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Kollmann A, Lohr D, Ankenbrand MJ, Bille M, Terekhov M, Hock M, Elabyad I, Baltes S, Reiter T, Schnitter F, Bauer WR, Hofmann U, Schreiber LM. Cardiac function in a large animal model of myocardial infarction at 7 T: deep learning based automatic segmentation increases reproducibility. Sci Rep 2024; 14:11009. [PMID: 38744988 PMCID: PMC11094053 DOI: 10.1038/s41598-024-61417-4] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/06/2024] [Indexed: 05/16/2024] Open
Abstract
Cardiac magnetic resonance (CMR) imaging allows precise non-invasive quantification of cardiac function. It requires reliable image segmentation for myocardial tissue. Clinically used software usually offers automatic approaches for this step. These are, however, designed for segmentation of human images obtained at clinical field strengths. They reach their limits when applied to preclinical data and ultrahigh field strength (such as CMR of pigs at 7 T). In our study, eleven animals (seven with myocardial infarction) underwent four CMR scans each. Short-axis cine stacks were acquired and used for functional cardiac analysis. End-systolic and end-diastolic images were labelled manually by two observers and inter- and intra-observer variability were assessed. Aiming to make the functional analysis faster and more reproducible, an established deep learning (DL) model for myocardial segmentation in humans was re-trained using our preclinical 7 T data (n = 772 images and labels). We then tested the model on n = 288 images. Excellent agreement in parameters of cardiac function was found between manual and DL segmentation: For ejection fraction (EF) we achieved a Pearson's r of 0.95, an Intraclass correlation coefficient (ICC) of 0.97, and a Coefficient of variability (CoV) of 6.6%. Dice scores were 0.88 for the left ventricle and 0.84 for the myocardium.
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Affiliation(s)
- Alena Kollmann
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - David Lohr
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany.
| | - Markus J Ankenbrand
- Faculty of Biology, Center for Computational and Theoretical Biology (CCTB), University of Würzburg, Würzburg, Germany
| | - Maya Bille
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - Maxim Terekhov
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - Michael Hock
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - Ibrahim Elabyad
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - Steffen Baltes
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - Theresa Reiter
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
- Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany
| | - Florian Schnitter
- Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany
| | - Wolfgang R Bauer
- Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany
| | - Ulrich Hofmann
- Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany
| | - Laura M Schreiber
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
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Ignatyeva O, Gostev V, Taraskina A, Tsvetkova I, Pavlova P, Sulian O, Ageevets V, Likholetova D, Chulkova P, Nikitina E, Matkava L, Terekhov M, Lisovaya D, Kashtanova D, Ivanov M, Kalinogorskaya O, Avdeeva A, Zhirkov A, Goleva O, Zakharenko S, Zhdanov K, Strizheletsky V, Gomon Y, Kruglov A, Ni O, Noskova T, Gorbova I, Cherenkova G, Shlyk I, Afanasyev A, Yudin V, Makarov V, Sidorenko S, Yudin S. General dynamics of the URT microbiome and microbial signs of recovery in COVID-19 patients. Benef Microbes 2024; 15:145-164. [PMID: 38412868 DOI: 10.1163/18762891-bja00004] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 02/01/2024] [Indexed: 02/29/2024]
Abstract
COVID-19 is caused by an airborne virus, SARS-CoV-2. The upper respiratory tract (URT) is, therefore, the first system to endure the attack. Inhabited by an assemblage of microbial communities, a healthy URT wards off the invasion. However, once invaded, it becomes destabilised, which could be crucial to the establishment and progression of the infection. We examined 696 URT samples collected from 285 COVID-19 patients at three time-points throughout their hospital stay and 100 URT samples from 100 healthy controls. We used 16S ribosomal RNA sequencing to evaluate the abundance of various bacterial taxa, α-diversity, and β-diversity of the URT microbiome. Ordinary least squares regression was used to establish associations between the variables, with age, sex, and antibiotics as covariates. The URT microbiome in the COVID-19 patients was distinctively different from that of healthy controls. In COVID-19 patients, the abundance of 16 genera was significantly reduced. A total of 47 genera were specific to patients, whereas only 2 were unique to controls. The URT samples collected at admission differed more from the control than from the samples collected at later stages of treatment. The following four genera originally depleted in the patients grew significantly by the end of treatment: Fusobacterium, Haemophilus, Neisseria, and Stenotrophomonas. Our findings strongly suggest that SARS-CoV-2 caused significant changes in the URT microbiome, including the emergence of numerous atypical taxa. These findings may indicate increased instability of the URT microbiome in COVID-19 patients. In the course of the treatment, the microbial composition of the URT of COVID-19 patients tended toward that of controls. These microbial changes may be interpreted as markers of recovery.
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Affiliation(s)
- O Ignatyeva
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - V Gostev
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
- Mechnikov North-Western State Medical University, 41 Kirochnaya St., Saint Petersburg, 191015, Russian Federation
| | - A Taraskina
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - I Tsvetkova
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - P Pavlova
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
- Saint-Petersburg State University, 7-9 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russian Federation
| | - O Sulian
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - V Ageevets
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - D Likholetova
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - P Chulkova
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - E Nikitina
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - L Matkava
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - M Terekhov
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - D Lisovaya
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - D Kashtanova
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - M Ivanov
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - O Kalinogorskaya
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - A Avdeeva
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
- Saint-Petersburg State University, 7-9 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russian Federation
| | - A Zhirkov
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - O Goleva
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - S Zakharenko
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
| | - K Zhdanov
- Kirov Military Medical Academy, 6 Akademika Lebedeva St., Saint Petersburg, 194044, Russian Federation
| | - V Strizheletsky
- Saint-Petersburg State University, 7-9 Universitetskaya Naberezhnaya, Saint Petersburg, 199034, Russian Federation
| | - Y Gomon
- Pavlov First Saint-Petersburg State Medical University, 6-8 Lva Tolstogo St., Saint Petersburg, 197022, Russian Federation
| | - A Kruglov
- Moscow Multidisciplinary Clinical Centre 'Kommunarka', 8 Sosenskiy Stan, Kommunarka, Moscow, 142770, Russian Federation
| | - O Ni
- Moscow Multidisciplinary Clinical Centre 'Kommunarka', 8 Sosenskiy Stan, Kommunarka, Moscow, 142770, Russian Federation
| | - T Noskova
- Botkin Clinical Hospital of Infectious Diseases, 3 Mirgorodskaya St., Saint Petersburg, 191167, Russian Federation
| | - I Gorbova
- Botkin Clinical Hospital of Infectious Diseases, 3 Mirgorodskaya St., Saint Petersburg, 191167, Russian Federation
| | - G Cherenkova
- Botkin Clinical Hospital of Infectious Diseases, 3 Mirgorodskaya St., Saint Petersburg, 191167, Russian Federation
| | - I Shlyk
- Pavlov First Saint-Petersburg State Medical University, 6-8 Lva Tolstogo St., Saint Petersburg, 197022, Russian Federation
| | - A Afanasyev
- Pavlov First Saint-Petersburg State Medical University, 6-8 Lva Tolstogo St., Saint Petersburg, 197022, Russian Federation
| | - V Yudin
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - V Makarov
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
| | - S Sidorenko
- Pediatric Research and Clinical Centre for Infectious Diseases, Federal Biomedical Agency of Russia, 9 Professora Popova St., Saint Petersburg, 197022, Russian Federation
- Mechnikov North-Western State Medical University, 41 Kirochnaya St., Saint Petersburg, 191015, Russian Federation
| | - S Yudin
- Centre for Strategic Planning and Management of Biomedical Health Risks, Federal Biomedical Agency of Russia, 10/1 Pogodinskaya St., Moscow, 119121, Russian Federation
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Terekhov M, Elabyad IA, Lohr D, Reiter T, Kögler C, Lanz T, Schreiber LM. Complementary analysis of specific absorption rate safety for an 8Tx/16Rx array with central symmetry of elements for magnetic resonance imaging of the human heart and abdominopelvic organs at 7 T. NMR Biomed 2023; 36:e5023. [PMID: 37620002 DOI: 10.1002/nbm.5023] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 05/16/2023] [Accepted: 07/16/2023] [Indexed: 08/26/2023]
Abstract
A complementary safety assessment of the specific absorption rate (SAR) of the electromagnetic energy was performed in a prototype 8Tx/16Rx RF array for cardiac magnetic resonance imaging (MRI) at 7 T. The study aimed to address two critical aspects of 7-T SAR safety not always explicitly examined by coil vendors: (i) the influence of an RF-array position on a peak SAR value, and (ii) the risk of exceeding the permitted maximal SAR in the tissue surrounding conductive passive implants. The full-wave 3D electromagnetic simulations for the thorax with shifted array position and the whole-body volume in the presence of a dental retainer, an intrauterine contraceptive device (IUD), and a hip joint implant, were performed for two human voxel models. The effect of the array displacement on the SAR was simulated for seven array locations on the thorax shifted from the central position in different directions on 50 mm. The peak SAR values for both models were analyzed for the three phase-only transmit vectors optimized for B1 + homogeneity and transmit efficiency. Peak SAR values due to the shifts of the array position increase up to ≈50%. The worst-case peak SAR value for a dental retainer was found to be in the range of 10% of the maximal SAR in the tissue within the array's borders. For the IUD and artificial hip joint implants the effect was found to be negligible (peak SAR < 1% of the SAR within array borders). In addition to simulations for cardiac MRI, we performed a preliminary B1 + shimming and SAR-safety analysis for the same RF-array at various positions lower on the body trunk to assess a potential application in imaging abdominopelvic organs (prostate, kidney, and liver). The most promising target for an ad hoc alternative application of the array was found to be the prostate.
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Affiliation(s)
- Maxim Terekhov
- Department of Cardiovascular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Würzburg (UKW), Würzburg, Germany
| | - Ibrahim A Elabyad
- Department of Cardiovascular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Würzburg (UKW), Würzburg, Germany
| | - David Lohr
- Department of Cardiovascular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Würzburg (UKW), Würzburg, Germany
| | - Theresa Reiter
- Department of Internal Medicine I/Cardiology, University Hospital Würzburg (UKW), Würzburg, Germany
| | | | | | - Laura M Schreiber
- Department of Cardiovascular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Würzburg (UKW), Würzburg, Germany
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Schreiber LM, Lohr D, Baltes S, Vogel U, Elabyad IA, Bille M, Reiter T, Kosmala A, Gassenmaier T, Stefanescu MR, Kollmann A, Aures J, Schnitter F, Pali M, Ueda Y, Williams T, Christa M, Hofmann U, Bauer W, Gerull B, Zernecke A, Ergün S, Terekhov M. Ultra-high field cardiac MRI in large animals and humans for translational cardiovascular research. Front Cardiovasc Med 2023; 10:1068390. [PMID: 37255709 PMCID: PMC10225557 DOI: 10.3389/fcvm.2023.1068390] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 04/04/2023] [Indexed: 06/01/2023] Open
Abstract
A key step in translational cardiovascular research is the use of large animal models to better understand normal and abnormal physiology, to test drugs or interventions, or to perform studies which would be considered unethical in human subjects. Ultrahigh field magnetic resonance imaging (UHF-MRI) at 7 T field strength is becoming increasingly available for imaging of the heart and, when compared to clinically established field strengths, promises better image quality and image information content, more precise functional analysis, potentially new image contrasts, and as all in-vivo imaging techniques, a reduction of the number of animals per study because of the possibility to scan every animal repeatedly. We present here a solution to the dual use problem of whole-body UHF-MRI systems, which are typically installed in clinical environments, to both UHF-MRI in large animals and humans. Moreover, we provide evidence that in such a research infrastructure UHF-MRI, and ideally combined with a standard small-bore UHF-MRI system, can contribute to a variety of spatial scales in translational cardiovascular research: from cardiac organoids, Zebra fish and rodent hearts to large animal models such as pigs and humans. We present pilot data from serial CINE, late gadolinium enhancement, and susceptibility weighted UHF-MRI in a myocardial infarction model over eight weeks. In 14 pigs which were delivered from a breeding facility in a national SARS-CoV-2 hotspot, we found no infection in the incoming pigs. Human scanning using CINE and phase contrast flow measurements provided good image quality of the left and right ventricle. Agreement of functional analysis between CINE and phase contrast MRI was excellent. MRI in arrested hearts or excised vascular tissue for MRI-based histologic imaging, structural imaging of myofiber and vascular smooth muscle cell architecture using high-resolution diffusion tensor imaging, and UHF-MRI for monitoring free radicals as a surrogate for MRI of reactive oxygen species in studies of oxidative stress are demonstrated. We conclude that UHF-MRI has the potential to become an important precision imaging modality in translational cardiovascular research.
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Affiliation(s)
- Laura M. Schreiber
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - David Lohr
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Steffen Baltes
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Ulrich Vogel
- Institute for Hygiene and Microbiology, University of Wuerzburg, Wuerzburg, Germany
| | - Ibrahim A. Elabyad
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maya Bille
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Theresa Reiter
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
- Department of Internal Medicine I/Cardiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Aleksander Kosmala
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
- Department of Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Tobias Gassenmaier
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
- Department of Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maria R. Stefanescu
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Alena Kollmann
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Julia Aures
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Florian Schnitter
- Department of Internal Medicine I/Cardiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Mihaela Pali
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Yuichiro Ueda
- Institute of Anatomy and Cell Biology, Julius-Maximilians-University, Wuerzburg, Germany
| | - Tatiana Williams
- Department of Cardiovascular Genetics, Comprehensive Heart Failure Center Wuerzburg, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Martin Christa
- Department of Internal Medicine I/Cardiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Ulrich Hofmann
- Department of Internal Medicine I/Cardiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Wolfgang Bauer
- Department of Internal Medicine I/Cardiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Brenda Gerull
- Department of Internal Medicine I/Cardiology, University Hospital Wuerzburg, Wuerzburg, Germany
- Department of Cardiovascular Genetics, Comprehensive Heart Failure Center Wuerzburg, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Alma Zernecke
- Institute of Experimental Biomedicine, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Süleyman Ergün
- Institute of Anatomy and Cell Biology, Julius-Maximilians-University, Wuerzburg, Germany
| | - Maxim Terekhov
- Department of Cardiovascular Imaging and Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center Wuerzburg (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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Terekhov M, Elabyad IA, Lohr D, Hofmann U, Schreiber LM. High-resolution imaging of the excised porcine heart at a whole-body 7 T MRI system using an 8Tx/16Rx pTx coil. MAGMA 2023; 36:279-293. [PMID: 37027119 PMCID: PMC10140105 DOI: 10.1007/s10334-023-01077-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 03/09/2023] [Accepted: 03/14/2023] [Indexed: 04/28/2023]
Abstract
INTRODUCTION MRI of excised hearts at ultra-high field strengths ([Formula: see text]≥7 T) can provide high-resolution, high-fidelity ground truth data for biomedical studies, imaging science, and artificial intelligence. In this study, we demonstrate the capabilities of a custom-built, multiple-element transceiver array customized for high-resolution imaging of excised hearts. METHOD A dedicated 16-element transceiver loop array was implemented for operation in parallel transmit (pTx) mode (8Tx/16Rx) of a clinical whole-body 7 T MRI system. The initial adjustment of the array was performed using full-wave 3D-electromagnetic simulation with subsequent final fine-tuning on the bench. RESULTS We report the results of testing the implemented array in tissue-mimicking liquid phantoms and excised porcine hearts. The array demonstrated high efficiency of parallel transmits characteristics enabling efficient pTX-based B1+-shimming. CONCLUSION The receive sensitivity and parallel imaging capability of the dedicated coil were superior to that of a commercial 1Tx/32Rx head coil in both SNR and T2*-mapping. The array was successfully tested to acquire ultra-high-resolution (0.1 × 0.1 × 0.8 mm voxel) images of post-infarction scar tissue. High-resolution (isotropic 1.6 mm3 voxel) diffusion tensor imaging-based tractography provided high-resolution information about normal myocardial fiber orientation.
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Affiliation(s)
- Maxim Terekhov
- Comprehensive Heart Failure Center (CHFC), Department of Cardiovascular Imaging, University Hospital Würzburg, Am Schwarzenberg 15, 97078, Würzburg, Germany.
| | - Ibrahim A Elabyad
- Comprehensive Heart Failure Center (CHFC), Department of Cardiovascular Imaging, University Hospital Würzburg, Am Schwarzenberg 15, 97078, Würzburg, Germany
| | - David Lohr
- Comprehensive Heart Failure Center (CHFC), Department of Cardiovascular Imaging, University Hospital Würzburg, Am Schwarzenberg 15, 97078, Würzburg, Germany
| | - Ulrich Hofmann
- Department of Internal Medicine I / Cardiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Laura M Schreiber
- Comprehensive Heart Failure Center (CHFC), Department of Cardiovascular Imaging, University Hospital Würzburg, Am Schwarzenberg 15, 97078, Würzburg, Germany
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Shang Y, Theilenberg S, Terekhov M, Mattar W, Peng B, Jambawalikar SR, Schreiber LM, Juchem C. High-resolution simulation of B 0 field conditions in the human heart from segmented computed tomography images. NMR Biomed 2022; 35:e4739. [PMID: 35393706 DOI: 10.1002/nbm.4739] [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: 10/12/2021] [Revised: 04/04/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
B0 inhomogeneity leads to imaging artifacts in cardiac magnetic resonance imaging (MRI), in particular dark band artifacts with steady-state free precession pulse sequences. The limited spatial resolution of MR-derived in vivo B0 maps and the lack of population data prevent systematic analysis of the problem at hand and the development of optimized B0 shim strategies. We used readily available clinical computed tomography (CT) images to simulate the B0 conditions in the human heart at high spatial resolution. Calculated B0 fields showed consistency with MRI-based B0 measurements. The B0 maps for both the simulations and in vivo measurements showed local field inhomogeneities in the vicinity of lung tips with dominant Z3 spherical harmonic terms in the field distribution. The presented simulation approach allows for the derivation of B0 field conditions at high spatial resolution from CT images and enables the development of subject- and population-specific B0 shim strategies for the human heart.
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Affiliation(s)
- Yun Shang
- Department of Biomedical Engineering, Columbia University in the City of New York, New York, New York, USA
| | - Sebastian Theilenberg
- Department of Biomedical Engineering, Columbia University in the City of New York, New York, New York, USA
| | - Maxim Terekhov
- Section of Medical Physics, Department of Radiology, Mainz University Hospital, Mainz, Germany
- Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center (CHFC), Würzburg, Germany
| | - Wolfram Mattar
- Section of Medical Physics, Department of Radiology, Mainz University Hospital, Mainz, Germany
| | - Boyu Peng
- Department of Radiology, Columbia University in the City of New York, New York, New York, USA
| | - Sachin R Jambawalikar
- Department of Biomedical Engineering, Columbia University in the City of New York, New York, New York, USA
- Department of Radiology, Columbia University in the City of New York, New York, New York, USA
| | - Laura M Schreiber
- Section of Medical Physics, Department of Radiology, Mainz University Hospital, Mainz, Germany
- Chair of Molecular and Cellular Imaging, Comprehensive Heart Failure Center (CHFC), Würzburg, Germany
| | - Christoph Juchem
- Department of Biomedical Engineering, Columbia University in the City of New York, New York, New York, USA
- Department of Radiology, Columbia University in the City of New York, New York, New York, USA
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Elabyad IA, Terekhov M, Lohr D, Bille M, Hock M, Schreiber LM. A novel antisymmetric 16-element transceiver dipole antenna array for parallel transmit cardiac MRI in pigs at 7 T. NMR Biomed 2022; 35:e4726. [PMID: 35277907 DOI: 10.1002/nbm.4726] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 09/13/2021] [Revised: 02/23/2022] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
To improve parallel transmit (pTx) and receive performance for cardiac MRI (cMRI) in pigs at 7 T, a dedicated transmit/receive (Tx/Rx), 16-element antisymmetric dipole antenna array, which combines L-shaped and straight dipoles, was designed, implemented, and evaluated in both cadavers and animals in vivo. Electromagnetic-field simulations were performed with the new 16-element dipole antenna array loaded with a pig thorax-shaped phantom and compared with an eight-element array of straight dipoles. The new dipole array was interfaced to a 7 T scanner in pTx mode (8Tx/16Rx). Imaging performance of the novel array was validated through MRI measurements in a pig phantom, an 85 kg pig cadaver, and two pigs in vivo (74 and 81 kg). Due to the improved decoupling between interleaved L-shaped and straight dipole elements, the 16-element dipole array fits within the same outer dimensions as an eight-element array of straight dipoles. This provides improvement of both transmit and receive characteristics and additional degrees of freedom for B1+ shimming. The antisymmetric dipole array demonstrated efficient suppression of destructive interferences in the B1+ field, with up to 25% improvement in the B1+ homogeneity achieved using static pTx-RFPA B1+ shimming in comparison with the hardware-adjusted state, which was optimized for single transmit. High-resolution (0.5 × 0.5 × 4 mm3 ) anatomical images of the heart after cardiac arrest proved good transmit and receive characteristics of the novel array design. Parallel imaging with an acceleration factor up to R = 6 was possible while maintaining a mean g factor of 1.55 within the pig heart. CINE images acquired in vivo in two pigs demonstrated SNR and parallel imaging capabilities similar to those of a reference 8Tx/16Rx dedicated loop array for cMRI in pigs.
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Affiliation(s)
- Ibrahim A Elabyad
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maxim Terekhov
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - David Lohr
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maya Bille
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Michael Hock
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Laura M Schreiber
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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8
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Elabyad IA, Terekhov M, Lohr D, Bille M, Hock M, Schreiber LM. A novel antisymmetric 16-element transceiver dipole antenna array for parallel transmit cardiac MRI in pigs at 7 T. NMR Biomed 2022. [PMID: 35277907 DOI: 10.1002/nbm.4726:e4726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
To improve parallel transmit (pTx) and receive performance for cardiac MRI (cMRI) in pigs at 7 T, a dedicated transmit/receive (Tx/Rx), 16-element antisymmetric dipole antenna array, which combines L-shaped and straight dipoles, was designed, implemented, and evaluated in both cadavers and animals in vivo. Electromagnetic-field simulations were performed with the new 16-element dipole antenna array loaded with a pig thorax-shaped phantom and compared with an eight-element array of straight dipoles. The new dipole array was interfaced to a 7 T scanner in pTx mode (8Tx/16Rx). Imaging performance of the novel array was validated through MRI measurements in a pig phantom, an 85 kg pig cadaver, and two pigs in vivo (74 and 81 kg). Due to the improved decoupling between interleaved L-shaped and straight dipole elements, the 16-element dipole array fits within the same outer dimensions as an eight-element array of straight dipoles. This provides improvement of both transmit and receive characteristics and additional degrees of freedom for B1+ shimming. The antisymmetric dipole array demonstrated efficient suppression of destructive interferences in the B1+ field, with up to 25% improvement in the B1+ homogeneity achieved using static pTx-RFPA B1+ shimming in comparison with the hardware-adjusted state, which was optimized for single transmit. High-resolution (0.5 × 0.5 × 4 mm3 ) anatomical images of the heart after cardiac arrest proved good transmit and receive characteristics of the novel array design. Parallel imaging with an acceleration factor up to R = 6 was possible while maintaining a mean g factor of 1.55 within the pig heart. CINE images acquired in vivo in two pigs demonstrated SNR and parallel imaging capabilities similar to those of a reference 8Tx/16Rx dedicated loop array for cMRI in pigs.
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Affiliation(s)
- Ibrahim A Elabyad
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maxim Terekhov
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - David Lohr
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maya Bille
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Michael Hock
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Laura M Schreiber
- Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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9
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Herz S, Stefanescu MR, Lohr D, Vogel P, Kosmala A, Terekhov M, Weng AM, Grunz JP, Bley TA, Schreiber LM. Effects of image homogeneity on stenosis visualization at 7 T in a coronary artery phantom study: With and without B1-shimming and parallel transmission. PLoS One 2022; 17:e0270689. [PMID: 35767553 PMCID: PMC9242506 DOI: 10.1371/journal.pone.0270689] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 06/15/2022] [Indexed: 11/18/2022] Open
Abstract
Background To investigate the effects of B1-shimming and radiofrequency (RF) parallel transmission (pTX) on the visualization and quantification of the degree of stenosis in a coronary artery phantom using 7 Tesla (7 T) magnetic resonance imaging (MRI). Methods Stenosis phantoms with different grades of stenosis (0%, 20%, 40%, 60%, 80%, and 100%; 5 mm inner vessel diameter) were produced using 3D printing (clear resin). Phantoms were imaged with four different concentrations of diluted Gd-DOTA representing established arterial concentrations after intravenous injection in humans. Samples were centrally positioned in a thorax phantom of 30 cm diameter filled with a custom-made liquid featuring dielectric properties of muscle tissue. MRI was performed on a 7 T whole-body system. 2D-gradient-echo sequences were acquired with an 8-channel transmit 16-channel receive (8 Tx / 16 Rx) cardiac array prototype coil with and without pTX mode. Measurements were compared to those obtained with identical scan parameters using a commercially available 1 Tx / 16 Rx single transmit coil (sTX). To assess reproducibility, measurements (n = 15) were repeated at different horizontal angles with respect to the B0-field. Results B1-shimming and pTX markedly improved flip angle homogeneity across the thorax phantom yielding a distinctly increased signal-to-noise ratio (SNR) averaged over a whole slice relative to non-manipulated RF fields. Images without B1-shimming showed shading artifacts due to local B1+-field inhomogeneities, which hampered stenosis quantification in severe cases. In contrast, B1-shimming and pTX provided superior image homogeneity. Compared with a conventional sTX coil higher grade stenoses (60% and 80%) were graded significantly (p<0.01) more precise. Mild to moderate grade stenoses did not show significant differences. Overall, SNR was distinctly higher with B1-shimming and pTX than with the conventional sTX coil (inside the stenosis phantoms 14%, outside the phantoms 32%). Both full and half concentration (10.2 mM and 5.1 mM) of a conventional Gd-DOTA dose for humans were equally suitable for stenosis evaluation in this phantom study. Conclusions B1-shimming and pTX at 7 T can distinctly improve image homogeneity and therefore provide considerably more accurate MR image analysis, which is beneficial for imaging of small vessel structures.
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Affiliation(s)
- Stefan Herz
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
- * E-mail:
| | - Maria R. Stefanescu
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - David Lohr
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - Patrick Vogel
- Department of Experimental Physics V, University of Würzburg, Würzburg, Germany
| | - Aleksander Kosmala
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Maxim Terekhov
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
| | - Andreas M. Weng
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Jan-Peter Grunz
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Thorsten A. Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany
| | - Laura M. Schreiber
- Comprehensive Heart Failure Center (CHFC), Chair of Molecular and Cellular Imaging, University Hospital Würzburg, Würzburg, Germany
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Righesso LAR, Terekhov M, Götz H, Ackermann M, Emrich T, Schreiber LM, Müller WEG, Jung J, Rojas JP, Al-Nawas B. Dynamic contrast-enhanced magnetic resonance imaging for monitoring neovascularization during bone regeneration-a randomized in vivo study in rabbits. Clin Oral Investig 2021; 25:5843-5854. [PMID: 33786647 PMCID: PMC8443511 DOI: 10.1007/s00784-021-03889-6] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 03/12/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Micro-computed tomography (μ-CT) and histology, the current gold standard methods for assessing the formation of new bone and blood vessels, are invasive and/or destructive. With that in mind, a more conservative tool, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), was tested for its accuracy and reproducibility in monitoring neovascularization during bone regeneration. Additionally, the suitability of blood perfusion as a surrogate of the efficacy of osteoplastic materials was evaluated. MATERIALS AND METHODS Sixteen rabbits were used and equally divided into four groups, according to the time of euthanasia (2, 3, 4, and 6 weeks after surgery). The animals were submitted to two 8-mm craniotomies that were filled with blood or autogenous bone. Neovascularization was assessed in vivo through DCE-MRI, and bone regeneration, ex vivo, through μ-CT and histology. RESULTS The defects could be consistently identified, and their blood perfusion measured through DCE-MRI, there being statistically significant differences within the blood clot group between 3 and 6 weeks (p = 0.029), and between the former and autogenous bone at six weeks (p = 0.017). Nonetheless, no significant correlations between DCE-MRI findings on neovascularization and μ-CT (r =-0.101, 95% CI [-0.445; 0.268]) or histology (r = 0.305, 95% CI [-0.133; 0.644]) findings on bone regeneration were observed. CONCLUSIONS These results support the hypothesis that DCE-MRI can be used to monitor neovascularization but contradict the premise that it could predict bone regeneration as well.
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Affiliation(s)
- L A R Righesso
- Clinic for Oral and Maxillofacial Surgery and Plastic Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Augustusplatz 2, 55131, Mainz, Germany.
| | - M Terekhov
- Molecular and Cellular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - H Götz
- Cell Biology Unit, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstrasse 1, 55131, Mainz, Germany
| | - M Ackermann
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 13, 55128, Mainz, Germany
| | - T Emrich
- Department of Radiology, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstrasse 1, 55131, Mainz, Germany
- Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC, 29425, USA
- German Center for Cardiovascular Research (DZHK), Partner-Site Rhine-Main, Potsdamer Strasse 58, 10785, Berlin, Germany
| | - L M Schreiber
- Molecular and Cellular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - W E G Müller
- Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128, Mainz, Germany
| | - J Jung
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyung Hee University, 23, Kyung Hee Dae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - J P Rojas
- Private Practice, Av. La Dehesa, 181, Santiago, Chile
| | - B Al-Nawas
- Clinic for Oral and Maxillofacial Surgery and Plastic Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Augustusplatz 2, 55131, Mainz, Germany
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11
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Terekhov M, Elabyad IA, Schreiber LM. Global optimization of default phases for parallel transmit coils for ultra-high-field cardiac MRI. PLoS One 2021; 16:e0255341. [PMID: 34358243 PMCID: PMC8346258 DOI: 10.1371/journal.pone.0255341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 11/10/2020] [Accepted: 07/14/2021] [Indexed: 11/19/2022] Open
Abstract
The development of novel multiple-element transmit-receive arrays is an essential factor for improving B1+ field homogeneity in cardiac MRI at ultra-high magnetic field strength (B0 > = 7.0T). One of the key steps in the design and fine-tuning of such arrays during the development process is finding the default driving phases for individual coil elements providing the best possible homogeneity of the combined B1+-field that is achievable without (or before) subject-specific B1+-adjustment in the scanner. This task is often solved by time-consuming (brute-force) or by limited efficiency optimization methods. In this work, we propose a robust technique to find phase vectors providing optimization of the B1-homogeneity in the default setup of multiple-element transceiver arrays. The key point of the described method is the pre-selection of starting vectors for the iterative solver-based search to maximize the probability of finding a global extremum for a cost function optimizing the homogeneity of a shaped B1+-field. This strategy allows for (i) drastic reduction of the computation time in comparison to a brute-force method and (ii) finding phase vectors providing a combined B1+-field with homogeneity characteristics superior to the one provided by the random-multi-start optimization approach. The method was efficiently used for optimizing the default phase settings in the in-house-built 8Tx/16Rx arrays designed for cMRI in pigs at 7T.
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Affiliation(s)
- Maxim Terekhov
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center, University Hospital Wuerzburg, Wuerzburg, Germany
- * E-mail:
| | - Ibrahim A. Elabyad
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Laura M. Schreiber
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center, University Hospital Wuerzburg, Wuerzburg, Germany
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12
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Righesso L, Jung J, Terekhov M, Götz H, Ackermann M, Emrich T, Müller W, Rojas JP, Al‐Nawas B. Dynamic contrast‐enhanced magnetic resonance imaging for monitoring angiogenesis during bone regeneration – a randomized pilot study in rabbits. Clin Oral Implants Res 2020. [DOI: 10.1111/clr.5_13643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Leonardo Righesso
- Clinic for Oral and Maxillofacial Surgery and Plastic Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Junho Jung
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyung Hee University, Seoul, South Korea
| | - Maxim Terekhov
- Comprehensive Heart Failure Center, University Hospital, Würzburg, Germany
| | - Herman Götz
- Cell Biology Unit, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Maximilian Ackermann
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Tilman Emrich
- Department of Radiology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Werner Müller
- Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | | | - Bilal Al‐Nawas
- Clinic for Oral and Maxillofacial Surgery and Plastic Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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13
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Hock M, Terekhov M, Stefanescu MR, Lohr D, Herz S, Reiter T, Ankenbrand M, Kosmala A, Gassenmaier T, Juchem C, Schreiber LM. B 0 shimming of the human heart at 7T. Magn Reson Med 2020; 85:182-196. [PMID: 32700791 DOI: 10.1002/mrm.28423] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 01/31/2023]
Abstract
PURPOSE Inhomogeneities of the static magnetic B0 field are a major limiting factor in cardiac MRI at ultrahigh field (≥ 7T), as they result in signal loss and image distortions. Different magnetic susceptibilities of the myocardium and surrounding tissue in combination with cardiac motion lead to strong spatio-temporal B0 -field inhomogeneities, and their homogenization (B0 shimming) is a prerequisite. Limitations of state-of-the-art shimming are described, regional B0 variations are measured, and a methodology for spherical harmonics shimming of the B0 field within the human myocardium is proposed. METHODS The spatial B0 -field distribution in the heart was analyzed as well as temporal B0 -field variations in the myocardium over the cardiac cycle. Different shim region-of-interest selections were compared, and hardware limitations of spherical harmonics B0 shimming were evaluated by calibration-based B0 -field modeling. The role of third-order spherical harmonics terms was analyzed as well as potential benefits from cardiac phase-specific shimming. RESULTS The strongest B0 -field inhomogeneities were observed in localized spots within the left-ventricular and right-ventricular myocardium and varied between systolic and diastolic cardiac phases. An anatomy-driven shim region-of-interest selection allowed for improved B0 -field homogeneity compared with a standard shim region-of-interest cuboid. Third-order spherical harmonics terms were demonstrated to be beneficial for shimming of these myocardial B0 -field inhomogeneities. Initial results from the in vivo implementation of a potential shim strategy were obtained. Simulated cardiac phase-specific shimming was performed, and a shim term-by-term analysis revealed periodic variations of required currents. CONCLUSION Challenges in state-of-the-art B0 shimming of the human heart at 7 T were described. Cardiac phase-specific shimming strategies were found to be superior to vendor-supplied shimming.
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Affiliation(s)
- Michael Hock
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maxim Terekhov
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maria Roxana Stefanescu
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - David Lohr
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Stefan Herz
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Diagnostic and Interventional Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Theresa Reiter
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Internal Medicine I, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Markus Ankenbrand
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Aleksander Kosmala
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Diagnostic and Interventional Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Tobias Gassenmaier
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Diagnostic and Interventional Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Christoph Juchem
- Department of Biomedical Engineering, Columbia University, New York, New York, USA.,Department of Radiology, Columbia University, New York, New York, USA
| | - Laura Maria Schreiber
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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14
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Lohr D, Terekhov M, Veit F, Schreiber LM. Longitudinal assessment of tissue properties and cardiac diffusion metrics of the ex vivo porcine heart at 7 T: Impact of continuous tissue fixation using formalin. NMR Biomed 2020; 33:e4298. [PMID: 32207190 DOI: 10.1002/nbm.4298] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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: 11/20/2019] [Revised: 02/18/2020] [Accepted: 03/05/2020] [Indexed: 05/12/2023]
Abstract
In this study we aimed to assess the effects of continuous formalin fixation on diffusion and relaxation metrics of the ex vivo porcine heart at 7 T. Magnetic resonance imaging was performed on eight piglet hearts using a 7 T whole body system. Hearts were measured fresh within 3 hours of cardiac arrest followed by immersion in 10% neutral buffered formalin. T2* and T2 were assessed using a gradient multi-echo and multi-echo spin echo sequence, respectively. A spin echo and a custom stimulated echo sequence were employed to assess diffusion time-dependent changes in metrics of cardiac diffusion tensor imaging. SNR was determined for b = 0 images. Scans were performed for 5 mm thick apical, midcavity and basal slices (in-plane resolution: 1 mm) and repeated 7, 15, 50, 100 and 200 days postfixation. Eigenvalues of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) decreased significantly (P < 0.05) following fixation. Relative to fresh hearts, FA values 7 and 200 days postfixation were 90% and 80%, while respective relative ADC values at those fixation stages were 78% and 92%. Statistical helix and sheetlet angle distributions as well as respective mean and median values showed no systematic influence of continuous formalin fixation. Similar to changes in the ADC, values for T2 , T2* and SNR dropped initially postfixation. Respective relative values compared with fresh hearts at day 7 were 64%, 79% and 68%, whereas continuous fixation restored T2 , T2* and SNR leading to relative values of 74%, 100%, and 81% at day 200, respectively. Relaxation parameters and diffusion metrics are significantly altered by continuous formalin fixation. The preservation of microstructure metrics following prolonged fixation is a key finding that may enable future studies of ventricular remodeling in cardiac pathologies.
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Affiliation(s)
- David Lohr
- Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maxim Terekhov
- Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Franziska Veit
- Tissue Engineering and Regenerative Medicine (TERM), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Laura Maria Schreiber
- Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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15
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Elabyad IA, Terekhov M, Stefanescu MR, Lohr D, Fischer M, Schreiber LM. Design of a novel antisymmetric coil array for parallel transmit cardiac MRI in pigs at 7 T. J Magn Reson 2019; 305:195-208. [PMID: 31306985 DOI: 10.1016/j.jmr.2019.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [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: 05/08/2019] [Revised: 06/12/2019] [Accepted: 07/04/2019] [Indexed: 05/12/2023]
Abstract
The design, simulation, assembly and testing of a novel dedicated antisymmetric transmit/receive (Tx/Rx) coil array to demonstrate the feasibility of cardiac magnetic resonance imaging (cMRI) in pigs at 7 T was described. The novel antisymmetric array is composed of eight elements based on mirrored and reversed loop orientations to generate varying B1+ field harmonics for RF shimming. The central four loop elements formed together a pair of antisymmetric L-shaped channels to allow good decoupling between all neighboring elements of the entire array. The antisymmetric array was compared to a standard symmetric rectilinear loop array with an identical housing dimension. Both arrays were driven in the parallel transmit (pTx) mode forming an 8-channel transmit and 16-channel receive (8Tx/16Rx) coil array, where the same posterior array was combined with both anterior arrays. The hardware and imaging performance of the dedicated cardiac arrays were validated and compared by means of electromagnetic (EM) simulations, bench-top measurements, phantom, and ex-vivo MRI experiments with 46 kg female pig. Combined signal-to-noise ratio (SNR), geometry factor (g-factor), noise correlation maps, and high resolution ex-vivo cardiac images were acquired with an in-plane resolution of 0.3 mm × 0.3 mm using both arrays. The novel antisymmetric array enhanced the SNR within the heart by about two times and demonstrated good decoupling and improved control of the B1+ field distributions for RF shimming compared to the standard coil array. Parallel imaging with acceleration factor (R) up to 4 was possible using the novel antisymmetric coil array while maintaining the mean g-factor within the heart region of 1.13.
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Affiliation(s)
- Ibrahim A Elabyad
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany; Department of Electronics and Communications Engineering, Thebes Higher Institute of Engineering, Cairo, Egypt.
| | - M Terekhov
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany.
| | - M R Stefanescu
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany.
| | - D Lohr
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany.
| | - M Fischer
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany.
| | - L M Schreiber
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany.
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16
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Lohr D, Terekhov M, Weng AM, Schroeder A, Walles H, Schreiber LM. Spin echo based cardiac diffusion imaging at 7T: An ex vivo study of the porcine heart at 7T and 3T. PLoS One 2019; 14:e0213994. [PMID: 30908510 PMCID: PMC6433440 DOI: 10.1371/journal.pone.0213994] [Citation(s) in RCA: 9] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 03/05/2019] [Indexed: 02/03/2023] Open
Abstract
Purpose of this work was to assess feasibility of cardiac diffusion tensor imaging (cDTI) at 7 T in a set of healthy, unfixed, porcine hearts using various parallel imaging acceleration factors and to compare SNR and derived cDTI metrics to a reference measured at 3 T. Magnetic resonance imaging was performed on 7T and 3T whole body systems using a spin echo diffusion encoding sequence with echo planar imaging readout. Five reference (b = 0 s/mm2) images and 30 diffusion directions (b = 700 s/mm2) were acquired at both 7 T and 3 T using a GRAPPA acceleration factor R = 1. Scans at 7 T were repeated using R = 2, R = 3, and R = 4. SNR evaluation was based on 30 reference (b = 0 s/mm2) images of 30 slices of the left ventricle and cardiac DTI metrics were compared within AHA segmentation. The number of hearts scanned at 7 T and 3 T was n = 11. No statistically significant differences were found for evaluated helix angle, secondary eigenvector angle, fractional anisotropy and apparent diffusion coefficient at the different field strengths, given sufficiently high SNR and geometrically undistorted images. R≥3 was needed to reduce susceptibility induced geometric distortions to an acceptable amount. On average SNR in myocardium of the left ventricle was increased from 29±3 to 44±6 in the reference image (b = 0 s/mm2) when switching from 3 T to 7 T. Our study demonstrates that high resolution, ex vivo cDTI is feasible at 7 T using commercial hardware.
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Affiliation(s)
- David Lohr
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
- * E-mail:
| | - Maxim Terekhov
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Andreas Max Weng
- Department of Diagnostic and Interventional Radiology, University of Wuerzburg, Wuerzburg, Germany
| | - Anja Schroeder
- Chair Tissue Engineering and Regenerative Medicine (TERM), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Heike Walles
- Translational Center Regenerative Therapies (TLC-RT), Fraunhofer Institute for Silicate Research (ISC), Wuerzburg, Germany
| | - Laura Maria Schreiber
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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Ehrenfeld JM, Wanderer JP, Terekhov M, Rothman BS, Sandberg WS. A Perioperative Systems Design to Improve Intraoperative Glucose Monitoring Is Associated with a Reduction in Surgical Site Infections in a Diabetic Patient Population. Anesthesiology 2017; 126:431-440. [PMID: 28106608 DOI: 10.1097/aln.0000000000001516] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Diabetic patients receiving insulin should have periodic intraoperative glucose measurement. The authors conducted a care redesign effort to improve intraoperative glucose monitoring. METHODS With approval from Vanderbilt University Human Research Protection Program (Nashville, Tennessee), the authors created an automatic system to identify diabetic patients, detect insulin administration, check for recent glucose measurement, and remind clinicians to check intraoperative glucose. Interrupted time series and propensity score matching were used to quantify pre- and postintervention impact on outcomes. Chi-square/likelihood ratio tests were used to compare surgical site infections at patient follow-up. RESULTS The authors analyzed 15,895 cases (3,994 preintervention and 11,901 postintervention; similar patient characteristics between groups). Intraoperative glucose monitoring rose from 61.6 to 87.3% in cases after intervention (P = 0.0001). Recovery room entry hyperglycemia (fraction of initial postoperative glucose readings greater than 250) fell from 11.0 to 7.2% after intervention (P = 0.0019), while hypoglycemia (fraction of initial postoperative glucose readings less than 75) was unchanged (0.6 vs. 0.9%; P = 0.2155). Eighty-seven percent of patients had follow-up care. After intervention the unadjusted surgical site infection rate fell from 1.5 to 1.0% (P = 0.0061), a 55.4% relative risk reduction. Interrupted time series analysis confirmed a statistically significant surgical site infection rate reduction (P = 0.01). Propensity score matching to adjust for confounders generated a cohort of 7,604 well-matched patients and confirmed a statistically significant surgical site infection rate reduction (P = 0.02). CONCLUSIONS Anesthesiologists add healthcare value by improving perioperative systems. The authors leveraged the one-time cost of programming to improve reliability of intraoperative glucose management and observed improved glucose monitoring, increased insulin administration, reduced recovery room hyperglycemia, and fewer surgical site infections. Their analysis is limited by its applied quasiexperimental design.
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Affiliation(s)
- Jesse M Ehrenfeld
- From the Departments of Anesthesiology, Surgery, Biomedical Informatics, Health Policy, Vanderbilt University School of Medicine, Nashville, Tennessee (J.M.E.); Department of Surgery, Uniformed Services University of the Health Sciences, Vanderbilt University Hospital, Nashville, Tennessee (J.M.E.); Departments of Anesthesiology and Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee (J.P.W.); and Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee (M.T., B.S.R., W.S.S.)
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Hagaman DH, Ehrenfeld JM, Terekhov M, Kla KM, Hamm J, Brumley M, Wanderer JP. Compliance Is Contagious: Using Informatics Methods to Measure the Spread of a Documentation Standard From a Preoperative Clinic. J Perianesth Nurs 2017; 33:436-443. [PMID: 30077286 DOI: 10.1016/j.jopan.2016.08.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 08/25/2016] [Accepted: 08/26/2016] [Indexed: 11/30/2022]
Abstract
PURPOSE Preoperative documentation is essential to coordinated care and has the potential for standardization, which may facilitate downstream clinical management. DESIGN An observational pre/post standardization design was used. METHODS We analyzed the implementation of a preoperative documentation standardization intervention in Vanderbilt's Preoperative Evaluation Clinic (VPEC) and its impact outside VPEC. A phased intervention consisted of clinician education with monthly feedback, followed by the development of a compliance dashboard and inclusion in Ongoing Professional Performance Evaluation system by VPEC. A follow-up survey was administered to measure the impact on clinical management. FINDINGS Adherence to standardization was improved with the addition of electronic feedback. Implementation of this system in the preoperative clinic had significant impact outside VPEC. Trainee status was a significant predictor of adoption of the standardized format. CONCLUSIONS Adoption of a preoperative documentation standard in a clinic had a positive impact on standardization practices in a perioperative system.
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Denysenkov V, Terekhov M, Maeder R, Fischer S, Zangos S, Vogl T, Prisner TF. Continuous-flow DNP polarizer for MRI applications at 1.5 T. Sci Rep 2017; 7:44010. [PMID: 28290535 PMCID: PMC5349512 DOI: 10.1038/srep44010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 02/02/2017] [Indexed: 01/28/2023] Open
Abstract
Here we describe a new hyperpolarization approach for magnetic resonance imaging applications at 1.5 T. Proton signal enhancements of more than 20 were achieved with a newly designed multimode microwave resonator situated inside the bore of the imager and used for Overhauser dynamic nuclear polarization of the water proton signal. Different from other approaches in our setup the hyperpolarization is achieved continuously by liquid water flowing through the polarizer under continuous microwave excitation. With an available flow rate of up to 1.5 ml/min, which should be high enough for DNP MR angiography applications in small animals like mice and rats. The hyperpolarized liquid cooled to physiological temperature can be routed by a mechanical switch to a quartz capillary for injection into the blood vessels of the target object. This new approach allows hyperpolarization of protons without the need of an additional magnet and avoids the losses arising from the transfer of the hyperpolarized solution between magnets. The signal-to-noise improvement of this method is demonstrated on two- and three-dimensional phantoms of blood vessels.
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Affiliation(s)
- V Denysenkov
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
| | - M Terekhov
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - R Maeder
- Institute of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - S Fischer
- Institute of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - S Zangos
- Institute of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - T Vogl
- Institute of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - T F Prisner
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
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Triphan SMF, Jobst BJ, Anjorin A, Sedlaczek O, Wolf U, Terekhov M, Hoffmann C, Ley S, Düber C, Biederer J, Kauczor HU, Jakob PM, Wielpütz MO. Reproducibility and comparison of oxygen-enhanced T1 quantification in COPD and asthma patients. PLoS One 2017; 12:e0172479. [PMID: 28207845 PMCID: PMC5312969 DOI: 10.1371/journal.pone.0172479] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 02/06/2017] [Indexed: 12/25/2022] Open
Abstract
T1 maps have been shown to yield useful diagnostic information on lung function in patients with chronic obstructive pulmonary disease (COPD) and asthma, both for native T1 and ΔT1, the relative reduction while breathing pure oxygen. As parameter quantification is particularly interesting for longitudinal studies, the purpose of this work was both to examine the reproducibility of lung T1 mapping and to compare T1 found in COPD and asthma patients using IRSnapShotFLASH embedded in a full MRI protocol. 12 asthma and 12 COPD patients (site 1) and further 15 COPD patients (site 2) were examined on two consecutive days. In each patient, T1 maps were acquired in 8 single breath-hold slices, breathing first room air, then pure oxygen. Maps were partitioned into 12 regions each to calculate average values. In asthma patients, the average T1,RA = 1206ms (room air) was reduced to T1,O2 = 1141ms under oxygen conditions (ΔT1 = 5.3%, p < 5⋅10−4), while in COPD patients both native T1,RA = 1125ms was significantly shorter (p < 10−3) and the relative reduction to T1,O2 = 1081ms on average ΔT1 = 4.2%(p < 10−5). On the second day, with T1,RA = 1186ms in asthma and T1,RA = 1097ms in COPD, observed values were slightly shorter on average in all patient groups. ΔT1 reduction was the least repeatable parameter and varied from day to day by up to 23% in individual asthma and 30% in COPD patients. While for both patient groups T1 was below the values reported for healthy subjects, the T1 and ΔT1 found in asthmatics lies between that of the COPD group and reported values for healthy subjects, suggesting a higher blood volume fraction and better ventilation. However, it could be demonstrated that lung T1 quantification is subject to notable inter-examination variability, which here can be attributed both to remaining contrast agent from the previous day and the increased dependency of lung T1 on perfusion and thus current lung state.
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Affiliation(s)
- Simon M. F. Triphan
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Experimental Physics 5, Julius-Maximilians Universität Würzburg, Würzburg, Germany
- * E-mail:
| | - Bertram J. Jobst
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
| | - Angela Anjorin
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
| | - Oliver Sedlaczek
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
| | - Ursula Wolf
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Radiology, Mainz University Medical School, Mainz, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
| | - Maxim Terekhov
- Department of Radiology, Mainz University Medical School, Mainz, Germany
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Christian Hoffmann
- Department of Radiology, Mainz University Medical School, Mainz, Germany
| | - Sebastian Ley
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Institute for Clinical Radiology, Ludwig Maximilians Universität München, Munich, Germany
| | - Christoph Düber
- Department of Radiology, Mainz University Medical School, Mainz, Germany
| | - Jürgen Biederer
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Radiologie Darmstadt, Department of Radiology Hospital Gross-Gerau, Gross-Gerau, Germany
| | - Hans-Ulrich Kauczor
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
| | - Peter M. Jakob
- Department of Experimental Physics 5, Julius-Maximilians Universität Würzburg, Würzburg, Germany
| | - Mark O. Wielpütz
- Department of Diagnostic & Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany
- Translational Lung Research Center Heidelberg (TLRC), Member of the German Lung Research Center (DZL), Heidelberg, Germany
- Department of Diagnostic & Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany
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McEvoy MD, Wanderer JP, King AB, Geiger TM, Tiwari V, Terekhov M, Ehrenfeld JM, Furman WR, Lee LA, Sandberg WS. A perioperative consult service results in reduction in cost and length of stay for colorectal surgical patients: evidence from a healthcare redesign project. Perioper Med (Lond) 2016; 5:3. [PMID: 26855773 PMCID: PMC4743367 DOI: 10.1186/s13741-016-0028-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 01/29/2016] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND A major restructuring of perioperative care delivery is required to reduce cost while improving patient outcomes. In a test implementation of this notion, we developed and implemented a perioperative consult service (PCS) for colorectal surgery patients. METHODS A 6-month planning process was undertaken to engage key stakeholders from surgery, nursing, and anesthesia in a healthcare redesign project that resulted in the creation of a PCS to implement a coordinated clinical pathway. After Institutional Review Board (IRB) approval, data were collected for all elective colorectal procedures for three phases: phase 0 (pre-implementation; 1/2014-6/2014), phase 1 (7/2014-10/2014), and phase 2 (11/2014-10/2015). Length of stay (primary endpoint; LOS), total hospital cost, use of clinical pathway components, markers of functional recovery, and readmission and reoperation rates were analyzed. Outcomes and patient characteristics among phases were compared by two-tailed t tests and Wilcoxon rank-sum tests. Categorical variables were analyzed by chi-square and Fisher's exact tests. RESULTS We studied 544 patients (phase 0 = 179; phase 1 = 124; phase 2 = 241), with 365 consecutive patients being cared for in the redesigned care structure. Median LOS was reduced and sustained after implementation (phase 0, 4.24 days; phase 1, 3.32 days; phase 2, 3.32 days, P < 0.01 phase 0 v. phases 1 and 2), and mean LOS was reduced in phase 2 (phase 0, 5.26 days; phase 1, 4.93 days; phase 2, 4.36 days, P < 0.01 phase 0 v. phase 2). Total hospital cost was reduced by 17 % (P = 0.05, median). Application of clinical pathway components was higher in phases 1 and 2 compared to phase 0 (P < 0.01 for all components except anti-emetics); measures of functional recovery improved with successive phases. Reoperation and 30-day readmission rates were no different in phase 1 or phase 2 compared to phase 0 (P > 0.15). CONCLUSIONS Restructuring of perioperative care delivery through the launch of a PCS-reduced LOS and total cost in a significant and sustainable fashion for colorectal surgery patients. Based on the success of this care redesign project, hospital administration is funding expansion to additional services.
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Affiliation(s)
- Matthew D. McEvoy
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - Jonathan P. Wanderer
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Biomedical Informatics, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - Adam B. King
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - Timothy M. Geiger
- />Division of Colon and Rectal Surgery, Vanderbilt University School of Medicine, 1161 21st Ave South, D5248, Nashville, TN 37232-2543 USA
| | - Vikram Tiwari
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Biomedical Informatics, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - Maxim Terekhov
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - Jesse M. Ehrenfeld
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Biomedical Informatics, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Surgery, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Health Policy, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - William R. Furman
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Surgery, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - Lorri A. Lee
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Division of Neuroanesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
| | - Warren S. Sandberg
- />Department of Anesthesiology, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Biomedical Informatics, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
- />Department of Surgery, Vanderbilt University School of Medicine, Vanderbilt University Hospital, Nashville, TN 37232 USA
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Terekhov M, Krummenacker J, Denysenkov V, Gerz K, Prisner T, Schreiber LM. Characterization and optimization of the visualization performance of continuous flow overhauser DNP hyperpolarized water MRI: Inversion recovery approach. Magn Reson Med 2015; 75:985-96. [PMID: 25884985 DOI: 10.1002/mrm.25574] [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] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 11/11/2014] [Accepted: 11/15/2014] [Indexed: 01/08/2023]
Abstract
PURPOSE Overhauser dynamic nuclear polarization (DNP) allows the production of liquid hyperpolarized substrate inside the MRI magnet bore as well as its administration in continuous flow mode to acquire MR images with enhanced signal-to-noise ratio. We implemented inversion recovery preparation in order to improve contrast-to-noise ratio and to quantify the overall imaging performance of Overhauser DNP-enhanced MRI. METHOD The negative enhancement created by DNP in combination with inversion recovery (IR) preparation allows canceling selectively the signal originated from Boltzmann magnetization and visualizing only hyperpolarized fluid. The theoretical model describing gain of MR image intensity produced by steady-state continuous flow DNP hyperpolarized magnetization was established and proved experimentally. RESULTS A precise quantification of signal originated purely from DNP hyperpolarization was achieved. A temperature effect on longitudinal relaxation had to be taken into account to fit experimental results with numerical prediction. CONCLUSION Using properly adjusted IR preparation, the complete zeroing of thermal background magnetization was achieved, providing an essential increase of contrast-to-noise ratio of DNP-hyperpolarized water images. To quantify and optimize the steady-state conditions for MRI with continuous flow DNP, an approach similar to that incorporating transient-state thermal magnetization equilibrium in spoiled fast field echo imaging sequences can be used.
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Affiliation(s)
- Maxim Terekhov
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - Jan Krummenacker
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany.,Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany
| | - Vasyl Denysenkov
- Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany
| | - Kathrin Gerz
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - Thomas Prisner
- Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany
| | - Laura Maria Schreiber
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany
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Güldner M, Becker S, Wolf U, Düber C, Friesenecker A, Gast KK, Heil W, Hoffmann C, Karpuk S, Otten EW, Rivoire J, Salhi Z, Scholz A, Schreiber LM, Terekhov M. Application unit for the administration of contrast gases for pulmonary magnetic resonance imaging: optimization of ventilation distribution for (3) He-MRI. Magn Reson Med 2014; 74:884-93. [PMID: 25213218 DOI: 10.1002/mrm.25433] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 08/05/2014] [Accepted: 08/06/2014] [Indexed: 11/05/2022]
Abstract
PURPOSE MRI of lung airspaces using gases with MR-active nuclei ((3) He, (129) Xe, and (19) F) is an important area of research in pulmonary imaging. The volume-controlled administration of gas mixtures is important for obtaining quantitative information from MR images. State-of-the-art gas administration using plastic bags (PBs) does not allow for a precise determination of both the volume and timing of a (3) He bolus. METHODS A novel application unit (AU) was built according to the requirements of the German medical devices law. Integrated spirometers enable the monitoring of the inhaled gas flow. The device is particularly suited for hyperpolarized (HP) gases (e.g., storage and administration with minimal HP losses). The setup was tested in a clinical trial (n = 10 healthy volunteers) according to the German medicinal products law using static and dynamic ventilation HP-(3) He MRI. RESULTS The required specifications for the AU were successfully realized. Compared to PB-administration, better reproducibility of gas intrapulmonary distribution was observed when using the AU for both static and dynamic ventilation imaging. CONCLUSION The new AU meets the special requirements for HP gases, which are storage and administration with minimal losses. Our data suggest that gas AU-administration is superior to manual modes for determining the key parameters of dynamic ventilation measurements.
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Affiliation(s)
- M Güldner
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | | | - U Wolf
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - C Düber
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | | | - K K Gast
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - W Heil
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - C Hoffmann
- Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - S Karpuk
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - E W Otten
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - J Rivoire
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
| | - Z Salhi
- Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany
| | - A Scholz
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
| | - L M Schreiber
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
| | - M Terekhov
- Department of Radiology, Section of Medical Physics, University Medical Center Mainz, Mainz, Germany
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Wolf U, Hoffmann C, Terekhov M, Bojadzic N, Karpuk S, Düber C, Korn S, Gast KK. Offene monozentrische He-MRT-Studie an Asthma Patienten: Effekt der Bronchodilatation auf Ventilationsdefekte und Lungenfunktion: erste Ergebnisse. ROFO-FORTSCHR RONTG 2014. [DOI: 10.1055/s-0034-1373421] [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: 10/25/2022]
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Terekhov M, Scholz A, Schreiber LM. Measurement of anesthetic uptake kinetics in the brain using (19)F MRI and cross-correlation analysis after pulsed application. MAGMA 2013; 27:107-11. [PMID: 23760558 DOI: 10.1007/s10334-013-0380-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 04/25/2013] [Accepted: 05/02/2013] [Indexed: 11/29/2022]
Abstract
OBJECT We present a pilot study based on (19)F-MRI to measure fast and slow wash-in and wash-out kinetics of volatile anesthetics in pig brain. METHOD The periodic administration of anesthetics in pulsed mode is used to enhance the sensitivity of the anesthetic concentration detection by (19)F-MRI signal. Temporal correlation analysis allows mapping the kinetics time constants. RESULTS The clear correlation response to anesthetics concentration changes was found in the brain region in comparison with fatty tissues. CONCLUSION The methodology may yield important pharmacological findings on regional effect of the anesthetics in brain and be a step towards human studies.
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Affiliation(s)
- Maxim Terekhov
- Department of Radiology, Section of Medical Physics, Johannes Gutenberg University Medical Center Mainz, Langenbeckstrasse 1, 55131, Mainz, Germany,
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Wolf U, Gueldner M, Terekhov M, Hoffmann C, Gast KK, Dueber C. 3He-MRT der Lunge: Vergleich von 2 Applikationsmethoden an gesunden Probanden. ROFO-FORTSCHR RONTG 2013. [DOI: 10.1055/s-0033-1346283] [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: 10/26/2022]
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Kleschyov AL, Sen' V, Golubev V, Münnemann K, Hinderberger D, Lackner KJ, Weber S, Terekhov M, Schreiber LM, Münzel T. Heparin-polynitroxides: synthesis and preliminary evaluation as cardiovascular EPR/MR imaging probes and extracellular space-targeted antioxidants. Eur J Med Chem 2012; 58:265-71. [PMID: 23127990 DOI: 10.1016/j.ejmech.2012.09.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 07/11/2012] [Accepted: 09/24/2012] [Indexed: 10/27/2022]
Abstract
We report here the synthesis of heparin-polynitroxide derivatives (HPNs) in which nitroxide moieties are linked either to uronic acid or glycosamine residues of the heparin macromolecule. HPNs have low anticoagulant activity, possess superoxide scavenging properties, bind to the vascular endothelium/extra-cellular matrix and can be detected by EPR and MRI techniques. As the vascular wall-targeted redox-active paramagnetic compounds, HPNs may have both diagnostic (molecular MRI) and therapeutic (ecSOD mimics) applications.
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Affiliation(s)
- Andrei L Kleschyov
- Second Medical Department, University Medical Center, Johannes Gutenberg University, Mainz 55131, Germany.
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Bauman G, Scholz A, Rivoire J, Terekhov M, Friedrich J, de Oliveira A, Semmler W, Schreiber LM, Puderbach M. Lung ventilation- and perfusion-weighted Fourier decomposition magnetic resonance imaging: in vivo validation with hyperpolarized 3He and dynamic contrast-enhanced MRI. Magn Reson Med 2012; 69:229-37. [PMID: 22392633 DOI: 10.1002/mrm.24236] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 01/14/2012] [Accepted: 02/13/2012] [Indexed: 12/22/2022]
Abstract
The purpose of this work was to validate ventilation-weighted (VW) and perfusion-weighted (QW) Fourier decomposition (FD) magnetic resonance imaging (MRI) with hyperpolarized (3)He MRI and dynamic contrast-enhanced perfusion (DCE) MRI in a controlled animal experiment. Three healthy pigs were studied on 1.5-T MR scanner. For FD MRI, the VW and QW images were obtained by postprocessing of time-resolved lung image sets. DCE acquisitions were performed immediately after contrast agent injection. (3)He MRI data were acquired following the administration of hyperpolarized helium and nitrogen mixture. After baseline MR scans, pulmonary embolism was artificially produced. FD MRI and DCE MRI perfusion measurements were repeated. Subsequently, atelectasis and air trapping were induced, which followed with FD MRI and (3)He MRI ventilation measurements. Distributions of signal intensities in healthy and pathologic lung tissue were compared by statistical analysis. Images acquired using FD, (3)He, and DCE MRI in all animals before the interventional procedure showed homogeneous ventilation and perfusion. Functional defects were detected by all MRI techniques at identical anatomical locations. Signal intensity in VW and QW images was significantly lower in pathological than in healthy lung parenchyma. The study has shown usefulness of FD MRI as an alternative, noninvasive, and easily implementable technique for the assessment of acute changes in lung function.
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Affiliation(s)
- Grzegorz Bauman
- Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany.
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Krummenacker JG, Denysenkov VP, Terekhov M, Schreiber LM, Prisner TF. DNP in MRI: an in-bore approach at 1.5 T. J Magn Reson 2012; 215:94-99. [PMID: 22248644 DOI: 10.1016/j.jmr.2011.12.015] [Citation(s) in RCA: 22] [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] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 12/16/2011] [Accepted: 12/18/2011] [Indexed: 05/31/2023]
Abstract
We have used liquid state ("Overhauser") Dynamic Nuclear Polarization (DNP) to significantly enhance the signal to noise ratio (SNR) of Magnetic Resonance Imaging (MRI). For the first time this was achieved by hyperpolarizing directly in the MRI-scanner field of 1.5 T in continuous flow mode and immediately delivering the hyperpolarized substance to the imaging site to ensure maximum contrast between hyperpolarized sample and sample at thermal polarization. We achieve a maximum absolute signal enhancement factor of 98; while the hyperpolarized sample is transported at a flow rate of up to 30 ml/h yielding an average flow speed up to 470 mm/s over a distance of approximately 80 mm. A spatial imaging resolution of 100 μm with a signal to noise ratio of 25 was achieved on the flowing sample. Application to MRI contrast enhancement or microfluidic imaging can be envisaged immediately.
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Affiliation(s)
- Jan G Krummenacker
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany.
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Terekhov M, Rivoire J, Scholz A, Wolf U, Karpuk S, Salhi Z, Koebrich R, David M, Schreiber LM. Measurement of gas transport kinetics in high-frequency oscillatory ventilation (HFOV) of the lung using hyperpolarized (3)He magnetic resonance imaging. J Magn Reson Imaging 2011; 32:887-94. [PMID: 20882619 DOI: 10.1002/jmri.22318] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To protect the patient with acute respiratory distress syndrome from ventilator associated lung injury (VALI) high-frequency oscillatory ventilation (HFOV) is used. Clinical experience has proven that HFOV is an efficient therapy when conventional artificial ventilation is insufficient. However, the optimal settings of HFOV parameters, eg, tidal volumes, pressure amplitudes and frequency for maximal lung protection, and efficient gas exchange are not established unambiguously. METHODS In this work magnetic resonance imaging (MRI) with hyperpolarized (3)He was employed to visualize the redistribution of gas within the cadaver pig lung during HFOV. The saturated slice method was used to characterize fast gas kinetics. RESULTS The strong differences in kinetics were observed for HFOV-driven gas exchange in comparison with diffusive gas transport (apnea). The significant regional and HFOV frequency dependence was detected for washout and gas exchange within the lungs. Gas redistribution was much faster in posterior than in anterior parts of the lungs during HFOV, in contrast to minor differences with an opposite trend observed in apnea. CONCLUSION The method shows significant potential for visualization and quantification of gas redistribution under HFOV and may help in optimization of the parameters to improve the clinical effect of HFOV for patients.
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Affiliation(s)
- Maxim Terekhov
- Section of Medical Physics, Department of Radiology, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany.
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Santoro D, Rivoire J, Meise F, Terekhov M, Salhi Z, Gast K, Schreiber LM. Three-dimensional mapping of the B
1
field using an optimized phase-based method: Application to hyperpolarized 3
He in lungs. Magn Reson Med 2010; 65:1166-72. [DOI: 10.1002/mrm.22683] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 07/29/2010] [Accepted: 09/19/2010] [Indexed: 11/08/2022]
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Friedrich J, Rivoire J, Terekhov M, Scholz AW, Köbrich R, Schreiber LM. 19-F-Gas-MRT zur Untersuchung des Gasflusses während Hochfrequenz-Oszillations-Ventilation (HFOV). ROFO-FORTSCHR RONTG 2010. [DOI: 10.1055/s-0030-1268287] [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: 10/18/2022]
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Wolf U, Scholz A, Terekhov M, Koebrich R, David M, Schreiber LM. Visualization of inert gas wash-out during high-frequency oscillatory ventilation using fluorine-19 MRI. Magn Reson Med 2010; 64:1478-83. [DOI: 10.1002/mrm.22528] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Rivoire J, Terekhov M, Meise FM, Gast K, Salhi Z, Schreiber LM. Flip-angle measurement by magnetization inversion: Calibration of magnetization nutation angle in hyperpolarized 3
He magnetic resonance imaging lung experiments. Magn Reson Med 2010; 65:399-408. [DOI: 10.1002/mrm.22638] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 07/02/2010] [Accepted: 08/24/2010] [Indexed: 11/06/2022]
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Meise FM, Rivoire J, Terekhov M, Wiggins GC, Keil B, Karpuk S, Salhi Z, Wald LL, Schreiber LM. Design and evaluation of a 32-channel phased-array coil for lung imaging with hyperpolarized 3-helium. Magn Reson Med 2010; 63:456-64. [PMID: 20099333 DOI: 10.1002/mrm.22265] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Imaging with hyperpolarized 3-helium is becoming an increasingly important technique for MRI diagnostics of the lung but is hampered by long breath holds (>20 sec), which are not always applicable in patients with severe lung disease like chronic obstructive pulmonary disease (COPD) or alpha-1-anti-trypsin deficiency. Additionally, oxygen-induced depolarization decay during the long breath holds complicates interpretation of functional data such as apparent diffusion coefficients. To address these issues, we describe and validate a 1.5-T, 32-channel array coil for accelerated (3)He lung imaging and demonstrate its ability to speed up imaging (3)He. A signal-to-noise ratio increase of up to a factor of 17 was observed compared to a conventional double-resonant birdcage for unaccelerated imaging, potentially allowing increased image resolution or decreased gas production requirements. Accelerated imaging of the whole lung with one-dimensional and two-dimensional acceleration factors of 4 and 4 x 2, respectively, was achieved while still retaining excellent image quality. Finally, the potential of highly parallel detection in lung imaging is demonstrated with high-resolution morphologic and functional images.
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Affiliation(s)
- Florian M Meise
- Section of Medical Physics, Department of Diagnostic and Interventional Radiology, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany
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Meise FM, Rivoire J, Terekhov M, Wiggins GC, Keil B, Wald LL, Schreiber WG. Parallele Bildgebung von hyperpolarisiertem 3He mit einer 32-Kanal-Spule. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221424] [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: 10/20/2022]
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Meise F, Rivoire J, Terekhov M, Santoro D, Kapuk S, Salhi Z, Gast K, Schreiber W. Perspektiven der Lungen-MRT mit hyperpolarisiertem 3-Helium unter Verwendung von paralleler Bildgebung. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1208349] [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: 10/21/2022]
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38
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Shukoor MI, Natalio F, Fischer S, Terekhov M, Schreiber W, Schröder HC, Müller WEG, Tremel W. Functionalized Magnetic Nano-particles for Selective Targeting and Sensing of Cells. Z Anorg Allg Chem 2008. [DOI: 10.1002/zaac.200870146] [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: 11/05/2022]
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39
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Terekhov M, Wolf U, Scholz A, Schreiber WG. Schnelles In-vivo-19F-MRT-T1-Mapping zur Messung der Konzentration von fluorinierten Gasen in der Lunge. ROFO-FORTSCHR RONTG 2008. [DOI: 10.1055/s-2008-1073739] [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: 10/21/2022]
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40
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Wolf U, Scholz A, Terekhov M, Schreiber WG. 19F-MRT der Lunge eines Wash-Outs von C4F8-Gas unter Hochfrequenzoszillationsbeatmung (HFOV). ROFO-FORTSCHR RONTG 2008. [DOI: 10.1055/s-2008-1073585] [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: 10/21/2022]
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41
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Meise FM, Wolf UA, Scholz A, Terekhov M, Bönner FA, Schreiber WG. Bildgebung der Rattenlunge mit 13CO2. ROFO-FORTSCHR RONTG 2007. [DOI: 10.1055/s-2007-976897] [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: 10/21/2022]
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Terekhov M, Neutzler S, Aluas M, Hoepfel D, Oellrich LR. NMR measurements of gaseous sulfur hexafluoride (SF6) to probe the cross-linking of EPDM rubber. Magn Reson Chem 2005; 43:926-36. [PMID: 16086305 DOI: 10.1002/mrc.1648] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The effects of embedding gaseous SF6 into EPDM rubber were investigated using NMR methods. It was found that observed sorption and desorption processes follow the behavior of the dual mode sorption model. A strong correlation was found between EPDM cross-linking and transversal relaxation time of embedded SF6. EPDM samples with different cross-link densities, preliminarily determined by 1H transversal relaxation using the Gotlib model and Litvinov's method, were investigated using embedded SF6. The sensitivity of the 19F transversal relaxation rate of SF6 to the EPDM cross-link density variation was found to be at least 10 times higher than for 1H in the polymer chain. First experiments on probing the swelling effects in EPDM due to its contact with polar liquids have been performed.
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Affiliation(s)
- M Terekhov
- Fachhochschule Karlsruhe, University of Applied Sciences, Moltkestrasse 30, D 76133 Karlsruhe, Germany.
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Neutzler S, Terekhov M, Hoepfel D, Oellrich LR. NMR investigation of gaseous SF6 confinement into EPDM rubber. Magn Reson Imaging 2005; 23:321-3. [PMID: 15833636 DOI: 10.1016/j.mri.2004.11.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2004] [Accepted: 11/15/2004] [Indexed: 11/19/2022]
Abstract
The confinement process of gaseous sulphurhexafluoride (SF6) in ethylene-propylene-diene (EPDM) rubber was investigated by spectroscopic and spatially resolved NMR techniques. A strong elongation of T1 relaxation time of SF6 and a decrease of the diffusion coefficient were found. A possible explanation may be the strong restriction of molecular mobility due to interactions between SF6 and active centers of the EPDM.
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Affiliation(s)
- Sven Neutzler
- Institut für Technische Thermodynamik und Kältetechnik, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany
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Terekhov M, Höpfel D. MRI with the dipolar interaction refocusing techniques: analysis of the effectiveness for the solid-state polymers. Magn Reson Imaging 2004; 22:573-82. [PMID: 15120178 DOI: 10.1016/j.mri.2004.01.049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2003] [Accepted: 01/27/2004] [Indexed: 11/17/2022]
Abstract
The effectiveness of solid-echo and magic-echo phase-encoding solid-state magnetic resonance imaging methods was tested to determine possible improvement of sensitivity and spatial resolution for investigation of various types of solid polymers. The dipolar interaction refocusing pulse sequences have been used to elongate the possible phase-encoding period and to improve the signal sensitivity. The comparison of both dipolar refocusing techniques with conventional single point imaging method was made. The optimization of the phase-encoding time and magnetization recovery periods were performed basing on (1)H spectra and longitudinal relaxation measurements, respectively. The influence of imaging artifacts (intrinsic for each technique) on image quality was investigated. The effectiveness of the artifacts suppression methods was tested.
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Affiliation(s)
- M Terekhov
- Institut für Angewandte Forschung (IAF), Fachhochshule Karlsruhe-University of Applied Science, Karlsruhe, Germany
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Höpfel D, Kaniantoko K, Terekhov M. Magnetic Resonance Imaging (MRI) of fingers with a high spatial resolution using a low-field magnetic system. BIOMED ENG-BIOMED TE 2003; 47 Suppl 1 Pt 1:416-9. [PMID: 12451880 DOI: 10.1515/bmte.2002.47.s1a.416] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
For our low-field resistive MRI-System we have developed suitable rf-probes to be able to image fingers with a possibly high spatial resolution. To reduce the measurement time and to improve the signal/noiseratio, which is inherently bad in a low field system, we used a multi-echo sequence, accumulating up to six echo signals for each image. For a 256 x 256 pixel matrix we achieved with this technique a spatial resolution of 176 microns/pixel in measuring times between 4 and 5 minutes. In comparison to healthy persons also first MR-images of patients suffering on arthrosis at the fingers and small joint injures were acquired. Using a 512 x 512 pixel matrix and a field of view of 5 cm images with a resolution of 80 microns/pixel were recorded in a total measuring time of less than 10 minutes.
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Affiliation(s)
- D Höpfel
- Institut für Innovation und Transfer der FH Karlsruhe-Hochschule für Technik Sensorsystemtechnik.
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