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Serša I. Comparison of driven equilibrium and standard spin-echo sequence in MR microscopy: Analysis of signal dependence on RF pulse imperfection and diffusion. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 359:107624. [PMID: 38241847 DOI: 10.1016/j.jmr.2024.107624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/03/2024] [Accepted: 01/12/2024] [Indexed: 01/21/2024]
Abstract
Rapid MR imaging of slowly relaxing samples is often challenging. The most commonly used solutions are found in multi spin-echo (RARE) sequences or gradient-echo (GE) sequences, which allow faster imaging of such samples with multiple acquisitions of k-space lines per excitation or imaging with very short repetition times (TRs). Another solution is the use of a spin-echo (SE) sequence superimposed with a driven equilibrium Fourier transform (DEFT) method. Such a (DE-SE) imaging sequence has two refocusing RF pulses that produce two spin-echoes. In the first echo, the signal is acquired from the k-space line, and in the second echo, a 90° RF pulse is applied, typically 180° out of phase with respect to the excitation RF pulse. This last RF pulse allows almost complete magnetization reversal back to the longitudinal orientation with minimal magnetization loss. The DE-SE sequence and its RARE variant are widely used in clinical imaging, but its use in MR microscopy has some peculiarities related to the usually less perfect RF pulse flip angles and diffusion. In this study, their effects are first theoretically analyzed and later verified by experiments on test samples performed on a 9.4 T system for MR microscopy. Experiments on a water-filled tube for TE = 3.4 ms and TR = 25-200 ms showed that the DE-SE sequence produces about 10 times more signal than the SE sequence in this TR range. Finally, the performance of the DE-SE sequence compared to the SE sequence was demonstrated on a biological sample. The presented DE-SE sequence has been shown to be effective for rapid imaging of samples with long T1 relaxation times in MR microscopy and can also be considered as a suitable method for rapid proton density weighed imaging of materials.
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Affiliation(s)
- Igor Serša
- Jožef Stefan Institute, Ljubljana, Slovenia; Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
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Moisture Distribution during Water Absorption of Ordinary Portland Cement Mortars Obtained with Low-Field Unilateral Magnetic Resonance. MATERIALS 2021; 14:ma14154279. [PMID: 34361473 PMCID: PMC8346991 DOI: 10.3390/ma14154279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 07/24/2021] [Accepted: 07/25/2021] [Indexed: 11/17/2022]
Abstract
Moisture distribution in cement-based materials is important from the durability point of view. In the present study, a portable three-magnet array with an elliptical surface radio frequency coil was used to undertake magnetic resonance measurements of moisture content in ordinary Portland cement mortar and concrete samples. Measurements along the length of the samples during capillary water absorption produced moisture content profiles that were compared with reference profiles acquired using a magnetic resonance imaging instrument. Profiles obtained with the three-magnet array were similar in shape and in penetration depth to those acquired with magnetic resonance imaging. The correlation coefficient between the moisture content measured with both techniques was r2 = 0.97. Similar values of saturated permeability of the mortars with identical w/c ratio were computed with the Hydrus 1D software based on the moisture content profiles. Additionally, inverse Laplace transformation of the signal decays provided the water-filled pore size distribution in saturated and unsaturated regions of the samples. The three-magnet array was successfully used to acquire nuclear magnetic resonance signal from a concrete sample, which was not possible with the magnetic resonance imaging instrument using the single-point imaging technique.
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Mehdizad M, Fullard L, Galvosas P, Holland D. Quantitative measurement of solid fraction in a silo using SPRITE. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 325:106935. [PMID: 33639595 DOI: 10.1016/j.jmr.2021.106935] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/24/2021] [Accepted: 02/06/2021] [Indexed: 06/12/2023]
Abstract
The purpose of this study is to develop MRI methods to measure the solid fraction in granular flows quantitatively. It is increasingly recognised that solid fraction plays a key role in granular rheology, but experimental characterisation of it during flow is challenging. Here centric sectoral-SPRITE imaging is applied to image mustard seeds discharging from a 3D-printed hopper. Quantitative images are obtained after considering and correcting artefacts that may arise from flow and relaxation. The image intensity is then further corrected for spatial variations in the B1 field. Various maps of nominally homogeneous samples were tested to correct for variations in the B1 field. The B1 field was found to be sensitive to the geometry of the sample and the material in the sample. Hence, here static images of the seeds in the hopper were used to correct for B1 field variations. Moreover, small signal variations were observed from measurements performed on different days owing to subtle differences in the spectrometer operation. Here an internal standard was used to scale the signal intensity and correct for these variations. Following these corrections, a linear correlation (R2 = 0.999) was observed between the scaled image intensities and the known solid fractions of packed samples with solid fractions between 0.55 and 0.64. This correlation was used as a calibration of the 3D image of the hopper to extract quantitative time-averaged spatial maps of solid fraction during steady flow. The measurements were confirmed to be quantitative by also measuring the velocity of the particles. Together these measurements were used to calculate a mass flow rate in the hopper, which was consistent with the mass flow measured gravimetrically.
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Affiliation(s)
- Maral Mehdizad
- Department of Chemical and Process Engineering, University of Canterbury, New Zealand
| | - Luke Fullard
- School of Fundamental Sciences, and Massey University, New Zealand
| | - Petrik Galvosas
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University, New Zealand
| | - Daniel Holland
- Department of Chemical and Process Engineering, University of Canterbury, New Zealand.
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Covington KL, Goroncy AK, Lehmann TE, Kou Z, Wang H, Alvarado V. Analysis of
ZTE MRI
application to sandstone and carbonate. AIChE J 2020. [DOI: 10.1002/aic.17074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | | | | | - Zuhao Kou
- Department of Chemical Engineering University of Wyoming Laramie Wyoming USA
| | - Heng Wang
- Department of Chemical Engineering University of Wyoming Laramie Wyoming USA
| | - Vladimir Alvarado
- Department of Chemical Engineering University of Wyoming Laramie Wyoming USA
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O'Brien-Moran Z, Bowen CV, Rioux JA, Brewer KD. Cell density quantification with TurboSPI: R 2* mapping with compensation for off-resonance fat modulation. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2019; 33:469-481. [PMID: 31872356 DOI: 10.1007/s10334-019-00817-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Tracking the migration of superparamagnetic iron oxide (SPIO)-labeled immune cells in vivo is valuable for understanding the immunogenic response to cancer and therapies. Quantitative cell tracking using TurboSPI-based R2* mapping is a promising development to improve accuracy in longitudinal studies on immune recruitment. However, off-resonance fat signal isochromats lead to modulations in the signal time-course that can be erroneously fit as R2* signal decay, overestimating the density of labeled cells, while excluding voxels with fat-typical modulations results in underestimation of cell density in voxels with mixed content. Approaches capable of accurate R2* estimation in the presence of fat are needed. METHODS We propose a dual-decay (separate R2f* and R2w* for fat and water) Dixon-based signal model that accounts for the presence of fat in a voxel to provide better estimates of SPIO-induced dephasing. This model was tested in silico, in phantoms with varying quantities of fat and SPIO-labeled cells, and in 5 mice injected with SPIO-labeled CD8+ T cells. RESULTS In silico single voxel simulations illustrate how the proposed dual-decay model provides stable R2w* estimates that are invariant to fat content. The proposed model outperforms previous methods when applied to in vitro samples of SPIO-labeled cells and oil prepared with oil content ≥ 15%. Preliminary in vivo results show that, compared to previous methods, the dual-decay model improves the balance of R2* mapping in fat-dense areas, which will yield more reliable analysis in future cell tracking studies. DISCUSSION The proposed model is a promising tool for quantitative TurboSPI R2* cell tracking, with further refinements offering the possibility of better specificity and sensitivity.
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Affiliation(s)
- Zoe O'Brien-Moran
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada.,Dalhousie University, Halifax, NS, Canada
| | - Chris Van Bowen
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada.,Dalhousie University, Halifax, NS, Canada
| | - James Allen Rioux
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada.,Dalhousie University, Halifax, NS, Canada
| | - Kimberly Dawn Brewer
- Biomedical Translational Imaging Centre, IWK Health Centre and Nova Scotia Health Authority, Halifax, NS, Canada. .,Dalhousie University, Halifax, NS, Canada.
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Mikac U, Sepe A, Gradišek A, Kristl J, Apih T. Dynamics of water and xanthan chains in hydrogels studied by NMR relaxometry and their influence on drug release. Int J Pharm 2019; 563:373-383. [DOI: 10.1016/j.ijpharm.2019.04.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/21/2019] [Accepted: 04/06/2019] [Indexed: 12/12/2022]
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Węglarz WP, Krzyżak A, Machowski G, Stefaniuk M. ZTE MRI in high magnetic field as a time effective 3D imaging technique for monitoring water ingress in porous rocks at sub-millimetre resolution. Magn Reson Imaging 2018; 47:54-59. [DOI: 10.1016/j.mri.2017.11.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 11/16/2017] [Accepted: 11/21/2017] [Indexed: 10/18/2022]
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Xiao D, Balcom BJ. T 2 selective π Echo-Planar Imaging for porous media MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 277:52-58. [PMID: 28232286 DOI: 10.1016/j.jmr.2017.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/04/2017] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
The π Echo Planar Imaging (PEPI) method has recently been modified to permit proton density imaging of fluids in porous media with moderate T2 and short T2∗ signal components. In many applications, it is desirable to discriminate multiple T2 components within each image voxel. T2 selective imaging is explored in this paper through adiabatic inversion as a magnetization preparation with PEPI readout. When prior information of the sample relaxation times is known, responses of different species to broadband adiabatic inversion pulses can be predicted by Bloch equation simulation. Different relaxation components can be acquired by combining the images with and without inversion preparation pulses. T2 weighting can be easily introduced in the PEPI sequence by shifting the spatial encoding gradients based on its spin echo nature. T2 decay curves can be extracted for each image voxel from a series of T2 weighted images and spatially resolved T2 distributions can be generated. This method is reliable but slow. The two methods were implemented to image porous media samples with PEPI the common basis of spatial resolution. The results of both methods agree remarkably well.
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Affiliation(s)
- Dan Xiao
- MRI Research Center, Department of Physics, University of New Brunswick, 8 Bailey Drive, Fredericton NB E3B 5A3, Canada.
| | - Bruce J Balcom
- MRI Research Center, Department of Physics, University of New Brunswick, 8 Bailey Drive, Fredericton NB E3B 5A3, Canada.
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3D single point imaging with compressed sensing provides high temporal resolution R 2* mapping for in vivo preclinical applications. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2016; 30:41-55. [PMID: 27503309 DOI: 10.1007/s10334-016-0583-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 07/13/2016] [Accepted: 07/25/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Purely phase-encoded techniques such as single point imaging (SPI) are generally unsuitable for in vivo imaging due to lengthy acquisition times. Reconstruction of highly undersampled data using compressed sensing allows SPI data to be quickly obtained from animal models, enabling applications in preclinical cellular and molecular imaging. MATERIALS AND METHODS TurboSPI is a multi-echo single point technique that acquires hundreds of images with microsecond spacing, enabling high temporal resolution relaxometry of large-R 2* systems such as iron-loaded cells. TurboSPI acquisitions can be pseudo-randomly undersampled in all three dimensions to increase artifact incoherence, and can provide prior information to improve reconstruction. We evaluated the performance of CS-TurboSPI in phantoms, a rat ex vivo, and a mouse in vivo. RESULTS An algorithm for iterative reconstruction of TurboSPI relaxometry time courses does not affect image quality or R 2* mapping in vitro at acceleration factors up to 10. Imaging ex vivo is possible at similar acceleration factors, and in vivo imaging is demonstrated at an acceleration factor of 8, such that acquisition time is under 1 h. CONCLUSIONS Accelerated TurboSPI enables preclinical R 2* mapping without loss of data quality, and may show increased specificity to iron oxide compared to other sequences.
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ZTE imaging of tight sandstone rocks at 9.4 T — Comparison with standard NMR analysis at 0.05 T. Magn Reson Imaging 2016; 34:492-5. [DOI: 10.1016/j.mri.2015.12.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 12/03/2015] [Accepted: 12/07/2015] [Indexed: 11/17/2022]
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Mikac U, Sepe A, Baumgartner S, Kristl J. The Influence of High Drug Loading in Xanthan Tablets and Media with Different Physiological pH and Ionic Strength on Swelling and Release. Mol Pharm 2016; 13:1147-57. [DOI: 10.1021/acs.molpharmaceut.5b00955] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Urša Mikac
- Jožef Stefan
Institute, 1000 Ljubljana, Slovenia
| | - Ana Sepe
- Jožef Stefan
Institute, 1000 Ljubljana, Slovenia
| | - Saša Baumgartner
- Faculty
of Pharmacy, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Julijana Kristl
- Faculty
of Pharmacy, University of Ljubljana, 1000 Ljubljana, Slovenia
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Piesnack S, Oechtering G, Ludewig E. [Options for the reduction of magnetic susceptibility artifacts caused by implanted microchips in 0.5 Tesla magnetic resonance imaging]. TIERARZTLICHE PRAXIS. AUSGABE K, KLEINTIERE/HEIMTIERE 2015; 43:83-92. [PMID: 25727725 DOI: 10.15654/tpk-140663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/27/2014] [Indexed: 06/04/2023]
Abstract
OBJECTIVE Microchips contain ferromagnetic materials, which lead to severe focal image interferences when performing magnetic resonance imaging (MRI). Very small animals are particularly prone to these susceptibility artifacts, which may hinder analysis of the neck-region MRI image. We investigated the impact of sequence type on the artifact's size and determined the optimal imaging parameters to minimize these artifacts. Furthermore, the minimum distance between the microchip and the spinal canal required to assess the spinal structures should be determined. MATERIAL AND METHODS Investigations were performed on the cadavers of 26 cats and two dogs using a low-field MRI System (field strength 0.5 Tesla). To quantify susceptibility artifacts, several sequence types (spin echo, turbo-spin echo (TSE), gradient echo) and imaging parameters (echo time (TE), voxel volume, frequency direction) were systematically varied. Additionally, computed tomography imaging was performed to determine the distance between the microchip and the spinal canal. RESULTS The size of the artifact was smallest with T1-weighted TSE sequences. A short TE (10 ms) and a small voxel size (acquisition matrix 256 x 256 pixels, field of view 160 mm, slice thickness 2 mm) significantly reduced artifact size. Furthermore, it could be shown that by changing the frequency- and phase-encoding direction, the shape and orientation of the maximum dimension of the artifact could be influenced. Even when using an optimized T1-weighted TSE sequence, it was impossible to evaluate the spinal cord when the distance between the microchip and the center of the spinal canal was < 19 mm. CONCLUSION AND CLINICAL RELEVANCE In MR studies of the cervical spine of small dogs and cats, microchips can cause severe susceptibility artifacts. Because of the small distance between the microchip and the spinal structures, spinal evaluation may be limited or impossible. The investigations demonstrated that the adjustment of sequence parameters helps to significantly minimize artifact size and shape. The greatest reduction in artifact size was achieved by using a T1-weighted TSE sequence.
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Affiliation(s)
- S Piesnack
- Susann Piesnack, Klinik für Kleintiere der Universität Leipzig, An den Tierkliniken 23, 04103 Leipzig, E-Mail:
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Abstract
OBJECTIVE The purpose of this article is to explain the basic physics of imaging patients with metal implants, explain conflicting information regarding MRI scanning of "MR Conditional" devices, and relate our experience of scanning total joint arthroplasty (TJA) at our institution. CONCLUSION MRI near TJA is effective with appropriate imaging protocols and standardized safety precautions. Strict adherence to MR Conditional labeling may preclude broad use of MRI for TJA assessment.
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Magnetic resonance imaging of solid dental restoration materials using 3D UTE sequences: visualization and relaxometry of various compounds. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2013; 26:555-64. [PMID: 23525675 DOI: 10.1007/s10334-013-0373-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 10/27/2022]
Abstract
OBJECT Due to an increasing scientific interest in MR-imaging of carious lesions and teeth, an accurate signal characterization of dental restoration materials is necessary for optimization of MR sequence protocols and evaluation of material degradation. Therefore, signal yield and relaxation behavior of common dental restoration materials in comparison to those of dentine of extracted human teeth were assessed in vitro by ultrashort echo time (UTE) sequences. MATERIALS AND METHODS Eighteen material samples and dentine of two freshly extracted human teeth were investigated on a 3T whole-body clinical MR-scanner. Transverse (T2*) and longitudinal relaxation times (T1) were quantified using a recently published modified Ernst equation that takes relevant in-pulse relaxation effects into account. RESULTS All investigated samples could be successfully visualized but maximum signal yield was highly variable between samples. T1-values of the investigated dental restoration materials ranged between 28 and 365 ms, whereas T2*-values ranged between 96 and 917 μs. In contrast, T1-values of dentine (T1=545 ms±299 ms) were higher, while T2*-values (T2*=478 μs±271 μs) showed similar values. CONCLUSIONS Dental restoration materials and dentine of extracted human teeth can be visualized by UTE sequences and show a broad range of signal yield and relaxation times.
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Koff MF, Shah P, Koch KM, Potter HG. Quantifying image distortion of orthopedic materials in magnetic resonance imaging. J Magn Reson Imaging 2013; 38:610-8. [PMID: 23292702 DOI: 10.1002/jmri.23991] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 11/15/2012] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To determine the magnitude of image distortion between two-dimensional (2D) fast-spin-echo (FSE) images and 3D-MAVRIC by using a phantom with samples of common materials used in total joint arthroplasty. MATERIALS AND METHODS A phantom was constructed to hold samples of 316 stainless steel, cobalt chrome, titanium, and ultra-high molecular weight polyethylene (UHMWPE), and to permit tracking of points between 2D-FSE and 3D-MAVRIC sequences. Imaging was performed with a 1.5 Tesla scanner. The displacement of points between the two acquisitions in regions of varying distance from the material sample was calculated. Measured displacements were compared with theoretical displacements calculated from MAVRIC frequency field maps, and to the known phantom dimensions. RESULTS Bulk in-plane artifacts increased from the control scan (0.20 ± 0.07 mm), to UHMWPE (0.23 ± 0.04 mm), titanium (0.40 ± 0.34 mm), cobalt chrome (1.35 ± 0.57 mm), and to stainless steel (2.56 ± 0.62 mm). A similar pattern was found for bulk through-plane measurements: control scan (0.36 ± 0.08 mm), UHMWPE (0.38 ± 0.05 mm), titanium (1.11 ± 0.51 mm), and cobalt chrome (2.08 ± 1.83 mm). Large distortions were observed near the metal samples, and reduced with distance from the samples. The differences between the measured displacement and theoretical displacement was typically less than one pixel or one slice dimension for in-plane and through-plane measurements, respectively. The difference between the 3D-MAVRIC and known dimensions of the phantom was less than two pixels, whereas the results for the 2D-FSE were less consistent. CONCLUSION Distortion was reduced in 3D-MAVRIC scans. Measured distortions corresponded well to theoretical calculations from frequency field map data.
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Affiliation(s)
- Matthew F Koff
- Hospital for Special Surgery, Department of Radiology and Imaging, New York, New York, USA.
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Romanenko K, Xiao D, Balcom BJ. Velocity field measurements in sedimentary rock cores by magnetization prepared 3D SPRITE. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 223:120-128. [PMID: 22967892 DOI: 10.1016/j.jmr.2012.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 08/03/2012] [Accepted: 08/04/2012] [Indexed: 06/01/2023]
Abstract
A time-efficient MRI method suitable for quantitative mapping of 3-D velocity fields in sedimentary rock cores, and granular samples is discussed. The method combines the 13-interval Alternating-Pulsed-Gradient Stimulated-Echo (APGSTE) scheme and three-dimensional Single Point Ramped Imaging with T(1) Enhancement (SPRITE). Collecting a few samples near the q-space origin and employing restricted k-space sampling dramatically improves the performance of the imaging method. The APGSTE-SPRITE method is illustrated through mapping of 3-D velocity field in a macroscopic bead pack and heterogeneous sandstone and limestone core plugs. The observed flow patterns are consistent with a general trend for permeability to increase with the porosity. Domains of low permeability obstruct the flow within the core volume. Water tends to flow along macroscopic zones of higher porosity and across zones of lower porosity.
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Affiliation(s)
- Konstantin Romanenko
- MRI Centre, Department of Physics, University of New Brunswick, P.O. Box 4400, 8 Bailey Drive, Fredericton, Canada E3B 5A3.
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Koptyug IV. MRI of mass transport in porous media: drying and sorption processes. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 65:1-65. [PMID: 22781314 DOI: 10.1016/j.pnmrs.2011.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 12/05/2011] [Indexed: 06/01/2023]
Affiliation(s)
- Igor V Koptyug
- International Tomography Center, SB RAS, 3A Institutskaya Str., Novosibirsk 630090, Russian Federation.
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Leisen J, Gomez IJ, Roper JA, Meredith JC, Beckham HW. Spatially resolved solid-state 1H NMR for evaluation of gradient-composition polymeric libraries. ACS COMBINATORIAL SCIENCE 2012; 14:415-24. [PMID: 22676634 DOI: 10.1021/co200210c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polyurethane libraries consisting of films with composition gradients of aliphatic polyisocyanate and hydroxy-terminated polyacrylate resin were characterized using methods of (1)H NMR microimaging (i.e., magnetic resonance imaging, (MRI)) and solid-state NMR. Molecular mobilities and underlying structural information were extracted as a function of the relative content of each of the two components. Routine NMR microimaging using the spin-echo sequence only allows investigations of transverse relaxation of magnetization at echo times >2 ms. A single-exponential decay was found, which is likely due to free, noncross-linked polymer chains. The mobility of these chains decreases with increasing content of the aliphatic polyisocyanate. The concept of a 1D NMR profiler is introduced as a novel modality for library screening, which allows the convenient measurement of static solid-state NMR spectra as a function of spatial location along a library sample that is repositioned in the rf coil between experiments. With this setup the complete transverse relaxation function was measured using Bloch decays and spin echoes. For all positions within the gradient-composition film, relaxation data consisted of at least three components that were attributed to a rigid highly cross-linked resin, an intermediate cross-linked but mobile constituent, and the highly mobile free polymer chains (the latter is also detectable by MRI). Analysis of this overall relaxation function measured via Bloch decays and spin echoes revealed only minor changes in the mobilities of the individual fractions. Findings with respect to the most mobile components are consistent with the results obtained by NMR microimaging. The major effect is the significant increase in the rigid-component fraction with the addition of the hydroxy-terminated polyacrylate resin.
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Affiliation(s)
| | | | - John A. Roper
- The Dow Chemical Company, Midland, Michigan 48674, United States
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Romanenko K, Balcom BJ. Permeability mapping in naturally heterogeneous sandstone cores by magnetization prepared centric-scan sprite. AIChE J 2012. [DOI: 10.1002/aic.13778] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Human tooth pulp anatomy visualization by 3D magnetic resonance microscopy. Radiol Oncol 2012; 46:1-7. [PMID: 22933973 PMCID: PMC3423768 DOI: 10.2478/v10019-012-0018-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 01/19/2012] [Indexed: 11/20/2022] Open
Abstract
Background Precise assessment of dental pulp anatomy is of an extreme importance for a successful endodontic treatment. As standard radiographs of teeth provide very limited information on dental pulp anatomy, more capable methods are highly appreciated. One of these is 3D magnetic resonance (MR) microscopy of which diagnostic capabilities in terms of a better dental pulp anatomy assessment were evaluated in the study. Materials and methods Twenty extracted human teeth were scanned on a 2.35 T MRI system for MR microscopy using the 3D spin-echo method that enabled image acquisition with isotropic resolution of 100 μm. The 3D images were then post processed by ImageJ program (NIH) to obtain advanced volume rendered views of dental pulps. Results MR microscopy at 2.35 T provided accurate data on dental pulp anatomy in vitro. The data were presented as a sequence of thin 2D slices through the pulp in various orientations or as volume rendered 3D images reconstructed form arbitrary view-points. Sequential 2D images enabled only an approximate assessment of the pulp, while volume rendered 3D images were more precise in visualization of pulp anatomy and clearly showed pulp diverticles, number of pulp canals and root canal anastomosis. Conclusions This in vitro study demonstrated that MR microscopy could provide very accurate 3D visualization of dental pulp anatomy. A possible future application of the method in vivo may be of a great importance for the endodontic treatment.
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Fagan MA, Sederman AJ, Johns ML. MR imaging of ore for heap bioleaching studies using pure phase encode acquisition methods. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 216:121-127. [PMID: 22341859 DOI: 10.1016/j.jmr.2012.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 01/17/2012] [Accepted: 01/22/2012] [Indexed: 05/31/2023]
Abstract
Various MRI techniques were considered with respect to imaging of aqueous flow fields in low grade copper ore. Spin echo frequency encoded techniques were shown to produce unacceptable image distortions which led to pure phase encoded techniques being considered. Single point imaging multiple point acquisition (SPI-MPA) and spin echo single point imaging (SESPI) techniques were applied. By direct comparison with X-ray tomographic images, both techniques were found to be able to produce distortion-free images of the ore packings at 2 T. The signal to noise ratios (SNRs) of the SESPI images were found to be superior to SPI-MPA for equal total acquisition times; this was explained based on NMR relaxation measurements. SESPI was also found to produce suitable images for a range of particles sizes, whereas SPI-MPA SNR deteriorated markedly as particles size was reduced. Comparisons on a 4.7 T magnet showed significant signal loss from the SPI-MPA images, the effect of which was accentuated in the case of unsaturated flowing systems. Hence it was concluded that SESPI was the most robust imaging method for the study of copper ore heap leaching hydrology.
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Affiliation(s)
- Marijke A Fagan
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK.
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24
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Dahlberg C, Dvinskikh SV, Schuleit M, Furó I. Polymer Swelling, Drug Mobilization and Drug Recrystallization in Hydrating Solid Dispersion Tablets Studied by Multinuclear NMR Microimaging and Spectroscopy. Mol Pharm 2011; 8:1247-56. [DOI: 10.1021/mp200051e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Carina Dahlberg
- Division of Physical Chemistry and Industrial NMR Centre, Department of Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
- YKI, Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden
| | - Sergey V. Dvinskikh
- Division of Physical Chemistry and Industrial NMR Centre, Department of Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Michael Schuleit
- Forum 1, Pharmaceutical & Analytical Development, Novartis Pharma AG, Novartis Campus, CH 4056 Basel, Switzerland
| | - István Furó
- Division of Physical Chemistry and Industrial NMR Centre, Department of Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
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25
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Kirsch S, Schad LR. Single-slice mapping of ultrashort T(2). JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 210:133-136. [PMID: 21353799 DOI: 10.1016/j.jmr.2011.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 02/01/2011] [Accepted: 02/02/2011] [Indexed: 05/30/2023]
Abstract
In this communication we present a method for single-slice mapping of ultrashort transverse relaxation times T(2). The RF pulse sequence consists of a spin echo preparation of the magnetization followed by slice-selective ultrashort echo time (UTE) imaging with radial k-space sampling. In order to keep the minimum echo time as small as possible, avoid out-of-slice contamination and signal contamination due to unwanted echoes, the implemented pulse sequence employs a slice-selective 180° RF refocusing pulse and a 4-step phase cycle. The slice overlap of the two slice-selective RF pulses was investigated. An acceptable Gaussian slice profile could be achieved by adjusting the strength of the two slice-selection gradients. The method was tested on a short T(2) phantom consisting of an arrangement of a roll of adhesive tape, an eraser, a piece of modeling dough made of Plasticine®, and a 10% w/w agar gel. The T(2) measurements on the phantom revealed exponential signal decays for all samples with T(2)(adhesive tape)=(0.5 ± 0.1)ms, T(2)(eraser)=(2.33 ± 0.07)ms, T(2)(Plasticine®)=(2.8 ± 0.06)ms, and T(2)(10%agar)=(9.5 ± 0.83)ms. The T(2) values obtained by the mapping method show good agreement with the T(2) values obtained by a non-selective T(2) measurement. For all samples, except the adhesive tape, the effective transverse relaxation time T(2)(∗) was significantly shorter than T(2). Depending on the scanner hardware the presented method allows mapping of T(2) down to a few hundreds of microseconds. Besides investigating material samples, the presented method can be used to study the rapidly decaying MR-signal from biological tissue (e.g.: bone, cartilage, and tendon) and quadrupolar nuclei (e.g.: (23)Na, (35)Cl, and (17)O).
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Affiliation(s)
- Stefan Kirsch
- Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany.
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26
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Mikac U, Kristl J, Baumgartner S. Using quantitative magnetic resonance methods to understand better the gel-layer formation on polymer-matrix tablets. Expert Opin Drug Deliv 2011; 8:677-92. [DOI: 10.1517/17425247.2011.566554] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Koch KM, Hargreaves BA, Pauly KB, Chen W, Gold GE, King KF. Magnetic resonance imaging near metal implants. J Magn Reson Imaging 2011; 32:773-87. [PMID: 20882607 DOI: 10.1002/jmri.22313] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The desire to apply magnetic resonance imaging (MRI) techniques in the vicinity of embedded metallic hardware is increasing. The soft-tissue contrast available with MR techniques is advantageous in diagnosing complications near an increasing variety of MR-safe metallic hardware. Near such hardware, the spatial encoding mechanisms utilized in conventional MRI methods are often severely compromised. Mitigating these encoding difficulties has been the focus of numerous research investigations over the past two decades. Such approaches include view-angle tilting, short echo-time projection reconstruction acquisitions, single-point imaging, prepolarized MRI, and postprocessing image correction. Various technical advances have also enabled the recent development of two alternative approaches that have shown promising clinical potential. Here, the physical principals and proposed solutions to the problem of MRI near embedded metal are discussed.
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Affiliation(s)
- K M Koch
- Applied Science Laboratory, GE Healthcare, Waukesha, Wisconsin 53188, USA.
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28
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Mikac U, Sepe A, Kristl J, Baumgartner S. A new approach combining different MRI methods to provide detailed view on swelling dynamics of xanthan tablets influencing drug release at different pH and ionic strength. J Control Release 2010; 145:247-56. [DOI: 10.1016/j.jconrel.2010.04.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 04/12/2010] [Accepted: 04/18/2010] [Indexed: 10/19/2022]
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29
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Stevenson R, Harrison ST, Mantle MD, Sederman AJ, Moraczewski TL, Johns ML. Analysis of partial suspension in stirred mixing cells using both MRI and ERT. Chem Eng Sci 2010. [DOI: 10.1016/j.ces.2009.10.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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30
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Dvinskikh SV, Szutkowski K, Furó I. MRI profiles over very wide concentration ranges: application to swelling of a bentonite clay. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 198:146-150. [PMID: 19233697 DOI: 10.1016/j.jmr.2009.01.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 01/27/2009] [Accepted: 01/28/2009] [Indexed: 05/27/2023]
Abstract
In MRI investigation of soils, clays, and rocks, mainly mobile water is detected, similarly to that in biological and medical samples. However, the spin relaxation properties of water in these materials and/or low water concentration may make it difficult to use standard MRI approaches. Despite these limitations, one can combine MRI techniques developed for solid and liquid states and use independent information on relaxation properties of water, interacting with the material of interest, to obtain true images of both water and material content. We present procedures for obtaining such true density maps and demonstrate their use for studying the swelling of bentonite clay by water. A constant time imaging protocol provides 1D mapping of the clay distribution in regions with clay concentration above 10 vol%. T(1) relaxation time imaging is employed to monitor the clay content down to 10(-3) vol%. Data provided by those two approaches are in good agreement in the overlapping range of concentrations. Covering five orders of magnitude of clay concentration, swelling of sodium-exchanged bentonite clays from pre-compacted pellets into a gel phase is followed in detail.
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Affiliation(s)
- S V Dvinskikh
- Division of Physical Chemistry, Department of Chemistry, Royal Institute of Technology, Teknikringen 36, SE-10044 Stockholm, Sweden.
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31
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Romanenko KV, Cano-Barrita PFDJ, Balcom BJ. (35)Cl profiling using centric scan SPRITE with variable flip angle excitation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 198:24-30. [PMID: 19201634 DOI: 10.1016/j.jmr.2009.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 12/04/2008] [Accepted: 01/08/2009] [Indexed: 05/27/2023]
Abstract
An efficient MRI technique for quantitative density profiling of samples with fast spin-lattice relaxation (T(1)<5ms) is introduced. The pulse scheme is based on the 1D centric scan SPRITE technique. Strong excitation of the sample at the k-space origin improves the sensitivity with respect to the original centric scan SPRITE technique. Radio frequency pulse durations are defined so as to provide uniform excitation of the sample at every k-space point. For a particular k-space point the pulse duration is required to be less than the inverse sample bandwidth. Simulations permit one to examine distortions from ideal profile geometry due to flip angle and spin-lattice relaxation effects. The proposed technique is especially suitable for the observation of low sensitivity samples, in particular, low-gamma nuclei like (35)Cl. In some cases, this strategy permits one to reduce the number of scans, i.e. the experiment time, by a factor of 100, depending on hardware, sample length and tolerable resolution loss. The designed pulse scheme is tested on cylindrical agar gel and type 1 Portland cement paste phantoms prepared to provide (1)H and (35)Cl signals, respectively.
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Affiliation(s)
- Konstantin V Romanenko
- MRI Centre, Department of Physics, University of New Brunswick, P.O. Box 4400, Fredericton, NB, Canada E3B 5A3
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32
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Three-Dimensional Ultrashort Echo Time Imaging of Solid Polymers on a 3-Tesla Whole-Body MRI Scanner. Invest Radiol 2008; 43:802-8. [DOI: 10.1097/rli.0b013e318188601f] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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33
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Węglarz W, Hemelaar M, van der Linden K, Franciosi N, van Dalen G, Windt C, Blonk H, van Duynhoven J, Van As H. Real-time mapping of moisture migration in cereal based food systems with Aw contrast by means of MRI. Food Chem 2008. [DOI: 10.1016/j.foodchem.2007.04.077] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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34
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Romanzetti S, Halse M, Kaffanke J, Zilles K, Balcom BJ, Shah NJ. A comparison of three SPRITE techniques for the quantitative 3D imaging of the 23Na spin density on a 4T whole-body machine. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 179:64-72. [PMID: 16325438 DOI: 10.1016/j.jmr.2005.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 11/11/2005] [Accepted: 11/11/2005] [Indexed: 05/05/2023]
Abstract
Sodium density maps acquired with three SPRITE-based methods have been compared in terms of the resulting quantitative information as well as image quality and acquisition times. Consideration of factors relevant for the clinical implementation of SPRITE shows that the Conical-SPRITE variant is preferred because of a 20-fold reduction in acquisition time, slightly improved image quality, and no loss of quantitative information. The acquisition of a 3D data set (32x32x16; FOV=256x256x160 mm) for the quantitative determination of sodium density is demonstrated. In vivo Conical-SPRITE 23Na images of the brain of a healthy volunteer were acquired in 30 min with a resolution of 7.5x7.5x7.5 mm and a signal-to-noise ratio of 23 in cerebrospinal fluid and 17 in brain tissue.
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Affiliation(s)
- S Romanzetti
- Institute of Medicine, Research Centre Jülich, 52425 Jülich, Germany
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35
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Ramos-Cabrer P, Van Duynhoven JPM, Timmer H, Nicolay K. Monitoring of moisture redistribution in multicomponent food systems by use of magnetic resonance imaging. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2006; 54:672-7. [PMID: 16448166 DOI: 10.1021/jf052246z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Differences in water activity within multicomponent food systems inevitably lead to moisture (re)distribution phenomena, hence deteriorating textural quality during shelf life. Noninvasive assessment of moisture transport in such systems would promote mechanistic understanding and enable rational development of strategies to control migration. Magnetic resonance imaging (MRI) is an ideal candidate for such a measurement technique, but its use in systems with low-moisture components (e.g., cereal materials) is seriously hampered because of reduced transverse relaxation times. In this work, we report two MRI protocols for the noninvasive and quantitative assessment of moisture transport in multicomponent food products. The first protocol is suitable to study relatively slow (days/weeks) processes, whereas the second one is designed to study fast (hours) moisture transport. We have successfully applied this methodology to quantify moisture transport within multicomponent food systems, with adequate temporal and spatial resolution.
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Affiliation(s)
- Pedro Ramos-Cabrer
- Department of Experimental in vivo NMR, Image Sciences Institute (ISI), University Medical Centre, Bolognalaan 30, 3583 CJ Utrecht, The Netherlands
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36
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Marica F, Chen Q, Hamilton A, Hall C, Al T, Balcom BJ. Spatially resolved measurement of rock core porosity. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 178:136-41. [PMID: 16216540 DOI: 10.1016/j.jmr.2005.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Revised: 09/09/2005] [Accepted: 09/13/2005] [Indexed: 05/04/2023]
Abstract
Density weighted, centric scan, Conical SPRITE MRI techniques are applied in the current work for local porosity measurements in fluid saturated porous media. The methodology is tested on a series of sandstone core samples. These samples vary in both porosity and degree of local heterogeneity due to bedding plane structure. The MRI porosity measurement is in good agreement with traditional gravimetric measurements of porosity. Spatially resolved porosity measurements reveal significant porosity variation in some samples. This novel MRI technique should have applications to the characterization of local porosity in a wide variety of porous media.
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Affiliation(s)
- F Marica
- MRI Centre, Department of Physics, University of New Brunswick, Fredericton, NB, Canada E3B 5A3
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37
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Kaffanke J, Dierkes T, Romanzetti S, Halse M, Rioux J, Leach MO, Balcom B, Shah NJ. Application of the chirp z-transform to MRI data. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 178:121-8. [PMID: 16216539 DOI: 10.1016/j.jmr.2005.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2005] [Revised: 08/07/2005] [Accepted: 09/06/2005] [Indexed: 05/04/2023]
Abstract
A version of the chirp z-transform (CZT) enabling signal intensity and phase-preserving field-of-view scaling has been programmed. The algorithm is important for all single-point imaging sequences such as SPRITE when used with multiple data acquisition for T2* mapping or signal averaging. CZT has particular utility for SPRITE imaging of nuclei with short relaxation times such as sodium at high field. Here, a complete theory of the properties of CZT is given. This method operates entirely in k-space. It is compared with a conventional interpolation approach that works in image space after the application of a fast Fourier transformation.
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Affiliation(s)
- J Kaffanke
- Institute of Medicine, Research Centre Jülich, D-52425 Jülich, Germany
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38
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Alam TM, Cherry BR, Minard KR, Celina M. Relaxation Nuclear Magnetic Resonance Imaging Investigation of Heterogeneous Aging in a Hydroxy-Terminated Polybutadiene-Based Elastomer. Macromolecules 2005. [DOI: 10.1021/ma051906y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- T. M. Alam
- Sandia National Laboratories, Albuquerque, New Mexico 87185, and Pacific Northwest National Laboratory, Richland, Washington 99352
| | - B. R. Cherry
- Sandia National Laboratories, Albuquerque, New Mexico 87185, and Pacific Northwest National Laboratory, Richland, Washington 99352
| | - K. R. Minard
- Sandia National Laboratories, Albuquerque, New Mexico 87185, and Pacific Northwest National Laboratory, Richland, Washington 99352
| | - M. Celina
- Sandia National Laboratories, Albuquerque, New Mexico 87185, and Pacific Northwest National Laboratory, Richland, Washington 99352
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39
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Zhang Z, Ouriadov AV, Willson C, Balcom BJ. Membrane gas diffusion measurements with MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 176:215-22. [PMID: 16054409 DOI: 10.1016/j.jmr.2005.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 06/13/2005] [Accepted: 06/14/2005] [Indexed: 05/03/2023]
Abstract
Gas transport across polymeric membranes is fundamental to many filtering and separation technologies. To elucidate transport mechanisms, and understand the behaviors of membrane materials, accurate measurement of transport properties is required. We report a new magnetic resonance imaging (MRI) methodology to measure membrane gas phase diffusion coefficients. The MRI challenges of low spin density and short gas phase relaxation times, especially for hydrogen gas, have been successfully overcome with a modified one-dimensional, single-point ramped imaging with T(1) enhancement, measurement. We have measured the diffusion coefficients of both hydrogen gas and sulfur-hexafluoride in a model polymeric membrane of potential interest as a gas separator in metal hydride batteries. The experimental apparatus is a modified one-dimensional diaphragm cell which permits measurement of the diffusion coefficient in experimental times of less than 1 min. The H(2) gas diffusion coefficient in the membrane was 0.54 +/- 0.01 mm(2)/s, while that of sulfur-hexafluoride was 0.14 +/- 0.01 mm(2)/s, at ambient conditions.
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Affiliation(s)
- Ziheng Zhang
- MRI Centre, Department of Physics, University of New Brunswick, Fredericton, NB, Canada E3B 5A3
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40
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Ramos-Cabrer P, van Duynhoven JPM, Van der Toorn A, Nicolay K. MRI of hip prostheses using single-point methods: in vitro studies towards the artifact-free imaging of individuals with metal implants. Magn Reson Imaging 2005; 22:1097-103. [PMID: 15527996 DOI: 10.1016/j.mri.2004.01.061] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2003] [Accepted: 01/30/2004] [Indexed: 10/26/2022]
Abstract
Use of magnetic resonance imaging (MRI) in individuals with orthopedic implants is limited because of the large distortions caused by metallic components. As a possible solution for this problem, we suggest the use of single-point imaging (SPI) methods, which are immune to the susceptibility artifacts observed with conventional MRI methods. A further advantage of SPI, based on the fact that signal encoding is achieved in ultra-short times (as short as tens of microseconds), is that they enable the direct visualization of the polymeric elements of the implants, allowing the detection of possible implant failures. We present in vitro SPI images of polymeric sockets of two hip prostheses together with artifact-free images of gelatin phantoms containing their respective metallic stems. These data underscore the great potential of the SPI technique for obtaining artifact-free images of individuals with large metal implants.
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Affiliation(s)
- P Ramos-Cabrer
- Department of Experimental in vivo NMR, Image Sciences Institute, University Medical Center, Utrecht, The Netherlands.
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41
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Minard KR, Timchalk C, Corley RA. T2-shortening of 3He gas by magnetic microspheres. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 173:90-96. [PMID: 15705517 DOI: 10.1016/j.jmr.2004.11.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Revised: 11/24/2004] [Indexed: 05/24/2023]
Abstract
In a gas-filled material like the lung parenchyma, the transverse relaxation time (T2) for 3He is shortened by the deposition of magnetic microspheres and rapid molecular diffusion through induced field distortions. Here, this unique relaxation process is described theoretically and predicted T2-shortening is validated using pressurized 3He gas in a foam model of alveolar airways. Results demonstrate that: (1) significant T2-shortening is induced by microsphere deposition, (2) shortened 3He T2s are accurately predicted, and (3) measured relaxation times are exploitable for quantifying local deposition patterns. Based on these findings the feasibility of imaging inhaled particulates in vivo with hyperpolarized 3He is examined and performance projections are formulated.
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Affiliation(s)
- Kevin R Minard
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA.
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42
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Cherry B, Alam T. Relaxation nuclear magnetic resonance imaging (R-NMRI) of PDMS/PDPS siloxane copolymer desiccation. POLYMER 2004. [DOI: 10.1016/j.polymer.2004.05.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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43
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Halse M, Rioux J, Romanzetti S, Kaffanke J, MacMillan B, Mastikhin I, Shah NJ, Aubanel E, Balcom BJ. Centric scan SPRITE magnetic resonance imaging: optimization of SNR, resolution, and relaxation time mapping. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2004; 169:102-117. [PMID: 15183362 DOI: 10.1016/j.jmr.2004.04.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Revised: 04/05/2004] [Indexed: 05/24/2023]
Abstract
Two strategies for the optimization of centric scan SPRITE (single point ramped imaging with T1 enhancement) magnetic resonance imaging techniques are presented. Point spread functions (PSF) for the centric scan SPRITE methodologies are numerically simulated, and the blurring manifested in a centric scan SPRITE image through PSF convolution is characterized. Optimal choices of imaging parameters and k-space sampling scheme are predicted to obtain maximum signal-to-noise ratio (SNR) while maintaining acceptable image resolution. The point spread function simulation predictions are verified experimentally. The acquisition of multiple FID points following each RF excitation is described and the use of the Chirp z-Transform algorithm for the scaling of field of view (FOV) of the reconstructed images is illustrated. Effective recombination of the rescaled images for SNR improvement and T*2 mapping is demonstrated.
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Affiliation(s)
- M Halse
- MRI Centre, Department of Physics, University of New Brunswick, Fredericton, NB, Canada
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44
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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] [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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45
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Halse M, Goodyear DJ, MacMillan B, Szomolanyi P, Matheson D, Balcom BJ. Centric scan SPRITE magnetic resonance imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2003; 165:219-229. [PMID: 14643703 DOI: 10.1016/j.jmr.2003.08.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two rapid, pure phase encode, centric scan, Single Point Ramped Imaging with T1-Enhancement (SPRITE) MRI methods are described. Each retains the benefits of the standard SPRITE method, most notably the ability to image short T2* systems, while increasing the sensitivity and generality of the technique. The Spiral-SPRITE method utilizes a modified Archimedean spiral k-space trajectory. The Conical-SPRITE method utilizes a system of spirals mapped to conical surfaces to sample the k-space cube. The sampled k-space points are naturally Cartesian grid points, eliminating the requirement of a re-gridding procedure prior to image reconstruction. The effects of transient state behaviour on image resolution and signal/noise are explored.
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Affiliation(s)
- Meghan Halse
- Department of Physics, MRI Centre, PO Box 4400, University of New Brunswick, Fredericton, NB, Canada E3B 5A3
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Mastikhin IV, Mullally H, MacMillan B, Balcom BJ. Water content profiles with a 1D centric SPRITE acquisition. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2002; 156:122-130. [PMID: 12081449 DOI: 10.1006/jmre.2002.2544] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The purpose of this work is to develop a rapid MRI method amenable to profiling with minimal or no T(1) relaxation weighting. The behavior of a signal during a centric SPRITE acquisition is analyzed. It is shown that the technique can be made immune to a broad range of T(1) changes. In a properly executed measurement, only T(2)* and proton density parameters define the image intensity. A T(2)* mapping technique can be easily applied, separating T(2)* and proton density contributions to the image. A drying soil sample with low initial water content is experimentally studied as a demonstration of the technique. A characteristic baseline artifact is easily removed from the profiles by a simple operation.
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Affiliation(s)
- I V Mastikhin
- MRI Centre, Department of Physics, University of New Brunswick, Fredericton, Canada E3B 5A3
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Bär NK, Balcom BJ, Ruthven DM. Direct Measurement of Transient Concentration Profiles in Adsorbent Particles and Chromatographic Columns by MRI. Ind Eng Chem Res 2002. [DOI: 10.1021/ie010821s] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nils-Karsten Bär
- MRI Centre, Department of Physics, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3 Canada, and Department of Chemical Engineering, University of Maine, Orono, Maine 04469
| | - Bruce J. Balcom
- MRI Centre, Department of Physics, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3 Canada, and Department of Chemical Engineering, University of Maine, Orono, Maine 04469
| | - Douglas M. Ruthven
- MRI Centre, Department of Physics, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3 Canada, and Department of Chemical Engineering, University of Maine, Orono, Maine 04469
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Saito K, Hatakeyama M, Komaki I, Katoh K. Solid state NMR studies for a new carbonization process with high temperature preheating. J Mol Struct 2002. [DOI: 10.1016/s0022-2860(01)00740-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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49
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Troutman MY, Mastikhin IV, Balcom BJ, Eads TM, Ziegler GR. Moisture migration in soft-panned confections during engrossing and aging as observed by magnetic resonance imaging. J FOOD ENG 2001. [DOI: 10.1016/s0260-8774(00)00167-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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50
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Szomolanyi P, Goodyear D, Balcom B, Matheson D. SPIRAL-SPRITE: a rapid single point MRI technique for application to porous media. Magn Reson Imaging 2001; 19:423-8. [PMID: 11445323 DOI: 10.1016/s0730-725x(01)00260-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study presents the application of a new, rapid, single point MRI technique which samples k space with spiral trajectories. The general principles of the technique are outlined along with application to porous concrete samples, solid pharmaceutical tablets and gas phase imaging. Each sample was chosen to highlight specific features of the method.
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Affiliation(s)
- P Szomolanyi
- MRI Centre, Departments of Physics and Chemistry, University of New Brunswick, Fredericton, NB, Canada
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