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  • Journal cover
    Springer
    Online: 1.1993 –
    Publisher: Springer
    Print ISSN: 0968-5243
    Electronic ISSN: 1352-8661
    Topics: Medicine , Physics
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  • Publication Date: 2012-08-13
    Description:    PET and MRI are established clinical tools which provide complementary information, but clinical workflow limits widespread clinical application of both modalities in combination. The two modalities are usually situated in different hospital departments and operated and reported independently, and patients are referred for both scans, often consecutively. With the advent of PET/MR as a new hybrid imaging modality there is now a possibility of addressing these concerns. There are two different design philosophies for integrated PET/MR imaging—positioning PET inside the MRI magnet or in tandem, similar to PET/CT. The Ingenuity TF PET/MR by Philips Healthcare is a sequential PET/MR tomograph combining state-of-the-art time-of-flight PET and high-field MRI with parallel transmission capabilities. In this review article we describe the technology implemented in the system, for example RF and magnetic shielding, MR-based attenuation correction, peculiarities in scatter correction, MR system optimisation, and the philosophy behind its design. Furthermore, we provide an overview of how the system has been used during the last two years, and expectations of how the use of PET/MR may continue in the years to come. On the basis of these observations and experiences we discuss the utility of the system, clinical workflow and acquisition times, and possible ways of optimization. Content Type Journal Article Category Review Article Pages 1-19 DOI 10.1007/s10334-012-0330-y Authors Antonis Kalemis, Philips Healthcare, Guildford Business Park, Guildford, Surrey GU2 8XH, UK Bénédicte M. A. Delattre, Philips Healthcare, Rte des Avouillons 16, 1196 Gland, Switzerland Susanne Heinzer, Philips Healthcare, Allmendstrasse 140, 8027 Zurich, Switzerland Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-08-07
    Description:    Advances in the new-generation of ultra-high-resolution, brain-dedicated positron emission tomography-magnetic resonance imaging (PET/MRI) systems have begun to provide many interesting insights into the molecular dynamics of the brain. First, the finely delineated structural information from ultra-high-field MRI can help us to identify accurate landmark structures, thereby making it easier to locate PET activation sites that are anatomically well-correlated with metabolic or ligand-specific organs in the neural structures in the brain. This synergistic potential of PET/MRI imaging is discussed in terms of neuroscience and neurological research from both translational and basic research perspectives. Experimental results from the hippocampus, thalamus, and brainstem obtained with 18 F-fluorodeoxyglucose and 11 C-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)benzonitrile are used to demonstrate the potential of this new brain PET/MRI system. Content Type Journal Article Category Review Article Pages 1-9 DOI 10.1007/s10334-012-0329-4 Authors Zang Hee Cho, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Young Don Son, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Eun Jung Choi, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Hang Keun Kim, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Jeong Hee Kim, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Sang Yoon Lee, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Seiji Ogawa, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Young Bo Kim, Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Republic of Korea Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-05-17
    Description: Object   The nuclear magnetic resonance (NMR) mobile-universal-surface-explorer (MOUSE) was evaluated in a pilot study to determine its ability to detect physiological changes in human skin caused by physical or pharmacological interventions. Materials and methods   The left lower arm skin thicknesses of ten male subjects were measured five times using a Profile NMR-MOUSE ® ( 1 H, 19 MHz) before and after a venous occlusion manoeuvre. In five of the subjects, the T 2eff relaxation times were derived from a bi-exponential fitting and were determined in the dermis and subcutis before and after applying a salve containing capsaicin. Results   The dermis (including the epidermis) showed rather homogeneous signal amplitudes. The subcutis was characterised by higher and more variable amplitudes. The full-skin thickness values were affirmed by ultrasound imaging. The NMR profiles did not show significant skin swelling due to venous occlusion. In the dermis, capsaicin caused significant ( p  < 0.05) decreases in both components of T 2eff (100 ± 19 ms–19 ± 10 ms; 9.5 ± 0.5 ms–7.2 ± 1.6 ms). In the subcutis, the T 2eff was not affected. Conclusion   In principle, NMR-MOUSE profiles are capable of detecting skin structure. However, precise measurements are jeopardised by poor reproducibility, long acquisition times, and incompatibility between the geometries of the sensitive area of the instrument and the non-planar structure of the skin. In the dermis, T 2eff contrast could be used to detect the changes in tissue composition caused by inflammatory reactions. Content Type Journal Article Category Research Article Pages 1-12 DOI 10.1007/s10334-012-0317-8 Authors Darius Kornetka, Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt (DLR e.V.), Linder Höhe, 51147 Cologne, Germany Martin Trammer, Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt (DLR e.V.), Linder Höhe, 51147 Cologne, Germany Jochen Zange, Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt (DLR e.V.), Linder Höhe, 51147 Cologne, Germany Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-07-02
    Description: Object   An approach has been recently introduced for acquiring arbitrary 2D NMR spectra or images in a single scan, based on the use of frequency-swept RF pulses for the sequential excitation and acquisition of the spins response. This spatiotemporal-encoding ( SPEN ) approach enables a unique, voxel-by-voxel refocusing of all frequency shifts in the sample, for all instants throughout the data acquisition. The present study investigates the use of this full - refocusing aspect of SPEN - based imaging in the multi - shot MRI of objects, subject to sizable field inhomogeneities that complicate conventional imaging approaches. Materials and methods   2D MRI experiments were performed at 7 T on phantoms and on mice in vivo, focusing on imaging in proximity to metallic objects. Fully refocused SPEN-based spin echo imaging sequences were implemented, using both Cartesian and back-projection trajectories, and compared with k-space encoded spin echo imaging schemes collected on identical samples under equal bandwidths and acquisition timing conditions. Results   In all cases assayed, the fully refocused spatiotemporally encoded experiments evidenced a ca. 50 % reduction in signal dephasing in the proximity of the metal, as compared to analogous results stemming from the k-space encoded spin echo counterparts. Conclusion   The results in this study suggest that SPEN-based acquisition schemes carry the potential to overcome strong field inhomogeneities, of the kind that currently preclude high-field, high-resolution tissue characterizations in the neighborhood of metallic implants. Content Type Journal Article Category Research Article Pages 1-10 DOI 10.1007/s10334-012-0318-7 Authors Noam Ben-Eliezer, Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot, Israel Eddy Solomon, Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot, Israel Elad Harel, Chemistry Department, Northwestern University, Evanston, IL 60201, USA Nava Nevo, Biological Regulation Department, Weizmann Institute of Science, 76100 Rehovot, Israel Lucio Frydman, Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot, Israel Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-07-14
    Description: Object   Paramagnetic nanoparticles, mainly rare earth oxides and hydroxides, have been produced these last few years for use as MRI contrast agents. They could become an interesting alternative to iron oxide particles. However, their relaxation properties are not well understood. Materials and methods   Magnetometry, 1 H and 2 H NMR relaxation results at different magnetic fields and electron paramagnetic resonance are used to investigate the relaxation induced by paramagnetic particles. When combined with computer simulations of transverse relaxation, they allow an accurate description of the relaxation induced by paramagnetic particles. Results   For gadolinium hydroxide particles, both T 1 and T 2 relaxation are due to a chemical exchange of protons between the particle surface and bulk water, called inner sphere relaxation. The inner sphere is also responsible for T 1 relaxation of dysprosium, holmium, terbium and erbium containing particles. However, for these latter compounds, T 2 relaxation is caused by water diffusion in the field inhomogeneities created by the magnetic particle, the outer-sphere relaxation mechanism. The different relaxation behaviors are caused by different electron relaxation times (estimated by electron paramagnetic resonance). Conclusion   These findings may allow tailoring paramagnetic particles: ultrasmall gadolinium oxide and hydroxide particles for T 1 contrast agents, with shapes ensuring the highest surface-to-volume ratio. All the other compounds present interesting T 2 relaxation performance at high fields. These results are in agreement with computer simulations and theoretical predictions of the outer-sphere and static dephasing regime theories. The T 2 efficiency would be optimum for spherical particles of 40–50 nm radius. Content Type Journal Article Category Research Article Pages 1-12 DOI 10.1007/s10334-012-0326-7 Authors Quoc Lam Vuong, Biological Physics Department, University of Mons—UMONS, 20 Place du Parc, 7000 Mons, Belgium Sabine Van Doorslaer, Department of Physics, University of Antwerp, Antwerp, Belgium Jean-Luc Bridot, Department of Chemistry, Université Laval, Quebec City, QC G1V 0A6, Canada Corradina Argante, Biological Physics Department, University of Mons—UMONS, 20 Place du Parc, 7000 Mons, Belgium Gabriela Alejandro, Department of Physics, University of Antwerp, Antwerp, Belgium Raphaël Hermann, Institut für Festkörperforschung, JCNS und JARA-FIT, Forschungszentrum, Jülich GmbH, Jülich, Germany Sabrina Disch, Institut für Festkörperforschung, JCNS und JARA-FIT, Forschungszentrum, Jülich GmbH, Jülich, Germany Carlos Mattea, Fakultät für Mathematik und Naturwissenschaften, FG Technische Physik II/Polymerphysik, Technische Universität Ilmenau, Ilmenau, Germany Siegfried Stapf, Fakultät für Mathematik und Naturwissenschaften, FG Technische Physik II/Polymerphysik, Technische Universität Ilmenau, Ilmenau, Germany Yves Gossuin, Biological Physics Department, University of Mons—UMONS, 20 Place du Parc, 7000 Mons, Belgium Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-08-13
    Description: Object   Until now, a three-directional velocity field has mostly been obtained by velocity encoding in three directions, which is very time-consuming and hence not usually used in clinical routine. We show the feasibility of combining in-plane tagging with through-plane tissue phase mapping (TPM) to encode a three-directional velocity field at 3 T with reduced overall acquisition time. Materials and methods   Assessment of a three-directional velocity field was performed for 10 healthy volunteers. The motion patterns obtained by use of five different sequences including three-directional TPM, TPM in the through-plane direction, TPM in the through-plane direction with horizontal or vertical tagging lines, and TPM in the through-plane direction combined with a tagging grid were evaluated and compared. Results   A three-dimensional velocity field can be obtained in approximately half the acquisition time by combining through-plane TPM with in-plane tagging. Although the velocity information is derived by different means, differences between the information obtained by three-directional TPM encoding and the suggested technique are only minor. Conclusion   The combination of tagging and TPM enables assessment of the three-directional velocity field in nearly half the time taken when the conventional three-directional TPM sequence is used. Content Type Journal Article Category Research Article Pages 1-9 DOI 10.1007/s10334-012-0333-8 Authors Anja Lutz, Department of Internal Medicine II, University Hospital of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany Jan Paul, Department of Internal Medicine II, University Hospital of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany Axel Bornstedt, Department of Internal Medicine II, University Hospital of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany Gerd Ulrich Nienhaus, Institute of Applied Physics and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany Patrick Etyngier, Medisys Research Lab, Philips Healthcare, 33 rue de Verdun, 92156 Suresnes, France Peter Bernhardt, Department of Internal Medicine II, University Hospital of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany Wolfgang Rottbauer, Department of Internal Medicine II, University Hospital of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany Volker Rasche, Department of Internal Medicine II, University Hospital of Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-08-13
    Description:    Quantitative PET imaging requires an attenuation map to correct for attenuation. In stand-alone PET or PET/CT, the attenuation map is usually derived from a transmission scan or CT image, respectively. In PET/MR, these methods will most likely not be used. Therefore, attenuation correction has long been regarded as one of the major challenges in the development of PET/MR. In the past few years, much progress has been made in this field. In this review, the challenges faced in attenuation correction for PET/MR are discussed. Different methods have been proposed to overcome these challenges. An overview of the MR-based (template-based and voxel-based), transmission-based and emission-based methods and the results that have been obtained is provided. Although several methods show promising results, no single method fulfils all of the requirements for the ideal attenuation correction method for PET/MR. Therefore, more work is still necessary in this field. To allow implementation in routine clinical practice, extensive evaluation of the proposed methods is necessary to demonstrate robustness and automation. Content Type Journal Article Category Review Article Pages 1-18 DOI 10.1007/s10334-012-0334-7 Authors Vincent Keereman, MEDISIP, Department of Electronics and Information Systems, Ghent University-IBBT-IBiTech, De Pintelaan 185, 9000 Ghent, Belgium Pieter Mollet, MEDISIP, Department of Electronics and Information Systems, Ghent University-IBBT-IBiTech, De Pintelaan 185, 9000 Ghent, Belgium Yannick Berker, Department of Experimental Molecular Imaging, RWTH Aachen University Hospital, Aachen, Germany Volkmar Schulz, Department of Experimental Molecular Imaging, RWTH Aachen University Hospital, Aachen, Germany Stefaan Vandenberghe, MEDISIP, Department of Electronics and Information Systems, Ghent University-IBBT-IBiTech, De Pintelaan 185, 9000 Ghent, Belgium Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-08-20
    Description: Object   This study proposes a scale space based algorithm for automated segmentation of single-shot tagged images of modest SNR. Furthermore the algorithm was designed for analysis of discontinuous or shearing types of motion, i.e. segmentation of broken tag patterns. Materials and methods   The proposed algorithm utilises non-linear scale space for automatic segmentation of single-shot tagged images. The algorithm's ability to automatically segment tagged shearing motion was evaluated in a numerical simulation and in vivo. A typical shearing deformation was simulated in a Shepp-Logan phantom allowing for quantitative evaluation of the algorithm's success rate as a function of both SNR and the amount of deformation. For a qualitative in vivo evaluation tagged images showing deformations in the calf muscles and eye movement in a healthy volunteer were acquired. Results   Both the numerical simulation and the in vivo tagged data demonstrated the algorithm’s ability for automated segmentation of single-shot tagged MR provided that SNR of the images is above 10 and the amount of deformation does not exceed the tag spacing. The latter constraint can be met by adjusting the tag delay or the tag spacing. Conclusion   The scale space based algorithm for automatic segmentation of single-shot tagged MR enables the application of tagged MR to complex (shearing) deformation and the processing of datasets with relatively low SNR. Content Type Journal Article Category Research Article Pages 1-10 DOI 10.1007/s10334-012-0332-9 Authors Andre M. J. Sprengers, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands Matthan W. A. Caan, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands Kevin M. Moerman, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands Aart J. Nederveen, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands Rolf M. Lamerichs, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands Jaap Stoker, Department of Radiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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  • Publication Date: 2012-09-10
    Description: Object   The aim of this study was to evaluate MR-based attenuation correction of PET emission data of the head, based on a previously described technique that calculates substitute CT (sCT) images from a set of MR images. Materials and methods   Images from eight patients, examined with 18 F-FLT PET/CT and MRI, were included. sCT images were calculated and co-registered to the corresponding CT images, and transferred to the PET/CT scanner for reconstruction. The new reconstructions were then compared with the originals. The effect of replacing bone with soft tissue in the sCT-images was also evaluated. Results   The average relative difference between the sCT-corrected PET images and the CT-corrected PET images was 1.6 % for the head and 1.9 % for the brain. The average standard deviations of the relative differences within the head were relatively high, at 13.2 %, primarily because of large differences in the nasal septa region. For the brain, the average standard deviation was lower, 4.1 %. The global average difference in the head when replacing bone with soft tissue was 11 %. Conclusion   The method presented here has a high rate of accuracy, but high-precision quantitative imaging of the nasal septa region is not possible at the moment. Content Type Journal Article Category Research Article Pages 1-10 DOI 10.1007/s10334-012-0339-2 Authors Anne Larsson, Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden Adam Johansson, Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden Jan Axelsson, Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden Tufve Nyholm, Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden Thomas Asklund, Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden Katrine Riklund, Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden Mikael Karlsson, Department of Radiation Sciences, Umeå University, 90187 Umeå, Sweden Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243
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