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Cao J, Ball IK, Cassidy B, Rae CD. Functional conductivity imaging: quantitative mapping of brain activity. Phys Eng Sci Med 2024:10.1007/s13246-024-01484-z. [PMID: 39259483 DOI: 10.1007/s13246-024-01484-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 08/28/2024] [Indexed: 09/13/2024]
Abstract
Theory and modelling suggest that detection of neuronal activity may be feasible using phase sensitive MRI methods. Successful detection of neuronal activity both in vitro and in vivo has been described while others have reported negative results. Magnetic resonance electrical properties tomography may be a route by which signal changes can be identified. Here, we report successful and repeatable detection at 3 Tesla of human brain activation in response to visual and somatosensory stimuli using a functional version of tissue conductivity imaging (funCI). This detects activation in both white and grey matter with apparent tissue conductivity changes of 0.1 S/m (17-20%, depending on the tissue baseline conductivity measure) allowing visualization of complete system circuitry. The degree of activation scales with the degree of the stimulus (duration or contrast). The conductivity response functions show a distinct timecourse from that of traditional fMRI haemodynamic (BOLD or Blood Oxygenation Level Dependent) response functions, peaking within milliseconds of stimulus cessation and returning to baseline within 3-4 s. We demonstrate the utility of the funCI approach by showing robust activation of the lateral somatosensory circuitry on stimulation of an index finger, on stimulation of a big toe or of noxious (heat) stimulation of the face as well as activation of visual circuitry on visual stimulation in up to five different individuals. The sensitivity and repeatability of this approach provides further evidence that magnetic resonance imaging approaches can detect brain activation beyond changes in blood supply.
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Affiliation(s)
- Jun Cao
- Neuroscience Research Australia, 139 Barker St, Randwick, NSW, 2031, Australia
| | - Iain K Ball
- Philips Australia & New Zealand, North Ryde, NSW, 2113, Australia
| | - Benjamin Cassidy
- Neuroscience Research Australia, 139 Barker St, Randwick, NSW, 2031, Australia
- Pathfinder Exploration LLC, Tonopah, NV, USA
| | - Caroline D Rae
- Neuroscience Research Australia, 139 Barker St, Randwick, NSW, 2031, Australia.
- School of Psychology, The University of New South Wales, Sydney, NSW, 2052, Australia.
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Cao J, Ball IK, Summerell E, Humburg P, Denson T, Rae CD. Effect of Ethanol on Brain Electrical Tissue Conductivity in Social Drinkers. J Magn Reson Imaging 2024. [PMID: 39105662 DOI: 10.1002/jmri.29548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 07/09/2024] [Accepted: 07/11/2024] [Indexed: 08/07/2024] Open
Abstract
BACKGROUND How the biophysics of electrical conductivity measures relate to brain activity is poorly understood. The sedative, ethanol, reduces metabolic activity but its impact on brain electrical conductivity is unknown. PURPOSE To investigate whether ethanol reduces brain electrical tissue conductivity. STUDY TYPE Prospective. SUBJECTS Fifty-two healthy volunteers (aged 18-37 years, 22 females, 30 males). FIELD STRENGTH/SEQUENCE 3 T, T1-weighted, multi-shot, turbo-field echo (TFE); 3D balanced fast-field echo (bFFE). ASSESSMENT Brain gray and white matter tissue conductivity measured with phase-based magnetic resonance electrical properties tomography (MREPT) compared before and 20 minutes after ethanol consumption (0.7 g/kg body weight). Differential conductivity whole brain maps were generated for three subgroups: those with strong (∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$ > 0.1 S/m; N = 33), weak (0.02 S/m ≤ ∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$ ≤ 0.1 S/m; N = 9) conductivity decrease, and no significant response (∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$ < 0.02 S/m, N = 10). Maps were compared in the strong response group where breath alcohol rose between scans, vs. those where it fell. STATISTICAL TESTS Average breath alcohol levels were compared to the differential conductivity maps using linear regression. T-maps were generated (threshold P < 0.05 and P < 0.001; minimum cluster 48 mm3). Differential conductivity maps were compared with ANOVA. RESULTS Whole-group analysis showed decreased conductivity that did not survive statistical thresholding. Strong responders (N = 33) showed a consistent pattern of significantly decreased conductivity (∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$ > 0.1 S/m) in frontal/occipital and cerebellar white matter. The weak response group (N = 9) showed a similar pattern of conductivity decrease (0.02 S/m ≤ ∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$ ≤ 0.1 S/m). There was no significant relationship with breath alcohol levels, alcohol use, age, ethnicity, or sex. The strong responders' regional response was different between ascending (N = 12) or descending (N = 20) alcohol during the scan. DATA CONCLUSION Ethanol reduces brain tissue conductivity in a participant-dependent and spatially dependent fashion. EVIDENCE LEVEL 1 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Jun Cao
- Neuroscience Research Australia, Sydney, New South Wales, Australia
| | - Iain K Ball
- Philips Australia & New Zealand, North Ryde, New South Wales, Australia
| | - Elizabeth Summerell
- School of Psychology, The University of New South Wales, Sydney, New South Wales, Australia
| | - Peter Humburg
- Mark Wainwright Analytical Centre, Stats Central, The University of New South Wales, Sydney, New South Wales, Australia
| | - Tom Denson
- School of Psychology, The University of New South Wales, Sydney, New South Wales, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- School of Psychology, The University of New South Wales, Sydney, New South Wales, Australia
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Montrazi ET, Sasson K, Agemy L, Peters DC, Brenner O, Scherz A, Frydman L. High-sensitivity deuterium metabolic MRI differentiates acute pancreatitis from pancreatic cancers in murine models. Sci Rep 2023; 13:19998. [PMID: 37968574 PMCID: PMC10652017 DOI: 10.1038/s41598-023-47301-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/11/2023] [Indexed: 11/17/2023] Open
Abstract
Deuterium metabolic imaging (DMI) is a promising tool for investigating a tumor's biology, and eventually contribute in cancer diagnosis and prognosis. In DMI, [6,6'-2H2]-glucose is taken up and metabolized by different tissues, resulting in the formation of HDO but also in an enhanced formation of [3,3'-2H2]-lactate at the tumor site as a result of the Warburg effect. Recent studies have shown DMI's suitability to highlight pancreatic cancer in murine models by [3,3'-2H2]-lactate formation; an important question is whether DMI can also differentiate between these tumors and pancreatitis. This differentiation is critical, as these two diseases are hard to distinguish today radiologically, but have very different prognoses requiring distinctive treatments. Recent studies have shown the limitations that hyperpolarized MRI faces when trying to distinguish these pancreatic diseases by monitoring the [1-13C1]-pyruvate→[1-13C1]-lactate conversion. In this work, we explore DMI's capability to achieve such differentiation. Initial tests used a multi-echo (ME) SSFP sequence, to identify any metabolic differences between tumor and acute pancreatitis models that had been previously elicited very similar [1-13C1]-pyruvate→[1-13C1]-lactate conversion rates. Although ME-SSFP provides approximately 5 times greater signal-to-noise ratio (SNR) than the standard chemical shift imaging (CSI) experiment used in DMI, no lactate signal was observed in the pancreatitis model. To enhance lactate sensitivity further, we developed a new, weighted-average, CSI-SSFP approach for DMI. Weighted-average CSI-SSFP improved DMI's SNR by another factor of 4 over ME-SSFP-a sensitivity enhancement that sufficed to evidence natural abundance 2H fat in abdominal images, something that had escaped the previous approaches even at ultrahigh (15.2 T) MRI fields. Despite these efforts to enhance DMI's sensitivity, no lactate signal could be detected in acute pancreatitis models (n = 10; [3,3'-2H2]-lactate limit of detection < 100 µM; 15.2 T). This leads to the conclusion that pancreatic tumors and acute pancreatitis may be clearly distinguished by DMI, based on their different abilities to generate deuterated lactate.
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Affiliation(s)
- Elton T Montrazi
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Keren Sasson
- Department of Plant and Environmental Science, Weizmann Institute of Science, Rehovot, Israel
| | - Lilach Agemy
- Department of Plant and Environmental Science, Weizmann Institute of Science, Rehovot, Israel
| | - Dana C Peters
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, USA
| | - Ori Brenner
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | - Avigdor Scherz
- Department of Plant and Environmental Science, Weizmann Institute of Science, Rehovot, Israel
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel.
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Bauman G, Lee NG, Tian Y, Bieri O, Nayak KS. Submillimeter lung MRI at 0.55 T using balanced steady-state free precession with half-radial dual-echo readout (bSTAR). Magn Reson Med 2023; 90:1949-1957. [PMID: 37317635 DOI: 10.1002/mrm.29757] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/20/2023] [Accepted: 05/23/2023] [Indexed: 06/16/2023]
Abstract
PURPOSE To demonstrate the feasibility of high-resolution morphologic lung MRI at 0.55 T using a free-breathing balanced steady-state free precession half-radial dual-echo imaging technique (bSTAR). METHODS Self-gated free-breathing bSTAR (TE1 /TE2 /TR of 0.13/1.93/2.14 ms) lung imaging in five healthy volunteers and a patient with granulomatous lung disease was performed using a 0.55 T MR-scanner. A wobbling Archimedean spiral pole (WASP) trajectory was used to ensure a homogenous coverage of k-space over multiple breathing cycles. WASP uses short-duration interleaves randomly tilted by a small polar angle and rotated by a golden angle about the polar axis. Data were acquired continuously over 12:50 min. Respiratory-resolved images were reconstructed off-line using compressed sensing and retrospective self-gating. Reconstructions were performed with a nominal resolution of 0.9 mm and a reduced isotropic resolution of 1.75 mm corresponding to shorter simulated scan times of 8:34 and 4:17 min, respectively. Analysis of apparent SNR was performed in all volunteers and reconstruction settings. RESULTS The technique provided artifact-free morphologic lung images in all subjects. The short TR of bSTAR in conjunction with a field strength of 0.55 T resulted in a complete mitigation of off-resonance artifacts in the chest. Mean SNR values in healthy lung parenchyma for the 12:50 min scan were 3.6 ± 0.8 and 24.9 ± 6.2 for 0.9 mm and 1.75 mm reconstructions, respectively. CONCLUSION This study demonstrates the feasibility of morphologic lung MRI with a submillimeter isotropic spatial resolution in human subjects with bSTAR at 0.55 T.
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Affiliation(s)
- Grzegorz Bauman
- Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Nam G Lee
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Ye Tian
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Oliver Bieri
- Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland
- Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Krishna S Nayak
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
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Cao J, Ball I, Humburg P, Dokos S, Rae C. Repeatability of brain phase-based magnetic resonance electric properties tomography methods and effect of compressed SENSE and RF shimming. Phys Eng Sci Med 2023; 46:753-766. [PMID: 36995580 DOI: 10.1007/s13246-023-01248-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 03/19/2023] [Indexed: 03/31/2023]
Abstract
Magnetic resonance electrical properties tomography (MREPT) is an emerging imaging modality to noninvasively measure tissue conductivity and permittivity. Implementation of MREPT in the clinic requires repeatable measurements at a short scan time and an appropriate protocol. The aim of this study was to investigate the repeatability of conductivity measurements using phase-based MREPT and the effects of compressed SENSE (CS), and RF shimming on the precision of conductivity measurements. Conductivity measurements using turbo spin echo (TSE) and three-dimensional balanced fast field echo (bFFE) with CS factors were repeatable. Conductivity measurement using bFFE phase showed smaller mean and variance that those measured by TSE. The conductivity measurements using bFFE showed minimal deviation with CS factors up to 8, with deviation increasing at CS factors > 8. Subcortical structures produced less consistent measurements than cortical parcellations at higher CS factors. RF shimming using full slice coverage 2D dual refocusing echo acquisition mode (DREAM) and full coverage 3D dual TR approaches further improved measurement precision. BFFE is a more optimal sequence than TSE for phase-based MREPT in brain. Depending on the area of the brain being measured, the scan can be safely accelerated with compressed SENSE without sacrifice of precision, offering the potential to employ MREPT in clinical research and applications. RF shimming with better field mapping further improves precision of the conductivity measures.
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Affiliation(s)
- Jun Cao
- Neuroscience Research Australia, 139 Barker St, Randwick, NSW, 2031, Australia
- School of Biomedical Sciences, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Iain Ball
- Philips Australia & New Zealand, North Ryde, NSW, 2113, Australia
| | - Peter Humburg
- Neuroscience Research Australia, 139 Barker St, Randwick, NSW, 2031, Australia
- Mark Wainwright Analytical Centre, Stats Central, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Caroline Rae
- Neuroscience Research Australia, 139 Barker St, Randwick, NSW, 2031, Australia.
- School of Psychology, The University of New South Wales, Kensington, NSW, 2052, Australia.
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Peters DC, Markovic S, Bao Q, Preise D, Sasson K, Agemy L, Scherz A, Frydman L. Improving deuterium metabolic imaging (DMI) signal-to-noise ratio by spectroscopic multi-echo bSSFP: A pancreatic cancer investigation. Magn Reson Med 2021; 86:2604-2617. [PMID: 34196041 DOI: 10.1002/mrm.28906] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 06/07/2021] [Accepted: 06/07/2021] [Indexed: 12/15/2022]
Abstract
PURPOSE Deuterium metabolic imaging (DMI) maps the uptake of deuterated precursors and their conversion into lactate and other markers of tumor metabolism. Even after leveraging 2 H's short T1 s, DMI's signal-to-noise ratio (SNR) is limited. We hypothesize that a multi-echo balanced steady-state free precession (ME-bSSFP) approach would increase SNR compared to chemical shift imaging (CSI), while achieving spectral isolation of the metabolic precursors and products. METHODS Suitably tuned 2 H ME-bSSFP (five echo times [TEs], ΔTE = 2.2 ms, repetition time [TR]/flip-angle = 12 ms/60°) was implemented at 15.2T and compared to CSI (TR/flip-angle = 95 ms/90°) regarding SNR and spectral isolation, in simulations, in deuterated phantoms and for the in vivo diagnosis of a mouse tumor model of pancreatic adenocarcinoma (N = 10). RESULTS Simulations predicted an SNR increase vs. CSI of 3-5, and that the peaks of 2 H-water, 2 H6,6' -glucose, and 2 H3,3' -lactate can be well isolated by ME-bSSFP; phantoms confirmed this. In vivo, at equal spatial resolution (1.25 × 1.25 mm2 ) and scan time (10 min), 2 H6,6' -glucose's and 2 H3,3' -lactate's SNR were indeed higher for bSSFP than for CSI, three-fold for glucose (57 ± 30 vs. 19 ± 11, P < .001), doubled for water (13 ± 5 vs. 7 ± 3, P = .005). The time courses and overall localization of all metabolites agreed well, comparing CSI against ME-bSSFP. However, a clearer localization of glucose in kidneys and bladder, the detection of glucose-avid rims in certain tumors, and a heterogeneous pattern of intra-tumor lactate production could only be observed using ME-bSSFP's higher resolution. CONCLUSIONS ME-bSSFP provides greater SNR per unit time than CSI, providing for higher spatial resolution mapping of glucose uptake and lactate production in tumors.
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Affiliation(s)
- Dana C Peters
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
| | - Stefan Markovic
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Qingjia Bao
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Dina Preise
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Keren Sasson
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Lilach Agemy
- Department of Plant and Environmental Science, Weizmann Institute of Science, Rehovot, Israel
| | - Avigdor Scherz
- Department of Plant and Environmental Science, Weizmann Institute of Science, Rehovot, Israel
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
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Bauman G, Bieri O. Balanced steady‐state free precession thoracic imaging with half‐radial dual‐echo readout on smoothly interleaved archimedean spirals. Magn Reson Med 2019; 84:237-246. [DOI: 10.1002/mrm.28119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/22/2019] [Accepted: 11/19/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Grzegorz Bauman
- Division of Radiological Physics Department of Radiology University of Basel Hospital Basel Switzerland
- Department of Biomedical Engineering University of Basel Basel Switzerland
| | - Oliver Bieri
- Division of Radiological Physics Department of Radiology University of Basel Hospital Basel Switzerland
- Department of Biomedical Engineering University of Basel Basel Switzerland
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Lanza GM. Dual-Contrast 19F/ 1H Magnetic Resonance Imaging to Characterize Myocardial Infarct Healing. Circ Cardiovasc Imaging 2019; 11:e008457. [PMID: 30571326 DOI: 10.1161/circimaging.118.008457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Gregory M Lanza
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
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Hansen ESS, Pedersen SF, Pedersen SB, Bøtker HE, Kim WY. Validation of contrast enhanced cine steady-state free precession and T2-weighted CMR for assessment of ischemic myocardial area-at-risk in the presence of reperfusion injury. Int J Cardiovasc Imaging 2019; 35:1039-1045. [DOI: 10.1007/s10554-019-01569-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/21/2019] [Indexed: 11/27/2022]
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Maunder A, Rao M, Robb F, Wild JM. Optimization of steady-state free precession MRI for lung ventilation imaging with 19 F C 3 F 8 at 1.5T and 3T. Magn Reson Med 2019; 81:1130-1142. [PMID: 30387911 PMCID: PMC6491987 DOI: 10.1002/mrm.27479] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/26/2018] [Accepted: 07/11/2018] [Indexed: 12/12/2022]
Abstract
PURPOSE To optimize 19 F imaging pulse sequences for perfluoropropane (C3 F8 ) gas human lung ventilation MRI considering intrinsic in vivo relaxation parameters at both 1.5T and 3T. METHODS Optimization of the imaging parameters for both 3D spoiled gradient (SPGR) and steady-state free precession (SSFP) 19 F imaging sequences with inhaled 79% C3 F8% and 21% oxygen was performed. Phantom measurements were used to validate simulations of SNR. In vivo parameter mapping and sequence optimization and comparison was performed by imaging the lungs of a healthy adult volunteer. T1 and T2* mapping was performed in vivo to optimize sequence parameters for in vivo lung MRI. The performance of SSFP and SPGR was then evaluated in vivo at 1.5T and 3T. RESULTS The in vivo T2* of C3 F8 was shown to be dependent upon lung inflation level (2.04 ms ± 36% for residual volume and 3.14 ms ± 28% for total lung capacity measured at 3T), with lower T2* observed near the susceptibility interfaces of the diaphragm and around pulmonary blood vessels. Simulation and phantom measurements indicate that a factor of ~2-3 higher SNR can be achieved with SSFP when compared with optimized SPGR. In vivo lung imaging showed a 1.7 factor of improvement in SNR achieved at 1.5T, while the theoretical improvement at 3T was not attained due to experimental SAR constraints, shorter in vivo T1 , and B0 inhomogeneity. CONCLUSION SSFP imaging provides increased SNR in lung ventilation imaging of C3 F8 demonstrated at 1.5T with optimized SSFP similar to the SNR that can be obtained at 3T with optimized SPGR.
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Affiliation(s)
- Adam Maunder
- POLARIS, Unit of Academic Radiology, Department of IICDUniversity of SheffieldSheffieldUnited Kingdom
| | - Madhwesha Rao
- POLARIS, Unit of Academic Radiology, Department of IICDUniversity of SheffieldSheffieldUnited Kingdom
| | - Fraser Robb
- POLARIS, Unit of Academic Radiology, Department of IICDUniversity of SheffieldSheffieldUnited Kingdom
- GE HealthcareAuroraOhio
| | - Jim M. Wild
- POLARIS, Unit of Academic Radiology, Department of IICDUniversity of SheffieldSheffieldUnited Kingdom
- Insigneo Institute for In silico medicineSheffieldUnited Kingdom
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Bauman G, Pusterla O, Bieri O. Functional lung imaging with transient spoiled gradient echo. Magn Reson Med 2018; 81:1915-1923. [DOI: 10.1002/mrm.27535] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 08/06/2018] [Accepted: 08/27/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Grzegorz Bauman
- Division of Radiological Physics, Department of Radiology University of Basel Hospital Basel Switzerland
- Department of Biomedical Engineering University of Basel Basel Switzerland
| | - Orso Pusterla
- Division of Radiological Physics, Department of Radiology University of Basel Hospital Basel Switzerland
- Department of Biomedical Engineering University of Basel Basel Switzerland
| | - Oliver Bieri
- Division of Radiological Physics, Department of Radiology University of Basel Hospital Basel Switzerland
- Department of Biomedical Engineering University of Basel Basel Switzerland
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Kuetting DLR, Dabir D, Luetkens J, Feisst A, Homsi R, Thomas D, Schild HH, Sprinkart AM. Flip angle optimization for balanced SSFP: Cardiac cine imaging following the application of standard extracellular contrast agent (gadobutrol). J Magn Reson Imaging 2017; 47:255-261. [PMID: 28429574 DOI: 10.1002/jmri.25728] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 03/22/2017] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To investigate the effect of the flip angle (FA) on the blood-myocardium contrast and to define the FA leading to highest image quality in contrast-enhanced balanced steady-state free precession (bSSFP) images. bSSFP images provide excellent contrast between myocardium and blood with high signal-to-noise and contrast-to-noise ratios (SNR, CNR). In clinical practice, bSSFP images are typically acquired following the injection of extracellular contrast agents (ECAs), although ECAs decrease the blood-myocardium contrast. MATERIALS AND METHODS First, a theoretical optimization was performed to determine the FA that maximizes CNR in bSSFP imaging 2-20 minutes after application of ECA. Second signal-ratios, contrast, SNR, and CNR were assessed in vivo in 25 patients in bSSFP images at 1.5T acquired before (FA = 50°) and 10-15 minutes after (FAs = 50°, 80°, 90°, 100°) application of a double-dose contrast agent. Image quality was assessed by two readers. RESULTS Simulations yielded FAs in the range of 85-100° for optimal CNR in contrast-enhanced images. In vivo comparison of conventionally acquired cine images (FA 50°) showed an increase in CNR between blood and myocardium by 57% in diastole and 78% in systole in adapted contrast-enhanced bSSFP images (FA 100°). Contrast-enhanced images with an FA of 100° were rated highest in image quality assessment. CONCLUSION By means of FA adaptation a similar blood-myocardium contrast can be achieved in contrast-enhanced bSSFP as in unenhanced bSSFP imaging with an increase in CNR. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:255-261.
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Affiliation(s)
| | - Darius Dabir
- Department of Radiology, University of Bonn, Bonn, Germany
| | | | - Andreas Feisst
- Department of Radiology, University of Bonn, Bonn, Germany
| | - Rami Homsi
- Department of Radiology, University of Bonn, Bonn, Germany
| | - Daniel Thomas
- Department of Radiology, University of Bonn, Bonn, Germany
| | - Hans H Schild
- Department of Radiology, University of Bonn, Bonn, Germany
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Lalude OO, Lerakis S. Cardiovascular Magnetic Resonance Imaging. Interv Cardiol 2016. [DOI: 10.1002/9781118983652.ch10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
| | - Stamatios Lerakis
- Emory University School of Medicine and Georgia Institute of Technology; Atlanta GA USA
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Accuracy of Liver Fat Quantification With Advanced CT, MRI, and Ultrasound Techniques: Prospective Comparison With MR Spectroscopy. AJR Am J Roentgenol 2016; 208:92-100. [PMID: 27726414 DOI: 10.2214/ajr.16.16565] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE The purpose of this study was to prospectively evaluate the accuracy of proton-density fat-fraction, single- and dual-energy CT (SECT and DECT), gray-scale ultrasound (US), and US shear-wave elastography (US-SWE) in the quantification of hepatic steatosis with MR spectroscopy (MRS) as the reference standard. SUBJECTS AND METHODS Fifty adults who did not have symptoms (23 men, 27 women; mean age, 57 ± 5 years; body mass index, 27 ± 5) underwent liver imaging with un-enhanced SECT, DECT, gray-scale US, US-SWE, proton-density fat-fraction MRI, and MRS for this prospective trial. MRS voxels for the reference standard were colocalized with all other modalities under investigation. For SECT (120 kVp), attenuation values were recorded. For rapid-switching DECT (80/140 kVp), monochromatic images (70-140 keV) and fat density-derived material decomposition images were reconstructed. For proton-density fat fraction MRI, a quantitative chemical shift-encoded method was used. For US, echogenicity was evaluated on a qualitative 0-3 scale. Quantitative US shear-wave velocities were also recorded. Data were analyzed by linear regression for each technique compared with MRS. RESULTS There was excellent correlation between MRS and both proton-density fat-fraction MRI (r2 = 0.992; slope, 0.974; intercept, -0.943) and SECT (r2 = 0.856; slope, -0.559; intercept, 35.418). DECT fat attenuation had moderate correlation with MRS measurements (r2 = 0.423; slope, 0.034; intercept, 8.459). There was good correlation between qualitative US echogenicity and MRS measurements with a weighted kappa value of 0.82. US-SWE velocity did not have reliable correlation with MRS measurements (r2 = 0.004; slope, 0.069; intercept, 6.168). CONCLUSION Quantitative MRI proton-density fat fraction and SECT fat attenuation have excellent linear correlation with MRS measurements and can serve as accurate noninvasive biomarkers for quantifying steatosis. Material decomposition with DECT does not improve the accuracy of fat quantification over conventional SECT attenuation. US-SWE has poor accuracy for liver fat quantification.
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Schmieder AH, Caruthers SD, Keupp J, Wickline SA, Lanza GM. Recent Advances in 19Fluorine Magnetic Resonance Imaging with Perfluorocarbon Emulsions. ENGINEERING (BEIJING, CHINA) 2015; 1:475-489. [PMID: 27110430 PMCID: PMC4841681 DOI: 10.15302/j-eng-2015103] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The research roots of 19fluorine (19F) magnetic resonance imaging (MRI) date back over 35 years. Over that time span, 1H imaging flourished and was adopted worldwide with an endless array of applications and imaging approaches, making magnetic resonance an indispensable pillar of biomedical diagnostic imaging. For many years during this timeframe, 19F imaging research continued at a slow pace as the various attributes of the technique were explored. However, over the last decade and particularly the last several years, the pace and clinical relevance of 19F imaging has exploded. In part, this is due to advances in MRI instrumentation, 19F/1H coil designs, and ultrafast pulse sequence development for both preclinical and clinical scanners. These achievements, coupled with interest in the molecular imaging of anatomy and physiology, and combined with a cadre of innovative agents, have brought the concept of 19F into early clinical evaluation. In this review, we attempt to provide a slice of this rich history of research and development, with a particular focus on liquid perfluorocarbon compound-based agents.
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Affiliation(s)
- Anne H. Schmieder
- Division of Cardiology, Washington University School of Medical, St. Louis, MO 63110, USA
| | - Shelton D. Caruthers
- Toshiba Medical Research Institute USA, Inc., Cleveland, OH 44143, USA
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA
| | - Jochen Keupp
- Philips Research Hamburg, Hamburg 22335, Germany
| | - Samuel A. Wickline
- Division of Cardiology, Washington University School of Medical, St. Louis, MO 63110, USA
| | - Gregory M. Lanza
- Division of Cardiology, Washington University School of Medical, St. Louis, MO 63110, USA
- Correspondence author.
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16
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Varga-Szemes A, Muscogiuri G, Schoepf UJ, De Cecco CN, Wichmann JL, Mangold S, Caruso D, Fuller SR, Spottiswoode BS, van der Geest RJ, Suranyi P. Overview of Myocardial T1 Mapping Applications. CURRENT RADIOLOGY REPORTS 2015. [DOI: 10.1007/s40134-015-0114-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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17
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Srinivasan S, Ennis DB. Optimal flip angle for high contrast balanced SSFP cardiac cine imaging. Magn Reson Med 2014; 73:1095-103. [DOI: 10.1002/mrm.25228] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 01/24/2014] [Accepted: 03/02/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Subashini Srinivasan
- Department of Radiological Sciences; University of California; Los Angeles California USA
- Department of Bioengineering; University of California; Los Angeles California USA
| | - Daniel B. Ennis
- Department of Radiological Sciences; University of California; Los Angeles California USA
- Department of Bioengineering; University of California; Los Angeles California USA
- Biomedical Physics Interdepartmental Program; University of California; Los Angeles California USA
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Review of T1 Mapping Methods: Comparative Effectiveness Including Reproducibility Issues. CURRENT CARDIOVASCULAR IMAGING REPORTS 2014. [DOI: 10.1007/s12410-013-9252-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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19
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Pelot NA, Bowen CV. Quantification of superparamagnetic iron oxide using inversion recovery balanced steady-state free precession. Magn Reson Imaging 2013; 31:953-60. [PMID: 23601361 DOI: 10.1016/j.mri.2013.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 02/19/2013] [Accepted: 03/09/2013] [Indexed: 11/29/2022]
Abstract
Cellular and molecular MRI trafficking studies using superparamagnetic iron oxide (SPIO) have greatly improved non-invasive investigations of disease progression and drug efficacy, but thus far, these studies have largely been restricted to qualitative assessment of hypo- or hyperintense areas near SPIO. In this work, SPIO quantification using inversion recovery balanced steady-state free precession (IR-bSSFP) was demonstrated at 3T by extracting R2 values from a monoexponential model (P. Schmitt et al., 2004). A low flip angle was shown to reduce the apparent recovery rate of the IR-bSSFP time course, thus extending the dynamic range of quantification. However, low flip angle acquisitions preclude the use of traditional methods for combining RF phase-cycled images to reduce banding artifacts arising from off-resonance due to B0 inhomogeneity. To achieve R2 quantification of SPIO, we present a new algorithm applicable to low flip angle IR-bSSFP acquisitions that is specifically designed to identify on-resonance acquisitions. We demonstrate in this work, using both theoretical and empirical methods, that the smallest estimated R2 from multiple RF phase-cycled acquisitions correspond well to the on-resonance time course. Using this novel minimum R2 algorithm, homogeneous R2 maps and linear R2 calibration curves were created up to 100μg(Fe)/mL with 20° flip angles, despite substantial B0 inhomogeneity. In addition, we have shown this technique to be feasible for pre-clinical research: the minimum R2 algorithm was resistant to off-resonance in a single slice mouse R2 map, whereas maximum intensity projection resulted in banding artifacts and overestimated R2 values. With the application of recent advances in accelerated acquisitions, IR-bSSFP has the potential to quantify SPIO in vivo, thus providing important information for oncology, immunology, and regenerative medicine MRI studies.
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Affiliation(s)
- Nicole A Pelot
- Department of Biomedical Engineering, Duke University, Room 136 Hudson Hall, Box 90281, Durham, NC 27708-0281, USA.
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Oshinski JN, Delfino JG, Sharma P, Gharib AM, Pettigrew RI. Cardiovascular magnetic resonance at 3.0 T: current state of the art. J Cardiovasc Magn Reson 2010; 12:55. [PMID: 20929538 PMCID: PMC2964699 DOI: 10.1186/1532-429x-12-55] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 10/07/2010] [Indexed: 12/12/2022] Open
Abstract
There are advantages to conducting cardiovascular magnetic resonance (CMR) studies at a field strength of 3.0 Telsa, including the increase in bulk magnetization, the increase in frequency separation of off-resonance spins, and the increase in T1 of many tissues. However, there are significant challenges to routinely performing CMR at 3.0 T, including the reduction in main magnetic field homogeneity, the increase in RF power deposition, and the increase in susceptibility-based artifacts.In this review, we outline the underlying physical effects that occur when imaging at higher fields, examine the practical results these effects have on the CMR applications, and examine methods used to compensate for these effects. Specifically, we will review cine imaging, MR coronary angiography, myocardial perfusion imaging, late gadolinium enhancement, and vascular wall imaging.
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Affiliation(s)
- John N Oshinski
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road, Room AG34, Atlanta, GA 30322, USA
- Department of Biomedical Engineering, Emory University and the Georgia Institute of Technology, 101 Woodruff Circle Woodruff Memorial Building, Suite 2001, Atlanta, Georgia 30322, USA
| | - Jana G Delfino
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road, Room AG34, Atlanta, GA 30322, USA
| | - Puneet Sharma
- Department of Radiology, Emory University School of Medicine, 1364 Clifton Road, Room AG34, Atlanta, GA 30322, USA
| | - Ahmed M Gharib
- Laboratory of Integrative Cardiovascular Imaging, Department of Radiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Bldg. 10, Rm. 3-5340, MSC 1263, 10 Center Dr., Bethesda, MD 20892, USA
| | - Roderic I Pettigrew
- Laboratory of Integrative Cardiovascular Imaging, Department of Radiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Bldg. 10, Rm. 3-5340, MSC 1263, 10 Center Dr., Bethesda, MD 20892, USA
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21
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Bieri O. An analytical description of balanced steady-state free precession with finite radio-frequency excitation. Magn Reson Med 2010; 65:422-31. [DOI: 10.1002/mrm.22626] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 07/09/2010] [Accepted: 08/10/2010] [Indexed: 11/09/2022]
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Mohammadi-Nejad AR, Hossein-Zadeh GA, Soltanian-Zadeh H. Quantitative evaluation of optimal imaging parameters for single-cell detection in MRI using simulation. Magn Reson Imaging 2010; 28:408-17. [DOI: 10.1016/j.mri.2009.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 08/20/2009] [Accepted: 11/25/2009] [Indexed: 10/20/2022]
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Gonzalez-Lara LE, Xu X, Hofstetrova K, Pniak A, Brown A, Foster PJ. In vivo magnetic resonance imaging of spinal cord injury in the mouse. J Neurotrauma 2009; 26:753-62. [PMID: 19397403 DOI: 10.1089/neu.2008.0704] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The feasibility of performing high-resolution in vivo magnetic resonance imaging (MRI) to visualize the injured mouse spinal cord using a three-dimensional (3D)-FIESTA (fast imaging employing steady state acquisition) pulse sequence, in a clip compression injury model, is presented. Images were acquired using a 3-Tesla clinical whole-body MR system equipped with a high-performance gradient coil insert. High-resolution mouse cord images were used to detect and monitor the cord lesions for 6 weeks after spinal cord injury (SCI). The epicenter of the injury appeared as a region of mixed signal intensities on day 2 post-SCI. Regions of signal hypointensity appeared at the lesion site by 2 weeks post-SCI and became more apparent with time. In some mice, large cyst-like lesions were detected rostral to the lesion epicenter, as early as 2 weeks post-SCI, and increased in volume with time. In addition, MRI was used to detect and monitor iron-labeled mesenchymal stem cells (MSCs) after their transplantation into the injured cord. MSCs appeared as large, obvious regions of signal loss in the cord, which decreased in size over time.
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Beerbaum P, Sarikouch S, Laser KT, Greil G, Burchert W, Körperich H. Coronary anomalies assessed by whole-heart isotropic 3D magnetic resonance imaging for cardiac morphology in congenital heart disease. J Magn Reson Imaging 2009; 29:320-7. [PMID: 19161183 DOI: 10.1002/jmri.21655] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE To determine the value of whole-heart three-dimensional magnetic resonance imaging (MRI) for coronary artery imaging in children/adolescents with congenital heart disease (CHD). MATERIALS AND METHODS Forty children/adolescents (median age: 14 years, range 2.6-25.8) with CHD underwent free-breathing navigator-gated isotropic three-dimensional steady-state free-precession (3D-SSFP) MRI for cardiac morphology. Two observers independently evaluated visibility of origin, course, vessel lengths, image quality (IQ), and contrast between coronary lumen and myocardium. A subgroup was compared with cardiac catheter. RESULTS The total scan time was 6.3 +/- 3.2 minutes (mean +/- SD, at mean heart rate 76 +/- 15/min). The mean vessel length for right coronary artery (RCA) by observer 1 was 97 +/- 43 mm (observer 2: 94 +/- 37 mm), for left main and anterior descending artery (LM/LAD) 91 +/- 40 mm (observer 2: 90 +/- 40 mm), and for left circumflex artery (LCX) 64 +/- 28mm (observer 2: 66 +/- 28 mm). The mean vessel contrast was 0.34 +/- 0.05 (range: 0.23-0.45; maximum = 1, minimum = 0). On a 4-level score (1 = nondiagnostic, 4 = excellent), mean IQ scores ranged between 2.3-2.9 (+/-0.8-1.0). Both observers agreed on the presence/proximal course of RCA in 40/40, LM/LAD in 38/40, and LCX in 36/40 patients. There was complete agreement with invasive coronary angiography available in 12/40 patients (six anomalies). CONCLUSION Isotropic whole-heart 3D-MRI for cardiac morphology allows reliable discrimination between normal and abnormal coronary anatomy in children/adolescents with CHD.
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Affiliation(s)
- Philipp Beerbaum
- Division of Imaging Sciences, King's College London, Guy's & St Thomas' Hospital, London, UK
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Low Dose Gadobenate Dimeglumine for Imaging Of Chronic Myocardial Infarction in Comparison With Standard Dose Gadopentetate Dimeglumine. Invest Radiol 2009; 44:95-104. [DOI: 10.1097/rli.0b013e3181911eab] [Citation(s) in RCA: 30] [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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26
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Buerke B, Allkemper T, Kugel H, Bremer C, Evers S, Kooijman H, Heindel W, Tombach B. Qualitative and quantitative analysis of routinely postprocessed (CLEAR) CE-MRA data sets: are SNR and CNR calculations reliable? Acad Radiol 2008; 15:1111-7. [PMID: 18692751 DOI: 10.1016/j.acra.2008.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 01/28/2008] [Accepted: 04/07/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE AND OBJECTIVES To evaluate objective image quality parameters for contrast-enhanced magnetic resonance angiography (CE-MRA), contrast-to-noise (CNR), and signal-to-noise ratio (SNR) calculations based on signal intensity (SI) and standard deviation (SD) measurements of the vessel, the surrounding tissue (eg, muscle), and the background noise outside the body are commonly used. However, modern magnetic resonance scanners often use dedicated software algorithms such as Constant LEvel AppeaRance (CLEAR) to improve image quality, which may affect the established methods of SNR and CNR calculation. The purpose of this study was to intraindividually evaluate the feasibility of conventional techniques used for SNR and CNR calculation of MRA data sets that have been reconstructed with both, a standard (non-CLEAR) and a CLEAR algorithm. METHODS Supra-aortic high-resolution CE-MRA of 11 patients with headache symptoms was performed at 1.5 T using reconstruction algorithms generating both, non-CLEAR and CLEAR-corrected images from the acquired data set. A qualitative analysis with regard to image quality and contrast level was performed by two radiologists applying a score system. For quantitative analysis, distribution of SI values was measured in regions of interest in the common carotid artery (CCA) and the C1 segment of the internal carotid artery in identical positions of both data sets for intraindividual comparison of SNR and CNR calculations. For that purpose, three different equations were used for background noise assessment by determining the SD of SIs measured in the air outside the body (Eq. A), the soft tissue adjacent to the analyzed vessel segment (Eq. B), and in a contrast-medium filled tube (reference standard), which was placed around the patient's neck (Eq. C). RESULTS The qualitative analysis documented an improved image quality and a higher contrast level for CLEAR-based data sets. SNR and CNR calculations of the CCA and the C1 segment were significantly different for both reconstruction algorithms when using the background noise outside the body for image noise assessment (P<.05 [CCA]; P<.05 [C1]). SNR and CNR calculations based on the soft tissue adjacent to the analyzed segment or a reference standard were comparable. CONCLUSIONS For comparative analysis of CE-MRA data sets, SNR and CNR calculations based on SD determination of the background noise signal measured outside the body are not applicable for CE-MRA data sets reconstructed with a CLEAR-based algorithm. Therefore, noise should rather be assessed in the perivascular tissue to enable proper comparative analysis of CLEAR-enhanced CE-MRA data sets.
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Bookwalter CA, Griswold MA, Sunshine JL, Duerk JL. Analysis of signal-to-noise behavior in Cartesian continuous sampling sequences: Predictions and experimental validation of opportunities for improved image SNR. Magn Reson Med 2007; 58:819-24. [PMID: 17899601 DOI: 10.1002/mrm.21321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Image signal-to-noise ratio (SNR) limits many MRI applications. Here we propose a method to improve SNR based on continuous sampling (CS) during each TR without significant increases in acquisition time. The general concept of CS is defined here as sampling the NMR signal immediately after slice excitation including ramp times, both the dephase and rephase lobes, the phase-encoding (PE) gradient application, and the slice refocusing gradient. This study analyzes several cases of CS and demonstrates a specific case where sampling occurs during an isolated and balanced readout gradient in order to increase SNR in a rectilinear Cartesian sequence without significantly increasing overall acquisition time. The noise correlation consequences of rectilinear CS are mathematically derived and proven through simulation. The SNR improvement of up to approximately 40% measured in both phantom and asymptomatic human volunteer images is comparable to theoretical prediction of increased SNR proportional to the increase in the square root of the sampling time.
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Affiliation(s)
- Candice A Bookwalter
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
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Miller KL, Smith SM, Jezzard P, Wiggins GC, Wiggins CJ. Signal and noise characteristics of SSFP FMRI: a comparison with GRE at multiple field strengths. Neuroimage 2007; 37:1227-36. [PMID: 17706432 DOI: 10.1016/j.neuroimage.2007.06.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2007] [Revised: 06/04/2007] [Accepted: 06/06/2007] [Indexed: 11/20/2022] Open
Abstract
Recent work has proposed the use of steady-state free precession (SSFP) as an alternative to the conventional methods for obtaining functional MRI (FMRI) data. The contrast mechanism in SSFP is likely to be related to conventional FMRI signals, but the details of the signal changes may differ in important ways. Functional contrast in SSFP has been proposed to result from several different mechanisms, which are likely to contribute in varying degrees depending on the specific parameters used in the experiment. In particular, the signal dynamics are likely to differ depending on whether the sequence is configured to scan in the SSFP transition band or passband. This work describes experiments that explore the source of SSFP FMRI signal changes by comparing SSFP data to conventional gradient-recalled echo (GRE) data. Data were acquired at a range of magnetic field strengths and repetition times, for both transition band and passband methods. The signal properties of SSFP and GRE differ significantly, confirming a different source of functional contrast in SSFP. In addition, the temporal noise properties are significantly different, with important implications for SSFP FMRI sequence optimisation.
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Affiliation(s)
- Karla L Miller
- Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, UK, and A.A. Martinos Center, Massachusetts General Hospital, Charlestown, USA.
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Michaely HJ, Kramer H, Oesingmann N, Lodemann KP, Reiser MF, Schoenberg SO. Semiquantitative assessment of first-pass renal perfusion at 1.5 T: comparison of 2D saturation recovery sequences with and without parallel imaging. AJR Am J Roentgenol 2007; 188:919-26. [PMID: 17377024 DOI: 10.2214/ajr.06.0567] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The purpose of this study was to assess the feasibility and reliability of measurements performed with true fast imaging with steady-state free precession (FISP) and turbo fast low-angle shot (FLASH) sequences with parallel imaging compared with those obtained with turbo FLASH sequences without parallel imaging in first-pass renal perfusion MRI. SUBJECTS AND METHODS The subjects in this prospective study were 15 healthy men who volunteered to undergo MRI for acquisition of renal perfusion measurements. Imaging was performed at 1.5 T with the following three techniques after administration of gadobenate dimeglumine at 4 mL/s: saturation recovery (SR) turbo FLASH sequences without parallel imaging, SR turbo FLASH sequences with parallel imaging, and SR true FISP sequences. The spatial resolution was 2.3 x 2.6 x 8 mm with a temporal resolution of four slices per second (turbo FLASH without parallel imaging and true FISP) or six slices per second (turbo FLASH with parallel imaging). The semiquantitative perfusion parameters mean transit time and maximal upslope were determined. Signal-to-noise ratio (SNR), delta ratio, and time to maximal signal intensity also were determined. Image quality was rated in consensus. RESULTS Image quality was best for turbo FLASH sequences without parallel imaging compared with true FISP and turbo FLASH sequences with parallel imaging. True FISP sequences yielded the highest baseline SNR (26.7) but the lowest delta ratio (3.2). Turbo FLASH sequences without and with parallel imaging had significantly lower SNRs (9.6 and 9.3) and significantly higher delta ratios (5.1 and 5.0). The first-pass perfusion parameters mean transit time and time to maximal signal intensity were independent of the technique used. CONCLUSION It seems that at 1.5 T, turbo FLASH sequences without parallel imaging are the best approach to renal first-pass perfusion imaging.
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Affiliation(s)
- Henrik J Michaely
- Department of Clinical Radiology, University of Munich, Grosshadern-Campus, Marchionistrasse 15, Munich, Germany, 81377.
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Gold GE, Hargreaves BA, Reeder SB, Block WF, Kijowski R, Vasanawala SS, Kornaat PR, Bammer R, Newbould R, Bangerter NK, Beaulieu CF. Balanced SSFP imaging of the musculoskeletal system. J Magn Reson Imaging 2007; 25:270-8. [PMID: 17260387 DOI: 10.1002/jmri.20819] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Magnetic resonance imaging (MRI), with its unique ability to image and characterize soft tissue noninvasively, has emerged as one of the most accurate imaging methods available to diagnose bone and joint pathology. Currently, most evaluation of musculoskeletal pathology is done with two-dimensional acquisition techniques such as fast spin echo (FSE) imaging. The development of three-dimensional fast imaging methods based on balanced steady-state free precession (SSFP) shows great promise to improve MRI of the musculoskeletal system. These methods may allow acquisition of fluid sensitive isotropic data that can be reformatted into arbitrary planes for improved detection and visualization of pathology. Sensitivity to fluid and fat suppression are important issues in these techniques to improve delineation of cartilage contours, for detection of marrow edema and derangement of other joint structures.
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Affiliation(s)
- Garry E Gold
- Department of Radiology, Stanford University, Stanford, California, USA.
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Ibrahim ESH, Stuber M, Schär M, Osman NF. Improved myocardial tagging contrast in cine balanced SSFP images. J Magn Reson Imaging 2007; 24:1159-67. [PMID: 17031834 DOI: 10.1002/jmri.20730] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To improve the tag persistence throughout the whole cardiac cycle by providing a constant tag-contrast throughout all the cardiac phases when using balanced steady-state free precession (bSSFP) imaging. MATERIALS AND METHODS The flip angles of the imaging radiofrequency pulses were optimized to compensate for the tagging contrast-to-noise ratio (Tag-CNR) fading at later cardiac phases in bSSFP imaging. Complementary spatial modulation of magnetization (CSPAMM) tagging was implemented to improve the Tag-CNR. Numerical simulations were performed to examine the behavior of the Tag-CNR with the proposed method, and to compare the resulting Tag-CNR with that obtained from the more commonly used spoiled gradient echo (SPGR) imaging. A gel phantom, as well as five healthy human volunteers, were scanned on a 1.5T scanner using bSSFP imaging with and without the proposed technique. The phantom was also scanned with SPGR imaging. RESULTS With the proposed technique, the Tag-CNR remained almost constant during the whole cardiac cycle. Using bSSFP imaging, the Tag-CNR was about double that of SPGR. CONCLUSION The tag persistence was significantly improved when the proposed method was applied, with better Tag-CNR during the diastolic cardiac phase. The improved Tag-CNR will support automated tagging analysis and quantification methods.
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Affiliation(s)
- El-Sayed H Ibrahim
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21287, USA.
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Wild JM, Teh K, Woodhouse N, Paley MNJ, Fichele S, de Zanche N, Kasuboski L. Steady-state free precession with hyperpolarized 3He: experiments and theory. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 183:13-24. [PMID: 16890464 DOI: 10.1016/j.jmr.2006.07.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 07/12/2006] [Accepted: 07/12/2006] [Indexed: 05/11/2023]
Abstract
The magnetization response of hyperpolarized 3He gas to a steady-state free precession (SSFP) sequence was simulated using matrix product operators. The simulations included the effects of flip angle (alpha), sequence timings, resonant frequency, gas diffusion coefficient, imaging gradients, T1 and T2. Experiments performed at 1.5 T, on gas phantoms and with healthy human subjects, confirm the predicted theory, and indicate increased SNR with SSFP through use of higher flip angles when compared to optimized spoiled gradient echo (SPGR). Simulations and experiments show some compromise to the SNR and some point spread function broadening at high alpha due to the incomplete refocusing of transverse magnetization, caused by diffusion dephasing from the readout gradient. Mixing of gas polarization levels by diffusion between slices is also identified as a source of signal loss in SSFP at higher alpha through incomplete refocusing. Nevertheless, in the sample experiments, a SSFP sequence with an optimized flip angle of alpha=20 degrees, and 128 sequential phase encoding views, showed a higher SNR when compared to SPGR (alpha=7.2 degrees) with the same bandwidth. Some of the gas sample experiments demonstrated a transient signal response that deviates from theory in the initial phase. This was identified as being caused by radiation damping interactions between the large initial transverse magnetization and the high quality factor (Q=250) birdcage resonator. In 3He NMR experiments, performed without imaging gradients, diffusion dephasing can be mitigated, and the effective T2 is relatively long (1 s). Under these circumstances the SSFP sequence behaves like a CPMG sequence with sinalpha/2 weighting of SNR. Experiments and simulations were also performed to characterize the off-resonance behaviour of the SSFP HP 3He signal. Characteristic banding artifacts due to off-resonance harmonic beating were observed in some of the in vivo SSFP images, for instance in axial slices close to the diaphragm where B0 inhomogeneity is highest. Despite these artifacts, a higher SNR was observed with SSFP in vivo when compared to the SPGR sequence. The trends predicted by theory of increasing SSFP SNR with increasing flip angle were observed in the range alpha=10-20 degrees without compromise to image quality through blurring caused by excessive k-space filtering.
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Affiliation(s)
- Jim M Wild
- Unit of Academic Radiology, University of Sheffield, C floor, Royal Hallamshire Hospital, Glossop Road, S10 2JF, UK.
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Caruthers SD, Neubauer AM, Hockett FD, Lamerichs R, Winter PM, Scott MJ, Gaffney PJ, Wickline SA, Lanza GM. In vitro demonstration using 19F magnetic resonance to augment molecular imaging with paramagnetic perfluorocarbon nanoparticles at 1.5 Tesla. Invest Radiol 2006; 41:305-12. [PMID: 16481914 DOI: 10.1097/01.rli.0000199281.60135.6a] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES This study explored the use of F spectroscopy and imaging with targeted perfluorocarbon nanoparticles for the simultaneous identification of multiple bio-signatures at 1.5 T. MATERIALS AND METHODS Two nanoparticle emulsions with perfluoro-15-crown-5-ether (CE) or perfluorooctylbromide (PFOB) cores were targeted in vitro to fibrin clot phantoms (n=12) in 4 progressive ratios using biotin-avidin interactions. The CE nanoparticles incorporated gadolinium. Fluorine images were acquired using steady-state gradient-echo techniques; spectra using volume-selective and nonselective sampling. RESULTS On conventional T1-weighted imaging, clots with CE nanoparticles enhanced as expected, with intensity decreasing monotonically with CE concentration. All clots were visualized using wide bandwidth fluorine imaging, while restricted bandwidth excitation permitted independent imaging of CE or PFOB nanoparticles. Furthermore, F imaging and spectroscopy allowed visual and quantitative confirmation of relative perfluorocarbon nanoparticle distributions. CONCLUSIONS F MRI/S molecular imaging of perfluorocarbon nanoparticles in vitro suggests that noninvasive phenotypic characterization of pathologic bio-signatures is feasible at clinical field strengths.
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Affiliation(s)
- Shelton D Caruthers
- Division of Cardiology, Washington University Medical School, St. Louis, Missouri 63110, USA.
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Lebel RM, Menon RS, Bowen CV. Relaxometry model of strong dipolar perturbers for balanced-SSFP: application to quantification of SPIO loaded cells. Magn Reson Med 2006; 55:583-91. [PMID: 16450353 DOI: 10.1002/mrm.20799] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Magnetic resonance microscopy using magnetically labeled cells is an emerging discipline offering the potential for non-destructive studies targeting numerous cellular events in medical research. The present work develops a technique to quantify superparamagnetic iron-oxide (SPIO) loaded cells using fully balanced steady state free precession (b-SSFP) imaging. An analytic model based on phase cancellation was derived for a single particle and extended to predict mono-exponential decay versus echo time in the presence of multiple randomly distributed particles. Numerical models verified phase incoherence as the dominant contrast mechanism and evaluated the model using a full range of tissue decay rates, repetition times, and flip angles. Numerical simulations indicated a relaxation rate enhancement (DeltaR(2b)=0.412 gamma . LMD) proportional to LMD, the local magnetic dose (the additional sample magnetization due to the SPIO particles), a quantity related to the concentration of contrast agent. A phantom model of SPIO loaded cells showed excellent agreement with simulations, demonstrated comparable sensitivity to gradient echo DeltaR(*) (2) enhancements, and 14 times the sensitivity of spin echo DeltaR(2) measurements. We believe this model can be used to facilitate the generation of quantitative maps of targeted cell populations.
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Affiliation(s)
- R Marc Lebel
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
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Gold GE, Reeder SB, Yu H, Kornaat P, Shimakawa AS, Johnson JW, Pelc NJ, Beaulieu CF, Brittain JH. Articular cartilage of the knee: rapid three-dimensional MR imaging at 3.0 T with IDEAL balanced steady-state free precession--initial experience. Radiology 2006; 240:546-51. [PMID: 16801369 DOI: 10.1148/radiol.2402050288] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. In this study, iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) balanced steady-state free precession (bSSFP), fat-suppressed bSSFP, and fat-suppressed spoiled gradient-echo (GRE) sequences for 3.0-T magnetic resonance (MR) imaging of articular knee cartilage were prospectively compared in five healthy volunteers. Cartilage and fluid signal-to-noise ratio (SNR), cartilage-fluid contrast-to-noise ratio (CNR), SNR efficiency, CNR efficiency, image quality, and fat suppression were compared. Fat-suppressed bSSFP and IDEAL bSSFP had higher SNR efficiency of cartilage (P < .01) than did GRE. IDEAL bSSFP had higher cartilage-fluid CNR efficiency than did fat-suppressed bSSFP or GRE (P < .01). Fat-suppressed bSSFP and IDEAL bSSFP had higher image quality than did GRE (P < .01). GRE and IDEAL bSSFP had significantly better fat-water separation or fat saturation than did fat-suppressed bSSFP (P < .05). IDEAL bSSFP is a promising method for imaging articular knee cartilage.
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Affiliation(s)
- Garry E Gold
- Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, SO-68B, Stanford, CA 94305-5105, USA.
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Gold GE, Burstein D, Dardzinski B, Lang P, Boada F, Mosher T. MRI of articular cartilage in OA: novel pulse sequences and compositional/functional markers. Osteoarthritis Cartilage 2006; 14 Suppl A:A76-86. [PMID: 16716605 DOI: 10.1016/j.joca.2006.03.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Accepted: 03/17/2006] [Indexed: 02/02/2023]
Abstract
Osteoarthritis (OA) is a leading cause of disability worldwide. Magnetic resonance imaging (MRI), with its unique ability to image and characterize soft tissue non-invasively, has proven valuable in assessing cartilage in OA. The development of new, fast imaging methods with high contrast show promise to improve the magnetic resonance (MR) evaluation of this disease. In addition to morphologic MRI methods, MRI contrast mechanisms under development may reveal detailed information about the physiology of cartilage. It is anticipated that these and other MRI techniques will play an increasingly important role in assessing the success or failure of therapies for OA. On December 5 and 6, 2002, OMERACT (Outcome Measures in Rheumatology Clinical Trials) and OARSI (Osteoarthritis Research Society International) held a workshop in Bethesda, MD aiming at providing a state-of-the-art review of imaging outcome measures for OA of the knee to help guide scientists and pharmaceutical companies in the use of MRI in multi-site studies of OA. Applications of MRI were initially reviewed by a multidisciplinary, international panel of expert scientists and physicians from academia, the pharmaceutical industry and regulatory agencies. The findings of the panel were then presented to a wider group of participants for open discussion. The following report summarizes the results of these discussions with respect to novel MRI pulse sequences for evaluating articular cartilage of the knee in OA and notes any additional advances that have been made since.
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Abstract
Magnetic resonance imaging (MRI), which provides superior soft-tissue imaging and no known harmful effects, has the potential as an alternative modality to guide various medical interventions. This review will focus on MR-guided endovascular interventions and present its current state and future outlook. In the first technical part, enabling technologies such as developments in fast imaging, catheter devices, and visualization techniques are examined. This is followed by a clinical survey that includes proof-of-concept procedures in animals and initial experience in human subjects. In preclinical experiments, MRI has already proven to be valuable. For example, MRI has been used to guide and track targeted cell delivery into or around myocardial infarctions, to guide atrial septal puncture, and to guide the connection of portal and systemic venous circulations. Several investigational MR-guided procedures have already been reported in patients, such as MR-guided cardiac catheterization, invasive imaging of peripheral artery atheromata, selective intraarterial MR angiography, and preliminary angioplasty and stent placement. In addition, MR-assisted transjugular intrahepatic portosystemic shunt procedures in patients have been shown in a novel hybrid double-doughnut x-ray/MRI system. Numerous additional investigational human MR-guided endovascular procedures are now underway in several medical centers around the world. There are also significant hurdles: availability of clinical-grade devices, device-related safety issues, challenges to patient monitoring, and acoustic noise during imaging. The potential of endovascular interventional MRI is great because as a single modality, it combines 3-dimensional anatomic imaging, device localization, hemodynamics, tissue composition, and function.
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Affiliation(s)
- Cengizhan Ozturk
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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Banerjee S, Han ET, Krug R, Newitt DC, Majumdar S. Application of refocused steady-state free-precession methods at 1.5 and 3 T to in vivo high-resolution MRI of trabecular bone: simulations and experiments. J Magn Reson Imaging 2005; 21:818-25. [PMID: 15906346 DOI: 10.1002/jmri.20348] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To evaluate the potential of fully-balanced steady-state free-precession (SSFP) sequences in in vivo high-resolution (HR) MRI of trabecular bone at field strengths of 1.5 and 3 T by simulation and experimental methods. MATERIALS AND METHODS Using simulation studies, refocused SSFP acquisition was optimized for our imaging purposes with a focus on signal-to-noise ratio (SNR) and SNR efficiency. The signal behavior in trabecular bone was estimated using a magnetostatic model of the trabecular bone and marrow. Eight normal volunteers were imaged at the proximal femur, calcaneus, and the distal tibia on a GE Signa scanner at 1.5 and at 3 T with an optimized single-acquisition SSFP sequence (three-dimensional FIESTA) and an optimized multiple-acquisition SSFP sequence (three-dimensional FIESTA-c). Images were also acquired with a fast gradient echo (FGRE) sequence for evaluation of the SNR performance of SSFP methods. RESULTS Refocused SSFP images outperformed FGRE acquisitions in both SNR and SNR efficiency at both field strengths. At 3 T, susceptibility effects were visible in FIESTA and FGRE images and much reduced in FIESTA-c images. The magnitude of SNR boost at 3 T was closely predicted by simulations. CONCLUSION Single-acquisition SSFP (at 1.5 T) and multiple-acquisition SSFP (at 3 T) hold great potential for HR-MRI of trabecular bone.
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Affiliation(s)
- Suchandrima Banerjee
- Department of Radiology, University of California, San Francisco, San Francisco, California 94107, USA
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Martin DR, Friel HT, Danrad R, De Becker J, Hussain SM. Approach to Abdominal Imaging at 1.5 Tesla and Optimization at 3 Tesla. Magn Reson Imaging Clin N Am 2005; 13:241-54, v-vi. [PMID: 15935310 DOI: 10.1016/j.mric.2005.03.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This article reviews fundamental principles and sequence techniques that have been used successfully for imaging diseases of the abdomen and pelvis at 1.5 Tesla. This article also introduces concepts and the specific alteration of sequence parameters for optimization of abdominal-pelvic imaging at 3 Tesla.
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Affiliation(s)
- Diego R Martin
- Department of Radiology, Emory University School of Medicine, 1365 Clifton Road NE, Atlanta, GA 30322, USA.
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