tissues to coagulate proteins and kill cells. Recently magnetic resonance imaging(MRI) has been used, with extracorporeal or intracavitary focused transducers and cylindrical interstitial applicators, to monitor Temperature distribution and provide feedback during heating procedures. If intraluminal applicators are used, the active part is in contact with the region of interest and it is essential to provide an accurate view of heat deposition and the extent of coagulation necrosis close to the transducer. The purpose of this study was to develop a 10 mm diameter intraluminal ultrasound applicator, designed to treat oesophageal cancers and compatible with MRI “real-time” Temperature Mapping. The active part of the ultrasound applicator, covered by a latex balloon, is a 15×8 mm 2 plane transducer, which is in contact with the tumours during treatment. Each ultrasound exposure generates coagulation necrosis, in an area with the approximate shape of a rectangular parallelepiped up to 10 mm deep. When the exposures were repeated by rotating the applicator on its axis, sector-based or cylindrical volumes of necrosis could be produced, matching the shape of oesophageal cancers.Ex vivo trials were performed to demonstrate the applicator’s compatibility with a clinical MRI scanner (1.5 T). MRI signals were acquired without any magnetic susceptibility distortion, even close to the applicator. Fast (0.72 images per second) 2D Temperature Mapping was performed during ultrasound exposure, using Temperature-related proton resonance frequency shift at a resolution of 0.5 ° C . Coagulation necrosis viewed with inversion recovery sequences, were in good agreement with the qualitative macroscopic observations made for the few cases tested in this study.
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real time mr Temperature Mapping of rabbit liver in vivo during thermal ablation
Magnetic Resonance in Medicine, 2003Co-Authors: Claudia Weidensteiner, Bruno Quesson, Noureddine Kerioui, Hervé Trillaud, Benedicte Cairegana, Anne Rullier, Chrit T. W. MoonenAbstract:It has been shown that quantitative MRI thermometry using the proton resonance frequency (PRF) method can be used to noninvasively monitor the evolution of tissue Temperature, and to guide minimally-invasive tumor ablation based on local hyperthermia. Although hepatic tumors are among the main targets for thermal ablation, PRF-based Temperature MRI of the liver is difficult to perform because of motion artifacts, fat content, and low T. In this study the stability of real-time thermometry was tested on a clinical 1.5 T scanner for rabbit liver in vivo. The fast segmented EPI principle was used together with respiratory gating to limit respiratory motion artifacts. Lipid signal suppression was achieved with a binomial excitation pulse. Saturation slabs were applied to suppress artifacts due to flowing blood. The respiratory-gated MR thermometry in the rabbit liver in vivo showed a standard deviation (SD) of 1–3°C with a temporal resolution of 3 s per slice and 1.4 mm × 1.9 mm spatial resolution in plane (slice thickness = 5 mm). The method was used to guide thermal ablation experiments with a clinical infrared laser. The estimated size of the necrotic area, based on the thermal dose calculated from MR Temperature maps, corresponded well with the actual lesion size determined by histology and conventional MR images obtained 5 days posttreatment. These results show that quantitative MR Temperature Mapping can be obtained in the liver in vivo, and can be used for real-time control of thermal ablation and for lesion size prediction. Magn Reson Med 50:322–330, 2003. © 2003 Wiley-Liss, Inc.
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WSCG - Real-Time Artefact Corrections For Quantitative MR Temperature Mapping
2003Co-Authors: Baudouin Denis De Senneville, Pascal Desbarats, Bruno Quesson, Chrit T. W. MoonenAbstract:Apart from anatomical and physiological imaging, MRI can also be used to produce Temperature maps. Our objective is to obtain such maps in real-time to monitor mini-invasive thermal therapies. The acquisition procedure of Temperature MRI produces specific artefacts : noise generated by MRI, motion artefacts and geometric distortions. Here, numerical methods are described for attenuation of such artefacts. The methods are based on a physical description of the origin of such artefacts in MR Temperature Mapping.
Christian Bergaud - One of the best experts on this subject based on the ideXlab platform.
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Unprecedented switching endurance affords for high-resolution surface Temperature Mapping using a spin-crossover film.
Nature communications, 2020Co-Authors: Karl Ridier, Christian Bergaud, Alin-ciprian Bas, Yuteng Zhang, Lucie Routaboul, Lionel Salmon, Gábor Molnár, Azzedine BousseksouAbstract:Temperature measurement at the nanoscale is of paramount importance in the fields of nanoscience and nanotechnology, and calls for the development of versatile, high-resolution thermometry techniques. Here, the working principle and quantitative performance of a cost-effective nanothermometer are experimentally demonstrated, using a molecular spin-crossover thin film as a surface Temperature sensor, probed optically. We evidence highly reliable thermometric performance (diffraction-limited sub-µm spatial, µs temporal and 1 °C thermal resolution), which stems to a large extent from the unprecedented quality of the vacuum-deposited thin films of the molecular complex [Fe(HB(1,2,4-triazol-1-yl)3)2] used in this work, in terms of fabrication and switching endurance (>107 thermal cycles in ambient air). As such, our results not only afford for a fully-fledged nanothermometry method, but set also a forthcoming stage in spin-crossover research, which has awaited, since the visionary ideas of Olivier Kahn in the 90’s, a real-world, technological application. Developing novel thermometry techniques for nanoscale Temperature measurements are vital for realizing efficient thermal management of nanoscale devices. Here, the authors report thermally stable spin-crossover material-based nanothermometers for high-resolution surface Temperature Mapping.
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high spatial resolution surface Temperature Mapping using fluorescent thermometry
Small, 2008Co-Authors: Peter Löw, Beomjoon Kim, Nobuyuki Takama, Christian BergaudAbstract:The characterization of Temperature and thermal properties is of particular importance in micro- and nanotechnology. Considering the highly increased density of structures and the increased power dissipation per unit area associated with miniaturization, good thermal design is of great importance for device reliability and performance. Locating hot spots, for example, on a microelectronic circuit, can be of great value in evaluating a design, optimizing the performance, and performing failure analysis. [1,2] Apart from the industrial applications of micro- and nanoscale thermometry, fundamental questions of the thermal behavior, for example, thermal transfer at a scale comparable to the phonon wavelength, [3] could be more effectively addressed with improved characterization tools. The common approach for Mapping Temperature on the microscale is based on infrared microscopy, which relies on the analysis of the thermal radiation that is emitted from any material. IR microscopy is a well-established technique and can be used with relative ease for Temperature Mapping on large scales. However, the technique suffers from a diffractionlimited resolution, giving it an optimal spatial resolution of around 5 mm. [2,4,5] Nanoscale scientists typically use scanning thermal microscopy (SThM) for high-resolution measurements. Since the invention of the scanning probe microscope at the beginning of the 1980s, [6] several scanning probes for thermal characterization have been developed. The thermal probes used are generally based on either thermocouple or thermistor elements. [7–11] Other approaches have proposed bimaterial cantilevers or fluorescent particles as Temperaturesensing probes. [12–14] The highest spatial resolution obtained
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High‐Spatial‐Resolution Surface‐Temperature Mapping Using Fluorescent Thermometry
Small (Weinheim an der Bergstrasse Germany), 2008Co-Authors: Peter Löw, Beomjoon Kim, Nobuyuki Takama, Christian BergaudAbstract:The characterization of Temperature and thermal properties is of particular importance in micro- and nanotechnology. Considering the highly increased density of structures and the increased power dissipation per unit area associated with miniaturization, good thermal design is of great importance for device reliability and performance. Locating hot spots, for example, on a microelectronic circuit, can be of great value in evaluating a design, optimizing the performance, and performing failure analysis. [1,2] Apart from the industrial applications of micro- and nanoscale thermometry, fundamental questions of the thermal behavior, for example, thermal transfer at a scale comparable to the phonon wavelength, [3] could be more effectively addressed with improved characterization tools. The common approach for Mapping Temperature on the microscale is based on infrared microscopy, which relies on the analysis of the thermal radiation that is emitted from any material. IR microscopy is a well-established technique and can be used with relative ease for Temperature Mapping on large scales. However, the technique suffers from a diffractionlimited resolution, giving it an optimal spatial resolution of around 5 mm. [2,4,5] Nanoscale scientists typically use scanning thermal microscopy (SThM) for high-resolution measurements. Since the invention of the scanning probe microscope at the beginning of the 1980s, [6] several scanning probes for thermal characterization have been developed. The thermal probes used are generally based on either thermocouple or thermistor elements. [7–11] Other approaches have proposed bimaterial cantilevers or fluorescent particles as Temperaturesensing probes. [12–14] The highest spatial resolution obtained
Dominique Cathignol - One of the best experts on this subject based on the ideXlab platform.
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In Vivo Experiments with Intraluminal Ultrasound Applicator Compatible with “Real‐Time” MR Temperature Mapping, designed for Oesophagus Tumour Ablation
AIP Conference Proceedings, 2005Co-Authors: David Melodelima, R. Salomir, Charles Mougenot, Y. Theillere, C. W. Moonen, Dominique CathignolAbstract:High intensity ultrasound has shown considerable ability to produce precise and deep thermal coagulation necrosis. Focused, cylindrical, spherical or plane transducers have been used to induce high Temperature elevation in tissues, in order to coagulate proteins and kill cells. Magnetic Resonance Imaging (MRI) has been used, with focused transducers and cylindrical interstitial applicators, to monitor Temperature distribution and provide Temperature feedback control during heating procedures. The active part of intraluminal applicators is positioned very close to the target region. It is therefore essential to provide accurate monitoring of heat deposition in the tissue layer near the transducer, in order to control the extension of coagulation necrosis. The purpose of this study was to develop a 10‐mm diameter intraluminal ultrasound applicator, designed to treat oesophageal cancers and compatible with “real‐time” MR Temperature Mapping. The ultrasound applicator was tested in vivo under real time, PRF b...
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Intraluminal ultrasound applicator compatible with magnetic resonance imaging "real-time" Temperature Mapping for the treatment of oesophageal tumours: an ex vivo study.
Medical physics, 2004Co-Authors: David Melodelima, Chrit T. W. Moonen, R. Salomir, Charles Mougenot, Frédéric Prat, Y. Theillere, Dominique CathignolAbstract:High intensity ultrasound has shown considerable ability to produce precise and deep thermal coagulation necrosis. Focused, cylindrical, spherical or plane transducers have been used to induce high Temperatures in tissues to coagulate proteins and kill cells. Recently magnetic resonance imaging(MRI) has been used, with extracorporeal or intracavitary focused transducers and cylindrical interstitial applicators, to monitor Temperature distribution and provide feedback during heating procedures. If intraluminal applicators are used, the active part is in contact with the region of interest and it is essential to provide an accurate view of heat deposition and the extent of coagulation necrosis close to the transducer. The purpose of this study was to develop a 10 mm diameter intraluminal ultrasound applicator, designed to treat oesophageal cancers and compatible with MRI “real-time” Temperature Mapping. The active part of the ultrasound applicator, covered by a latex balloon, is a 15×8 mm 2 plane transducer, which is in contact with the tumours during treatment. Each ultrasound exposure generates coagulation necrosis, in an area with the approximate shape of a rectangular parallelepiped up to 10 mm deep. When the exposures were repeated by rotating the applicator on its axis, sector-based or cylindrical volumes of necrosis could be produced, matching the shape of oesophageal cancers.Ex vivo trials were performed to demonstrate the applicator’s compatibility with a clinical MRI scanner (1.5 T). MRI signals were acquired without any magnetic susceptibility distortion, even close to the applicator. Fast (0.72 images per second) 2D Temperature Mapping was performed during ultrasound exposure, using Temperature-related proton resonance frequency shift at a resolution of 0.5 ° C . Coagulation necrosis viewed with inversion recovery sequences, were in good agreement with the qualitative macroscopic observations made for the few cases tested in this study.
Bruno Quesson - One of the best experts on this subject based on the ideXlab platform.
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Quantitative magnetic resonance Temperature Mapping for real-time monitoring of radiofrequency ablation of the liver: an ex vivo study.
European radiology, 2006Co-Authors: Olivier Seror, Bruno Quesson, Hervé Trillaud, Matthieu Lepetit-coiffé, Chrit T. W. MoonenAbstract:We evaluated the feasibility and accuracy of real-time magnetic resonance (MR) thermometry for monitoring radiofrequency (RF) ablation in the liver. Continuous MR Temperature Mapping was used to monitor bipolar RF ablations performed in ex vivo livers with and without flow using two parallel electrodes. Macroscopic inspection of ablation zones was compared with thermal dose maps (TDm) and T1-weighted inversion recovery turbo spin echo (IR-TSE) images for their size and shape and the influence of flow. Pearson’s correlation (r), Bland and Altman tests and kappa (χK) tests were performed. The mean differences in ablation zone size between macroscopic and TDm and IR-TSE measurements were +4 mm and −2 mm, respectively. TDm was well correlated with macroscopy (r=0.77 versus r=0.44 for IR-TSE). TDm was found to be more precise for shape recognition (χK=0.73 versus χK=0.55 for IR-TSE) and for detection of an intact ring of liver due to the cooling effect of flow which was impossible with IR-TSE. Simultaneous monitoring of RF ablation by MR thermometry is feasible and reliable for predicting the shape of ablation zones and the impact of the heat-sink effect of flow. Further studies are needed to confirm these results in vivo.
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ICIP (3) - 3D motion estimation for on-line MR Temperature Mapping
IEEE International Conference on Image Processing 2005, 2005Co-Authors: B. D. De Senneville, Pascal Desbarats, Bruno Quesson, Chrit T. W. MoonenAbstract:Magnetic resonance (MR) Temperature Mapping can be used to monitor Temperature changes during minimally invasive thermal therapies during the procedure. Robust 3D estimation of organ displacement during the intervention is hardly feasible due to technical limitations (spatial and temporal resolution are not sufficient to perform classic 3D registration methods on anatomical images). However, organ displacements due to physiological activity (heart and respiration) may induce important artifacts on apparent Temperature maps and prevent the treatment of a tumor with an external heating device. Recent development has allowed increasing external information for 3D motion estimation. This paper presents a new method that exploits image information for robust 3D motion estimation from MR images, in order to make possible the treatment of organs such as the kidney, and to improve the precision of Temperature estimation using the proton resonance frequency (PRF) shift. The motion estimation described in this paper consists of two steps: a reference volume is initially computed in a preparation phase; during the intervention a 3D displacement vector is estimated on-line for each pixel of the acquired images by using this reference volume. This method can be applied to any type of image sequences and thus is not restricted to MR images.
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Stability of real-time MR Temperature Mapping in healthy and diseased human liver
Journal of Magnetic Resonance Imaging, 2004Co-Authors: Claudia Weidensteiner, Bruno Quesson, Noureddine Kerioui, Baudouin Denis De Senneville, Hervé Trillaud, Chrit MoonenAbstract:Purpose: To determine the stability and quality of MR Temperature Mapping using the proton resonance frequency (PRF) method in the liver of hepatic tumor patients. Material and Methods: The standard deviation of a series of Temperature maps was determined in 30 patients (21 cirrhotic livers with carcinoma, 9 non-cirrhotic livers with metastasis or angioma) and in 5 volunteers at normal body Temperature under free breathing. A respiratory-gated segmented EPI sequence (3 slices in 1 expiration phase) was performed with SENSE acceleration on a 1.5 T scanner. Motion corrupted images were identified by calculation of the cross-correlation coefficient and discarded. Results: A T 2* range of 10-33 ms was found with especially low values in advanced cirrhotic livers. The mean Temperature standard deviation in patients was 2.3°C (range 1.5-5.0°C). The stability in healthy livers was slightly better than that in cirrhotic livers, and it was higher in the right than in the left liver. The gaiting failed in 4 % of the images when the respiratory cycle was irregular, leading to motion artifacts and errors in the Temperature maps. Conclusion: The achieved Temperature stability and image quality makes real-time quantitative monitoring of thermal ablation of liver tumors feasible on a clinical scanner.
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real time mr Temperature Mapping of rabbit liver in vivo during thermal ablation
Magnetic Resonance in Medicine, 2003Co-Authors: Claudia Weidensteiner, Bruno Quesson, Noureddine Kerioui, Hervé Trillaud, Benedicte Cairegana, Anne Rullier, Chrit T. W. MoonenAbstract:It has been shown that quantitative MRI thermometry using the proton resonance frequency (PRF) method can be used to noninvasively monitor the evolution of tissue Temperature, and to guide minimally-invasive tumor ablation based on local hyperthermia. Although hepatic tumors are among the main targets for thermal ablation, PRF-based Temperature MRI of the liver is difficult to perform because of motion artifacts, fat content, and low T. In this study the stability of real-time thermometry was tested on a clinical 1.5 T scanner for rabbit liver in vivo. The fast segmented EPI principle was used together with respiratory gating to limit respiratory motion artifacts. Lipid signal suppression was achieved with a binomial excitation pulse. Saturation slabs were applied to suppress artifacts due to flowing blood. The respiratory-gated MR thermometry in the rabbit liver in vivo showed a standard deviation (SD) of 1–3°C with a temporal resolution of 3 s per slice and 1.4 mm × 1.9 mm spatial resolution in plane (slice thickness = 5 mm). The method was used to guide thermal ablation experiments with a clinical infrared laser. The estimated size of the necrotic area, based on the thermal dose calculated from MR Temperature maps, corresponded well with the actual lesion size determined by histology and conventional MR images obtained 5 days posttreatment. These results show that quantitative MR Temperature Mapping can be obtained in the liver in vivo, and can be used for real-time control of thermal ablation and for lesion size prediction. Magn Reson Med 50:322–330, 2003. © 2003 Wiley-Liss, Inc.
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WSCG - Real-Time Artefact Corrections For Quantitative MR Temperature Mapping
2003Co-Authors: Baudouin Denis De Senneville, Pascal Desbarats, Bruno Quesson, Chrit T. W. MoonenAbstract:Apart from anatomical and physiological imaging, MRI can also be used to produce Temperature maps. Our objective is to obtain such maps in real-time to monitor mini-invasive thermal therapies. The acquisition procedure of Temperature MRI produces specific artefacts : noise generated by MRI, motion artefacts and geometric distortions. Here, numerical methods are described for attenuation of such artefacts. The methods are based on a physical description of the origin of such artefacts in MR Temperature Mapping.
Hervé Trillaud - One of the best experts on this subject based on the ideXlab platform.
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Quantitative magnetic resonance Temperature Mapping for real-time monitoring of radiofrequency ablation of the liver: an ex vivo study.
European radiology, 2006Co-Authors: Olivier Seror, Bruno Quesson, Hervé Trillaud, Matthieu Lepetit-coiffé, Chrit T. W. MoonenAbstract:We evaluated the feasibility and accuracy of real-time magnetic resonance (MR) thermometry for monitoring radiofrequency (RF) ablation in the liver. Continuous MR Temperature Mapping was used to monitor bipolar RF ablations performed in ex vivo livers with and without flow using two parallel electrodes. Macroscopic inspection of ablation zones was compared with thermal dose maps (TDm) and T1-weighted inversion recovery turbo spin echo (IR-TSE) images for their size and shape and the influence of flow. Pearson’s correlation (r), Bland and Altman tests and kappa (χK) tests were performed. The mean differences in ablation zone size between macroscopic and TDm and IR-TSE measurements were +4 mm and −2 mm, respectively. TDm was well correlated with macroscopy (r=0.77 versus r=0.44 for IR-TSE). TDm was found to be more precise for shape recognition (χK=0.73 versus χK=0.55 for IR-TSE) and for detection of an intact ring of liver due to the cooling effect of flow which was impossible with IR-TSE. Simultaneous monitoring of RF ablation by MR thermometry is feasible and reliable for predicting the shape of ablation zones and the impact of the heat-sink effect of flow. Further studies are needed to confirm these results in vivo.
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Stability of real-time MR Temperature Mapping in healthy and diseased human liver
Journal of Magnetic Resonance Imaging, 2004Co-Authors: Claudia Weidensteiner, Bruno Quesson, Noureddine Kerioui, Baudouin Denis De Senneville, Hervé Trillaud, Chrit MoonenAbstract:Purpose: To determine the stability and quality of MR Temperature Mapping using the proton resonance frequency (PRF) method in the liver of hepatic tumor patients. Material and Methods: The standard deviation of a series of Temperature maps was determined in 30 patients (21 cirrhotic livers with carcinoma, 9 non-cirrhotic livers with metastasis or angioma) and in 5 volunteers at normal body Temperature under free breathing. A respiratory-gated segmented EPI sequence (3 slices in 1 expiration phase) was performed with SENSE acceleration on a 1.5 T scanner. Motion corrupted images were identified by calculation of the cross-correlation coefficient and discarded. Results: A T 2* range of 10-33 ms was found with especially low values in advanced cirrhotic livers. The mean Temperature standard deviation in patients was 2.3°C (range 1.5-5.0°C). The stability in healthy livers was slightly better than that in cirrhotic livers, and it was higher in the right than in the left liver. The gaiting failed in 4 % of the images when the respiratory cycle was irregular, leading to motion artifacts and errors in the Temperature maps. Conclusion: The achieved Temperature stability and image quality makes real-time quantitative monitoring of thermal ablation of liver tumors feasible on a clinical scanner.
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real time mr Temperature Mapping of rabbit liver in vivo during thermal ablation
Magnetic Resonance in Medicine, 2003Co-Authors: Claudia Weidensteiner, Bruno Quesson, Noureddine Kerioui, Hervé Trillaud, Benedicte Cairegana, Anne Rullier, Chrit T. W. MoonenAbstract:It has been shown that quantitative MRI thermometry using the proton resonance frequency (PRF) method can be used to noninvasively monitor the evolution of tissue Temperature, and to guide minimally-invasive tumor ablation based on local hyperthermia. Although hepatic tumors are among the main targets for thermal ablation, PRF-based Temperature MRI of the liver is difficult to perform because of motion artifacts, fat content, and low T. In this study the stability of real-time thermometry was tested on a clinical 1.5 T scanner for rabbit liver in vivo. The fast segmented EPI principle was used together with respiratory gating to limit respiratory motion artifacts. Lipid signal suppression was achieved with a binomial excitation pulse. Saturation slabs were applied to suppress artifacts due to flowing blood. The respiratory-gated MR thermometry in the rabbit liver in vivo showed a standard deviation (SD) of 1–3°C with a temporal resolution of 3 s per slice and 1.4 mm × 1.9 mm spatial resolution in plane (slice thickness = 5 mm). The method was used to guide thermal ablation experiments with a clinical infrared laser. The estimated size of the necrotic area, based on the thermal dose calculated from MR Temperature maps, corresponded well with the actual lesion size determined by histology and conventional MR images obtained 5 days posttreatment. These results show that quantitative MR Temperature Mapping can be obtained in the liver in vivo, and can be used for real-time control of thermal ablation and for lesion size prediction. Magn Reson Med 50:322–330, 2003. © 2003 Wiley-Liss, Inc.
