1
|
Boudries D, Massot P, Parzy E, Seren S, Mellet P, Franconi JM, Miraux S, Bezançon E, Marque SRA, Audran G, Muetzel M, Wintzheimer S, Fidler F, Thiaudiere E. A system for in vivo on-demand ultra-low field Overhauser-enhanced 3D-Magnetic resonance imaging. J Magn Reson 2023; 348:107383. [PMID: 36724576 DOI: 10.1016/j.jmr.2023.107383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/13/2023] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
Development of very-low field MRI is an active area of research. It aims at reducing operating costs and improve portability. However, the signal-to-noise issue becomes prominent at ultra-low field (<1 mT), especially for molecular imaging purposes that addresses specific biochemical events. In the context of preclinical molecular MRI of abnormal proteolysis the paper describes a MRI system able to produce Overhauser-enhanced MR images in living rats through in situ Dynamic Nuclear Polarization at 206 µT using stable and non-toxic nitroxides. In parallel conventional images are generated at 206 µT following pre-polarization at 20 mT. Results show that nitroxides are visualized in 3D within a few minutes in the lungs, kidneys and bladder post-administration. This system will be used for molecular imaging of inflammation using protease-specific nitroxide probes.
Collapse
Affiliation(s)
| | - Philippe Massot
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
| | - Elodie Parzy
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
| | - Seda Seren
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
| | - Philippe Mellet
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France; INSERM, Bordeaux, France
| | | | - Sylvain Miraux
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
| | - Eric Bezançon
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
| | - Sylvain R A Marque
- Aix-Marseille University, CNRS, ICR, UMR 7273, F-13013 Marseille, France
| | - Gérard Audran
- Aix-Marseille University, CNRS, ICR, UMR 7273, F-13013 Marseille, France
| | | | | | - Florian Fidler
- Würzburg University Fraunhofer IIS D-97074 Würzburg, Germany
| | - Eric Thiaudiere
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France.
| |
Collapse
|
2
|
Wenderoth S, Müssig S, Prieschl J, Genin E, Heuzé K, Fidler F, Haddad D, Wintzheimer S, Mandel K. Optically Sensitive and Magnetically Identifiable Supraparticles as Indicators of Surface Abrasion. Nano Lett 2022; 22:2762-2768. [PMID: 35311292 DOI: 10.1021/acs.nanolett.1c04773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Identifying and ensuring the integrity of products plays an important role in today's globalized world. Miniaturized information taggants in the packaging surface are therefore required to monitor the product itself instead of applying external labels. Ideally, multiple types of information are stored in such additives. In this work, micrometer-sized core-shell particles (supraparticles) were developed to provide material surfaces with both an identifier and a surface abrasion indication functionality. The core of the supraparticles contains iron oxide nanoparticles that allow identification of the surface with a spectral magnetic code resolved by magnetic particle spectroscopy. The fluorescent silica nanoparticles in the supraparticle shell can be abraded by mechanical stress and resolved by fluorescence spectroscopy. This provides information about the mechanical integrity of the system. The application as surfaces, that contain several types of information in one supraparticle, was demonstrated here by incorporating such bifunctional supraparticles as additives in a surface coating.
Collapse
Affiliation(s)
- Sarah Wenderoth
- Chair of Chemical Technology of Materials Synthesis, Julius-Maximilians-University Würzburg, Röntgenring 11, D97070 Würzburg, Germany
- Fraunhofer-Institute for Silicate Research ISC, Neunerplatz 2, D97082 Würzburg, Germany
| | - Stephan Müssig
- Departement of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 1, D91058 Erlangen, Germany
| | - Johannes Prieschl
- Departement of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 1, D91058 Erlangen, Germany
| | - Emilie Genin
- University Bordeaux, ISM, UMR-5255, F-33400 Talence, France
- CNRS, ISM, UMR5255, F-33400 Talence, France
| | - Karine Heuzé
- University Bordeaux, ISM, UMR-5255, F-33400 Talence, France
- CNRS, ISM, UMR5255, F-33400 Talence, France
| | - Florian Fidler
- Magnetic Resonance and X-ray Imaging Department, Development Center X-ray Technology, Fraunhofer-Institute for Integrated Circuits IIS, Am Hubland, 97074 Würzburg, Germany
| | - Daniel Haddad
- Magnetic Resonance and X-ray Imaging Department, Development Center X-ray Technology, Fraunhofer-Institute for Integrated Circuits IIS, Am Hubland, 97074 Würzburg, Germany
| | - Susanne Wintzheimer
- Fraunhofer-Institute for Silicate Research ISC, Neunerplatz 2, D97082 Würzburg, Germany
- Departement of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 1, D91058 Erlangen, Germany
| | - Karl Mandel
- Fraunhofer-Institute for Silicate Research ISC, Neunerplatz 2, D97082 Würzburg, Germany
- Departement of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 1, D91058 Erlangen, Germany
| |
Collapse
|
3
|
Hanea AM, Wilkinson DP, McBride M, Lyon A, van Ravenzwaaij D, Singleton Thorn F, Gray C, Mandel DR, Willcox A, Gould E, Smith ET, Mody F, Bush M, Fidler F, Fraser H, Wintle BC. Mathematically aggregating experts' predictions of possible futures. PLoS One 2021; 16:e0256919. [PMID: 34473784 PMCID: PMC8412308 DOI: 10.1371/journal.pone.0256919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 08/18/2021] [Indexed: 12/05/2022] Open
Abstract
Structured protocols offer a transparent and systematic way to elicit and combine/aggregate, probabilistic predictions from multiple experts. These judgements can be aggregated behaviourally or mathematically to derive a final group prediction. Mathematical rules (e.g., weighted linear combinations of judgments) provide an objective approach to aggregation. The quality of this aggregation can be defined in terms of accuracy, calibration and informativeness. These measures can be used to compare different aggregation approaches and help decide on which aggregation produces the "best" final prediction. When experts' performance can be scored on similar questions ahead of time, these scores can be translated into performance-based weights, and a performance-based weighted aggregation can then be used. When this is not possible though, several other aggregation methods, informed by measurable proxies for good performance, can be formulated and compared. Here, we develop a suite of aggregation methods, informed by previous experience and the available literature. We differentially weight our experts' estimates by measures of reasoning, engagement, openness to changing their mind, informativeness, prior knowledge, and extremity, asymmetry or granularity of estimates. Next, we investigate the relative performance of these aggregation methods using three datasets. The main goal of this research is to explore how measures of knowledge and behaviour of individuals can be leveraged to produce a better performing combined group judgment. Although the accuracy, calibration, and informativeness of the majority of methods are very similar, a couple of the aggregation methods consistently distinguish themselves as among the best or worst. Moreover, the majority of methods outperform the usual benchmarks provided by the simple average or the median of estimates.
Collapse
Affiliation(s)
- A M Hanea
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - D P Wilkinson
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - M McBride
- Centre for Environmental Policy, Imperial College London, London, United Kingdom
| | - A Lyon
- DelphiCloud, Amsterdam, The Netherlands
| | - D van Ravenzwaaij
- Faculty of Behavioural and Social Sciences, University of Groningen, Groningen, The Netherlands
| | - F Singleton Thorn
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - C Gray
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - D R Mandel
- Cognimotive Consulting Inc., Toronto, Ontario, Canada
| | - A Willcox
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - E Gould
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - E T Smith
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - F Mody
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - M Bush
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - F Fidler
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - H Fraser
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| | - B C Wintle
- MetaMelb Lab, University of Melbourne, Melbourne, Victoria, Australia
| |
Collapse
|
4
|
Müssig S, Kuttich B, Fidler F, Haddad D, Wintzheimer S, Kraus T, Mandel K. Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration. Nanoscale Adv 2021; 3:2822-2829. [PMID: 36134194 PMCID: PMC9417811 DOI: 10.1039/d1na00159k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 03/30/2021] [Indexed: 05/02/2023]
Abstract
The controlled agglomeration of superparamagnetic iron oxide nanoparticles (SPIONs) was used to rapidly switch their magnetic properties. Small-angle X-ray scattering (SAXS) and dynamic light scattering showed that tailored iron oxide nanoparticles with phase-changing organic ligand shells agglomerate at temperatures between 5 °C and 20 °C. We observed the concurrent change in magnetic properties using magnetic particle spectroscopy (MPS) with a temporal resolution on the order of seconds and found reversible switching of magnetic properties of SPIONs by changing their agglomeration state. The non-linear correlation between magnetization amplitude from MPS and agglomeration degree from SAXS data indicated that the agglomerates' size distribution affected magnetic properties.
Collapse
Affiliation(s)
- Stephan Müssig
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU) Egerlandstraße 1 91058 Erlangen Germany
| | - Björn Kuttich
- INM - Leibniz-Institute for New Materials Campus D2 2 66123 Saarbrücken Germany
| | - Florian Fidler
- Magnetic Resonance and X-ray Imaging Department, Development Center X-ray Technology, Fraunhofer Institute for Integrated Circuits IIS Am Hubland D-97074 Würzburg Germany
| | - Daniel Haddad
- Magnetic Resonance and X-ray Imaging Department, Development Center X-ray Technology, Fraunhofer Institute for Integrated Circuits IIS Am Hubland D-97074 Würzburg Germany
| | - Susanne Wintzheimer
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU) Egerlandstraße 1 91058 Erlangen Germany
| | - Tobias Kraus
- INM - Leibniz-Institute for New Materials Campus D2 2 66123 Saarbrücken Germany
- Colloid and Interface Chemistry, Saarland University 66123 Saarbrücken Germany
| | - Karl Mandel
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU) Egerlandstraße 1 91058 Erlangen Germany
- Fraunhofer-Institute for Silicate Research ISC Neunerplatz 2 97082 Würzburg Germany
| |
Collapse
|
5
|
Kilian T, Fidler F, Kasten A, Nietzer S, Landgraf V, Weiß K, Walles H, Westphal F, Hackenberg S, Grüttner C, Steinke M. Stem cell labeling with iron oxide nanoparticles: impact of 3D culture on cell labeling maintenance. Nanomedicine (Lond) 2016; 11:1957-70. [PMID: 27456272 DOI: 10.2217/nnm-2016-0042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
AIM We aimed to analyze the suitability of nanoparticles (M4E) for safe human mesenchymal stem cell (hMSC) labeling and determined cell labeling maintenance in 2D and 3D culture. MATERIALS & METHODS We investigated cell-particle interaction and the particles' impact on cell viability, growth and proliferation. We analyzed cell labeling maintenance in 2D and 3D culture invasively and noninvasively. RESULTS M4E do not affect cell viability, growth and proliferation and do not cause chromosomal aberrations. Cell labeling maintenance is up to five-times higher in 3D conditions compared with 2D culture. CONCLUSION M4E allow safe hMSC labeling and noninvasive identification. Our hMSC-loaded, 3D tissue-engineered construct could serve as a graft for regenerative therapies, in which M4E-labeled hMSCs can migrate to their target.
Collapse
Affiliation(s)
- Teresa Kilian
- Fraunhofer Institute for Interfacial Engineering & Biotechnology IGB, Translational Center "Regenerative Therapies for Oncology & Musculoskeletal Diseases" - Würzburg branch, Röntgenring 11, 97070 Würzburg, Germany
| | - Florian Fidler
- Research Center Magnetic-Resonance-Bavaria, Am Hubland, 97074 Würzburg, Germany
| | - Annika Kasten
- Department of Oral & Maxillofacial Surgery, Facial Plastic Surgery, Rostock University Medical Center, Schillingallee 35, 18057 Rostock, Germany
| | - Sarah Nietzer
- Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070 Würzburg, Germany
| | - Veronika Landgraf
- Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070 Würzburg, Germany
| | - Katrin Weiß
- Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070 Würzburg, Germany
| | - Heike Walles
- Fraunhofer Institute for Interfacial Engineering & Biotechnology IGB, Translational Center "Regenerative Therapies for Oncology & Musculoskeletal Diseases" - Würzburg branch, Röntgenring 11, 97070 Würzburg, Germany.,Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070 Würzburg, Germany
| | - Fritz Westphal
- Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Straße 4, 18119 Rostock, Germany
| | - Stephan Hackenberg
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic & Reconstructive Head & Neck Surgery, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080 Würzburg, Germany
| | - Cordula Grüttner
- Micromod Partikeltechnologie GmbH, Friedrich-Barnewitz-Straße 4, 18119 Rostock, Germany
| | - Maria Steinke
- Fraunhofer Institute for Interfacial Engineering & Biotechnology IGB, Translational Center "Regenerative Therapies for Oncology & Musculoskeletal Diseases" - Würzburg branch, Röntgenring 11, 97070 Würzburg, Germany.,Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070 Würzburg, Germany
| |
Collapse
|
6
|
Lother S, Schiff SJ, Neuberger T, Jakob PM, Fidler F. Design of a mobile, homogeneous, and efficient electromagnet with a large field of view for neonatal low-field MRI. MAGMA 2016; 29:691-8. [PMID: 26861046 DOI: 10.1007/s10334-016-0525-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Revised: 12/31/2015] [Accepted: 01/05/2016] [Indexed: 11/28/2022]
Abstract
OBJECTIVE In this work, a prototype of an effective electromagnet with a field-of-view (FoV) of 140 mm for neonatal head imaging is presented. The efficient implementation succeeded by exploiting the use of steel plates as a housing system. We achieved a compromise between large sample volumes, high homogeneity, high B0 field, low power consumption, light weight, simple fabrication, and conserved mobility without the necessity of a dedicated water cooling system. MATERIALS AND METHODS The entire magnetic resonance imaging (MRI) system (electromagnet, gradient system, transmit/receive coil, control system) is introduced and its unique features discussed. Furthermore, simulations using a numerical optimization algorithm for magnet and gradient system are presented. RESULTS Functionality and quality of this low-field scanner operating at 23 mT (generated with 500 W) is illustrated using spin-echo imaging (in-plane resolution 1.6 mm × 1.6 mm, slice thickness 5 mm, and signal-to-noise ratio (SNR) of 23 with a acquisition time of 29 min). B0 field-mapping measurements are presented to characterize the homogeneity of the magnet, and the B0 field limitations of 80 mT of the system are fully discussed. CONCLUSION The cryogen-free system presented here demonstrates that this electromagnet with a ferromagnetic housing can be optimized for MRI with an enhanced and homogeneous magnetic field. It offers an alternative to prepolarized MRI designs in both readout field strength and power use. There are multiple indications for the clinical medical application of such low-field devices.
Collapse
Affiliation(s)
- Steffen Lother
- Research Center Magnetic-Resonance-Bavaria (MRB), Am Hubland, 97074, Würzburg, Germany.
| | - Steven J Schiff
- Departments of Engineering Science and Mechanics, Neurosurgery, and Physics, Center of Neural Engineering, Penn State University, University Park, PA, USA
| | - Thomas Neuberger
- High Field MRI Facility, Huck Institutes of the Life Sciences, Penn State University, University Park, PA, USA.,Department of Biomedical Engineering, Penn State University, University Park, PA, USA
| | - Peter M Jakob
- Research Center Magnetic-Resonance-Bavaria (MRB), Am Hubland, 97074, Würzburg, Germany.,Department for Experimental Physics 5 (Biophysics), University of Wuerzburg, Würzburg, Germany
| | - Florian Fidler
- Research Center Magnetic-Resonance-Bavaria (MRB), Am Hubland, 97074, Würzburg, Germany
| |
Collapse
|
7
|
Gensler D, Mörchel P, Fidler F, Ritter O, Quick HH, Ladd ME, Bauer WR, Ertl G, Jakob PM, Nordbeck P. Myocardial T1: Quantification by Using an ECG-triggered Radial Single-Shot Inversion-Recovery MR Imaging Sequence. Radiology 2015; 274:879-87. [DOI: 10.1148/radiol.14131295] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
8
|
Kartäusch R, Helluy X, Jakob PM, Fidler F. Optimization of the AC-gradient method for velocity profile measurement and application to slow flow. J Magn Reson 2014; 248:131-6. [PMID: 25442782 DOI: 10.1016/j.jmr.2014.09.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 09/24/2014] [Accepted: 09/26/2014] [Indexed: 05/26/2023]
Abstract
This work presents a spectroscopic method to measure slow flow. Within a single shot the velocity distribution is acquired. This allows distinguishing rapidly between single velocities within the sampled volume with a high sensitivity. The technique is based on signal acquisition in the presence of a periodic gradient and a train of refocussing RF pulses. The theoretical model for trapezoidal bipolar pulse shaped gradients under consideration of diffusion and the outflow effect is introduced. A phase correction technique is presented that improves the spectral accuracy. Therefore, flow phantom measurements are used to validate the new sequence and the simulation based on the theoretical model. It was demonstrated that accurate parabolic flow profiles can be acquired and flow variations below 200 μm/s can be detected. Three post-processing methods that eliminate static background signal are also presented for applications in which static background signal dominates. Finally, this technique is applied to flow measurement of a small alder tree demonstrating a typical application of in vivo plant measurements.
Collapse
Affiliation(s)
- Ralf Kartäusch
- Research Center for Magnetic Resonance Bavaria e.V., Würzburg, Germany.
| | - Xavier Helluy
- Germany Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany
| | - Peter Michael Jakob
- Research Center for Magnetic Resonance Bavaria e.V., Würzburg, Germany; Germany Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany
| | - Florian Fidler
- Research Center for Magnetic Resonance Bavaria e.V., Würzburg, Germany
| |
Collapse
|
9
|
Vogel P, Lother S, Rückert MA, Kullmann WH, Jakob PM, Fidler F, Behr VC. MRI Meets MPI: a bimodal MPI-MRI tomograph. IEEE Trans Med Imaging 2014; 33:1954-1959. [PMID: 25291350 DOI: 10.1109/tmi.2014.2327515] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
While magnetic particle imaging (MPI) constitutes a novel biomedical imaging technique for tracking superparamagnetic nanoparticles in vivo, unlike magnetic resonance imaging (MRI), it cannot provide anatomical background information. Until now these two modalities have been performed in separate scanners and image co-registration has been hampered by the need to reposition the sample in both systems as similarly as possible. This paper presents a bimodal MPI-MRI-tomograph that combines both modalities in a single system.MPI and MRI images can thus be acquired without moving the sample or replacing any parts in the setup. The images acquired with the presented setup show excellent agreement between the localization of the nanoparticles in MPI and the MRI background data. A combination of two highly complementary imaging modalities has been achieved.
Collapse
|
10
|
Nordbeck P, Fidler F, Friedrich MT, Weiss I, Warmuth M, Gensler D, Herold V, Geistert W, Jakob PM, Ertl G, Ritter O, Ladd ME, Bauer WR, Quick HH. Reducing RF-related heating of cardiac pacemaker leads in MRI: implementation and experimental verification of practical design changes. Magn Reson Med 2012; 68:1963-72. [PMID: 22383393 DOI: 10.1002/mrm.24197] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 01/04/2012] [Accepted: 01/13/2012] [Indexed: 11/08/2022]
Abstract
There are serious concerns regarding safety when performing magnetic resonance imaging in patients with implanted conductive medical devices, such as cardiac pacemakers, and associated leads, as severe incidents have occurred in the past. In this study, several approaches for altering an implant's lead design were systematically developed and evaluated to enhance the safety of implanted medical devices in a magnetic resonance imaging environment. The individual impact of each design change on radiofrequency heating was then systematically investigated in functional lead prototypes at 1.5 T. Radiofrequency-induced heating could be successfully reduced by three basic changes in conventional pacemaker lead design: (1) increasing the lead tip area, (2) increasing the lead conductor resistance, and (3) increasing outer lead insulation conductivity. The findings show that radiofrequency energy pickup in magnetic resonance imaging can be reduced and, therefore, patient safety can be improved with dedicated construction changes according to a "safe by design" strategy. Incorporation of the described alterations into implantable medical devices such as pacemaker leads can be used to help achieve favorable risk-benefit-ratios when performing magnetic resonance imaging in the respective patient group.
Collapse
Affiliation(s)
- Peter Nordbeck
- Department of Internal Medicine I-Cardiology, University Hospital Würzburg, Würzburg, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Gensler D, Fidler F, Ehses P, Warmuth M, Reiter T, Düring M, Ritter O, Ladd ME, Quick HH, Jakob PM, Bauer WR, Nordbeck P. MR safety: Fast T
1
thermometry of the RF-induced heating of medical devices. Magn Reson Med 2012; 68:1593-9. [PMID: 22287286 DOI: 10.1002/mrm.24171] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 12/01/2011] [Accepted: 12/29/2011] [Indexed: 11/11/2022]
Affiliation(s)
- D Gensler
- Research Center for Magnetic Resonance Bavaria e.V., Würzburg, Germany.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Schelhorn C, Jakob PM, Fidler F. Rapid spectroscopic velocity quantification using periodically oscillating gradients. J Magn Reson 2012; 214:175-183. [PMID: 22154282 DOI: 10.1016/j.jmr.2011.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 10/27/2011] [Accepted: 11/07/2011] [Indexed: 05/31/2023]
Abstract
In this work two spectroscopic methods are described which allow rapid flow velocity quantification in the presence of a parabolic velocity distribution. This method requires only a single excitation and is based on flow encoding by periodically oscillating gradients. In the shown spin echo variant additional refocusing pulses correct for field inhomogeneities. A theoretical model is introduced, which describes the course of the derived spectra even in high flow region, where a significant part of the encoded spins leaves the sensitive area of the coil during data acquisition (outflow-effect). It was demonstrated that both methods can quantify flow velocities within the velocity range of 1mm/s up to 36 cm/s in the presence of a parabolic flow velocity distribution. The maximum velocity of the parabolic distribution is indicated in this method by a peak in the acquired spectrum from which the velocity could be quantified. Flow velocity quantification by periodically oscillating gradients seems a reasonable and fast alternative to established imaging techniques.
Collapse
Affiliation(s)
- Constanze Schelhorn
- Research Center Magnetic-Resonance-Bavaria, Am Hubland, D-97074 Würzburg, Germany
| | | | | |
Collapse
|
13
|
Hoelscher UC, Lother S, Fidler F, Blaimer M, Jakob P. Quantification and localization of contrast agents using delta relaxation enhanced magnetic resonance at 1.5 T. MAGMA 2011; 25:223-31. [PMID: 22120687 DOI: 10.1007/s10334-011-0291-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 10/18/2011] [Accepted: 10/19/2011] [Indexed: 11/28/2022]
Abstract
OBJECT Delta relaxation enhanced magnetic resonance (dreMR) is a new imaging technique based on the idea of cycling the magnetic field B (0) during an imaging sequence. The method determines the field dependency of the relaxation rate (relaxation dispersion dR (1)/dB). This quantity is of particular interest in contrast agent imaging because the parameter can be used to determine contrast agent concentrations and increases the ability to localize the contrast agent. MATERIALS AND METHODS In this paper dreMR imaging was implemented on a clinical 1.5 T MR scanner combining conventional MR imaging with fast field-cycling. Two improvements to dreMR theory are presented describing the quantification of contrast agent concentrations from dreMR data and a correction for field-cycling with finite ramp times. RESULTS Experiments demonstrate the use of the extended theory and show the measurement of contrast agent concentrations with the dreMR method. A second experiment performs localization of a contrast agent with a significant improvement in comparison to conventional imaging. CONCLUSION dreMR imaging has been extended by a method to quantify contrast agent concentrations and improved for field-cycling with finite ramp times. Robust localization of contrast agents using dreMR imaging has been performed in a sample where conventional imaging delivers inconclusive results.
Collapse
|
14
|
Pannek K, Fidler F, Kartäusch R, Jakob PM, Hiller KH. Contrast agent derived determination of the total circulating blood volume using magnetic resonance. MAGMA 2011; 25:215-22. [PMID: 21928062 DOI: 10.1007/s10334-011-0282-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 08/31/2011] [Accepted: 08/31/2011] [Indexed: 10/17/2022]
Abstract
OBJECT Knowledge of the total circulating blood volume (TCBV) is essential for the treatment of a variety of medical conditions and blood disorders. To date, blood volume analysis is rarely carried out due to the disadvantages of available methods. Our aim was to develop a widely available, simple, fast, yet accurate method for the determination of the total circulating blood volume. MATERIALS AND METHODS Magnetic resonance (MR) is a well-established, non-invasive technique. In this article, we present a method that uses MR contrast agents for the determination of the blood volume. The dependence of MR relaxation times on the concentration of MR contrast agents allows the calculation of the volume the contrast agent has been diluted in. RESULTS In phantom and in vivo experiments we could demonstrate that TCBV can be determined with high accuracy and precision. CONCLUSION This work introduces a novel method for the determination of the total circulating blood volume using magnetic resonance contrast agents as tracers.
Collapse
Affiliation(s)
- Kerstin Pannek
- Research Center Magnetic-Resonance-Bavaria, Wuerzburg, Germany
| | | | | | | | | |
Collapse
|
15
|
Nordbeck P, Hiller KH, Fidler F, Warmuth M, Nahrendorf M, Jakob PM, Ertl G, Bauer WR, Ritter O. VISUALIZATION OF ACUTE AND SUBACUTE EP LESIONS IN PATIENTS AFTER ATRIAL FLUTTER ABLATION. J Am Coll Cardiol 2011. [DOI: 10.1016/s0735-1097(11)60033-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
16
|
Nordbeck P, Hiller KH, Fidler F, Warmuth M, Burkard N, Nahrendorf M, Jakob PM, Quick HH, Ertl G, Bauer WR, Ritter O. Feasibility of contrast-enhanced and nonenhanced MRI for intraprocedural and postprocedural lesion visualization in interventional electrophysiology: animal studies and early delineation of isthmus ablation lesions in patients with typical atrial flutter. Circ Cardiovasc Imaging 2011; 4:282-94. [PMID: 21415125 DOI: 10.1161/circimaging.110.957670] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Imaging of myocardial ablation lesions during electrophysiology procedures would enable superior guidance of interventions and immediate identification of potential complications. The aim of this study was to establish clinically suitable MRI-based imaging techniques for intraprocedural lesion visualization in interventional electrophysiology. METHODS AND RESULTS Interventional electrophysiology was performed under magnetic resonance guidance in an animal model, using a custom setup including magnetic resonance-conditional catheters. Various pulse sequences were explored for intraprocedural lesion visualization after radiofrequency ablation. The developed visualization techniques were then used to investigate lesion formation in patients immediately after ablation of atrial flutter. The animal studies in 9 minipigs showed that gadolinium-DTPA-enhanced T1-weighted and nonenhanced T2-weighted pulse sequences are particularly suitable for lesion visualization immediately after radiofrequency ablation. MRI-derived lesion size correlated well with autopsy (R(2)=0.799/0.709 for contrast-enhanced/nonenhanced imaging). Non-contrast agent-enhanced techniques were suitable for repetitive lesion visualization during electrophysiological interventions, thus allowing for intraprocedural monitoring of ablation success. The patient studies in 24 patients with typical atrial flutter several minutes to hours after cavotricuspid isthmus ablation confirmed the results from the animal experiments. Therapeutic lesions could be visualized in all patients using contrast-enhanced and also nonenhanced MRI with high contrast-to-noise ratio (94.6±35.2/111.1±32.6 versus 48.0±29.0/68.0±37.3 for ventricular/atrial lesions and contrast-enhanced versus nonenhanced imaging). CONCLUSIONS MRI allows for precise lesion visualization in electrophysiological interventions just minutes after radiofrequency ablation. Nonenhanced T2-weighted MRI is particularly feasible for intraprocedural delineation of lesion formation as lesions are detectable within minutes after radiofrequency delivery and imaging can be repeated during interventions.
Collapse
Affiliation(s)
- Peter Nordbeck
- Department of Internal Medicine I-Cardiology, University Hospital Würzburg, Würzburg, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Fidler F, Kasík J. [Complications of IPOM plasty--our experience]. Rozhl Chir 2009; 88:394-397. [PMID: 19750844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Laparoscopic IPOM (Intraperitoneal Onlay mesh, method of intraperitoneal placement of mesh) hernioplasty, using the artificial mesh and when the method is managed sufficiently, has been used mainly for larger ventral hernias either in linea alba or more for incisional and Spiegel hernias. IPOM hernioplasty were supposed to be the gold standard for these hernioplasties, mainly for their rapidity, total view during operation and good recovery after it. There have been performed these operations also for inguinal hernias at several Surgical departments. There is a lot of studies proving safety of this method. On the other hand there exist studies pointing out severe postoperative complications of this method. These are both inflammatory and adhesive and they make threat for their long-term manifestation after primary operation and also for every next abdominal operation. We have had patients with both of these complications in our set. Considering this method for hernioplasty, we stopped performing IPOM.
Collapse
Affiliation(s)
- F Fidler
- Oddelení vseobecné chirurgie, Nemocnice Na Homolce, Praha
| | | |
Collapse
|
18
|
Nordbeck P, Bauer WR, Fidler F, Warmuth M, Hiller KH, Nahrendorf M, Maxfield M, Wurtz S, Geistert W, Broscheit J, Jakob PM, Ritter O. Feasibility of real-time MRI with a novel carbon catheter for interventional electrophysiology. Circ Arrhythm Electrophysiol 2009; 2:258-67. [PMID: 19808476 DOI: 10.1161/circep.108.778357] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cardiac MRI offers 3D real-time imaging with unsurpassed soft tissue contrast without x-ray exposure. To minimize safety concerns and imaging artifacts in MR-guided interventional electrophysiology (EP), we aimed at developing a setup including catheters for ablation therapy based on carbon technology. METHODS AND RESULTS The setup, including a steerable carbon catheter, was tested for safety, image distortion, and feasibility of diagnostic EP studies and radiofrequency ablation at 1.5 T. MRI was performed in 3 different 1.5-T whole-body scanners using various receive coils and pulse sequences. To assess unintentional heating of the catheters by radiofrequency pulses of the MR scanner in vitro, a fluoroptic thermometry system was used to record heating at the catheter tip. Programmed stimulation and ablation therapy was performed in 8 pigs. There was no significant heating of the carbon catheters while using short, repetitive radiofrequency pulses from the MR system. Because there was no image distortion when using the carbon catheters, exact targeting of the lesion sites was possible. Both atrial and ventricular radiofrequency ablation procedures including atrioventricular node modulation were performed successfully in the scanner. Potential complications such as pericardial effusion after intentional perforation of the right ventricular free wall during ablation could be monitored in real time as well. CONCLUSIONS We describe a newly developed EP technology for interventional electrophysiology based on carbon catheters. The feasibility of this approach was demonstrated by safety testing and performing EP studies and ablation therapy with carbon catheters in the MRI environment.
Collapse
Affiliation(s)
- Peter Nordbeck
- Department of Internal Medicine I, University of Würzburg, Würzburg, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Blazej S, Cernohorský S, Fidler F, Cech M. [The upper mesenteric vein thrombosis following upper GIT robotic surgery--a case review]. Rozhl Chir 2009; 88:123-126. [PMID: 19526943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
It is now recognized that occlusion of the mesenteric veins not only may complicate a number of disease processes but may occur as a life-threatening complication after abdominal surgery. 54-year-old female patient with Leiden mutation that undergone bariatric operation after one month from the surgery rehospitalized and operated with the diagnosis of superior mesenteric vein thrombosis with unavoidable resection of the intestine. Patient's state after surgery with following aggressive hematologic treatment becomes better. Mesenteric and portal vein flow is more fluent as showed by repeated CT angiography scans in comparison with pre-operative status. Patient currently on oral anticoagulant therapy.
Collapse
Affiliation(s)
- S Blazej
- Chirurgické oddelení Nemocnice na Homolce, Praha
| | | | | | | |
Collapse
|
20
|
Nordbeck P, Weiss I, Ehses P, Ritter O, Warmuth M, Fidler F, Herold V, Jakob PM, Ladd ME, Quick HH, Bauer WR. Measuring RF-induced currents inside implants: Impact of device configuration on MRI safety of cardiac pacemaker leads. Magn Reson Med 2009; 61:570-8. [DOI: 10.1002/mrm.21881] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
21
|
Hromádka P, Cernohorský S, Baader M, Fidler F, Skach J, Príhodová L. [Thoracoscopic anatomical lung resection--lobectomy]. Rozhl Chir 2008; 87:542-545. [PMID: 19110949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The authors bring their first experience with a purely endoscopic anatomical lung resection - lobectomy with mediastinal lymphadenectomy. At the department of surgery, Liberec Hospital, we have, so far, done 5 operations using this new technique. Once left superior lobectomy and 4 left inferior lobectomies were carried out. We describe the procedures and surgical tactics in thoracoscopic operations using modern staplers and haemoclips. The aim was to compare the results and benefits of purely endoscopic versus "classical" operations and to dismantle the myth of the extreme finacial intensiveness of this procedure.
Collapse
Affiliation(s)
- P Hromádka
- Chirurgické oddelení, Krajská nemocnice Liberec.
| | | | | | | | | | | |
Collapse
|
22
|
Baumgartner W, Fidler F, Weth A, Habbecke M, Jakob P, Butenweg C, Böhme W. Investigating the locomotion of the sandfish in desert sand using NMR-imaging. PLoS One 2008; 3:e3309. [PMID: 18836551 PMCID: PMC2561000 DOI: 10.1371/journal.pone.0003309] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 09/07/2008] [Indexed: 11/19/2022] Open
Abstract
The sandfish (Scincus scincus) is a lizard having the remarkable ability to move through desert sand for significant distances. It is well adapted to living in loose sand by virtue of a combination of morphological and behavioural specializations. We investigated the bodyform of the sandfish using 3D-laserscanning and explored its locomotion in loose desert sand using fast nuclear magnetic resonance (NMR) imaging. The sandfish exhibits an in-plane meandering motion with a frequency of about 3 Hz and an amplitude of about half its body length accompanied by swimming-like (or trotting) movements of its limbs. No torsion of the body was observed, a movement required for a digging-behaviour. Simple calculations based on the Janssen model for granular material related to our findings on bodyform and locomotor behaviour render a local decompaction of the sand surrounding the moving sandfish very likely. Thus the sand locally behaves as a viscous fluid and not as a solid material. In this fluidised sand the sandfish is able to "swim" using its limbs.
Collapse
Affiliation(s)
- Werner Baumgartner
- Department of Cellular Neurobionics, RWTH-Aachen University, Aachen, Germany.
| | | | | | | | | | | | | |
Collapse
|
23
|
Nordbeck P, Fidler F, Weiss I, Warmuth M, Friedrich MT, Ehses P, Geistert W, Ritter O, Jakob PM, Ladd ME, Quick HH, Bauer WR. Spatial distribution of RF-induced E-fields and implant heating in MRI. Magn Reson Med 2008; 60:312-9. [PMID: 18666101 DOI: 10.1002/mrm.21475] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Peter Nordbeck
- Medizinische Klinik und Poliklinik I, Universität Würzburg, Würzburg, Germany.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Ehses P, Fidler F, Nordbeck P, Pracht ED, Warmuth M, Jakob PM, Bauer WR. MRI thermometry: Fast mapping of RF-induced heating along conductive wires. Magn Reson Med 2008; 60:457-61. [PMID: 18570323 DOI: 10.1002/mrm.21417] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Philipp Ehses
- Physikalisches Institut (EP 5), Universität Würzburg, Würzburg, Germany.
| | | | | | | | | | | | | |
Collapse
|
25
|
Bauersachs J, Störk S, Kung M, Waller C, Fidler F, Hoyer C, Frantz S, Weidemann F, Ertl G, Angermann CE. HMG CoA reductase inhibition and left ventricular mass in hypertrophic cardiomyopathy: a randomized placebo-controlled pilot study. Eur J Clin Invest 2007; 37:852-9. [PMID: 17973781 DOI: 10.1111/j.1365-2362.2007.01877.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Statins reduce cardiomyocyte hypertrophy in animal models of hypertrophic cardiomyopathy, aortic banding and heart failure after myocardial infarction. We investigated the effect of the hydroxymethylglutaryl coenzyme A reductase inhibitor atorvastatin on left ventricular (LV) mass in patients with hypertrophic cardiomyopathy in a randomized placebo-controlled double-blind pilot study. MATERIALS AND METHODS Patients with hypertrophic cardiomyopathy were randomized to be treated once daily by atorvastatin 80 mg or placebo for nine months. LV mass was assessed by serial cardiac magnetic resonance imaging. LV systolic and diastolic function was determined by echocardiography. Markers of collagen metabolism and inflammation were also assessed. RESULTS Out of 78 screened patients with hypertrophic cardiomyopathy 28 (2 x 14) patients were eligible for randomization. Eleven patients in each group completed the study with cardiac magnetic resonance imaging assessments meeting the evaluation standards at baseline and at follow-up. Low-density lipoprotein cholesterol levels in the atorvastatin group decreased from 3.24 +/- 1.14 mmol L(-1) (125 +/- 44 mg dL(-1)) at baseline to 1.37 +/- 0.49 mmol L(-1) (53 +/- 19 mg dL(-1)) at follow-up (P < 0.001), but were unchanged in the placebo group. Baseline LV mass was 228 +/- 51 g in the placebo and 232 +/- 67 g in the atorvastatin group. The primary endpoint of change in LV mass from baseline to follow-up was 2 +/- 10% in the atorvastatin group versus 0 +/- 13% in the placebo group (P = NS). Parameters of LV volumes and diameters, systolic and diastolic function, and markers of collagen metabolism were also unchanged in both groups. CONCLUSION In patients with hypertrophic cardiomyopathy, this randomized placebo-controlled double-blind pilot study did not demonstrate an effect of 9-month treatment with atorvastatin 80 mg on LV mass reduction.
Collapse
Affiliation(s)
- J Bauersachs
- Medizinische Klinik und Poliklinik I, Kardiologie, Julius-Maximilians-Universität Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
PURPOSE To demonstrate that the use of nonquantitative methods in oxygen-enhanced (OE) lung imaging can be problematic and to present a new approach for quantitative OE lung imaging, which fulfills the requirements for easy application in clinical practice. MATERIALS AND METHODS A total of 10 healthy volunteers and three non-small-cell lung cancer (NSCLC) patients were examined using a 1.5T scanner. OE imaging was performed using a snapshot fast low-angle shot (FLASH) T(1)-mapping technique (TE = 1.4 msec, TR = 3.5 msec) as well as a series of T(1)-weighted inversion recovery (IR) half- Fourier acquisition single-shot turbo spin-echo (HASTE) (TE(effective) = 43 msec, TE(inter) = 4.2 msec, and inversion time [TI] = 1200 msec) images. Semiquantitative relative signal enhancement ratios (RER) of T(1)-weighted images before and after inhalation of oxygen-enriched gas were compared to the quantitative change in T(1). A hybrid method is proposed that combines the advantages of T(1)-weighted imaging with the quantification provided by T(1)-mapping. To this end, the IR-HASTE images were transformed into quantitative parameter maps. To prevent mismatching and incorrect parameter maps, retrospective image selection was performed using a postprocessing navigator technique. RESULTS The RER was dependent on the intrinsic values of T(1) in the lung. Quantitative parameters, such as the decrease of T(1) after switching the breathing gas, were more suited to oxygen transfer quantification than to relative signal enhancement. The mean T(1) value during inhalation of room air (T(1,room)) for the volunteers was 1260 msec. This value decreased by about 10% after switching the breathing gas to carbogen. For the patients, the mean T(1,room) value was 1182 msec, which decreased by about 7% when breathing carbogen. The parameter maps generated using the proposed hybrid method deviated, on average, only about 1% from the T(1)-maps. CONCLUSION For the purpose of intersubject comparison, OE lung imaging should be performed quantitatively. The proposed hybrid technique produced reliable quantitative results in a short amount of time and, therefore, is suited for clinical use.
Collapse
|
27
|
Weidemann F, Wacker C, Rauch A, Bauer WR, Bijnens B, Sutherland GR, Ertl G, Voelker W, Fidler F, Strotmann JM. Sequential Changes of Myocardial Function During Acute Myocardial Infarction, in the Early and Chronic Phase After Coronary Intervention Described by Ultrasonic Strain Rate Imaging. J Am Soc Echocardiogr 2006; 19:839-47. [PMID: 16824992 DOI: 10.1016/j.echo.2006.01.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Indexed: 11/23/2022]
Abstract
OBJECTIVE The aim of this prospective clinical study was to follow up patients with acute myocardial infarction from the ischemic event, over the primary coronary intervention (PCI), up to the chronic phase after survived myocardial infarction by noninvasive strain rate (SR) imaging and to determine its role in the assessment of transmurality of infarction. METHODS In all, 41 patients with acute S-T elevation infarction were examined immediately before, 3 days after, and 5 months after PCI. Regional myocardial function was assessed by the use of ultrasonic SR imaging and peak systolic SR and systolic strain were extracted. In addition, late-enhancement (LE) imaging with magnetic resonance imaging was done after 5 months to assess the transmurality of residual scar distribution. RESULTS Magnetic resonance imaging showed that 8 patients had no LE (complete recovery = no-scar group), 16 patients had subendocardial LE (nontransmural infarction = NT group), and 17 patients had a transmural LE (transmural infarction = T group) in the region of interest. Before PCI both SR and strain were markedly reduced in the ischemic segments compared with the nonischemic remote region in all 3 groups (SR: ischemia = -0.6 +/- 0.3 s(-1); remote = -1.3 +/- 0.4 s(-1), P < .001). Three days after PCI, systolic SR only increased significantly in the regions that were not transmurally infarcted. After 5 months the measurement of systolic strain could accurately distinguish the different groups. (no-scar group = -24 +/- 5%, NT group = -13 +/- 4%, T group = -1 +/- 3%). CONCLUSIONS This clinical study shows that with SR imaging: (1) the ischemic segment can be precisely detected; (2) the absence of transmurality early after coronary intervention can be predicted; and (3) in the chronic phase the transmurality of scar distribution can be assessed.
Collapse
Affiliation(s)
- Frank Weidemann
- Department of Internal Medicine I/Center of Cardiovascular Medicine and Physics, University Wuerzburg, Wuerzburg, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Ritter O, Fidler F, Hiller KH, Matthias N, Bauer WR. Carbon electrodes for interventional EP and pacemakers in the MRI. Heart Rhythm 2005. [DOI: 10.1016/j.hrthm.2005.02.873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
29
|
Fidler F, Wacker CM, Dueren C, Weigel M, Jakob PM, Bauer WR, Haase A. Myocardial perfusion measurements by spin-labeling under different vasodynamic states. J Cardiovasc Magn Reson 2004; 6:509-16. [PMID: 15137335 DOI: 10.1081/jcmr-120030571] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
In this study absolute myocardial perfusion was determined using a spin-labeling magnetic resonance imaging (MRI) technique at 2 Tesla. The technique was applied to 16 healthy volunteers at resting conditions, adenosine-induced stress, and oxygen breathing. Overall myocardial quantitative perfusion was determined as 2.3 +/- 0.8 mL/g/min (rest), 4.2 +/- 1.0 mL/g/min (adenosine), and 1.6 +/- 0.6 mL/g/min (oxygen), respectively. T1 of left ventricular blood pool decreased from 1709 +/- 101 ms (rest) to 1423 +/- 61 ms (oxygen), whereas T1 of right ventricular blood did not change significantly (1586 +/- 126 ms and 1558 +/- 150 ms). In conclusion, the presented technique for quantification of myocardial perfusion is an alternative to contrast agent-based methods. The spin labeling method is noninvasive and easily repeatable and it could therefore become an important tool to study changes in myocardial perfusion under different vasodynamic states.
Collapse
Affiliation(s)
- Florian Fidler
- Department of Biophysics (EP5), University of Wuerzburg, Josef-Schneider-Str. 2, 97080 Wuerzburg, Germany
| | | | | | | | | | | | | |
Collapse
|
30
|
Arnold JFT, Fidler F, Wang T, Pracht ED, Schmidt M, Jakob PM. Imaging lung function using rapid dynamic acquisition of T 1-maps during oxygen enhancement. Magn Reson Mater Phy 2004; 16:246-53. [PMID: 15042464 DOI: 10.1007/s10334-004-0034-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2003] [Accepted: 12/19/2003] [Indexed: 10/26/2022]
Abstract
This paper describes imaging of lung function with oxygen-enhanced MRI using dynamically acquired T1 parameter maps, which allows an accurate, quantitative assessment of time constants of T1-enhancement and therefore lung function. Eight healthy volunteers were examined on a 1.5-T whole-body scanner. Lung T1-maps based on an IR Snapshot FLASH technique (TE = 1.4 ms, TR = 3.5 ms, FA = 7 (composite function )) were dynamically acquired from each subject. Without waiting for full relaxation between subsequent acquisition of T1-maps, one T1-map was acquired every 6.7 s. For comparison, all subjects underwent a standard pulmonary function test (PFT). Oxygen wash-in and wash-out time course curves of T1 relaxation rate (R1)-enhancement were obtained and time constants of oxygen wash-in (w(in)) and wash-out (w(out)) were calculated. Averaged over the whole right lung, the mean w(out) was 43.90 +/- 10.47 s and the mean (w(in)) was 51.20 +/- 15.53 s, thus about 17% higher in magnitude. Wash-in time constants correlated strongly with forced expired volume in one second in percentage of the vital capacity (FEV1 % VC) and with maximum expiratory flow at 25% vital capacity (MEF25), whereas wash-out time constants showed only weak correlation. Using oxygen-enhanced rapid dynamic acquisition of T1-maps, time course curves of R1-enhancement can be obtained. With w(in) and w(out) two new parameters for assessing lung function are available. Therefore, the proposed method has the potential to provide regional information of pulmonary function in various lung diseases.
Collapse
Affiliation(s)
- J F T Arnold
- Department of Physics, University of Würzburg, 97074 Würzburg, Germany.
| | | | | | | | | | | |
Collapse
|
31
|
Wacker CM, Fidler F, Dueren C, Hirn S, Jakob PM, Ertl G, Haase A, Bauer WR. Quantitative assessment of myocardial perfusion with a spin-labeling technique: preliminary results in patients with coronary artery disease. J Magn Reson Imaging 2004; 18:555-60. [PMID: 14579398 DOI: 10.1002/jmri.10386] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To determine perfusion and coronary reserve in human myocardium without contrast agent using a spin labeling technique. MATERIALS AND METHODS Assessment of myocardial perfusion is based on T1 measurements after global and slice-selective spin preparation. This magnetic resonance imaging (MRI) technique was applied to 12 healthy volunteers and 16 patients with suspected coronary artery disease under resting conditions and adenosine-induced vasodilatation. RESULTS In volunteers, quantitative perfusion was calculated as 2.4 +/- 1.2 mL/g/minute (rest) and 3.9 +/- 1.3 mL/g/minute (adenosine), respectively. Perfusion reserve was 2.1 +/- 0.6. In patients, when comparing perfusion reserve in the anterior and posterior myocardium, reduced values according to a stenotic supplying vessel could be seen in seven of 11 patients who underwent stress testing. In these patients, the relative difference of coronary reserve was 44% +/- 18%. Two patients without stenosis of coronary arteries showed no differences in coronary reserve (with a relative change of 2 +/- 2%). CONCLUSION In patients with single-vessel coronary artery disease, differences in coronary reserve were clearly detectable when comparing anterior and posterior myocardium. The spin labeling method is noninvasive and easily repeatable, and it could therefore become an important tool to study changes in myocardial perfusion.
Collapse
|
32
|
Wacker C, Fidler F, Dueren C, Jakob P, Bauer W. Quantitative Perfusionsbestimmung der Myokardperfusion mit der MRT ohne Kontrastmittel: erste Ergebnisse an Patienten mit koronarer Herzerkrankung. ROFO-FORTSCHR RONTG 2003. [DOI: 10.1055/s-2003-819904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
33
|
Abstract
In this study, a new strategy for slow flow imaging is proposed. The basic idea is to generate flow contrast on a microscopic level below the spatial resolution of an imaging experiment. Since a microscopic spin tagging scheme is used, this concept is called MiST (Microscopic Spin Tagging). MiST is not a single specific measurement sequence, but rather a new flow sensitive preparation concept which is highly flexible and can be carried out in many ways. The common principle in all possible realizations of MiST is a periodic tagging of magnetization in thin planes (100-200 microm) within the imaging voxels by means of spatially selective RF-pulses. Therefore, flow sensitivity occurs via inflow of fresh spins on a microscopic scale. With this approach, short evolution times are sufficient to introduce inflow contrast and a spatial dependence of inflow times is avoided. The flow sensitive preparation and image orientation are also not connected as they are in conventional time-of-flight techniques. Another powerful feature of MiST is that it can be designed as a non-subtraction method, which results in no signal from stationary spins. Here we present a first realization of the MiST concept and its validation in quantitative flow measurements to demonstrate the feasibility of the proposed preparation concept.
Collapse
Affiliation(s)
- Silvia Olt
- Physikalisches Institut, EP5, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
| | | | | | | | | |
Collapse
|
34
|
Pazdera M, Hladký M, Valdman J, Fidler F, Beno P. [Personal experience with mechanical intestinal anastomoses]. Rozhl Chir 2000; 79:571-2. [PMID: 11210614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The authors evaluated the results of operations of the large intestine and rectum on account of cancer, covering a 4-year period. In all instances a stapler or Valtrac were used. Dehiscence of the anastomosis was recorded in one instance.
Collapse
Affiliation(s)
- M Pazdera
- Oddĕlení vseobecné chirurgie, Nemocnice Na Homolce, Praha
| | | | | | | | | |
Collapse
|
35
|
Fidler F. [Biliary tract injury in laparoscopic cholecystectomy--case report]. Rozhl Chir 2000; 79:234-6. [PMID: 10916445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The author presents a case of injury of the efferent biliary pathways after laparoscopic cholecystectomy in a 81-year-old female patient. Reconstruction of the injury is always an important procedure for the patient not only with regard to immediate postoperative complications but also for his future life. Referring the patient to a superior department is indicated but often impossible. The author summarize briefly the principles of treatment. After revision which was more than 5 weeks after the primary operation the patient survived the reconstruction and is now, after 18 months, in good health.
Collapse
Affiliation(s)
- F Fidler
- Chirurgické oddĕlení nemocnice Na Homolce, Praha
| |
Collapse
|
36
|
Haase A, Odoj F, Von Kienlin M, Warnking J, Fidler F, Weisser A, Nittka M, Rommel E, Lanz T, Kalusche B, Griswold M. NMR probeheads forin vivo applications. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/1099-0534(2000)12:6<361::aid-cmr1>3.0.co;2-l] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
37
|
Gürlich R, Maruna P, Lindner J, Fidler F. [Evaluation of laparoscopic and laparotomy cholecystectomy by comparing the dynamics of acute phase proteins]. Rozhl Chir 1994; 73:214-7. [PMID: 7524166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The authors investigated in two groups of surgical patients subjected to laparoscopic (n = 10) and laparotomic (n = 10) cholecystectomy changes in the levels of nine acute stage proteins. The objective was to evaluate the extent of surgical stress of the two surgical procedures with regard to changes of serum levels of albumin, transfirrin, prealbumin, alpha 1-antitrypsin, alpha 1-acid glycoprotein, alpha 2-macroglobulin, haptoglobin, ceruloplasmin and C-reactive protein. Before operation no significant differences (p < 0.05) were found between the investigated indicators. Changes of acute stage proteins up to the third day following surgery indicate a lower surgical trauma and more favourable course during the early postoperative period in patients operated by the laparoscopic route.
Collapse
Affiliation(s)
- R Gürlich
- II. chirurgická klinika 1. LF UK, Praha
| | | | | | | |
Collapse
|
38
|
Abstract
Performance on tests of memory in 39 patients who met Center for Disease Control (CDC) criteria for chronic fatigue immune dysfunction syndrome (CFIDS) was compared with 23 depressed patients (DSM-III-R) and 129 healthy controls. Although the CFIDS patients had normal neuropsychological profiles, they significantly overestimated their ability (metamemory), performed significantly worse on tests of recall as context increased (e.g., recognition), made more errors when rehearsal was prevented, and had delayed mental scanning as memory load increased. The overall pattern indicated that CFIDS patients had a significant memory deficit, far worse than implied by CDC criteria. The pattern for CFIDS patients was consistent with temporal-limbic dysfunction and significantly different than depressed patients and control subjects.
Collapse
Affiliation(s)
- C A Sandman
- Fairview Developmental Center, Costa Mesa, CA 92626
| | | | | | | | | |
Collapse
|
39
|
Fidler F, Prosek V, Doucha M. [Dieulafoy's disease--an uncommon cause of severe gastrointestinal hemorrhage]. Rozhl Chir 1991; 70:503-5. [PMID: 1822627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Morbus Dieulafoy described in the European literature as exulceratio simplex, in the English and American literature as a gastric aneurysm or submucosal arterial malformation is a life endangering haemorrhage which, if treated conservatively, leads to death by exsanguination. It is haemorrhage from an aroded medium-sized or major artery with a possible mucosal defect with a minimal or no inflammatory reaction. The localization on the anterior or posterior wall of the fundus or body of the stomach is typical. There are, however, also cases of haemorrhage from a submucosal artery in other parts of the GIT--pylorus or even jejunum (3, 5). In the presented case-history the authors describe an atypically located source of haemorrhage in a parapapillary position on the descendent part of the duodenum.
Collapse
Affiliation(s)
- F Fidler
- II. chirurgická klinika FVL UK, Praha
| | | | | |
Collapse
|
40
|
Fidler F, Prosek V. [Acute acalculous cholecystitis as a postoperative complication-- the stress gallbladder]. Rozhl Chir 1991; 70:495-7. [PMID: 1822625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Acute acalculous cholecystitis (AACH) is a relatively rare disease in relation to postoperative complications. The majority of AACH are cured by conservative treatment along with the basic disease but if there are further complications relaparotomy and an adequate operation is necessary, as in the presented case.
Collapse
Affiliation(s)
- F Fidler
- II. chirurgická klinika FVL UK, Praha
| | | |
Collapse
|