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Tolkkinen K, Mailhiot SE, Selent A, Mankinen O, Henschel H, Nieminen MT, Hanni M, Kantola AM, Liimatainen T, Telkki VV. SPICY: a method for single scan rotating frame relaxometry. Phys Chem Chem Phys 2023; 25:13164-13169. [PMID: 37129427 PMCID: PMC10171246 DOI: 10.1039/d2cp05988f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
T 1ρ is an NMR relaxation mode that is sensitive to low frequency molecular motions, making it an especially valuable tool in biomolecular research. Here, we introduce a new method, SPICY, for measuring T1ρ relaxation times. In contrast to conventional T1ρ experiments, in which the sequence is repeated many times to determine the T1ρ time, the SPICY sequence allows determination of T1ρ within a single scan, shortening the experiment time remarkably. We demonstrate the method using 1H T1ρ relaxation dispersion experiments. Additionally, we combine the sequence with spatial encoding to produce 1D images in a single scan. We show that T1ρ relaxation times obtained using the single scan approach are in good agreement with those obtained using the traditional experiments.
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Affiliation(s)
| | | | - Anne Selent
- NMR Research Unit, University of Oulu, Oulu, Finland.
| | - Otto Mankinen
- NMR Research Unit, University of Oulu, Oulu, Finland.
| | - Henning Henschel
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Miika T Nieminen
- Research Unit of Health Sciences and Technology, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
- Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland
| | - Matti Hanni
- Research Unit of Health Sciences and Technology, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
- Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland
| | - Anu M Kantola
- NMR Research Unit, University of Oulu, Oulu, Finland.
| | - Timo Liimatainen
- Research Unit of Health Sciences and Technology, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
- Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland
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Borreguero J, Galve F, Algarín JM, Benlloch JM, Alonso J. Low field slice-selective ZTE imaging of ultra-short [Formula: see text] tissues based on spin-locking. Sci Rep 2023; 13:1662. [PMID: 36717649 PMCID: PMC9886919 DOI: 10.1038/s41598-023-28640-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
Magnetic Resonance Imaging of hard biological tissues is very challenging due to small proton abundance and ultra-short [Formula: see text] decay times, especially at low magnetic fields, where sample magnetization is weak. While several pulse sequences, such as Ultra-short Echo Time (UTE), Zero Echo Time (ZTE) and SWeep Imaging with Fourier Transformation (SWIFT), have been developed to cope with ultra-short lived MR signals, only the latter two hold promise of imaging tissues with sub-millisecond [Formula: see text] times at low fields. All these sequences are intrinsically volumetric, thus 3D, because standard slice selection using a long soft radio-frequency pulse is incompatible with ultra-short lived signals. The exception is UTE, where double half pulses can perform slice selection, although at the cost of doubling the acquisition time. Here we demonstrate that spin-locking is a versatile and robust method for slice selection for ultra-short lived signals, and present three ways of combining this pulse sequence with ZTE imaging of the selected slice. With these tools, we demonstrate slice-selected 2D ex vivo imaging of the hardest tissues in the body at low field (260 mT) within clinically acceptable times.
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Affiliation(s)
| | - Fernando Galve
- Institute for Molecular Imaging and Instrumentation, Spanish National Research Council, 46022 Valencia, Spain
- Institute for Molecular Imaging and Instrumentation, Universitat Politècnica de València, 46022 Valencia, Spain
| | - José M. Algarín
- Institute for Molecular Imaging and Instrumentation, Spanish National Research Council, 46022 Valencia, Spain
- Institute for Molecular Imaging and Instrumentation, Universitat Politècnica de València, 46022 Valencia, Spain
| | - José M. Benlloch
- Institute for Molecular Imaging and Instrumentation, Spanish National Research Council, 46022 Valencia, Spain
- Institute for Molecular Imaging and Instrumentation, Universitat Politècnica de València, 46022 Valencia, Spain
| | - Joseba Alonso
- Institute for Molecular Imaging and Instrumentation, Spanish National Research Council, 46022 Valencia, Spain
- Institute for Molecular Imaging and Instrumentation, Universitat Politècnica de València, 46022 Valencia, Spain
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3
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Tissue characterization using R 1rho dispersion imaging at low locking fields. Magn Reson Imaging 2021; 84:1-11. [PMID: 34052306 DOI: 10.1016/j.mri.2021.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/11/2021] [Accepted: 05/25/2021] [Indexed: 11/22/2022]
Abstract
Measurements of the variations of spin-locking relaxation rates (R1ρ) with locking field amplitude allow the derivation of quantitative parameters that describe different dynamic processes, such as slow molecular motions, chemical exchange and diffusion. In some samples, changes in R1ρ values between locking frequency 0 and 200 Hz may be dominated mainly by diffusion of water in intrinsic field gradients, while those at higher locking fields are due to exchange processes. The exchange and diffusion effects act independently of each other, as confirmed by simulation and experimentally. In tissues, the relevant intrinsic field gradients may arise from the magnetic inhomogeneities caused by microvascular blood so that R1ρ dispersion over weak locking field amplitudes (≤ 200 Hz) is affected by changes in capillary density and geometry. Here we first review the theoretical and experimental background to the interpretation of R1ρ dispersions caused by intrinsic magnetic susceptibility variations within the tissue. We then provide new empirical results of R1ρ dispersion imaging of the human brain and skeletal muscle at low locking field amplitudes for the first time and identify potential applications of R1ρ dispersion imaging in clinical studies.
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Sogabe T, Ueda H, Ito Y, Taniguchi Y, Kobayashi T. Dependence of stimulus-induced rotary saturation on the direction of target oscillating magnetic fields: A phantom and simulation study. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 321:106849. [PMID: 33128915 DOI: 10.1016/j.jmr.2020.106849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/23/2020] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
Several noninvasive techniques for the direct measurement of the neuronal activity using magnetic resonance imaging (MRI) have recently been reported. As a promising candidate, we focus on a spin-lock MRI sequence (i.e., stimulus-induced rotary saturation (SIRS)) directly measuring a tiny oscillating magnetic field. Previous phantom studies on SIRS have applied the target oscillating magnetic field parallel to the direction of the static magnetic field B0. However, in practice, the neuromagnetic fields are not always aligned in the same direction as in such a condition. This study investigates the MR signal changes during SIRS when the target magnetic field direction is not the same as that of the B0 field through both phantom experiments and Bloch simulations. The experimental results indicate that only the target magnetic field component along the B0 field affects the signal change, indicating that SIRS has partial sensitivity, even if the target magnetic fields are tilted from the B0 field. Furthermore, the simulation results show good agreements with the experimental results. These results clarify the sensitivity direction of SIRS-based fMRI and lead to the possibility that the direction of the generated neuromagnetic fields can be estimated, such that we can separate directional information from the other information contained in neuromagnetic fields (e.g., phase information).
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Affiliation(s)
- Tomoyuki Sogabe
- Department of Electrical Engineering, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Hiroyuki Ueda
- Department of Electrical Engineering, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yosuke Ito
- Department of Electrical Engineering, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yo Taniguchi
- Research & Development Group, Hitachi, Ltd., Japan
| | - Tetsuo Kobayashi
- Department of Electrical Engineering, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
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Shaffer JJ, Mani M, Schmitz SL, Xu J, Owusu N, Wu D, Magnotta VA, Wemmie JA. Proton Exchange Magnetic Resonance Imaging: Current and Future Applications in Psychiatric Research. Front Psychiatry 2020; 11:532606. [PMID: 33192650 PMCID: PMC7542226 DOI: 10.3389/fpsyt.2020.532606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022] Open
Abstract
Proton exchange provides a powerful contrast mechanism for magnetic resonance imaging (MRI). MRI techniques sensitive to proton exchange provide new opportunities to map, with high spatial and temporal resolution, compounds important for brain metabolism and function. Two such techniques, chemical exchange saturation transfer (CEST) and T1 relaxation in the rotating frame (T1ρ), are emerging as promising tools in the study of neurological and psychiatric illnesses to study brain metabolism. This review describes proton exchange for non-experts, highlights the current status of proton-exchange MRI, and presents advantages and drawbacks of these techniques compared to more traditional methods of imaging brain metabolism, including positron emission tomography (PET) and MR spectroscopy (MRS). Finally, this review highlights new frontiers for the use of CEST and T1ρ in brain research.
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Affiliation(s)
- Joseph J Shaffer
- Department of Radiology, University of Iowa, Iowa City, IA, United States
| | - Merry Mani
- Department of Radiology, University of Iowa, Iowa City, IA, United States
| | - Samantha L Schmitz
- Department of Psychiatry, University of Iowa, Iowa City, IA, United States
| | - Jia Xu
- Department of Radiology, University of Iowa, Iowa City, IA, United States
| | - Nana Owusu
- Department of Radiology, University of Iowa, Iowa City, IA, United States.,Pappajohn Biomedical Institute, University of Iowa, Iowa City, IA, United States.,Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
| | - Dee Wu
- Department of Radiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Vincent A Magnotta
- Department of Radiology, University of Iowa, Iowa City, IA, United States.,Department of Psychiatry, University of Iowa, Iowa City, IA, United States.,Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
| | - John A Wemmie
- Department of Psychiatry, University of Iowa, Iowa City, IA, United States.,Pappajohn Biomedical Institute, University of Iowa, Iowa City, IA, United States.,Department of Veterans Affairs Medical Center, Iowa City, IA, United States.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, United States.,Department of Neurosurgery, University of Iowa, Iowa City, IA, United States
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Combined morphological and functional liver MRI using spin-lattice relaxation in the rotating frame (T1ρ) in conjunction with Gadoxetic Acid-enhanced MRI. Sci Rep 2019; 9:2083. [PMID: 30765741 PMCID: PMC6375916 DOI: 10.1038/s41598-018-37689-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 12/12/2018] [Indexed: 12/13/2022] Open
Abstract
Noninvasive early detection of liver cirrhosis and fibrosis is essential for management and therapy. The aim was to investigated whether a combination of the functional parameter relative enhancement (RE) on Gadoxetic Acid magnetic resonance imaging (Gd-EOB-DTPA-enhanced MRI) and the fibrosis parameter T1ρ distinguishes cirrhosis and healthy liver. We analyzed patients with Gd-EOB-DTPA-enhanced MRI and T1ρ mapping. Signal intensity was measured before and after contrast; RE was calculated. T1ρ was measured with circular regions of interest (T1ρ-cROI). A quotient of RE and T1ρ-cROI was calculated: the fibrosis function quotient (FFQ). Cirrhosis was evaluated based on morphology and secondary changes. 213 datasets were included. The difference between cirrhotic and noncirrhotic liver was 51.11 ms vs. 47.56 ms for T1ρ-cROI (p < 0.001), 0.59 vs. 0.70 for RE (p < 0.001), and 89.53 vs. 70.83 for FFQ (p < 0.001). T1ρ-cROI correlated with RE, r = −0.14 (p < 0.05). RE had an AUC of 0.73. The largest AUC had the FFQ with 0.79. The best cutoff value was 48.34 ms for T1ρ-cROI, 0.70 for RE and 78.59 ms for FFQ. In conclusion T1ρ and RE can distinguish between cirrhotic and noncirrhotic liver. The FFQ, which is the combination of the two, improves diagnostic performance.
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Truong TK, Roberts KC, Woldorff MG, Song AW. Toward direct MRI of neuro-electro-magnetic oscillations in the human brain. Magn Reson Med 2019; 81:3462-3475. [PMID: 30652351 DOI: 10.1002/mrm.27654] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 11/12/2018] [Accepted: 12/13/2018] [Indexed: 11/07/2022]
Abstract
PURPOSE Neuroimaging techniques are widely used to investigate the function of the human brain, but none are currently able to accurately localize neuronal activity with both high spatial and temporal specificity. Here, a new in vivo MRI acquisition and analysis technique based on the spin-lock mechanism is developed to noninvasively image local magnetic field oscillations resulting from neuroelectric activity in specifiable frequency bands. METHODS Simulations, phantom experiments, and in vivo experiments using an eyes-open/eyes-closed task in 8 healthy volunteers were performed to demonstrate its sensitivity and specificity for detecting oscillatory neuroelectric activity in the alpha-band (8-12 Hz). A comprehensive postprocessing procedure was designed to enhance the neuroelectric signal, while minimizing any residual hemodynamic and physiological confounds. RESULTS The phantom results show that this technique can detect 0.06-nT magnetic field oscillations, while the in vivo results demonstrate that it can image task-based modulations of neuroelectric oscillatory activity in the alpha-band. Multiple control experiments and a comparison with conventional BOLD functional MRI suggest that the activation was likely not due to any residual hemodynamic or physiological confounds. CONCLUSION These initial results provide evidence suggesting that this new technique has the potential to noninvasively and directly image neuroelectric activity in the human brain in vivo. With further development, this approach offers the promise of being able to do so with a combination of spatial and temporal specificity that is beyond what can be achieved with existing neuroimaging methods, which can advance our ability to study the functions and dysfunctions of the human brain.
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Affiliation(s)
- Trong-Kha Truong
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
| | - Kenneth C Roberts
- Center for Cognitive Neuroscience, Duke University, Durham, North Carolina
| | - Marty G Woldorff
- Center for Cognitive Neuroscience, Duke University, Durham, North Carolina
| | - Allen W Song
- Brain Imaging and Analysis Center, Duke University, Durham, North Carolina
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8
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Gilani IA, Sepponen R. Quantitative rotating frame relaxometry methods in MRI. NMR IN BIOMEDICINE 2016; 29:841-861. [PMID: 27100142 DOI: 10.1002/nbm.3518] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 01/21/2016] [Accepted: 02/18/2016] [Indexed: 06/05/2023]
Abstract
Macromolecular degeneration and biochemical changes in tissue can be quantified using rotating frame relaxometry in MRI. It has been shown in several studies that the rotating frame longitudinal relaxation rate constant (R1ρ ) and the rotating frame transverse relaxation rate constant (R2ρ ) are sensitive biomarkers of phenomena at the cellular level. In this comprehensive review, existing MRI methods for probing the biophysical mechanisms that affect the rotating frame relaxation rates of the tissue (i.e. R1ρ and R2ρ ) are presented. Long acquisition times and high radiofrequency (RF) energy deposition into tissue during the process of spin-locking in rotating frame relaxometry are the major barriers to the establishment of these relaxation contrasts at high magnetic fields. Therefore, clinical applications of R1ρ and R2ρ MRI using on- or off-resonance RF excitation methods remain challenging. Accordingly, this review describes the theoretical and experimental approaches to the design of hard RF pulse cluster- and adiabatic RF pulse-based excitation schemes for accurate and precise measurements of R1ρ and R2ρ . The merits and drawbacks of different MRI acquisition strategies for quantitative relaxation rate measurement in the rotating frame regime are reviewed. In addition, this review summarizes current clinical applications of rotating frame MRI sequences. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Irtiza Ali Gilani
- Brain Research Unit, Department of Neuroscience and Biomedical Engineering, Aalto University, Aalto, Finland
- Advanced Magnetic Imaging Center, Aalto University, Aalto, Finland
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
| | - Raimo Sepponen
- Department of Electronics, School of Electrical Engineering, Aalto University, Aalto, Finland
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Johnson CP, Heo HY, Thedens DR, Wemmie JA, Magnotta VA. Rapid acquisition strategy for functional T1ρ mapping of the brain. Magn Reson Imaging 2014; 32:1067-77. [PMID: 25093630 PMCID: PMC4171198 DOI: 10.1016/j.mri.2014.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 05/27/2014] [Accepted: 07/25/2014] [Indexed: 11/29/2022]
Abstract
Functional T1ρ mapping has been proposed as a method to assess pH and metabolism dynamics in the brain with high spatial and temporal resolution. The purpose of this work is to describe and evaluate a variant of the spin-locked echo-planar imaging sequence for functional T1ρ mapping at 3T. The proposed sequence rapidly acquires a time series of T1ρ maps with 4.0second temporal resolution and 10 slices of volumetric coverage. Simulation, phantom, and in vivo experiments are used to evaluate many aspects of the sequence and its implementation including fidelity of measured T1ρ dynamics, potential confounds to the T1ρ response, imaging parameter tradeoffs, time series analysis approaches, and differences compared to blood oxygen level dependent functional magnetic resonance imaging. It is shown that the high temporal resolution and volumetric coverage of the sequence are obtained with some expense including underestimation of the T1ρ response, sensitivity to T1 dynamics, and reduced signal-to-noise ratio. In vivo studies using a flashing checkerboard functional magnetic resonance imaging paradigm suggest differences between T1ρ and blood oxygen level dependent activation patterns. Possible sources of the functional T1ρ response and potential sequence improvements are discussed. The capability of T1ρ to map whole-brain pH and metabolism dynamics with high temporal and spatial resolution is potentially unique and warrants further investigation and development.
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Affiliation(s)
| | - Hye-Young Heo
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA
| | | | - John A Wemmie
- Department of Psychiatry, University of Iowa, Iowa City, IA; Department of Veterans Affairs Medical Center, Iowa City, IA
| | - Vincent A Magnotta
- Department of Radiology, University of Iowa, Iowa City, IA; Department of Biomedical Engineering, University of Iowa, Iowa City, IA; Department of Psychiatry, University of Iowa, Iowa City, IA
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10
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Wang L, Regatte RR. T₁ρ MRI of human musculoskeletal system. J Magn Reson Imaging 2014; 41:586-600. [PMID: 24935818 DOI: 10.1002/jmri.24677] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 06/03/2014] [Indexed: 12/21/2022] Open
Abstract
Magnetic resonance imaging (MRI) offers the direct visualization of the human musculoskeletal (MSK) system, especially all diarthrodial tissues including cartilage, bone, menisci, ligaments, tendon, hip, synovium, etc. Conventional MRI techniques based on T1 - and T2 -weighted, proton density (PD) contrast are inconclusive in quantifying early biochemically degenerative changes in MSK system in general and articular cartilage in particular. In recent years, quantitative MR parameter mapping techniques have been used to quantify the biochemical changes in articular cartilage, with a special emphasis on evaluating joint injury, cartilage degeneration, and soft tissue repair. In this article we focus on cartilage biochemical composition, basic principles of T1ρ MRI, implementation of T1ρ pulse sequences, biochemical validation, and summarize the potential applications of the T1ρ MRI technique in MSK diseases including osteoarthritis (OA), anterior cruciate ligament (ACL) injury, and knee joint repair. Finally, we also review the potential advantages, challenges, and future prospects of T1ρ MRI for widespread clinical translation.
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Affiliation(s)
- Ligong Wang
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, Suzhou, Jiangsu, China
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Cartilage repair surgery: outcome evaluation by using noninvasive cartilage biomarkers based on quantitative MRI techniques? BIOMED RESEARCH INTERNATIONAL 2014; 2014:840170. [PMID: 24877139 PMCID: PMC4024422 DOI: 10.1155/2014/840170] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/25/2014] [Indexed: 12/13/2022]
Abstract
BACKGROUND New quantitative magnetic resonance imaging (MRI) techniques are increasingly applied as outcome measures after cartilage repair. OBJECTIVE To review the current literature on the use of quantitative MRI biomarkers for evaluation of cartilage repair at the knee and ankle. METHODS Using PubMed literature research, studies on biochemical, quantitative MR imaging of cartilage repair were identified and reviewed. RESULTS Quantitative MR biomarkers detect early degeneration of articular cartilage, mainly represented by an increasing water content, collagen disruption, and proteoglycan loss. Recently, feasibility of biochemical MR imaging of cartilage repair tissue and surrounding cartilage was demonstrated. Ultrastructural properties of the tissue after different repair procedures resulted in differences in imaging characteristics. T2 mapping, T1rho mapping, delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), and diffusion weighted imaging (DWI) are applicable on most clinical 1.5 T and 3 T MR scanners. Currently, a standard of reference is difficult to define and knowledge is limited concerning correlation of clinical and MR findings. The lack of histological correlations complicates the identification of the exact tissue composition. CONCLUSIONS A multimodal approach combining several quantitative MRI techniques in addition to morphological and clinical evaluation might be promising. Further investigations are required to demonstrate the potential for outcome evaluation after cartilage repair.
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Rane S, Spear JT, Zu Z, Donahue MJ, Gore JC. Functional MRI using spin lock editing preparation pulses. Magn Reson Imaging 2014; 32:813-8. [PMID: 24848291 DOI: 10.1016/j.mri.2014.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 04/03/2014] [Indexed: 10/25/2022]
Abstract
A novel approach for detecting blood oxygenation level-dependent (BOLD) signals in the brain is investigated using spin locking (SL) pulses to selectively edit the effects of extravascular diffusion in field gradients from different sized vascular structures. We show that BOLD effects from diffusion amongst susceptibility gradients will contribute significantly not only to transverse relaxation rates (R2* and R2) but also to R1ρ, the rate of longitudinal relaxation in the rotating frame. Similar to the ability of 180-degree pulses to refocus static dephasing effects in a spin echo, moderately strong SL pulses can also reduce contributions of diffusion in large-scale gradients and the choice of SL amplitude can be used to selectively emphasize smaller scale inhomogeneities (such as microvasculature) and to drastically reduce the influence of larger structures (such as veins). Moreover, measurements over a range of locking fields can be used to derive estimates of the spatial scales of intrinsic gradients. The method was used to detect BOLD activation in human visual cortex. Eight healthy young adults were imaged at 3T using a single-slice, SL-prepped turbo spin echo (TSE) sequence with spin-lock amplitudes ω1=80Hz and 400Hz, along with conventional T2*-weighted and T2-prepped sequences. The BOLD signal varied from 1.1±0.4 % (ω1=80Hz) to 0.7±0.2 % (at 400Hz), whereas the T2-weighted sequence measured 1.3±0.3 % and the T2* sequence measured 1.9±0.3 %. This new R1ρ functional contrast can be made selectively sensitive to intrinsic gradients of different spatial scales, thereby increasing the spatial specificity of the evoked response.
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Affiliation(s)
- Swati Rane
- Vanderbilt University Institute of Imaging Science, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - John T Spear
- Vanderbilt University Institute of Imaging Science, Nashville, TN, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA
| | - Zhongliang Zu
- Vanderbilt University Institute of Imaging Science, Nashville, TN, USA
| | - Manus J Donahue
- Vanderbilt University Institute of Imaging Science, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA; Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
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Liu Q, Tawackoli W, Pelled G, Fan Z, Jin N, Natsuaki Y, Bi X, Gart A, Bae H, Gazit D, Li D. Detection of low back pain using pH level-dependent imaging of the intervertebral disc using the ratio of R1ρ dispersion and -OH chemical exchange saturation transfer (RROC). Magn Reson Med 2014; 73:1196-205. [PMID: 24700573 DOI: 10.1002/mrm.25186] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 01/28/2014] [Accepted: 01/28/2014] [Indexed: 11/08/2022]
Abstract
PURPOSE Low pH is associated with intervertebral disc (IVD)-generated low back pain (LBP). The purpose of this work was to develop an in vivo pH level-dependent magnetic resonance imaging (MRI) method for detecting discogenic LBP, without using exogenous contrast agents. METHODS The ratio of R1ρ dispersion and chemical exchange saturation transfer (CEST) (RROC) was used for pH-level dependent imaging of the IVD while eliminating the effect of labile proton concentration. The technique was validated by numerical simulations and studies on phantoms and ex vivo porcine spines. Four male (ages 42.8 ± 18.3) and two female patients (ages 55.5 ± 2.1) with LBP and scheduled for discography were examined with the method on a 3.0 Tesla MR scanner. RROC measurements were compared with discography outcomes using paired t-test. RESULTS Simulation and phantom results indicated RROC is a concentration independent and pH level-dependent technique. Porcine spine study results found higher RROC value was related to lower pH level. Painful discs based on discography had significant higher RROC values than those with negative diagnosis (P < 0.05). CONCLUSION RROC imaging is a promising pH level dependent MRI technique that has the potential to be a noninvasive imaging tool to detect painful IVDs in vivo.
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Affiliation(s)
- Qi Liu
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Biomedical Engineering, Northwestern University, Chicago, Illinois, USA
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Johnson CP, Thedens DR, Magnotta VA. Precision-guided sampling schedules for efficient T1ρ mapping. J Magn Reson Imaging 2014; 41:242-50. [PMID: 24474423 DOI: 10.1002/jmri.24518] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 11/01/2013] [Indexed: 02/02/2023] Open
Abstract
PURPOSE To describe, assess, and implement a simple precision estimation framework for optimization of spin-lock time (TSL) sampling schedules for quantitative T1ρ mapping using a mono-exponential signal model. MATERIALS AND METHODS A method is described for estimating T1ρ precision, and a cost function based on the precision estimates is evaluated to determine efficient TSL sampling schedules. The validity of the framework was tested by imaging a phantom with various sampling schedules and comparing theoretical and experimental precision values. The method utility was demonstrated with in vivo T1ρ mapping of brain tissue using a similar procedure as the phantom experiment. To assist investigators, optimal sampling schedules are tabulated for various tissue types and an online calculator is implemented. RESULTS Theoretical and experimental precision values followed similar trends for both the phantom and in vivo experiments. The mean absolute percentage error (MAPE) of theoretical estimates of T1ρ map signal-to-noise ratio (SNR) was typically 5% in the phantom experiment and 33% in the in vivo demonstration. In both experiments, optimal TSL schedules yielded greater T1ρ map SNR efficiency than typical schedules. CONCLUSION The framework can be used to improve the imaging efficiency of T1ρ mapping protocols and to guide selection of imaging parameters.
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Affiliation(s)
- Casey P Johnson
- Department of Radiology, University of Iowa, Iowa City, Iowa, USA
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NAGAHARA S, UENO M, KOBAYASHI T. Spin-Lock Imaging for Direct Detection of Oscillating Magnetic Fields with MRI: Simulations and Phantom Studies. ADVANCED BIOMEDICAL ENGINEERING 2013. [DOI: 10.14326/abe.2.63] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Shizue NAGAHARA
- Department of Electrical Engineering, Graduate School of Engineering, Kyoto University
- Research Fellow of the Japan Society for the Promotion of Science
| | - Masahito UENO
- Department of Electrical Engineering, Graduate School of Engineering, Kyoto University
| | - Tetsuo KOBAYASHI
- Department of Electrical Engineering, Graduate School of Engineering, Kyoto University
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Yuan J, Li Y, Zhao F, Chan Q, Ahuja AT, Wang YXJ. Quantification of T(1ρ) relaxation by using rotary echo spin-lock pulses in the presence of B(0) inhomogeneity. Phys Med Biol 2012; 57:5003-16. [PMID: 22805278 DOI: 10.1088/0031-9155/57/15/5003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
T(1ρ) relaxation is traditionally described as a mono-exponential signal decay with spin-lock time. However, T(1ρ) quantification by fitting to the mono-exponential model can be substantially compromised in the presence of field inhomogeneities, especially for low spin-lock frequencies. The normal approach to address this issue involves the development of dedicated composite spin-lock pulses for artifact reduction while still using the mono-exponential model for T(1ρ) fitting. In this work, we propose an alternative approach for improved T(1ρ) quantification with the widely-used rotary echo spin-lock pulses in the presence of B(0) inhomogeneities by fitting to a modified theoretical model which is derived to reveal the dependence of T(1ρ)-prepared magnetization on T(1ρ), T(2ρ), spin-lock time, spin-lock frequency and off-resonance, without involving complicated spin-lock pulse design. It has potentials for T(1ρ) quantification improvement at low spin-lock frequencies. Improved T(1ρ) mapping was demonstrated on phantom and in vivo rat spin-lock imaging at 3 T compared to the mapping using the mono-exponential model.
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Affiliation(s)
- Jing Yuan
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China.
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Comparison of T1rho measurements in agarose phantoms and human patellar cartilage using 2D multislice spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot techniques at 3 T. AJR Am J Roentgenol 2011; 196:W174-9. [PMID: 21257859 DOI: 10.2214/ajr.10.4570] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The purpose of this article is to compare in vitro T1rho measurements in agarose phantoms and articular cartilage specimens using 2D multislice spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot MRI sequences. MATERIALS AND METHODS Six phantoms (agarose concentration, 2%, 3%, and 4%; n = 2 each) and 10 axially sliced patellar specimens from five cadaveric donors were scanned at 3 T. T1rho-weighted images were acquired using 2D spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot sequences. Regions of interest were analyzed to measure T1rho values centrally within phantoms, to evaluate effects of pulse sequence and agarose concentration. In patellar specimens, regions of interest were analyzed to measure T1rho values with respect to anatomic location (the medial and lateral facets and the median ridge in deep and superficial halves of the cartilage) as well as location that exhibited magic angle effect in proton density-weighted images, to evaluate the effects of pulse sequence, anatomic location, and magic angle. RESULTS In phantoms, T1rho values were similar (p = 0.9) between sequences but decreased significantly (p < 0.001), from ∼55 to ∼29 milliseconds, as agarose concentration increased from 2% to 4%. In cartilage specimens, T1rho values were also similar between sequences (p = 0.3) but were significantly higher (p < 0.001) in the superficial layer (95-120 milliseconds) compared with the deep layer (45-75 milliseconds). CONCLUSION T1rho measurements of human patellar cartilage specimens and agarose phantoms using 2D spiral and 3D magnetization prepared partitioned k-space spoiled gradient-echo snapshot sequences gave similar values. Lower T1rho values for phantoms with higher agarose concentrations and proteoglycan concentrations that are higher in deeper layers of cartilage than in superficial layers suggest that our method is sensitive to concentration of macromolecules in biologic tissues.
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Andronesi OC, Mintzopoulos D, Righi V, Psychogios N, Kesarwani M, He J, Yasuhara S, Dai G, Rahme LG, Tzika AA. Combined off-resonance imaging and T2 relaxation in the rotating frame for positive contrast MR imaging of infection in a murine burn model. J Magn Reson Imaging 2011; 32:1172-83. [PMID: 21031524 DOI: 10.1002/jmri.22349] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop novel magnetic resonance (MR) imaging methods to monitor accumulation of macrophages in inflammation and infection. Positive-contrast MR imaging provides an alternative to negative-contrast MRI, exploiting the chemical shift induced by ultra-small superparamagnetic iron-oxide (USPIO) nanoparticles to nearby water molecules. We introduce a novel combination of off-resonance (ORI) positive-contrast MRI and T(2ρ) relaxation in the rotating frame (ORI-T(2ρ)) for positive-contrast MR imaging of USPIO. MATERIALS AND METHODS We tested ORI-T(2ρ) in phantoms and imaged in vivo the accumulation of USPIO-labeled macrophages at the infection site in a mouse model of burn trauma and infection with Pseudomonas aeruginosa (PA). PA infection is clinically important. The USPIO nanoparticles were injected directly in the animals in solution, and macrophage labeling occurred in vivo in the animal model. RESULTS We observed a significant difference between ORI-T(2ρ) and ORI, which leads us to suggest that ORI-T(2ρ) is more sensitive in detecting USPIO signal. To this end, the ORI-T(2ρ) positive contrast method may prove to be of higher utility in future research. CONCLUSION Our results may have direct implications in the longitudinal monitoring of infection, and open perspectives for testing novel anti-infective compounds.
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Affiliation(s)
- Ovidiu C Andronesi
- Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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Witschey WRT, Borthakur A, Elliott MA, Magland J, McArdle EL, Wheaton A, Reddy R. Spin-locked balanced steady-state free-precession (slSSFP). Magn Reson Med 2010; 62:993-1001. [PMID: 19672947 DOI: 10.1002/mrm.22092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A spin-locked balanced steady-state free-precession (slSSFP) pulse sequence is described that combines a balanced gradient-echo acquisition with an off-resonance spin-lock pulse for fast MRI. The transient and steady-state magnetization trajectory was solved numerically using the Bloch equations and was shown to be similar to balanced steady-state free-precession (bSSFP) for a range of T(2)/T(1) and flip angles, although the slSSFP steady-state could be maintained with considerably lower radio frequency (RF) power. In both simulations and brain scans performed at 7T, slSSFP was shown to exhibit similar contrast and signal-to-noise ratio (SNR) efficiency to bSSFP, but with significantly lower power.
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Mellon EA, Beesam RS, Kasam M, Baumgardner JE, Borthakur A, Witschey WR, Reddy R. Single Shot T1ρ Magnetic Resonance Imaging Of Metabolically Generated Water In Vivo. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 645:279-86. [DOI: 10.1007/978-0-387-85998-9_42] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Witschey WRT, Borthakur A, Elliott MA, Fenty M, Sochor MA, Wang C, Reddy R. T1rho-prepared balanced gradient echo for rapid 3D T1rho MRI. J Magn Reson Imaging 2008; 28:744-54. [PMID: 18777535 DOI: 10.1002/jmri.21444] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop a T1rho-prepared, balanced gradient echo (b-GRE) pulse sequence for rapid three-dimensional (3D) T1rho relaxation mapping within the time constraints of a clinical exam (<10 minutes), examine the effect of acquisition on the measured T1rho relaxation time and optimize 3D T1rho pulse sequences for the knee joint and spine. MATERIALS AND METHODS A pulse sequence consisting of inversion recovery-prepared, fat saturation, T1rho-preparation, and b-GRE image acquisition was used to obtain 3D volume coverage of the patellofemoral and tibiofemoral cartilage and lower lumbar spine. Multiple T1rho-weighted images at various contrast times (spin-lock pulse duration [TSL]) were used to construct a T1rho relaxation map in both phantoms and in the knee joint and spine in vivo. The transient signal decay during b-GRE image acquisition was corrected using a k-space filter. The T1rho-prepared b-GRE sequence was compared to a standard T1rho-prepared spin echo (SE) sequence and pulse sequence parameters were optimized numerically using the Bloch equations. RESULTS The b-GRE transient signal decay was found to depend on the initial T1rho-preparation and the corresponding T1rho map was altered by variations in the point spread function with TSL. In a two compartment phantom, the steady state response was found to elevate T1rho from 91.4+/-6.5 to 293.8+/-31 and 66.9+/-3.5 to 661+/-207 with no change in the goodness-of-fit parameter R2. Phase encoding along the longest cartilage dimension and a transient signal decay k-space filter retained T1rho contrast. Measurement of T1rho using the T1rho-prepared b-GRE sequence matches standard T1rho-prepared SE in the medial patellar and lateral patellar cartilage compartments. T1rho-preparedb-GRE T1rho was found to have low interscan variability between four separate scans. Mean patellar cartilage T1rho was elevated compared to femoral and tibial cartilage T1rho. CONCLUSION The T1rho-prepared b-GRE acquisition rapidly and reliably accelerates T1rho quantification of tissues offset partially by a TSL-dependent point spread function.
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Affiliation(s)
- Walter R T Witschey
- Metabolic Magnetic Resonance Research and Computing Center, Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA.
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Witzel T, Lin FH, Rosen BR, Wald LL. Stimulus-induced Rotary Saturation (SIRS): a potential method for the detection of neuronal currents with MRI. Neuroimage 2008; 42:1357-65. [PMID: 18684643 DOI: 10.1016/j.neuroimage.2008.05.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 04/15/2008] [Accepted: 05/01/2008] [Indexed: 10/22/2022] Open
Abstract
Neuronal currents produce local transient and oscillatory magnetic fields that can be readily detected by MEG. Previous work attempting to detect these magnetic fields with MR focused on detecting local phase shifts and dephasing in T(2) or T(2)-weighted images. For temporally biphasic and multi-phasic local currents the sensitivity of these methods can be reduced through the cancellation of the accrued phase induced by positive and negative episodes of the neuronal current. The magnitude of the phase shift is also dependent on the distribution of the current within the voxel. Since spins on one side of a current source develop an opposite phase shift relative to those on the other side, there is likely to be significant cancellation within the voxel. We introduce a potential method for detecting neuronal currents though their resonant T(1rho) saturation during a spin-lock preparation period. The method is insensitive to the temporal and spatial cancellation effects since it utilizes the multi-phasic nature of the neuronal currents and thus is not sensitive to the sign of the local field. To produce a T(1)(rho) reduction, the Larmor frequency in the rotating frame, which is set by gammaB(1lock) (typically 20 Hz-5 kHz), must match the major frequency components of the stimulus-induced neuronal currents. We validate the method in MRI phantom studies. The rotary saturation spectra showed a sharp resonance when a current dipole within the phantom was driven at the Larmor frequency in the rotating frame. A 7 min block-design experiment was found to be sensitive to a current dipole strength of 56 nAm, an approximate magnetic field of 1 nT at 1.5 mm from the dipole. This dipole moment is similar to that seen using the phase shift method in a similar experimental setup by Konn et al. [Konn, D., Gowland, P., Bowtell, R., 2003. MRI detection of weak magnetic fields due to an extended current dipole in a conducting sphere: a model for direct detection of neuronal currents in the brain. Magn. Reson. Med. 50, 40-49], but is potentially less encumbered by temporal and spatial cancellation effects.
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Affiliation(s)
- Thomas Witzel
- Speech and Hearing Bioscience and Technology Program, Harvard-MIT Division of Health Sciences and Technology, USA.
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Li X, Han ET, Busse RF, Majumdar S. In vivo T(1rho) mapping in cartilage using 3D magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots (3D MAPSS). Magn Reson Med 2008; 59:298-307. [PMID: 18228578 DOI: 10.1002/mrm.21414] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
For T(1rho) quantification, a three-dimensional (3D) acquisition is desired to obtain high-resolution images. Current 3D methods that use steady-state spoiled gradient-echo (SPGR) imaging suffer from high SAR, low signal-to-noise ratio (SNR), and the need for retrospective correction of contaminating T(1) effects. In this study, a novel 3D acquisition scheme-magnetization-prepared angle-modulated partitioned-k-space SPGR snapshots (3D MAPSS)-was developed and used to obtain in vivo T(1rho) maps. Transient signal evolving towards the steady-state were acquired in an interleaved segmented elliptical centric phase encoding order immediately after a T(1rho) magnetization preparation sequence. RF cycling was applied to eliminate the adverse impact of longitudinal relaxation on quantitative accuracy. A variable flip angle train was designed to provide a flat signal response to eliminate the filtering effect in k-space caused by transient signal evolution. Experiments in phantoms agreed well with results from simulation. The T(1rho) values were 42.4 +/- 5.2 ms in overall cartilage of healthy volunteers. The average coefficient-of-variation (CV) of mean T(1rho) values (N = 4) for overall cartilage was 1.6%, with regional CV ranging from 1.7% to 8.7%. The fitting errors using MAPSS were significantly lower (P < 0.05) than those using sequences without RF cycling and variable flip angles.
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Affiliation(s)
- Xiaojuan Li
- Musculoskeletal Quantitative Imaging Research, Department of Radiology, University of California-San Francisco, 185 Berry Street, San Francisco, CA 94107, USA.
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Lindquist D. Is There a Role for MR Imaging in Monitoring Gene Therapy Response? Radiology 2007; 243:611-2. [PMID: 17517921 DOI: 10.1148/radiol.2433070080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Diana Lindquist
- Imaging Research Center Cincinnati Children's Hospital Medical Center,3333 Burnet Ave, ML 5031Cincinnati, OH 45229, USA.
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