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Woods JG, Achten E, Asllani I, Bolar DS, Dai W, Detre JA, Fan AP, Fernández-Seara M, Golay X, Günther M, Guo J, Hernandez-Garcia L, Ho ML, Juttukonda MR, Lu H, MacIntosh BJ, Madhuranthakam AJ, Mutsaerts HJ, Okell TW, Parkes LM, Pinter N, Pinto J, Qin Q, Smits M, Suzuki Y, Thomas DL, Van Osch MJ, Wang DJJ, Warnert EA, Zaharchuk G, Zelaya F, Zhao M, Chappell MA. Recommendations for quantitative cerebral perfusion MRI using multi-timepoint arterial spin labeling: Acquisition, quantification, and clinical applications. Magn Reson Med 2024; 92:469-495. [PMID: 38594906 PMCID: PMC11142882 DOI: 10.1002/mrm.30091] [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: 08/31/2023] [Revised: 02/09/2024] [Accepted: 03/07/2024] [Indexed: 04/11/2024]
Abstract
Accurate assessment of cerebral perfusion is vital for understanding the hemodynamic processes involved in various neurological disorders and guiding clinical decision-making. This guidelines article provides a comprehensive overview of quantitative perfusion imaging of the brain using multi-timepoint arterial spin labeling (ASL), along with recommendations for its acquisition and quantification. A major benefit of acquiring ASL data with multiple label durations and/or post-labeling delays (PLDs) is being able to account for the effect of variable arterial transit time (ATT) on quantitative perfusion values and additionally visualize the spatial pattern of ATT itself, providing valuable clinical insights. Although multi-timepoint data can be acquired in the same scan time as single-PLD data with comparable perfusion measurement precision, its acquisition and postprocessing presents challenges beyond single-PLD ASL, impeding widespread adoption. Building upon the 2015 ASL consensus article, this work highlights the protocol distinctions specific to multi-timepoint ASL and provides robust recommendations for acquiring high-quality data. Additionally, we propose an extended quantification model based on the 2015 consensus model and discuss relevant postprocessing options to enhance the analysis of multi-timepoint ASL data. Furthermore, we review the potential clinical applications where multi-timepoint ASL is expected to offer significant benefits. This article is part of a series published by the International Society for Magnetic Resonance in Medicine (ISMRM) Perfusion Study Group, aiming to guide and inspire the advancement and utilization of ASL beyond the scope of the 2015 consensus article.
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Affiliation(s)
- Joseph G. Woods
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Center for Functional Magnetic Resonance Imaging, Department of Radiology, University of California San Diego, La Jolla, California, USA
| | - Eric Achten
- Ghent Institute for Functional and Metabolic Imaging (GIfMI), Ghent University, Ghent, Belgium
| | - Iris Asllani
- Department of Neuroscience, University of Sussex, UK and Department of Biomedical Engineering, Rochester Institute of Technology, USA
| | - Divya S. Bolar
- Center for Functional Magnetic Resonance Imaging, Department of Radiology, University of California San Diego, La Jolla, California, USA
| | - Weiying Dai
- Department of Computer Science, State University of New York at Binghamton, Binghamton, NY, USA, 13902
| | - John A. Detre
- Department of Neurology, University of Pennsylvania, 3 Dulles Building, 3400 Spruce Street, Philadelphia, PA 19104 USA
| | - Audrey P. Fan
- Department of Biomedical Engineering, Department of Neurology, University of California Davis, Davis, CA, USA
| | - Maria Fernández-Seara
- Department of Radiology, Clínica Universidad de Navarra, Pamplona, Spain; IdiSNA, Instituto de Investigación Sanitaria de Navarra, Pamplona, Spain
| | - Xavier Golay
- UCL Queen Square Institute of Neurology, University College London, London, UK; Gold Standard Phantoms, UK
| | - Matthias Günther
- Imaging Physics, Fraunhofer Institute for Digital Medicine MEVIS, Bremen, Germany
- Departments of Physics and Electrical Engineering, University of Bremen, Bremen, Germany
| | - Jia Guo
- Department of Bioengineering, University of California Riverside, Riverside, CA, USA
| | | | - Mai-Lan Ho
- Department of Radiology, University of Missouri, Columbia, MO, USA. ORCID: 0000-0002-9455-1350
| | - Meher R. Juttukonda
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Hanzhang Lu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Bradley J. MacIntosh
- Hurvitz Brain Sciences Program, Centre for Brain Resilience & Recovery, Sunnybrook Research Institute, Toronto, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Computational Radiology & Artificial Intelligence unit, Oslo University Hospital, Oslo, Norway
| | - Ananth J. Madhuranthakam
- Department of Radiology and Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
| | - Henk-Jan Mutsaerts
- Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Radiology and Nuclear Medicine, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Brain Imaging, Amsterdam, The Netherlands
| | - Thomas W. Okell
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Laura M. Parkes
- School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, UK
| | - Nandor Pinter
- Dent Neurologic Institute, Buffalo, New York, USA; University at Buffalo Neurosurgery, Buffalo, New York, USA
| | - Joana Pinto
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Marion Smits
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
- Medical Delta, Delft, The Netherlands
- Erasmus MC Cancer Institute, Erasmus MC, Rotterdam, NL
| | - Yuriko Suzuki
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - David L. Thomas
- Department of Brain Repair and Rehabilitation, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Matthias J.P. Van Osch
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Danny JJ Wang
- Laboratory of FMRI Technology (LOFT), Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, USA
| | - Esther A.H. Warnert
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
- Erasmus MC Cancer Institute, Erasmus MC, Rotterdam, NL
| | - Greg Zaharchuk
- Department of Radiology, Stanford University, Stanford, CA, USA
| | - Fernando Zelaya
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, UK
| | - Moss Zhao
- Department of Radiology, Stanford University, Stanford, CA, USA
- Maternal & Child Health Research Institute, Stanford University, Stanford, CA, USA
| | - Michael A. Chappell
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, UK
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Greer JS, Wang Y, Udayakumar D, Hussain T, Madhuranthakam AJ. On the application of pseudo-continuous arterial spin labeled MRI for pulmonary perfusion imaging. Magn Reson Imaging 2023; 104:80-87. [PMID: 37769882 DOI: 10.1016/j.mri.2023.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/21/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
PURPOSE To evaluate different approaches for the effective assessment of pulmonary perfusion with a pseudo-continuous arterial spin labeled (pCASL) MRI. MATERIALS AND METHODS Four different approaches were evaluated: 1) Cardiac-triggered inferior vena cava (IVC) labeling; 2) IVC labeling with cardiac-triggered acquisition; 3) Right pulmonary artery (RPA) labeling with cardiac-triggered acquisition; and 4) Cardiac-triggered RPA labeling with background suppression (BGS). Each approach was evaluated in 5 healthy volunteers (n = 20) using coefficient of variation (COV) across averages. Approach 4 was also compared against a flow alternating inversion recovery (FAIR). RESULTS The IVC labeling (Approach 1) achieved perfusion-weighted images of both lungs, although this approach was more sensitive to variations in heart rate. Cardiac-triggered acquisitions using IVC (Approach 2) and RPA (Approach 3) labeling improved signal consistencies, but were incompatible with BGS. The cardiac-triggered RPA labeling with BGS (Approach 4) achieved a COV of 0.34 ± 0.03 (p < 0.05 compared to IVC labeling approaches) and resulted in perfusion value of 434 ± 64 mL/100 g/min, which was comparable to 451 ± 181 mL/100 g/min measured by FAIR (p = 0.82). DISCUSSION Pulmonary perfusion imaging using pCASL-MRI is highly sensitive to cardiac phase, and requires approaches to minimize flow-induced signal variations. Cardiac-triggered RPA labeling with BGS achieves reduced COV and enables robust pulmonary perfusion imaging.
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Affiliation(s)
- Joshua S Greer
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA; Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Yiming Wang
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Durga Udayakumar
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA; Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
| | - Tarique Hussain
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA; Department of Pediatrics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Ananth J Madhuranthakam
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA; Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA.
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3
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Woods JG, Schauman SS, Chiew M, Chappell MA, Okell TW. Time-encoded pseudo-continuous arterial spin labeling: Increasing SNR in ASL dynamic angiography. Magn Reson Med 2023; 89:1323-1341. [PMID: 36255158 PMCID: PMC10091734 DOI: 10.1002/mrm.29491] [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: 04/05/2022] [Revised: 08/28/2022] [Accepted: 09/23/2022] [Indexed: 02/01/2023]
Abstract
PURPOSE Dynamic angiography using arterial spin labeling (ASL) can provide detailed hemodynamic information. However, the long time-resolved readouts require small flip angles to preserve ASL signal for later timepoints, limiting SNR. By using time-encoded ASL to generate temporal information, the readout can be shortened. Here, the SNR improvements from using larger flip angles, made possible by the shorter readout, are quantitatively investigated. METHODS The SNR of a conventional protocol with nine Look-Locker readouts and a 4 × $$ \times $$ 3 time-encoded protocol with three Look-Locker readouts (giving nine matched timepoints) were compared using simulations and in vivo data. Both protocols were compared using readouts with constant flip angles (CFAs) and variable flip angles (VFAs), where the VFA scheme was designed to produce a consistent ASL signal across readouts. Optimization of the background suppression to minimize physiological noise across readouts was also explored. RESULTS The time-encoded protocol increased in vivo SNR by 103% and 96% when using CFAs or VFAs, respectively. Use of VFAs improved SNR compared with CFAs by 25% and 21% for the conventional and time-encoded protocols, respectively. The VFA scheme also removed signal discontinuities in the time-encoded data. Preliminary data suggest that optimizing the background suppression could improve in vivo SNR by a further 16%. CONCLUSIONS Time encoding can be used to generate additional temporal information in ASL angiography. This enables the use of larger flip angles, which can double the SNR compared with a non-time-encoded protocol. The shortened time-encoded readout can also lead to improved background suppression, reducing physiological noise and further improving SNR.
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Affiliation(s)
- Joseph G Woods
- Wellcome Centre for Integrated Neuroimaging, FMRIB, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - S Sophie Schauman
- Wellcome Centre for Integrated Neuroimaging, FMRIB, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom.,Department of Radiology, Stanford University, Stanford, California, USA
| | - Mark Chiew
- Wellcome Centre for Integrated Neuroimaging, FMRIB, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
| | - Michael A Chappell
- Wellcome Centre for Integrated Neuroimaging, FMRIB, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom.,Mental Health and Clinical Neurosciences, School of Medicine, University of Nottingham, Nottingham, United Kingdom.,Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom.,Nottingham Biomedical Research Centre, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Thomas W Okell
- Wellcome Centre for Integrated Neuroimaging, FMRIB, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom
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Koolstra K, Staring M, de Bruin P, van Osch MJP. Subject-specific optimization of background suppression for arterial spin labeling magnetic resonance imaging using a feedback loop on the scanner. NMR IN BIOMEDICINE 2022; 35:e4746. [PMID: 35466446 PMCID: PMC9539598 DOI: 10.1002/nbm.4746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 04/04/2022] [Accepted: 04/20/2022] [Indexed: 06/14/2023]
Abstract
Background suppression (BGS) in arterial spin labeling (ASL) magnetic resonance imaging leads to a higher temporal signal-to-noise ratio (tSNR) of the perfusion images compared with ASL without BGS. The performance of the BGS, however, depends on the tissue relaxation times and on inhomogeneities of the scanner's magnetic fields, which differ between subjects and are unknown at the moment of scanning. Therefore, we developed a feedback loop (FBL) mechanism that optimizes the BGS for each subject in the scanner during acquisition. We implemented the FBL for 2D pseudo-continuous ASL scans with an echo-planar imaging readout. After each dynamic scan, the acquired ASL images were automatically sent to an external computer and processed with a Python processing tool. Inversion times were optimized on the fly using 80 iterations of the Nelder-Mead method, by minimizing the signal intensity in the label image while maximizing the signal intensity in the perfusion image. The performance of this method was first tested in a four-component phantom. The regularization parameter was then tuned in six healthy subjects (three males, three females, age 24-62 years) and set as λ = 4 for all other experiments. The resulting ASL images, perfusion images, and tSNR maps obtained from the last 20 iterations of the FBL scan were compared with those obtained without BGS and with standard BGS in 12 healthy volunteers (five males, seven females, age 24-62 years) (including the six volunteers used for tuning of λ). The FBL resulted in perfusion images with a statistically significantly higher tSNR (2.20) compared with standard BGS (1.96) ( p < 5 x 10 - 3 , two-sided paired t-test). Minimizing signal in the label image furthermore resulted in control images, from which approximate changes in perfusion signal can directly be appreciated. This could be relevant to ASL applications that require a high temporal resolution. Future work is needed to minimize the number of initial acquisitions during which the performance of BGS is reduced compared with standard BGS, and to extend the technique to 3D ASL.
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Affiliation(s)
- Kirsten Koolstra
- Radiology, Division of Image ProcessingLeiden University Medical CenterLeidenThe Netherlands
| | - Marius Staring
- Radiology, Division of Image ProcessingLeiden University Medical CenterLeidenThe Netherlands
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5
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Huber J, Günther M, Channaveerappa M, Hoinkiss DC. Towards free breathing
3D ASL
imaging of the human liver using prospective motion correction. Magn Reson Med 2022; 88:711-726. [DOI: 10.1002/mrm.29234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 02/15/2022] [Accepted: 02/23/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Jörn Huber
- Imaging Physics, Fraunhofer Institute for Digital Medicine MEVIS Bremen Germany
| | - Matthias Günther
- Imaging Physics, Fraunhofer Institute for Digital Medicine MEVIS Bremen Germany
- Physics/Electrical Engineering, University of Bremen Bremen Germany
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6
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de Zwart JA, van Gelderen P, Duyn JH. Sensitivity limitations of high-resolution perfusion-based human fMRI at 7 Tesla. Magn Reson Imaging 2021; 84:135-144. [PMID: 34624401 DOI: 10.1016/j.mri.2021.09.014] [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: 06/08/2021] [Revised: 09/07/2021] [Accepted: 09/30/2021] [Indexed: 11/28/2022]
Abstract
The study of the brain's functional organization at laminar and columnar level of the cortex with blood oxygenation-level dependent (BOLD) functional MRI (fMRI) is affected by the contribution of large veins downstream from the microvascular response to brain activity. Blood volume- and especially perfusion-based techniques may reduce this problem because of their reduced sensitivity to venous effects, but may not allow the same spatial resolution because of smaller signal changes associated with brain activity. Here we investigated the practical resolution limits of perfusion-weighted fMRI in human visual stimulation experiments. For this purpose, we used a highly sensitive, single-shot perfusion labeling (SSPL) technique at 7 T and compared sensitivity to detect visual activation at low (2 mm, n = 10) and high (1 mm, n = 8) nominal isotropic spatial, and 3 s temporal, resolution with BOLD in 5½-minute-long experiments. Despite the smaller absolute signal change with activation, 2 mm resolution SSPL yielded comparable sensitivity to BOLD. This was attributed to a superior suppression of physiological noise with SSPL. However, at 1 mm nominal resolution, SSPL sensitivity fell on average at least 42% below that of BOLD, and detection of visual activation was compromised. This is explained by the fact that at high resolution, with both techniques, typically thermal noise rather than physiological noise dominates sensitivity. The observed sensitivity loss implies that to perform 1-mm resolution, perfusion weighted fMRI with a robustness similar to BOLD, scan times that are almost 3 times longer than the comparable BOLD experiment are required. This is in line with or slightly better than previous comparisons between perfusion-weighted fMRI and BOLD. The lower sensitivity has to be weighed against the spatial fidelity advantages of high-resolution perfusion-weighted fMRI.
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Affiliation(s)
- Jacco A de Zwart
- Advanced MRI section, Laboratory of Functional and Molecular Imaging, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - Peter van Gelderen
- Advanced MRI section, Laboratory of Functional and Molecular Imaging, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Jeff H Duyn
- Advanced MRI section, Laboratory of Functional and Molecular Imaging, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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7
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Sherwood MS, McIntire L, Madaris AT, Kim K, Ranganath C, McKinley RA. Intensity-Dependent Changes in Quantified Resting Cerebral Perfusion With Multiple Sessions of Transcranial DC Stimulation. Front Hum Neurosci 2021; 15:679977. [PMID: 34456695 PMCID: PMC8397582 DOI: 10.3389/fnhum.2021.679977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 07/15/2021] [Indexed: 11/13/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) to the left prefrontal cortex has been shown to produce broad behavioral effects including enhanced learning and vigilance. Still, the neural mechanisms underlying such effects are not fully understood. Furthermore, the neural underpinnings of repeated stimulation remain understudied. In this work, we evaluated the effects of the repetition and intensity of tDCS on cerebral perfusion [cerebral blood flow (CBF)]. A cohort of 47 subjects was randomly assigned to one of the three groups. tDCS of 1- or 2-mA was applied to the left prefrontal cortex on three consecutive days, and resting CBF was quantified before and after stimulation using the arterial spin labeling MRI and then compared with a group that received sham stimulation. A widespread decreased CBF was found in a group receiving sham stimulation across the three post-stimulation measures when compared with baseline. In contrast, only slight decreases were observed in the group receiving 2-mA stimulation in the second and third post-stimulation measurements, but more prominent increased CBF was observed across several brain regions including the locus coeruleus (LC). The LC is an integral region in the production of norepinephrine and the noradrenergic system, and an increased norepinephrine/noradrenergic activity could explain the various behavioral findings from the anodal prefrontal tDCS. A decreased CBF was observed in the 1-mA group across the first two post-stimulation measurements, similar to the sham group. This decreased CBF was apparent in only a few small clusters in the third post-stimulation scan but was accompanied by an increased CBF, indicating that the neural effects of stimulation may persist for at least 24 h and that the repeated stimulation may produce cumulative effects.
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Affiliation(s)
| | | | - Aaron T. Madaris
- Infoscitex, Inc., Beavercreek, OH, United States
- Department of Biomedical, Industrial and Human Factors Engineering, Wright State University, Dayton, OH, United States
| | - Kamin Kim
- Department of Psychology, University of California, Davis, Davis, CA, United States
| | - Charan Ranganath
- Department of Psychology, University of California, Davis, Davis, CA, United States
- Center for Neuroscience, University of California, Davis, Davis, CA, United States
| | - R. Andy McKinley
- Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH, United States
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8
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Franklin SL, Voormolen N, Bones IK, Korteweg T, Wasser MNJM, Dankers HG, Cohen D, van Stralen M, Bos C, van Osch MJP. Feasibility of Velocity-Selective Arterial Spin Labeling in Breast Cancer Patients for Noncontrast-Enhanced Perfusion Imaging. J Magn Reson Imaging 2021; 54:1282-1291. [PMID: 34121250 PMCID: PMC8518819 DOI: 10.1002/jmri.27781] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/30/2021] [Accepted: 06/01/2021] [Indexed: 12/04/2022] Open
Abstract
Background Dynamic contrast‐enhanced (DCE) MRI is the most sensitive method for detection of breast cancer. However, due to high costs and retention of intravenously injected gadolinium‐based contrast agent, screening with DCE‐MRI is only recommended for patients who are at high risk for developing breast cancer. Thus, a noncontrast‐enhanced alternative to DCE is desirable. Purpose To investigate whether velocity selective arterial spin labeling (VS‐ASL) can be used to identify increased perfusion and vascularity within breast lesions compared to surrounding tissue. Study Type Prospective. Population Eight breast cancer patients. Field Strength/Sequence A 3 T; VS‐ASL with multislice single‐shot gradient‐echo echo‐planar‐imaging readout. Assessment VS‐ASL scans were independently assessed by three radiologists, with 3–25 years of experience in breast radiology. Scans were scored on lesion visibility and artifacts, based on a 3‐point Likert scale. A score of 1 corresponded to “lesions being distinguishable from background” (lesion visibility), and “no or few artifacts visible, artifacts can be distinguished from blood signal” (artifact score). A distinction was made between mass and nonmass lesions (based on BI‐RADS lexicon), as assessed in the standard clinical exam. Statistical Tests Intra‐class correlation coefficient (ICC) for interobserver agreement. Results The ICC was 0.77 for lesion visibility and 0.84 for the artifact score. Overall, mass lesions had a mean score of 1.27 on lesion visibility and 1.53 on the artifact score. Nonmass lesions had a mean score of 2.11 on lesion visibility and 2.11 on the artifact score. Data Conclusion We have demonstrated the technical feasibility of bilateral whole‐breast perfusion imaging using VS‐ASL in breast cancer patients. Evidence Level 1 Technical Efficacy Stage 1
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Affiliation(s)
- Suzanne L Franklin
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.,Center for Image Sciences, University Medical Centre Utrecht, Utrecht, The Netherlands.,Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands
| | - Nora Voormolen
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Isabell K Bones
- Center for Image Sciences, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Tijmen Korteweg
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Martin N J M Wasser
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Henrike G Dankers
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Daniele Cohen
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marijn van Stralen
- Center for Image Sciences, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Clemens Bos
- Center for Image Sciences, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Matthias J P van Osch
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.,Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands
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9
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Kihira S, Koo C, Nael K, Belani P. Regional Parieto-occipital Hypoperfusion on Arterial Spin Labeling Associates with Major Depressive Disorder. Open Neuroimag J 2020. [DOI: 10.2174/1874440002013010030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background:
Reduced cerebral blood flow in parieto-occipital regions has been reported in neurodegenerative disorders using ASL. We aimed to investigate neuropsychiatric and neurodegenerative comorbidities that may associate with parieto-occipital region hypoperfusion.
Methods:
This was a retrospective single-center study. Between March 2017 to May 2018, adult patients who underwent brain MRI with the inclusion of ASL perfusion and who had bilateral reductions of CBF in the parieto-occipital regions were included. ASL was performed using a pseudo-continuous arterial spin labeling (pCASL) technique on 1.5T MR system. Age and gender-matched patients with no perfusion defect were concurrently collected. Comorbidity data was collected from EMR, including major depressive disorder, Alzheimer’s disease, Parkinson’s disease, Schizophrenia, anxiety disorder, hypertension, diabetes mellitus type II, coronary artery disease, and chronic kidney disease. A Pearson’s Chi-Square test was performed to assess for comorbidities associated with hypoperfusion of the parieto-occipital lobes.
Results:
Our patient cohort consisted of 93 patients with bilateral hypoperfusion in the parieto-occipital lobes and 93 age and gender-matched patients without corresponding perfusion defects based on ASL-CBF. Among the comorbidities assessed, there was a statistically significant association between hypoperfusion of the parieto-occipital lobes and major depressive disorder (p=0.004) and Parkinson’s disease (p=0.044). There was no statistically significant association for Alzheimer’s disease, generalized anxiety disorder, diabetes mellitus type II, hypertension, coronary artery disease, or chronic kidney disease.
Conclusion:
Major depressive disorder may be linked to regional parieto-occipital hypoperfusion on ASL.
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Iwamura M, Midorikawa H, Shibutani K, Kakuta A, Maruyama S, Yotsuya C, Tatsuo S, Fujita H, Kakehata S, Tsushima F, Nozaki A, Sugimoto K, Kakeda S. High-signal venous sinuses on MR angiography: discrimination between reversal of venous flow and arteriovenous shunting using arterial spin labeling. Neuroradiology 2020; 63:889-896. [PMID: 33089421 DOI: 10.1007/s00234-020-02588-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/15/2020] [Indexed: 11/29/2022]
Abstract
PURPOSE It is sometimes difficult to differentiate between high signals originating from a reverse flow on magnetic resonance angiography (MRA) and occult arteriovenous shunting. We attempted to determine whether arterial spin labeling (ASL) can be used to discriminate reversal of venous flow from arteriovenous shunting for high-signal venous sinuses on MR angiography. METHODS Two radiologists evaluated the signals of the venous sinus on MRA and ASL obtained from 364 cases without arteriovenous shunting. In addition, the findings on MRA were compared with those on ASL in an additional 13 patients who had dural arteriovenous fistula (DAVF). RESULTS In the 364 cases (728 sides) without arteriovenous shunting, a high signal due to reverse flow in the cavernous sinuses (CS) was observed on 99 sides (13.6%) on MRA and none on ASL. Of these cases, a high signal in the sigmoid sinus, transverse sinus, and internal jugular vein was seen on 3, 3, and 8 sides, respectively. All of these venous sinuses showed a high signal from the reverse flow on MRA images. CONCLUSION ASL is a simple and useful MR imaging sequence for differentiating between reversal of venous flow and CS DAVF. In the sigmoid and transverse sinus, ASL showed false-positives due to the reverse flow from the jugular vein, which may be a limitation of which radiologists should be aware.
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Affiliation(s)
- Masatoshi Iwamura
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
- Department of Interventional Neuroradiology, Aomori Prefectural Central Hospital, Aomori, Japan
| | - Hiroshi Midorikawa
- Department of Interventional Neuroradiology, Aomori Prefectural Central Hospital, Aomori, Japan
| | - Koichi Shibutani
- Department of Radiology, Aomori Prefectural Central Hospital, Aomori, Japan
| | - Akihisa Kakuta
- Department of Radiology, Aomori Prefectural Central Hospital, Aomori, Japan
| | - Sho Maruyama
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Chihiro Yotsuya
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Soichiro Tatsuo
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Hiromasa Fujita
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Shinya Kakehata
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Fumiyasu Tsushima
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Atsushi Nozaki
- MR Applications and Workflow Asia Pacific, GE Healthcare, Hino, Japan
| | - Koichiro Sugimoto
- Department of Radiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Shingo Kakeda
- Department of Radiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan.
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11
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Belani P, Kihira S, Pacheco F, Pawha P, Cruciata G, Nael K. Addition of arterial spin-labelled MR perfusion to conventional brain MRI: clinical experience in a retrospective cohort study. BMJ Open 2020; 10:e036785. [PMID: 32532776 PMCID: PMC7295400 DOI: 10.1136/bmjopen-2020-036785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
OBJECTIVE The usage of arterial spin labelling (ASL) perfusion has exponentially increased due to improved and faster acquisition time and ease of postprocessing. We aimed to report potential additional findings obtained by adding ASL to routine unenhanced brain MRI for patients being scanned in a hospital setting for various neurological indications. DESIGN Retrospective. SETTING Large tertiary hospital. PARTICIPANTS 676 patients. PRIMARY OUTCOME Additional findings from ASL sequence compared with conventional MRI. RESULTS Our patient cohorts consisted of 676 patients with 257 with acute infarcts and 419 without an infarct. Additional findings from ASL were observed in 13.9% (94/676) of patients. In the non-infarct group, additional findings from ASL were observed in 7.4% (31/419) of patients, whereas in patients with an acute infarct, supplemental information was obtained in 24.5% (63/257) of patients. CONCLUSION The addition of an ASL sequence to routine brain MRI in a hospital setting provides additional findings compared with conventional brain MRI in about 7.4% of patients with additional supplementary information in 24.5% of patients with acute infarct.
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Affiliation(s)
- Puneet Belani
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Shingo Kihira
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Felipe Pacheco
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Puneet Pawha
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Giuseppe Cruciata
- Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Kambiz Nael
- Department of Radiological Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
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12
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Sherwood MS, Parker JG, Diller EE, Ganapathy S, Bennett KB, Esquivel CR, Nelson JT. Self-directed down-regulation of auditory cortex activity mediated by real-time fMRI neurofeedback augments attentional processes, resting cerebral perfusion, and auditory activation. Neuroimage 2019; 195:475-489. [PMID: 30954710 DOI: 10.1016/j.neuroimage.2019.03.078] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 02/23/2019] [Accepted: 03/31/2019] [Indexed: 12/18/2022] Open
Abstract
In this work, we investigated the use of real-time functional magnetic resonance imaging (fMRI) with neurofeedback training (NFT) to teach volitional down-regulation of the auditory cortex (AC) using directed attention strategies as there is a growing interest in the application of fMRI-NFT to treat neurologic disorders. Healthy participants were separated into two groups: the experimental group received real feedback regarding activity in the AC; the control group was supplied sham feedback yoked from a random participant in the experimental group and matched for fMRI-NFT experience. Each participant underwent five fMRI-NFT sessions. Each session contained 2 neurofeedback runs where participants completed alternating blocks of "rest" and "lower" conditions while viewing a continuously-updated bar representing AC activation and listening to continuous noise. Average AC deactivation was extracted from each closed-loop neuromodulation run and used to quantify the control over AC (AC control), which was found to significantly increase across training in the experimental group. Additionally, behavioral testing was completed outside of the MRI on sessions 1 and 5 consisting of a subjective questionnaire to assess attentional control and two quantitative tests of attention. No significant changes in behavior were observed; however, there was a significant correlation between changes in AC control and attentional control. Also, in a neural assessment before and after fMRI-NFT, AC activity in response to continuous noise stimulation was found to significantly decrease across training while changes in AC resting perfusion were found to be significantly greater in the experimental group. These results may be useful in formulating effective therapies outside of the MRI, specifically for chronic tinnitus which is often characterized by hyperactivity of the primary auditory cortex and altered attentional processes. Furthermore, the modulation of attention may be useful in developing therapies for other disorders such as chronic pain.
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Affiliation(s)
- Matthew S Sherwood
- Department of Biomedical, Industrial & Human Factors Engineering, Wright State University, Dayton, OH, USA.
| | - Jason G Parker
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indiana University, IN, USA
| | - Emily E Diller
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indiana University, IN, USA; College of Health and Human Services, Purdue University, West Lafayette, IN, USA
| | - Subhashini Ganapathy
- Department of Biomedical, Industrial & Human Factors Engineering, Wright State University, Dayton, OH, USA; Department of Trauma Care, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
| | - Kevin B Bennett
- Department of Psychology, Wright State University, Dayton, OH, USA
| | - Carlos R Esquivel
- Department of Defense Hearing Center of Excellence, JBSA-Lackland, USA
| | - Jeremy T Nelson
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indiana University, IN, USA; Department of Defense Hearing Center of Excellence, JBSA-Lackland, USA; Ho-Chunk Inc., Alexandria, VA, USA
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13
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Chi L, Huang M, Pfaff AR, Huang J, Gerald RE, Woelk K. Capillary-tube package devices for the quantitative performance evaluation of nuclear magnetic resonance spectrometers and pulse sequences. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:123115. [PMID: 30599605 DOI: 10.1063/1.5052374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/05/2018] [Indexed: 06/09/2023]
Abstract
With the increased sensitivity of modern nuclear magnetic resonance (NMR) spectrometers, the minimum amount needed for chemical-shift referencing of NMR spectra has decreased to a point where a few microliters can be sufficient to observe a reference signal. The reduction in the amount of required reference material is the basis for the NMR Capillary-tube Package (CapPack) platform that utilizes capillary tubes with inner diameters smaller than 150 µm as NMR-tube inserts for external reference standards. It is shown how commercially available electrophoresis capillary tubes with outer diameters of 360 µm are filled with reference liquids or solutions and then permanently sealed by the arc discharge plasma of a commercially available fusion splicer normally employed for joining optical fibers. The permanently sealed capillaries can be used as external references for chemical-shift, signal-to-noise, resolution, and concentration calibration. Combining a number of permanently sealed capillaries to form CapPack devices leads to additional applications such as performance evaluation of NMR spectrometers and NMR pulse sequences. A 10-capillary-tube side-by-side Gradient CapPack device is used in combination with one or two constant gradients, produced by room-temperature shim coils, to monitor the excitation profiles of shaped pulses. One example illustrates the performance of hyperbolic secant (sech) pulses in the EXponentially Converging Eradication Pulse Train (EXCEPT) solvent suppression sequence. The excitation profile of the pulse sequence is obtained in a single gradient NMR experiment. A clustered T 1 CapPack device is introduced consisting of a coaxial NMR-tube insert that holds seven capillary tubes filled with aqueous solutions of different concentrations of the paramagnetic relaxation agent copper(ii) sulfate (CuSO4). The different CuSO4 concentrations lead to spin-lattice relaxation times in the seven capillary tubes that cover a range which extends to more than an order of magnitude. Clustered T 1 CapPack devices are best suited to quantify the effects that relaxation has on magnetizations and coherences during the execution of NMR experiments, which is demonstrated for the order-of-magnitude T 1 insensitivity of signal suppression with EXCEPT.
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Affiliation(s)
- Lingyu Chi
- Department of Chemistry, Missouri University of Science and Technology, 400 West 11th St., Rolla, Missouri 65409-0010, USA
| | - Ming Huang
- Department of Chemistry, Missouri University of Science and Technology, 400 West 11th St., Rolla, Missouri 65409-0010, USA
| | - Annalise R Pfaff
- Department of Chemistry, Missouri University of Science and Technology, 400 West 11th St., Rolla, Missouri 65409-0010, USA
| | - Jie Huang
- Department of Electrical and Computer Engineering, Missouri University of Science and Technology, 301 West 16th St., Rolla, Missouri 65409-0040, USA
| | - Rex E Gerald
- American Inventor Institute, 141 B Willows Edge Court, Willow Springs, Illinois 60480, USA
| | - Klaus Woelk
- Department of Chemistry, Missouri University of Science and Technology, 400 West 11th St., Rolla, Missouri 65409-0010, USA
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14
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Taso M, Guidon A, Alsop DC. Influence of background suppression and retrospective realignment on free-breathing renal perfusion measurement using pseudo-continuous ASL. Magn Reson Med 2018; 81:2439-2449. [PMID: 30474312 DOI: 10.1002/mrm.27575] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/24/2018] [Accepted: 09/27/2018] [Indexed: 12/27/2022]
Abstract
PURPOSE To assess the influence of background suppression and retrospective realignment on physiological noise and image quality in free-breathing renal pseudo-continuous arterial spin labeling (pCASL). METHODS Ten subjects were scanned at 3T with a pCASL prepared single-slice coronal acquisition through the kidneys under free breathing. Multiple acquisitions were performed with various levels of residual background signal based on optimization of pulse timings to achieve specific background suppression levels (<2%, <5%, <10%, <20%). A retrospective non-rigid motion-correction strategy was also implemented. RESULTS Decreasing level of residual background signal was associated with higher temporal SNR. The retrospective motion-correction provided an additional but not statistically significant improvement in tSNR. The highest image quality was obtained with the lowest level of residual background signal accompanied by the retrospective motion-correction, although no significant difference in quantitative renal blood-flow could be observed. CONCLUSIONS Renal perfusion measurement with ASL under free breathing is feasible and robust against physiological noise when using strong background suppression strategies. Finally, retrospective motion-correction further improves image quality but cannot replace background suppression.
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Affiliation(s)
- Manuel Taso
- Division of MRI Research, Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Arnaud Guidon
- Global MR applications and workflow, GE Healthcare, Boston, Massachusetts
| | - David C Alsop
- Division of MRI Research, Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
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15
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Sherwood MS, Madaris AT, Mullenger CR, McKinley RA. Repetitive Transcranial Electrical Stimulation Induces Quantified Changes in Resting Cerebral Perfusion Measured from Arterial Spin Labeling. Neural Plast 2018; 2018:5769861. [PMID: 30254668 PMCID: PMC6145313 DOI: 10.1155/2018/5769861] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 07/23/2018] [Accepted: 08/08/2018] [Indexed: 01/06/2023] Open
Abstract
The use of transcranial electrical stimulation (TES) as a method to augment neural activity has increased in popularity in the last decade and a half. The specific application of TES to the left prefrontal cortex has been shown to produce broad cognitive effects; however, the neural mechanisms underlying these effects remain unknown. In this work, we evaluated the effect of repetitive TES on cerebral perfusion. Stimulation was applied to the left prefrontal cortex on three consecutive days, and resting cerebral perfusion was quantified before and after stimulation using arterial spin labeling. Perfusion was found to decrease significantly more in a matched sham stimulation group than in a group receiving active stimulation across many areas of the brain. These changes were found to originate in the locus coeruleus and were broadly distributed in the neocortex. The changes in the neocortex may be a direct result of the stimulation or an indirect result via the changes in the noradrenergic system produced from the altered activity of the locus coeruleus. These findings indicate that anodal left prefrontal stimulation alters the activity of the locus coeruleus, and this altered activity may excite the noradrenergic system producing the broad behavioral effects that have been reported.
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Affiliation(s)
- Matthew S. Sherwood
- Infoscitex, a DCS company, 4027 Colonel Glenn Hwy, Beavercreek, OH 45431, USA
- Department of Biomedical, Industrial & Human Factors Engineering, Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 45435, USA
| | - Aaron T. Madaris
- Infoscitex, a DCS company, 4027 Colonel Glenn Hwy, Beavercreek, OH 45431, USA
- Department of Biomedical, Industrial & Human Factors Engineering, Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 45435, USA
| | | | - R. Andy McKinley
- Air Force Research Laboratory, U.S. Air Force, 2510 Fifth Street, Bldg 840, Wright-Patterson AFB, OH 45433-7951, USA
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16
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Taso M, Guidon A, Zhao L, Mortele KJ, Alsop DC. Pancreatic perfusion and arterial-transit-time quantification using pseudocontinuous arterial spin labeling at 3T. Magn Reson Med 2018; 81:542-550. [DOI: 10.1002/mrm.27435] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/11/2018] [Accepted: 06/06/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Manuel Taso
- Division of MRI Research, Department of Radiology; Beth Israel Deaconess Medical Center; Boston Massachusetts
- Harvard Medical School; Boston Massachusetts
| | - Arnaud Guidon
- Global MR Applications and Workflow; GE Healthcare; Boston Massachusetts
| | - Li Zhao
- Division of MRI Research, Department of Radiology; Beth Israel Deaconess Medical Center; Boston Massachusetts
- Harvard Medical School; Boston Massachusetts
| | - Koenraad J. Mortele
- Division of MRI Research, Department of Radiology; Beth Israel Deaconess Medical Center; Boston Massachusetts
- Harvard Medical School; Boston Massachusetts
| | - David C. Alsop
- Division of MRI Research, Department of Radiology; Beth Israel Deaconess Medical Center; Boston Massachusetts
- Harvard Medical School; Boston Massachusetts
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17
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Li Y, Dolui S, Xie DF, Wang Z. Priors-guided slice-wise adaptive outlier cleaning for arterial spin labeling perfusion MRI. J Neurosci Methods 2018; 307:248-253. [DOI: 10.1016/j.jneumeth.2018.06.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/13/2018] [Accepted: 06/13/2018] [Indexed: 12/20/2022]
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Jezzard P, Chappell MA, Okell TW. Arterial spin labeling for the measurement of cerebral perfusion and angiography. J Cereb Blood Flow Metab 2018; 38:603-626. [PMID: 29168667 PMCID: PMC5888859 DOI: 10.1177/0271678x17743240] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Arterial spin labeling (ASL) is an MRI technique that was first proposed a quarter of a century ago. It offers the prospect of non-invasive quantitative measurement of cerebral perfusion, making it potentially very useful for research and clinical studies, particularly where multiple longitudinal measurements are required. However, it has suffered from a number of challenges, including a relatively low signal-to-noise ratio, and a confusing number of sequence variants, thus hindering its clinical uptake. Recently, however, there has been a consensus adoption of an accepted acquisition and analysis framework for ASL, and thus a better penetration onto clinical MRI scanners. Here, we review the basic concepts in ASL and describe the current state-of-the-art acquisition and analysis approaches, and the versatility of the method to perform both quantitative cerebral perfusion measurement, along with quantitative cerebral angiographic measurement.
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Affiliation(s)
- Peter Jezzard
- 1 Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | - Thomas W Okell
- 1 Wellcome Centre for Integrative Neuroimaging, FMRIB Division, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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19
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Chen HJ, Roy TL, Wright GA. Perfusion measures for symptom severity and differential outcome of revascularization in limb ischemia: Preliminary results with arterial spin labeling reactive hyperemia. J Magn Reson Imaging 2017; 47:1578-1588. [PMID: 29193492 DOI: 10.1002/jmri.25910] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/13/2017] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Previously, a theoretical model based on microvascular physiology was established to facilitate the interpretation of calf perfusion dynamics recorded by arterial spin labeling (ASL). PURPOSE To investigate the clinical relevance of novel perfusion indices by comparing them to the symptoms, response to revascularization, and short-term functional outcome in patients with peripheral arterial disease (PAD). STUDY TYPE Prospective cohort study. POPULATION Nineteen patients with PAD. FIELD STRENGTH/SEQUENCE Pulsed ASL at 3T. ASSESSMENT The mid-calf reactive hyperemia induced by 2 minutes of arterial occlusion was recorded in PAD patients. The perfusion responses were characterized by the peak, time-to-peak, and physiological model-derived indices including the baseline perfusion fr , arterial resistance Ra , and compliance Ca , and sensitivity gATP and response time τATP of downstream microvasculature to metabolic stress. These indices were compared to the disease severity and outcome within 6 months after revascularization assessed by self-reported symptoms and the ankle-brachial index. Disease severity was categorized as asymptomatic, claudication, or critical limb ischemia. The outcome was categorized as symptom resolved or limited improvement. STATISTICAL TESTS Severity and outcome groups were compared using Mann-Whitney and Kruskal-Wallis tests with Holm-Sidak adjustments. RESULTS The peak perfusion decreased and model arterial resistance increased progressively with increasing severity of limb ischemia (P = 0.0402 and 0.0413, respectively). Eleven patients had a successful endovascular procedure, including six patients who had symptoms resolved, four patients who had remaining leg pain, and one patient lost to follow-up. The subjects with limited improvement had significantly lower preintervention microvascular sensitivity gATP than those with symptoms resolved (8.72 ± 1.46 vs. 4.93 ± 0.91, P = 0.0466). DATA CONCLUSION ASL reactive hyperemia reflects multiple aspects of the pathophysiology. Measures of macrovascular arterial disease are related to the manifested symptom severity, whereas preintervention gATP associated with microvascular dysfunction is related to prognosis following revascularization. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:1578-1588.
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Affiliation(s)
- Hou-Jen Chen
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Trisha L Roy
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Division of Vascular Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Graham A Wright
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
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Pfaff AR, McKee CE, Woelk K. Predicting the effect of relaxation during frequency-selective adiabatic pulses. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 284:99-103. [PMID: 29028544 DOI: 10.1016/j.jmr.2017.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/08/2017] [Accepted: 09/28/2017] [Indexed: 06/07/2023]
Abstract
Adiabatic half and full passages are invaluable for achieving uniform, B1-insensitive excitation or inversion of macroscopic magnetization across a well-defined range of NMR frequencies. To accomplish narrow frequency ranges with adiabatic pulses (<100Hz), long pulse durations at low RF power levels are necessary, and relaxation during these pulses may no longer be negligible. A numerical, discrete recursive combination of the Bloch equations for longitudinal and transverse relaxation with the optimized equation for adiabatic angular motion of magnetization is used to calculate the trajectory of magnetization including its relaxation during adiabatic hyperbolic secant pulses. The agreement of computer-calculated data with experimental results demonstrates that, in non-viscous, small-molecule fluids, it is possible to model magnetization and relaxation by considering standard T1 and T2 relaxation in the traditional rotating frame. The proposed model is aimed at performance optimizations of applications in which these pulses are employed. It differs from previous reports which focused on short high-power adiabatic pulses and relaxation that is governed by dipole-dipole interactions, cross polarization, or chemical exchange.
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Affiliation(s)
- Annalise R Pfaff
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
| | - Cailyn E McKee
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
| | - Klaus Woelk
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
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Kang KM, Sohn CH, You SH, Nam JG, Choi SH, Yun TJ, Yoo RE, Kim JH. Added Value of Arterial Spin-Labeling MR Imaging for the Differentiation of Cerebellar Hemangioblastoma from Metastasis. AJNR Am J Neuroradiol 2017; 38:2052-2058. [PMID: 28912280 PMCID: PMC7963584 DOI: 10.3174/ajnr.a5363] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 06/30/2017] [Indexed: 01/26/2023]
Abstract
BACKGROUND AND PURPOSE In adults with only cerebellar masses, hemangioblastoma and metastasis are the 2 most important differential diagnoses. Our aim was to investigate the added value of arterial spin-labeling MR imaging for differentiating hemangioblastoma from metastasis in patients with only cerebellar masses. MATERIALS AND METHODS This retrospective study included a homogeneous cohort comprising patients with only cerebellar masses, including 16 hemangioblastomas and 14 metastases. All patients underwent enhanced MR imaging, including arterial spin-labeling. First, the presence or absence of a hyperperfused mass was determined. Next, in the hyperperfused mass, relative tumor blood flow (mean blood flow in the tumor divided by blood flow measured in normal-appearing cerebellar tissue) and the size ratio (size in the arterial spin-labeling images divided by size in the postcontrast T1WI) were measured. To validate the arterial spin-labeling findings, 2 observers independently evaluated the conventional MR images and the combined set of arterial spin-labeling images. RESULTS All patients with hemangioblastomas and half of the patients with metastases presented with a hyperperfused mass (P < .001). The size ratio and relative tumor blood flow were significantly larger for hemangioblastomas than for metastases (P < .001 and P = .039, respectively). The size ratio revealed excellent diagnostic power (area under the curve = 0.991), and the relative tumor blood flow demonstrated moderate diagnostic power (area under the curve = 0.777). The diagnostic accuracy of both observers was significantly improved after the addition of arterial spin-labeling; the area under the curve improved from 0.574 to 0.969 (P < .001) for observer 2 and from 0.683 to 1 (P < .001) for observer 2. CONCLUSIONS Arterial spin-labeling imaging can aid in distinguishing hemangioblastoma from metastasis in patients with only cerebellar masses.
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Affiliation(s)
- K M Kang
- From the Department of Radiology (K.M.K., C.-H.S., J.G.N., S.H.C., T.J.Y., R.-E.Y., J.-h.K.), Seoul National University Hospital, Seoul, Korea
| | - C-H Sohn
- From the Department of Radiology (K.M.K., C.-H.S., J.G.N., S.H.C., T.J.Y., R.-E.Y., J.-h.K.), Seoul National University Hospital, Seoul, Korea
- Department of Radiology (C.-H.S., S.H.C.), Seoul National University College of Medicine, Seoul, Korea
| | - S-H You
- Department of Radiology (S.-H.Y.), Korea University Hospital, Seoul, Korea
| | - J G Nam
- From the Department of Radiology (K.M.K., C.-H.S., J.G.N., S.H.C., T.J.Y., R.-E.Y., J.-h.K.), Seoul National University Hospital, Seoul, Korea
| | - S H Choi
- From the Department of Radiology (K.M.K., C.-H.S., J.G.N., S.H.C., T.J.Y., R.-E.Y., J.-h.K.), Seoul National University Hospital, Seoul, Korea
- Department of Radiology (C.-H.S., S.H.C.), Seoul National University College of Medicine, Seoul, Korea
| | - T J Yun
- From the Department of Radiology (K.M.K., C.-H.S., J.G.N., S.H.C., T.J.Y., R.-E.Y., J.-h.K.), Seoul National University Hospital, Seoul, Korea
| | - R-E Yoo
- From the Department of Radiology (K.M.K., C.-H.S., J.G.N., S.H.C., T.J.Y., R.-E.Y., J.-h.K.), Seoul National University Hospital, Seoul, Korea
| | - J-H Kim
- From the Department of Radiology (K.M.K., C.-H.S., J.G.N., S.H.C., T.J.Y., R.-E.Y., J.-h.K.), Seoul National University Hospital, Seoul, Korea
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Kang KM, Sohn CH, Choi SH, Jung KH, Yoo RE, Yun TJ, Kim JH, Park SW. Detection of crossed cerebellar diaschisis in hyperacute ischemic stroke using arterial spin-labeled MR imaging. PLoS One 2017; 12:e0173971. [PMID: 28323841 PMCID: PMC5360263 DOI: 10.1371/journal.pone.0173971] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 03/01/2017] [Indexed: 11/24/2022] Open
Abstract
Background and purpose Arterial spin-labeling (ASL) was recently introduced as a noninvasive method to evaluate cerebral hemodynamics. The purposes of this study were to assess the ability of ASL imaging to detect crossed cerebellar diaschisis (CCD) in patients with their first unilateral supratentorial hyperacute stroke and to identify imaging or clinical factors significantly associated with CCD. Materials and methods We reviewed 204 consecutive patients who underwent MRI less than 8 hours after the onset of stroke symptoms. The inclusion criteria were supratentorial abnormality in diffusion-weighted images in the absence of a cerebellar or brain stem lesion, bilateral supratentorial infarction, subacute or chronic infarction, and MR angiography showing vertebrobasilar system disease. For qualitative analysis, asymmetric cerebellar hypoperfusion in ASL images was categorized into 3 grades. Quantitative analysis was performed to calculate the asymmetric index (AI). The patients’ demographic and clinical features and outcomes were recorded. Univariate and multivariate analyses were also performed. Results A total of 32 patients met the inclusion criteria, and 24 (75%) presented CCD. Univariate analyses revealed more frequent arterial occlusions, higher diffusion-weighted imaging (DWI) lesion volumes and higher initial NIHSS and mRS scores in the CCD-positive group compared with the CCD-negative group (all p < .05). The presence of arterial occlusion and the initial mRS scores were related with the AI (all p < .05). Multivariate analyses revealed that arterial occlusion and the initial mRS scores were significantly associated with CCD and AI. Conclusion ASL imaging could detect CCD in 75% of patients with hyperacute infarction. We found that CCD was more prevalent in patients with arterial occlusion, larger ischemic brain volumes, and higher initial NIHSS and mRS scores. In particular, vessel occlusion and initial mRS score appeared to be significantly related with CCD pathophysiology in the hyperacute stage.
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Affiliation(s)
- Koung Mi Kang
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Chul-Ho Sohn
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
- * E-mail:
| | - Seung Hong Choi
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Keun-Hwa Jung
- Department of Neurology, Clinical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Roh-Eul Yoo
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Tae Jin Yun
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Ji-hoon Kim
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Sun-Won Park
- Department of Radiology, Seoul National University Boramae Hospital, Seoul, Republic of Korea
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Shao X, Wang Y, Moeller S, Wang DJJ. A constrained slice-dependent background suppression scheme for simultaneous multislice pseudo-continuous arterial spin labeling. Magn Reson Med 2017; 79:394-400. [PMID: 28198576 DOI: 10.1002/mrm.26643] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/20/2017] [Accepted: 01/24/2017] [Indexed: 11/12/2022]
Abstract
PURPOSE To present a constrained slice-dependent (CSD) background-suppression (BS) scheme in 2D arterial spin labeling (ASL) using simultaneous multislice acquisition with blipped-CAIPIRINHA (controlled aliasing in parallel imaging results in higher acceleration). METHODS Background suppression for 2D acquisition is challenging because of the multiple nulling points required for sequential slice readout. Constrained slice-dependent BS exploits the simultaneous multislice technique to reduce the readout duration, and uses slice-dependent premodulation pulses to achieve BS across slice groups. The proposed scheme was evaluated by in vivo brain experiments at 3 Tesla with multiband acceleration factors up to four. The utility of CSD BS was demonstrated through comparison against standard 2D acquisitions as well as 3D-BS pseudo-continuous ASL (pCASL). RESULTS An average of 95% background signal reduction was achieved with CSD BS. As a result, the temporal signal-to-noise ratio (SNR) increased 48.2/39.9/36.9/36.0% and spatial SNR increased 132.5/80.0/63.5/54.2 in CSD-BS MB-1/2/3/4 scans, respectively. Whole-brain coverage was achievable with CSD-BS pCASL with MB-4, which yielded comparable spatial SNR as 3D BS pCASL. CONCLUSIONS The proposed CSD-BS scheme for 2D-SMS pCASL offers a promising approach for effective suppression of background signals across a wide range of T1 to achieve whole-brain perfusion imaging. Magn Reson Med 79:394-400, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Xingfeng Shao
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Soutern California, Los Angeles, California, USA
| | - Yi Wang
- MR Clinical Science, Philips Healthcare, Gainesville, Florida, USA
| | - Steen Moeller
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Danny J J Wang
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Soutern California, Los Angeles, California, USA
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Donahue MJ, Juttukonda MR, Watchmaker JM. Noise concerns and post-processing procedures in cerebral blood flow (CBF) and cerebral blood volume (CBV) functional magnetic resonance imaging. Neuroimage 2016; 154:43-58. [PMID: 27622397 DOI: 10.1016/j.neuroimage.2016.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/22/2016] [Accepted: 09/03/2016] [Indexed: 01/19/2023] Open
Abstract
Functional neuroimaging with blood oxygenation level-dependent (BOLD) contrast has emerged as the most popular method for evaluating qualitative changes in brain function in humans. At typical human field strengths (1.5-3.0T), BOLD contrast provides a measure of changes in transverse water relaxation rates in and around capillary and venous blood, and as such provides only a surrogate marker of brain function that depends on dynamic changes in hemodynamics (e.g., cerebral blood flow and volume) and metabolism (e.g., oxygen extraction fraction and the cerebral metabolic rate of oxygen consumption). Alternative functional neuroimaging methods that are specifically sensitive to these constituents of the BOLD signal are being developed and applied in a growing number of clinical and neuroscience applications of quantitative cerebral physiology. These methods require additional considerations for interpreting and quantifying their contrast responsibly. Here, an overview of two popular methods, arterial spin labeling and vascular space occupancy, is presented specifically in the context of functional neuroimaging. Appropriate post-processing and experimental acquisition strategies are summarized with the motivation of reducing sensitivity to noise and unintended signal sources and improving quantitative accuracy of cerebral hemodynamics.
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Affiliation(s)
- Manus J Donahue
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA; Neurology, Vanderbilt University School of Medicine, Nashville, TN, USA; Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - Meher R Juttukonda
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jennifer M Watchmaker
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
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Satterfield ET, Pfaff AR, Zhang W, Chi L, Gerald RE, Woelk K. EXponentially Converging Eradication Pulse Train (EXCEPT) for solvent-signal suppression in investigations with variable T(1) times. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 268:68-72. [PMID: 27179454 DOI: 10.1016/j.jmr.2016.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 05/06/2016] [Accepted: 05/08/2016] [Indexed: 06/05/2023]
Abstract
Selective presaturation is a common technique for suppressing excessive solvent signals during proton NMR analysis of dilute samples in protic solvents. When the solvent T1 relaxation time constant varies within a series of samples, parameters for the presaturation sequence must often be re-adjusted for each sample. The EXCEPT (EXponentially Converging Eradication Pulse Train) presaturation pulse sequence was developed to eliminate time consuming pulse-parameter re-optimization as long as the variation in the solvent's T1 remains within an order of magnitude. EXCEPT consists of frequency-selective inversion pulses with progressively decreasing interpulse delays. The interpulse delays were optimized to encompass T1 relaxation times ranging from 1 to 10s, but they can be easily adjusted by a single factor for other ranges that fall within an order of magnitude with respect to T1. Sequences with different numbers of inversion pulses were tested to maximize suppression while minimizing the number of pulses and thus the total time needed for suppression. The EXCEPT-16 experiment, where 16 denotes the number of inversion pulses, was found satisfactory for many standard applications. Experimental results demonstrate that EXCEPT provides effective T1-insensitive solvent suppression as predicted by the theory. The robustness of EXCEPT with respect to changes in solvent T1 allows NMR investigations to be carried out for a series of samples without the need for pulse-parameter re-optimization for each sample.
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Affiliation(s)
- Emmalou T Satterfield
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
| | - Annalise R Pfaff
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
| | - Wenjia Zhang
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
| | - Lingyu Chi
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
| | - Rex E Gerald
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
| | - Klaus Woelk
- Department of Chemistry, Missouri University of Science & Technology, 400 West 11th, Rolla, MO 65409-0010, USA.
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Principles and methods for automatic and semi-automatic tissue segmentation in MRI data. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2016; 29:95-110. [DOI: 10.1007/s10334-015-0520-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 11/26/2022]
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Kang KM, Sohn CH, Kim BS, Kim YI, Choi SH, Yun TJ, Kim JH, Park SW, Cheon GJ, Han MH. Correlation of Asymmetry Indices Measured by Arterial Spin-Labeling MR Imaging and SPECT in Patients with Crossed Cerebellar Diaschisis. AJNR Am J Neuroradiol 2015; 36:1662-8. [PMID: 26228883 DOI: 10.3174/ajnr.a4366] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/20/2015] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Crossed cerebellar diaschisis, not only a secondary result of supratentorial infarction but also an indicator of clinical outcomes, has frequently been reported on PET and SPECT but has been rarely described with arterial spin-labeling MR imaging. The purpose of this study was to determine the ability of arterial spin-labeling MR imaging to evaluate crossed cerebellar diaschisis compared with that of SPECT. To our knowledge, this is the first study to validate arterial spin-labeling in crossed cerebellar diaschisis by using SPECT as a reference standard. MATERIALS AND METHODS This study included 16 patients in whom crossed cerebellar diaschisis was shown on SPECT and 10 control subjects in whom crossed cerebellar diaschisis was not shown on SPECT. During the qualitative analysis, asymmetric cerebellar perfusion on arterial spin-labeling was divided into 1 of the following 3 grades by 2 blinded observers: the affected cerebellum was isointense compared with the unaffected cerebellum (grade I), it was slightly hypointense (grade II), or it was markedly hypointense (grade III). In the quantitative analysis, asymmetry indices were calculated by using SPECT and arterial spin-labeling images. For statistical analysis, κ statistics, the interobserver correlation coefficient, the independent t test, Pearson correlation, and linear regression analysis were used. RESULTS Almost all the diagnoses of crossed cerebellar diaschisis on SPECT were noted on arterial spin-labeling in both qualitative and quantitative analyses with good interobserver agreement (κ = 0.961; interobserver correlation coefficient, 0.806). The mean asymmetry index of arterial spin-labeling (26.06 ± 9.00) was significantly larger than that for SPECT (15.28 ± 5.34; P < .001). There was a significant positive correlation between the asymmetry indices obtained for SPECT and those for arterial spin-labeling (r = 0.77 [95% CI, 0.443-0.916]; P < .001). The relationship of asymmetry indices between SPECT and arterial spin-labeling (x, y) was calculated as y = 6.2131 + 1.2986x (R(2) = 0.592; P < .001). CONCLUSIONS Arterial spin-labeling can be a noninvasive alternative to SPECT for evaluating crossed cerebellar diaschisis.
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Affiliation(s)
- K M Kang
- From the Departments of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., M.H.H.) Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea
| | - C-H Sohn
- From the Departments of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., M.H.H.) Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea Institute of Radiation Medicine (C.-H.S., S.H.C., M.H.H.), Seoul National University Medical Research Center, Seoul, Republic of Korea
| | - B S Kim
- From the Departments of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., M.H.H.) Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Y I Kim
- Nuclear Medicine (Y.I.K., G.J.C.), Seoul National University Hospital, Seoul, Republic of Korea
| | - S H Choi
- From the Departments of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., M.H.H.) Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea Institute of Radiation Medicine (C.-H.S., S.H.C., M.H.H.), Seoul National University Medical Research Center, Seoul, Republic of Korea
| | - T J Yun
- From the Departments of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., M.H.H.) Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea
| | - J-h Kim
- From the Departments of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., M.H.H.) Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea
| | - S-W Park
- Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea Department of Radiology (S.-W.P.), Seoul National University Boramae Hospital, Seoul, Republic of Korea
| | - G J Cheon
- Nuclear Medicine (Y.I.K., G.J.C.), Seoul National University Hospital, Seoul, Republic of Korea
| | - M H Han
- From the Departments of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., M.H.H.) Department of Radiology (K.M.K., C.-H.S., B.S.K., S.H.C., T.J.Y., J.-h.K., S.-W.P., M.H.H.), Seoul National University College of Medicine, Seoul, Republic of Korea Institute of Radiation Medicine (C.-H.S., S.H.C., M.H.H.), Seoul National University Medical Research Center, Seoul, Republic of Korea
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Han M, Chiba K, Banerjee S, Carballido-Gamio J, Krug R. Variable flip angle three-dimensional fast spin-echo sequence combined with outer volume suppression for imaging trabecular bone structure of the proximal femur. J Magn Reson Imaging 2015; 41:1300-10. [PMID: 24956149 PMCID: PMC4275424 DOI: 10.1002/jmri.24673] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND To demonstrate the feasibility of using a variable flip angle three-dimensional fast spin-echo (3D VFA-FSE) sequence combined with outer volume suppression for imaging trabecular bone structure at the proximal femur in vivo at 3 Tesla. METHODS The 3D VFA-FSE acquisition was optimized to minimize blurring and to provide high signal-to-noise ratio (SNR) from bone marrow. Outer volume suppression was achieved by applying three quadratic-phase radio-frequency pulses. The SNR and trabecular bone structures from 3D VFA-FSE were compared with those from previously demonstrated multiple-acquisition 3D balanced steady-state free precision (bSSFP) using theoretical simulations, ex vivo experiments, and in vivo experiments. RESULTS Our simulation demonstrated that 3D VFA-FSE can provide at least 35% higher SNR than 3D bSSFP, which was confirmed by the ex vivo and in vivo experiments. The ex vivo experiments demonstrated a good correlation and agreement between bone structural paramters obtained with the two sequences. The proposed sequence depicted trabecular bone structure at the proxiaml femur in vivo well without visible suppression artifacts and provided a mean SNR of 11.0. CONCLUSION The 3D VFA-FSE sequence combined with outer volume suppression can depict the trabecular bone structure of the proximal femur in vivo with minimal blurring and high SNR efficiency.
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Affiliation(s)
- Misung Han
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA
| | - Ko Chiba
- Department of Orthopaedic Surgery, Nagasaki University School of Medicine, Nagasaki, Japan
| | | | - Julio Carballido-Gamio
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA
| | - Roland Krug
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA
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Dong J, Yang L, Su T, Yang X, Chen B, Zhang J, Wang X, Jiang X. Quantitative assessment of acute kidney injury by noninvasive arterial spin labeling perfusion MRI: a pilot study. SCIENCE CHINA-LIFE SCIENCES 2013; 56:745-50. [DOI: 10.1007/s11427-013-4503-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 04/24/2013] [Indexed: 12/25/2022]
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Schraml C, Schwenzer NF, Claussen CD, Martirosian P. Examination of Tissue Perfusion by Arterial Spin Labeling (ASL). CURRENT RADIOLOGY REPORTS 2013. [DOI: 10.1007/s40134-013-0009-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Yoo RE, Choi SH, Cho HR, Kim TM, Lee SH, Park CK, Park SH, Kim IH, Yun TJ, Kim JH, Sohn CH, Han MH, Chang KH. Tumor blood flow from arterial spin labeling perfusion MRI: A key parameter in distinguishing high-grade gliomas from primary cerebral lymphomas, and in predicting genetic biomarkers in high-grade gliomas. J Magn Reson Imaging 2013; 38:852-60. [DOI: 10.1002/jmri.24026] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 12/07/2012] [Indexed: 12/31/2022] Open
Affiliation(s)
- Roh-Eul Yoo
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
| | - Seung Hong Choi
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
| | - Hye Rim Cho
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
- Department of Radiation Applied Life Science; Seoul National University College of Medicine; Seoul Korea
| | - Tae Min Kim
- Department of Internal Medicine; Cancer Research Institute; Seoul National University College of Medicine; Seoul Korea
| | - Se-Hoon Lee
- Department of Internal Medicine; Cancer Research Institute; Seoul National University College of Medicine; Seoul Korea
| | - Chul-Kee Park
- Department of Neurosurgery; Biomedical Research Institute; Seoul National University College of Medicine; Seoul Korea
| | - Sung-Hye Park
- Department of Pathology; Seoul National University College of Medicine; Seoul Korea
| | - Il Han Kim
- Department of Radiation Oncology; Cancer Research Institute; Seoul National University College of Medicine; Seoul Korea
| | - Tae Jin Yun
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
| | - Ji-Hoon Kim
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
| | - Chul-Ho Sohn
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
| | - Moon Hee Han
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
| | - Kee Hyun Chang
- Department of Radiology; Seoul National University College of Medicine; Seoul Korea
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Zimmer F, Zöllner FG, Hoeger S, Klotz S, Tsagogiorgas C, Krämer BK, Schad LR. Quantitative renal perfusion measurements in a rat model of acute kidney injury at 3T: testing inter- and intramethodical significance of ASL and DCE-MRI. PLoS One 2013; 8:e53849. [PMID: 23308289 PMCID: PMC3538736 DOI: 10.1371/journal.pone.0053849] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 12/05/2012] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES To establish arterial spin labelling (ASL) for quantitative renal perfusion measurements in a rat model at 3 Tesla and to test the diagnostic significance of ASL and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in a model of acute kidney injury (AKI). MATERIAL AND METHODS ASL and DCE-MRI were consecutively employed on six Lewis rats, five of which had a unilateral ischaemic AKI. All measurements in this study were performed on a 3 Tesla MR scanner using a FAIR True-FISP approach and a TWIST sequence for ASL and DCE-MRI, respectively. Perfusion maps were calculated for both methods and the cortical perfusion of healthy and diseased kidneys was inter- and intramethodically compared using a region-of-interest based analysis. RESULTS/SIGNIFICANCE Both methods produce significantly different values for the healthy and the diseased kidneys (P<0.01). The mean difference was 147±47 ml/100 g/min and 141±46 ml/100 g/min for ASL and DCE-MRI, respectively. ASL measurements yielded a mean cortical perfusion of 416±124 ml/100 g/min for the healthy and 316±102 ml/100 g/min for the diseased kidneys. The DCE-MRI values were systematically higher and the mean cortical renal blood flow (RBF) was found to be 542±85 ml/100 g/min (healthy) and 407±119 ml/100 g/min (AKI). CONCLUSION Both methods are equally able to detect abnormal perfusion in diseased (AKI) kidneys. This shows that ASL is a capable alternative to DCE-MRI regarding the detection of abnormal renal blood flow. Regarding absolute perfusion values, nontrivial differences and variations remain when comparing the two methods.
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Affiliation(s)
- Fabian Zimmer
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank G. Zöllner
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- * E-mail:
| | - Simone Hoeger
- Department of Medicine V, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany
| | - Sarah Klotz
- Department of Medicine V, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany
| | - Charalambos Tsagogiorgas
- Clinic for Anaesthesiology and Intensive Care, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany
| | - Bernhard K. Krämer
- Department of Medicine V, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany
| | - Lothar R. Schad
- Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Dong HZ, Worters PW, Wu HH, Ingle RR, Vasanawala SS, Nishimura DG. Noncontrast-enhanced renal angiography using multiple inversion recovery and alternating TR balanced steady-state free precession. Magn Reson Med 2012; 70:527-36. [PMID: 23172805 DOI: 10.1002/mrm.24480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 08/07/2012] [Accepted: 08/09/2012] [Indexed: 01/05/2023]
Abstract
Noncontrast-enhanced renal angiography techniques based on balanced steady-state free precession avoid external contrast agents, take advantage of high inherent blood signal from the T 2 / T 1 contrast mechanism, and have short steady-state free precession acquisition times. However, background suppression is limited; inflow times are inflexible; labeling region is difficult to define when tagging arterial flow; and scan times are long. To overcome these limitations, we propose the use of multiple inversion recovery preparatory pulses combined with alternating pulse repetition time balanced steady-state free precession to produce renal angiograms. Multiple inversion recovery uses selective spatial saturation followed by four nonselective inversion recovery pulses to concurrently null a wide range of background T 1 species while allowing for adjustable inflow times; alternating pulse repetition time steady-state free precession maintains vessel contrast and provides added fat suppression. The high level of suppression enables imaging in three-dimensional as well as projective two-dimensional formats, the latter of which has a scan time as short as one heartbeat. In vivo studies at 1.5 T demonstrate the superior vessel contrast of this technique.
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Affiliation(s)
- Hattie Z Dong
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA.
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Zhang Y, San Emeterio Nateras O, Peng Q, Rosende CA, Duong TQ. Blood flow MRI of the human retina/choroid during rest and isometric exercise. Invest Ophthalmol Vis Sci 2012; 53:4299-305. [PMID: 22661466 DOI: 10.1167/iovs.11-9384] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate blood flow (BF) in the human retina/choroid during rest and handgrip isometric exercise using magnetic resonance imaging (MRI). METHODS Four healthy volunteers (25-36 years old) in multiple sessions (1-3) on different days. MRI studies were performed on a 3-Tesla scanner using a custom-made surface coil (7×5cm in diameter) at the spatial resolution of 0.5×0.8×6.0 mm. BF was measured using the pseudo-continuous arterial-spin-labeling technique with background suppression and turbo-spin-echo acquisition. During MRI, subjects rested for 1 minute followed by 1 minute of handgrip, repeating three times, while maintaining stable eye fixation on a target with cued eye blinks at the end of each data acquisition (every 4.6 seconds). RESULTS Robust BF of the unanesthetized human retina/choroid was detected. Basal BF in the posterior retina/choroid was 149±48 mL/100 mL/min with a mean heart rate of 60±5 beats per minute, mean arterial pressure of 78±5 mm Hg, ocular perfusion pressure of 67±4 mm Hg at rest (mean±SD, n=4 subjects). Handgrip significantly increased retina/choroid BF by 25%±7%, heart rate by 19%±8%, mean arterial pressure by 22%±5% (measured at the middle of the handgrip task), and ocular perfusion pressure by 25%±6% (averaged across the entire handgrip task) (P<0.01), but did not change intraocular pressure, arterial oxygen saturation, end-tidal CO2, and respiration rate (P>0.05). CONCLUSIONS This study demonstrates a novel MRI application to image quantitative BF of the human retina/choroid during rest and isometric exercise. Retina/choroid BF increases during brief handgrip exercise, paralleling increases in mean arterial pressure. Handgrip exercise changes ocular perfusion pressure free of potential drug side effect and can be done in the MRI scanner. MRI offers quantitative BF with large field of view without depth limitation, potentially providing insights into retinal pathophysiology.
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Affiliation(s)
- Yi Zhang
- Research Imaging Institute, Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX 78229, USA
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Vinogradov E, Soesbe TC, Balschi JA, Sherry AD, Lenkinski RE. pCEST: Positive contrast using Chemical Exchange Saturation Transfer. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 215:64-73. [PMID: 22237630 PMCID: PMC3288637 DOI: 10.1016/j.jmr.2011.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 12/13/2011] [Accepted: 12/14/2011] [Indexed: 05/11/2023]
Abstract
Chemical Exchange Saturation Transfer (CEST) contrast utilizes selective pre-saturation of a small pool of exchanging protons and subsequent detection of the decrease in bulk water signal. The CEST contrast is negative and requires detection of small signal change in the presence of a strong background signal. Here we develop a Positive CEST (pCEST) detection scheme utilizing the analogous nature of the CEST and off-resonance T(1)(ρ) experiments and exploring increased apparent relaxation rates in the presence of the selective pre-saturation. pCEST leads to the positive contrast, i.e., increased signal intensity as the result of the presence of the agent and RF pre-saturation. Simultaneously substantial background suppression is achieved. The contrast can be switched "ON" and "OFF", similar to the original CEST.
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Affiliation(s)
- Elena Vinogradov
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
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Le TT, Fischbein NJ, André JB, Wijman C, Rosenberg J, Zaharchuk G. Identification of venous signal on arterial spin labeling improves diagnosis of dural arteriovenous fistulas and small arteriovenous malformations. AJNR Am J Neuroradiol 2011; 33:61-8. [PMID: 22158927 DOI: 10.3174/ajnr.a2761] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE DAVFs and small AVMs are difficult to detect on conventional MR imaging/MRA or CTA examinations and often require DSA for definitive diagnosis. The purpose of this study was to assess the value of venous signal intensity on ASL imaging for making this diagnosis. MATERIALS AND METHODS Two neuroradiologists and 1 neurologist reviewed MR imaging studies in 26 patients, 15 of whom had DSA-proved DAVFs or small (<2 cm) AVMs. Pseudocontinuous ASL was performed at 1.5T with background-suppressed 3D-FSE readout. Using a 5-point scale, these readers assessed the likelihood of positive findings on a DSA study before and after reviewing the ASL findings. Agreement on imaging findings, including venous ASL signal intensity, was performed by using κ statistics. Logistic regression and ROC analysis were performed to determine which imaging findings improved diagnosis. RESULTS Venous ASL signal intensity was seen frequently in cases with positive findings on DSA. The sensitivity and specificity of venous ASL signal intensity for predicting positive findings on a DSA study were 78% and 85%, respectively. On ROC analysis, there was a significant increase in the AUC after review of the ASL images (AUC = 0.798 pre-ASL, AUC = 0.891 post-ASL; P = .02). Multivariate regression identified venous ASL signal intensity as the strongest predictor of positive findings on a DSA study, with an odds ratio of 17.3 (95% CI, 3.3-90.4). CONCLUSIONS Identifying venous ASL signal intensity improved detection of DAVFs and small AVMs. Attention to this finding may improve triage to DSA in patients with suspected small vascular malformations.
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Affiliation(s)
- T T Le
- Department of Radiology, Stanford University, CA, USA
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Shen Q, Duong TQ. Background suppression in arterial spin labeling MRI with a separate neck labeling coil. NMR IN BIOMEDICINE 2011; 24:1111-1118. [PMID: 21294207 PMCID: PMC3116975 DOI: 10.1002/nbm.1666] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 12/02/2010] [Accepted: 12/05/2010] [Indexed: 05/30/2023]
Abstract
In arterial spin labeling (ASL) MRI to measure cerebral blood flow (CBF), pair-wise subtraction of temporally adjacent non-labeled and labeled images often can not completely cancel the background static tissue signal because of temporally fluctuating physiological noise. While background suppression (BS) by inversion nulling improves CBF temporal stability, imperfect pulses compromise CBF contrast. Conventional BS techniques may not be applicable in small animals because the arterial transit time is short. This study presents a novel approach of BS to overcome these drawbacks using a separate 'neck' radiofrequency coil for ASL and a 'brain' radiofrequency coil for BS with the inversion pulse placed before spin labeling. The use of a separate 'neck' coil for ASL should also improve ASL contrast. This approach is referred to as the inversion-recovery BS with the two-coil continuous ASL (IR-cASL) technique. The temporal and spatial contrast-to-noise characteristics of basal CBF and CBF-based fMRI of hypercapnia and forepaw stimulation in rats at 7 Tesla were analyzed. IR-cASL yielded two times better temporal stability and 2.0-2.3 times higher functional contrast-to-noise ratios for hypercapnia and forepaw stimulation compared with cASL without BS in the same animals. The Bloch equations were modified to provide accurate CBF quantification at different levels of BS and for multislice acquisition where different slices have different degree of BS and residual degree of labeling. Improved basal CBF and CBF-based fMRI sensitivity should lead to more accurate CBF quantification and should prove useful for imaging low CBF conditions such as in white matter and stroke.
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Affiliation(s)
- Qiang Shen
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Radiology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Timothy Q. Duong
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Radiology, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Physiology, University of Texas Health Science Center, San Antonio, TX, USA
- South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, TX, USA
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Maleki N, Dai W, Alsop DC. Optimization of background suppression for arterial spin labeling perfusion imaging. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2011; 25:127-33. [PMID: 22009131 DOI: 10.1007/s10334-011-0286-3] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 08/29/2011] [Accepted: 09/22/2011] [Indexed: 10/16/2022]
Abstract
OBJECT To present an algorithm for optimization of background suppression pulse timing for arterial spin labeling (ASL) perfusion imaging. MATERIALS AND METHODS An algorithm for optimization of background suppression pulse timing is proposed. Numerical optimization of timing of the background suppression pulses is investigated in both constrained and unconstrained ASL sequences. The performance of the parameters from the algorithm is evaluated in phantom and also in vivo in five human subjects. RESULTS The background signal is suppressed to less than 1% across a broad range of T1s with a modest number of inversion pulses using the timings acquired from the numerical optimization algorithm proposed in this study. The performance of the parameters from the algorithm is also confirmed in vivo. CONCLUSION Successful background suppression over a broad range of tissues is achievable. Values for optimal pulse timing in both pulsed and continuous ASL studies are reported to facilitate sequence design with different labeling parameters.
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Affiliation(s)
- Nasim Maleki
- Department of Radiology, Children's Hospital Boston, 300 Longwood Ave, Boston, MA 02115, USA.
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Atanasova IP, Kim D, Lim RP, Storey P, Kim S, Guo H, Lee VS. Noncontrast MR angiography for comprehensive assessment of abdominopelvic arteries using quadruple inversion-recovery preconditioning and 3D balanced steady-state free precession imaging. J Magn Reson Imaging 2011; 33:1430-9. [PMID: 21591013 DOI: 10.1002/jmri.22564] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop a noncontrast magnetic resonance angiography (MRA) method for comprehensive evaluation of abdominopelvic arteries in a single 3D acquisition. MATERIALS AND METHODS A noncontrast MRA (NC MRA) pulse sequence was developed using four inversion-recovery (IR) pulses and 3D balanced steady-state free precession (b-SSFP) readout to provide arterial imaging from renal to external iliac arteries. Respiratory triggered, high spatial resolution (1.3 × 1.3 × 1.7 mm(3)) noncontrast angiograms were obtained in seven volunteers and ten patients referred for gadolinium-enhanced MRA (CE MRA). Images were assessed for diagnostic quality by two radiologists. Quantitative measurements of arterial signal contrast were also performed. RESULTS NC MRA imaging was successfully completed in all subjects in 7.0 ± 2.3 minutes. In controls, image quality of NC MRA averaged 2.79 ± 0.39 on a scale of 0-3, where 3 is maximum. Image quality of NC MRA (2.65 ± 0.41) was comparable to that of CE MRA (2.9 ± 0.32) in all patients. Contrast ratio measurements in patients demonstrated that NC MRA provides arterial contrast comparable to source CE MRA images with adequate venous and excellent background tissue suppression. CONCLUSION The proposed noncontrast MRA pulse sequence provides high-quality visualization of abdominopelvic arteries within clinically feasible scan times.
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Affiliation(s)
- Iliyana P Atanasova
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, New York 10016, USA.
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Dai W, Robson PM, Shankaranarayanan A, Alsop DC. Sensitivity calibration with a uniform magnetization image to improve arterial spin labeling perfusion quantification. Magn Reson Med 2011; 66:1590-600. [PMID: 21523824 DOI: 10.1002/mrm.22954] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 02/18/2011] [Accepted: 03/15/2011] [Indexed: 12/20/2022]
Abstract
Quantification of perfusion with arterial spin labeling MRI requires a calibration of the imaging sensitivity to water throughout the imaged volume. Since this sensitivity is affected by coil loading and other interactions between the subject and the scanner, the sensitivity must be calibrated in the subject at the time of scan. Conventional arterial spin labeling perfusion quantification assumes a uniform proton density and acquires a proton density reference image to serve as the calibration. This assumption, in the form of an assumed constant brain-blood partition coefficient, incorrectly adds inverse proton density weighting to the perfusion image. Here, a sensitivity calibration is proposed by generating a uniform magnetization image whose intensity is highly independent of brain tissue type. It is shown that such a uniform magnetization image can be achieved, and brain tissue perfusion values quantified with the sensitivity calibration agree with those quantified with a proton density image when segmentation of brain tissues is performed and appropriate partition coefficients are assumed. Quantification of brain tissue water density is also demonstrated using this sensitivity calibration. This approach can improve and simplify quantification of arterial spin labeling perfusion and may have broader applications to measurement of edema and sensitivity calibration for parallel imaging.
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Affiliation(s)
- Weiying Dai
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
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Peng Q, Zhang Y, Nateras OSE, van Osch MJP, Duong TQ. MRI of blood flow of the human retina. Magn Reson Med 2011; 65:1768-75. [PMID: 21590806 DOI: 10.1002/mrm.22763] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/25/2010] [Accepted: 11/24/2010] [Indexed: 12/25/2022]
Abstract
This study reports a high-resolution MRI approach to image basal blood flow and hypercapnia-induced blood-flow changes in the unanesthetized human retina on a 3-T MRI scanner. Pseudocontinuous arterial spin labeling technique with static tissue suppression was implemented to minimize movement artifacts and improve blood-flow sensitivity. Turbo spin-echo acquisition was used to achieve high spatial resolution free of susceptibility artifacts. The size, shape, and position of a custom-made receive radiofrequency coil were optimized for sensitivity in the posterior retina. Synchronized eye blink and respiration to the end of each data readout minimized eye movement and physiological fluctuation. Robust high-contrast blood-flow MRI of the unanesthetized human retina was obtained at 500 × 800 μm(2) in-plane resolution. Blood flow in the posterior retina was 93 ± 31 mL/(100 mL min) (mean ± standard deviation, N = 5). Hypercapnic inhalation (5% CO(2)) increased blood flow by 12 ± 4% relative to air (P < 0.01, N = 5). This study demonstrates the feasibility of blood-flow MRI of the retina of unanesthetized human. Because blood flow is tightly coupled to metabolic function under normal conditions and it is often perturbed in diseases, this approach could provide unique insights into retinal physiology and serve as an objective imaging biomarker for disease staging and testing of novel therapeutic strategies. This approach could open up new avenue of retinal research.
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Affiliation(s)
- Qi Peng
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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42
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Ishimori Y, Monma M, Kawamura H, Miyata T. Time spatial labeling inversion pulse cerebral MR angiography without subtraction by use of dual inversion recovery background suppression. Radiol Phys Technol 2010; 4:78-83. [DOI: 10.1007/s12194-010-0108-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 11/13/2010] [Accepted: 11/15/2010] [Indexed: 10/18/2022]
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Robson PM, Madhuranthakam AJ, Dai W, Pedrosa I, Rofsky NM, Alsop DC. Strategies for reducing respiratory motion artifacts in renal perfusion imaging with arterial spin labeling. Magn Reson Med 2009; 61:1374-87. [PMID: 19319891 DOI: 10.1002/mrm.21960] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Arterial spin labeling (ASL) perfusion measurements may have many applications outside the brain. In the abdomen, severe image artifacts can arise from motions between acquisitions of multiple signal averages in ASL, even with single-shot image acquisition. Background suppression and respiratory motion synchronization techniques can be used to ameliorate these artifacts. Two separate in vivo studies of renal perfusion imaging using pulsed continuous ASL (pCASL) were performed. The first study assessed various combinations of background suppression and breathing strategies. The second investigated the retrospective sorting of images acquired during free breathing based on respiratory position. Quantitative assessments of the test-retest repeatability of perfusion measurements and the image quality scored by two radiologists were made. Image quality was most significantly improved by using background suppression schemes and controlled breathing when compared to other combinations without background suppression or with free breathing, assessed by test-retests (5% level, F-test), and by radiologists' scores (5% level, Mann-Whitney U-test). Under free breathing, retrospectively sorting images based on respiratory position showed significant improvement. Both radiologists found 100% of the images had preferable image sharpness after sorting. High-quality renal perfusion measurements with reduced respiratory motion artifacts have been demonstrated using ASL when appropriate background suppression and breathing strategies are applied.
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Affiliation(s)
- Philip M Robson
- Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
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Yarnykh VL, Yuan C. Simultaneous outer volume and blood suppression by quadruple inversion-recovery. Magn Reson Med 2006; 55:1083-92. [PMID: 16598725 DOI: 10.1002/mrm.20880] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new method has been developed for reduced field-of-view (FOV) imaging with simultaneous blood suppression. This method combines suppression of signals from the outer volume and inflowing blood by using a small-FOV quadruple inversion-recovery (SFQIR) preparative pulse sequence consisting of two double-inversion pulse pairs separated by appropriate delays. Within each pair, inversion pulses are successively applied to the imaged slice and the slab orthogonal to the imaging plane with the thickness equal to the FOV size in the phase-encoding direction. Each double inversion results in the reinversion of the magnetization in the central part of the FOV, while the outer areas of the FOV and inflowing blood remain inverted. The SFQIR module was implemented for single- and multislice acquisition with a fast spin-echo readout sequence. Based on a theoretical model of the signal, the timing parameters of the sequence corresponding to the maximal suppression efficiency can be found by minimizing the variation of the normalized signal over the entire range of T1's that occur in tissues. The method was tested for black-blood imaging of the aorta and carotid arteries, and the results demonstrated its ability to eliminate motion and flow artifacts, reduce scan time, and improve spatial resolution.
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Affiliation(s)
- Vasily L Yarnykh
- Department of Radiology, University of Washington, Seattle, Washington 98195, USA.
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45
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Vazquez AL, Lee GR, Hernandez-Garcia L, Noll DC. Application of selective saturation to image the dynamics of arterial blood flow during brain activation using magnetic resonance imaging. Magn Reson Med 2006; 55:816-25. [PMID: 16506156 DOI: 10.1002/mrm.20813] [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] [Indexed: 12/13/2022]
Abstract
A saturation-based approach is proposed to image the arterial blood flow signal with temporal resolution of 1 to 2 s and in-plane spatial resolution of a few millimeters. Using a saturation approach to suppress the undesired background stationary signal allows the blood water that enters the slice to be imaged at some specified later time. Since the blood protons that are being imaged are not restricted to the intravascular space, this technique is also sensitive to tissue perfusion signal contributions. The signal uptake characteristics of the saturation method proposed were used to study the different signal contributions as a function of the acquisition parameters. A typical perfusion acquisition (FAIR) was also used for comparison. The proposed method was demonstrated in a functional motor activation experiment and the observed signal changes were smaller than those obtained using the FAIR acquisition. The dynamics of the saturation method and FAIR temporal signal changes were investigated and time constants between 2 and 44 s were estimated. The tissue signal contribution to the saturation method's signal was small over the range of acquisition parameters that sensitized it to the arterial compartment.
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Affiliation(s)
- Alberto L Vazquez
- Functional MRI Laboratory, University of Michigan, Ann Arbor, Michigan 48109-2108, USA.
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Green JD, Omary RA, Schirf BE, Tang R, Carr JC, Li D. Three-dimensional contrast-enhanced steady-state free precession for improved catheter-directed coronary magnetic resonance angiography. J Magn Reson Imaging 2006; 22:415-9. [PMID: 16104011 PMCID: PMC1435989 DOI: 10.1002/jmri.20390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To demonstrate the feasibility of three-dimensional thick-partition, contrast-enhanced, catheter-directed coronary artery magnetic resonance angiography (MRA) and test the hypothesis that three-dimensional imaging improves coronary artery background contrast-to-noise ratio (CNR) compared to two-dimensional imaging. MATERIALS AND METHODS Catheters were advanced into the coronary arteries of swine (N = 6) under MR guidance. Three-dimensional coronary MRA was performed after intracoronary injection of a small dose of contrast media using magnetization-prepared steady-state free precession (SSFP) with two thick partitions. For comparison, two magnetization-prepared two-dimensional SSFP scans were also performed, one with no signal averaging and one with two signal averages. All sequences had the same coverage and in-plane spatial resolution. RESULTS The coronary artery was successfully catheterized in all (6/6) animals. CNR for three-dimensional imaging was 11.1 +/- 1.2 for proximal arterial segments and 4.3 +/- 0.4 for distal segments. Without averaging, two-dimensional imaging CNRs for proximal and distal segments were 5.0 +/- 0.7 and 1.2 +/- 0.2, respectively. With averaging, two-dimensional imaging CNRs for proximal and distal segments were 9.4 +/- 1.5 and 2.9 +/- 0.4, respectively. Three-dimensional imaging showed a statistically significant increase in CNR over all two-dimensional imaging for both proximal and distal segments (P < 0.05). CONCLUSION Three-dimensional thick-partition, contrast-enhanced, catheter-directed coronary MRA is feasible and improves CNR over two-dimensional projection imaging.
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Affiliation(s)
- Jordin D. Green
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
- Department of Biomedical Engineering, Northwestern University, Chicago, Illinois, USA
| | - Reed A. Omary
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
| | - Brian E. Schirf
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
| | - Richard Tang
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
| | - James C. Carr
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
| | - Debiao Li
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
- Department of Biomedical Engineering, Northwestern University, Chicago, Illinois, USA
- *Address reprint request to: D.L., Suite 700, 448 East Ontario St., Chicago, IL 60611. E-mail:
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Green JD, Omary RA, Schirf BE, Tang R, Lu B, Gehl JA, Huang JJ, Carr JC, Pereles FS, Li D. Comparison of X-ray fluoroscopy and interventional magnetic resonance imaging for the assessment of coronary artery stenoses in swine. Magn Reson Med 2006; 54:1094-9. [PMID: 16217784 PMCID: PMC1343514 DOI: 10.1002/mrm.20699] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The accuracy of a two-step interventional MRI protocol to quantify coronary artery disease was compared to the clinical gold standard, X-ray angiography. Studies were conducted in nine swine with a surgically induced stenosis in the proximal left circumflex coronary artery. The two-step protocol consisted of catheter-directed magnetic resonance angiography (MRA), which was first used to localize the stenosis, followed by MRI cross-sectional images to quantify the degree of stenosis without the use of contrast agent. Line signal intensity profiles were drawn across the vessel diameter at the stenosis site and proximal to the stenosis for each data set to measure percentage stenosis for each animal. Catheter-directed MRA successfully detected eight of nine stenoses. Cross-sectional MRI accurately quantified each stenosis, with strong agreement to the measurements made using X-ray fluoroscopy (intraclass correlation coefficient = 0.955; P < 0.05). This study demonstrates that in the future interventional MRI may be an alternative to X-ray angiography for the detection and quantification of coronary artery disease.
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Affiliation(s)
| | | | | | | | | | | | - J. Jenny Huang
- Preventive Medicine, Northwestern University, Chicago, IL
| | | | | | - Debiao Li
- Departments of Radiology
- Biomedical Engineering, and
- Please send correspondence to: Debiao Li, Ph. D., Suite 700, 448 East Ontario St., Chicago, IL 60611, Tel: (312) 926-4245, Fax: (312) 926-5991. E-mail:
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Gui D, Tsekos NV. Fast magnetization-driven preparation for imaging of contrast-enhanced coronary arteries during intra-arterial injection of contrast agent. J Magn Reson Imaging 2006; 24:1151-8. [PMID: 17031833 DOI: 10.1002/jmri.20728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To implement a short-duration magnetization preparation sequence, which consists of a saturation followed by multiple inversion pulses, for imaging of short-T1 species and suppression of long-T1 species. MATERIALS AND METHODS Computer optimizations were performed to derive preparation schemes that 1) suppress long-T1 background species with T1>or=250 msec, 2) maximize the MZ of contrast-enhanced (CE) structures with T1<or=50 msec, and 3) have a preparation duration in the range of 200 msec. The optimized sequences were tested on a phantom and a pig model instrumented with an intracoronary catheter for infusion of contrast media. RESULTS Computer simulations generated preparation schemes with durations of 165-225 msec depending on the number of preparation pulses used, which generated saturation of over 98% for T1>250 msec, and about a 30% reduction for 20 msec<T1<50 msec. The phantom studies validated the performance of the optimized sequences. Coronary artery angiograms (380 msec for preparation and image acquisition) demonstrated signal-to-noise ratios (SNRs) in the range of 13-15.5 and contrast-to-noise ratios (CNRs) in the range of 6.3-7.1 in the CE coronary vessels. CONCLUSION This work demonstrates that fast magnetization-driven preparation schemes can be implemented for fast imaging of CE coronary vessels with efficient saturation of background species.
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Affiliation(s)
- Dawei Gui
- Cardiovascular Imaging Laboratory, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, Missouri 63110, USA
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Garcia DM, Duhamel G, Alsop DC. Efficiency of inversion pulses for background suppressed arterial spin labeling. Magn Reson Med 2005; 54:366-72. [PMID: 16032674 DOI: 10.1002/mrm.20556] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Background suppression strategies for arterial spin labeling (ASL) MRI offer reduced noise from motion and other system instabilities. However, the inversion pulses used for suppression can also attenuate the ASL signal, which may offset the advantages of background suppression. Numerical simulations were used to optimize the inversion efficiency of four candidate pulses over a range of radiofrequency (RF) and static magnetic field variations typical of in vivo imaging. Optimized pulses were then used within a pulsed ASL sequence to assess the pulses' in vivo inversion efficiencies for ASL. The measured in vivo inversion efficiency was significantly lower than theoretical predictions (e.g., 93% experimental compared to 99% theoretical) for the tangent hyperbolic pulse applied in a background suppression scheme. This inefficiency was supported by an in vitro study of human blood. These results suggest that slow magnetization transfer (MT) in blood, either with bound water or macromolecular protons, dominates the inversion inefficiency in blood. Despite the attenuated signal relative to unsuppressed ASL, the signal-to-noise ratio (SNR) with suppression was improved by 23-110% depending on the size of the region measured. Knowledge of efficiency will aid optimization of the number of suppression pulses and provide more accurate quantification of blood flow.
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Affiliation(s)
- Dairon M Garcia
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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Günther M, Oshio K, Feinberg DA. Single-shot 3D imaging techniques improve arterial spin labeling perfusion measurements. Magn Reson Med 2005; 54:491-8. [PMID: 16032686 DOI: 10.1002/mrm.20580] [Citation(s) in RCA: 231] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Arterial spin labeling (ASL) can be used to measure perfusion without the use of contrast agents. Due to the small volume fraction of blood vessels compared to tissue in the human brain (typ. 3-5%) ASL techniques have an intrinsically low signal-to-noise ratio (SNR). In this publication, evidence is presented that the SNR can be improved by using arterial spin labeling in combination with single-shot 3D readout techniques. Specifically, a single-shot 3D-GRASE sequence is presented, which yields a 2.8-fold increase in SNR compared to 2D EPI at the same nominal resolution. Up to 18 slices can be acquired in 2 min with an SNR of 10 or more for gray matter perfusion. A method is proposed to increase the reliability of perfusion quantification using QUIPSS II derivates by acquiring low-resolution maps of the bolus arrival time, which allows differentiation between lack of perfusion and delayed arrival of the labeled blood. For arterial spin labeling, single-shot 3D imaging techniques are optimal in terms of efficiency and might prove beneficial to improve reliability of perfusion quantitation in a clinical setup.
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