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Liao C, Yarach U, Cao X, Iyer SS, Wang N, Kim TH, Tian Q, Bilgic B, Kerr AB, Setsompop K. High-fidelity mesoscale in-vivo diffusion MRI through gSlider-BUDA and circular EPI with S-LORAKS reconstruction. Neuroimage 2023; 275:120168. [PMID: 37187364 PMCID: PMC10451786 DOI: 10.1016/j.neuroimage.2023.120168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/27/2023] [Accepted: 05/12/2023] [Indexed: 05/17/2023] Open
Abstract
PURPOSE To develop a high-fidelity diffusion MRI acquisition and reconstruction framework with reduced echo-train-length for less T2* image blurring compared to typical highly accelerated echo-planar imaging (EPI) acquisitions at sub-millimeter isotropic resolution. METHODS We first proposed a circular-EPI trajectory with partial Fourier sampling on both the readout and phase-encoding directions to minimize the echo-train-length and echo time. We then utilized this trajectory in an interleaved two-shot EPI acquisition with reversed phase-encoding polarity, to aid in the correction of off-resonance-induced image distortions and provide complementary k-space coverage in the missing partial Fourier regions. Using model-based reconstruction with structured low-rank constraint and smooth phase prior, we corrected the shot-to-shot phase variations across the two shots and recover the missing k-space data. Finally, we combined the proposed acquisition/reconstruction framework with an SNR-efficient RF-encoded simultaneous multi-slab technique, termed gSlider, to achieve high-fidelity 720 µm and 500 µm isotropic resolution in-vivo diffusion MRI. RESULTS Both simulation and in-vivo results demonstrate the effectiveness of the proposed acquisition and reconstruction framework to provide distortion-corrected diffusion imaging at the mesoscale with markedly reduced T2*-blurring. The in-vivo results of 720 µm and 500 µm datasets show high-fidelity diffusion images with reduced image blurring and echo time using the proposed approaches. CONCLUSIONS The proposed method provides high-quality distortion-corrected diffusion-weighted images with ∼40% reduction in the echo-train-length and T2* blurring at 500µm-isotropic-resolution compared to standard multi-shot EPI.
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Affiliation(s)
- Congyu Liao
- Department of Radiology, Stanford University, Stanford, CA, USA; Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Uten Yarach
- Radiologic Technology Department, Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - Xiaozhi Cao
- Department of Radiology, Stanford University, Stanford, CA, USA; Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
| | - Siddharth Srinivasan Iyer
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Nan Wang
- Department of Radiology, Stanford University, Stanford, CA, USA; Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Tae Hyung Kim
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA; Department of Computer Engineering, Hongik University, Seoul, South Korea
| | - Qiyuan Tian
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Berkin Bilgic
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Adam B Kerr
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA; Stanford Center for Cognitive and Neurobiological Imaging, Stanford University, Stanford, CA, USA
| | - Kawin Setsompop
- Department of Radiology, Stanford University, Stanford, CA, USA; Department of Electrical Engineering, Stanford University, Stanford, CA, USA
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Hermes D, Wu H, Kerr AB, Wandell BA. Measuring brain beats: Cardiac-aligned fast functional magnetic resonance imaging signals. Hum Brain Mapp 2022; 44:280-294. [PMID: 36308417 PMCID: PMC9783469 DOI: 10.1002/hbm.26128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 09/17/2022] [Accepted: 09/26/2022] [Indexed: 02/05/2023] Open
Abstract
Blood and cerebrospinal fluid (CSF) pulse and flow throughout the brain, driven by the cardiac cycle. These fluid dynamics, which are essential to healthy brain function, are characterized by several noninvasive magnetic resonance imaging (MRI) methods. Recent developments in fast MRI, specifically simultaneous multislice acquisition methods, provide a new opportunity to rapidly and broadly assess cardiac-driven flow, including CSF spaces, surface vessels and parenchymal vessels. We use these techniques to assess blood and CSF flow dynamics in brief (3.5 min) scans on a conventional 3 T MRI scanner in five subjects. Cardiac pulses are measured with a photoplethysmography (PPG) on the index finger, along with functional MRI (fMRI) signals in the brain. We, retrospectively, align the fMRI signals to the heartbeat. Highly reliable cardiac-gated fMRI temporal signals are observed in CSF and blood on the timescale of one heartbeat (test-retest reliability within subjects R2 > 50%). In blood vessels, a local minimum is observed following systole. In CSF spaces, the ventricles and subarachnoid spaces have a local maximum following systole instead. Slower resting-state scans with slice timing, retrospectively, aligned to the cardiac pulse, reveal similar cardiac-gated responses. The cardiac-gated measurements estimate the amplitude and phase of fMRI pulsations in the CSF relative to those in the arteries, an estimate of the local intracranial impedance. Cardiac aligned fMRI signals can provide new insights about fluid dynamics or diagnostics for diseases where these dynamics are important.
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Affiliation(s)
- Dora Hermes
- Department of Physiology and Biomedical EngineeringMayo ClinicRochesterMinnesotaUSA,Department of PsychologyStanford UniversityStanfordCaliforniaUSA
| | - Hua Wu
- Center for Cognitive and Neurobiological ImagingStanford UniversityStanfordCaliforniaUSA
| | - Adam B. Kerr
- Center for Cognitive and Neurobiological ImagingStanford UniversityStanfordCaliforniaUSA,Department of Electrical EngineeringStanford UniversityStanfordCaliforniaUSA
| | - Brian A. Wandell
- Department of PsychologyStanford UniversityStanfordCaliforniaUSA
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Tozzi L, Anene ET, Gotlib IH, Wintermark M, Kerr AB, Wu H, Seok D, Narr KL, Sheline YI, Whitfield-Gabrieli S, Williams LM. Convergence, preliminary findings and future directions across the four human connectome projects investigating mood and anxiety disorders. Neuroimage 2021; 245:118694. [PMID: 34732328 PMCID: PMC8727513 DOI: 10.1016/j.neuroimage.2021.118694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/11/2021] [Accepted: 10/29/2021] [Indexed: 12/31/2022] Open
Abstract
In this paper we provide an overview of the rationale, methods, and preliminary results of the four Connectome Studies Related to Human Disease investigating mood and anxiety disorders. The first study, "Dimensional connectomics of anxious misery" (HCP-DAM), characterizes brain-symptom relations of a transdiagnostic sample of anxious misery disorders. The second study, "Human connectome Project for disordered emotional states" (HCP-DES), tests a hypothesis-driven model of brain circuit dysfunction in a sample of untreated young adults with symptoms of depression and anxiety. The third study, "Perturbation of the treatment resistant depression connectome by fast-acting therapies" (HCP-MDD), quantifies alterations of the structural and functional connectome as a result of three fast-acting interventions: electroconvulsive therapy, serial ketamine therapy, and total sleep deprivation. Finally, the fourth study, "Connectomes related to anxiety and depression in adolescents" (HCP-ADA), investigates developmental trajectories of subtypes of anxiety and depression in adolescence. The four projects use comparable and standardized Human Connectome Project magnetic resonance imaging (MRI) protocols, including structural MRI, diffusion-weighted MRI, and both task and resting state functional MRI. All four projects also conducted comprehensive and convergent clinical and neuropsychological assessments, including (but not limited to) demographic information, clinical diagnoses, symptoms of mood and anxiety disorders, negative and positive affect, cognitive function, and exposure to early life stress. The first round of analyses conducted in the four projects offered novel methods to investigate relations between functional connectomes and self-reports in large datasets, identified new functional correlates of symptoms of mood and anxiety disorders, characterized the trajectory of connectome-symptom profiles over time, and quantified the impact of novel treatments on aberrant connectivity. Taken together, the data obtained and reported by the four Connectome Studies Related to Human Disease investigating mood and anxiety disorders describe a rich constellation of convergent biological, clinical, and behavioral phenotypes that span the peak ages for the onset of emotional disorders. These data are being prepared for open sharing with the scientific community following screens for quality by the Connectome Coordinating Facility (CCF). The CCF also plans to release data from all projects that have been pre-processed using identical state-of-the-art pipelines. The resultant dataset will give researchers the opportunity to pool complementary data across the four projects to study circuit dysfunctions that may underlie mood and anxiety disorders, to map cohesive relations among circuits and symptoms, and to probe how these relations change as a function of age and acute interventions. This large and combined dataset may also be ideal for using data-driven analytic approaches to inform neurobiological targets for future clinical trials and interventions focused on clinical or behavioral outcomes.
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Affiliation(s)
- Leonardo Tozzi
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Esther T Anene
- Psychiatry, Neurology, Radiology, University of Pennsylvania, Philadelphia PA, USA
| | | | | | - Adam B Kerr
- Center for Cognitive and Neurobiological Imaging, Stanford University, CA, USA; Electrical Engineering, Stanford University, CA, USA
| | - Hua Wu
- Electrical Engineering, Stanford University, CA, USA
| | - Darsol Seok
- Department of Psychiatry, University of Pennsylvania, Philadelphia PA, USA
| | - Katherine L Narr
- Neurology, Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA
| | - Yvette I Sheline
- Neurology, Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA.
| | | | - Leanne M Williams
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA; Sierra-Pacific Mental Illness Research, Education, and Clinical Center (MIRECC) Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA.
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4
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Hui SCN, Mikkelsen M, Zöllner HJ, Ahluwalia V, Alcauter S, Baltusis L, Barany DA, Barlow LR, Becker R, Berman JI, Berrington A, Bhattacharyya PK, Blicher JU, Bogner W, Brown MS, Calhoun VD, Castillo R, Cecil KM, Choi YB, Chu WCW, Clarke WT, Craven AR, Cuypers K, Dacko M, de la Fuente-Sandoval C, Desmond P, Domagalik A, Dumont J, Duncan NW, Dydak U, Dyke K, Edmondson DA, Ende G, Ersland L, Evans CJ, Fermin ASR, Ferretti A, Fillmer A, Gong T, Greenhouse I, Grist JT, Gu M, Harris AD, Hat K, Heba S, Heckova E, Hegarty JP, Heise KF, Honda S, Jacobson A, Jansen JFA, Jenkins CW, Johnston SJ, Juchem C, Kangarlu A, Kerr AB, Landheer K, Lange T, Lee P, Levendovszky SR, Limperopoulos C, Liu F, Lloyd W, Lythgoe DJ, Machizawa MG, MacMillan EL, Maddock RJ, Manzhurtsev AV, Martinez-Gudino ML, Miller JJ, Mirzakhanian H, Moreno-Ortega M, Mullins PG, Nakajima S, Near J, Noeske R, Nordhøy W, Oeltzschner G, Osorio-Duran R, Otaduy MCG, Pasaye EH, Peeters R, Peltier SJ, Pilatus U, Polomac N, Porges EC, Pradhan S, Prisciandaro JJ, Puts NA, Rae CD, Reyes-Madrigal F, Roberts TPL, Robertson CE, Rosenberg JT, Rotaru DG, O'Gorman Tuura RL, Saleh MG, Sandberg K, Sangill R, Schembri K, Schrantee A, Semenova NA, Singel D, Sitnikov R, Smith J, Song Y, Stark C, Stoffers D, Swinnen SP, Tain R, Tanase C, Tapper S, Tegenthoff M, Thiel T, Thioux M, Truong P, van Dijk P, Vella N, Vidyasagar R, Vovk A, Wang G, Westlye LT, Wilbur TK, Willoughby WR, Wilson M, Wittsack HJ, Woods AJ, Wu YC, Xu J, Lopez MY, Yeung DKW, Zhao Q, Zhou X, Zupan G, Edden RAE. Frequency drift in MR spectroscopy at 3T. Neuroimage 2021; 241:118430. [PMID: 34314848 PMCID: PMC8456751 DOI: 10.1016/j.neuroimage.2021.118430] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/18/2021] [Accepted: 07/22/2021] [Indexed: 11/17/2022] Open
Abstract
PURPOSE Heating of gradient coils and passive shim components is a common cause of instability in the B0 field, especially when gradient intensive sequences are used. The aim of the study was to set a benchmark for typical drift encountered during MR spectroscopy (MRS) to assess the need for real-time field-frequency locking on MRI scanners by comparing field drift data from a large number of sites. METHOD A standardized protocol was developed for 80 participating sites using 99 3T MR scanners from 3 major vendors. Phantom water signals were acquired before and after an EPI sequence. The protocol consisted of: minimal preparatory imaging; a short pre-fMRI PRESS; a ten-minute fMRI acquisition; and a long post-fMRI PRESS acquisition. Both pre- and post-fMRI PRESS were non-water suppressed. Real-time frequency stabilization/adjustment was switched off when appropriate. Sixty scanners repeated the protocol for a second dataset. In addition, a three-hour post-fMRI MRS acquisition was performed at one site to observe change of gradient temperature and drift rate. Spectral analysis was performed using MATLAB. Frequency drift in pre-fMRI PRESS data were compared with the first 5:20 minutes and the full 30:00 minutes of data after fMRI. Median (interquartile range) drifts were measured and showed in violin plot. Paired t-tests were performed to compare frequency drift pre- and post-fMRI. A simulated in vivo spectrum was generated using FID-A to visualize the effect of the observed frequency drifts. The simulated spectrum was convolved with the frequency trace for the most extreme cases. Impacts of frequency drifts on NAA and GABA were also simulated as a function of linear drift. Data from the repeated protocol were compared with the corresponding first dataset using Pearson's and intraclass correlation coefficients (ICC). RESULTS Of the data collected from 99 scanners, 4 were excluded due to various reasons. Thus, data from 95 scanners were ultimately analyzed. For the first 5:20 min (64 transients), median (interquartile range) drift was 0.44 (1.29) Hz before fMRI and 0.83 (1.29) Hz after. This increased to 3.15 (4.02) Hz for the full 30 min (360 transients) run. Average drift rates were 0.29 Hz/min before fMRI and 0.43 Hz/min after. Paired t-tests indicated that drift increased after fMRI, as expected (p < 0.05). Simulated spectra convolved with the frequency drift showed that the intensity of the NAA singlet was reduced by up to 26%, 44 % and 18% for GE, Philips and Siemens scanners after fMRI, respectively. ICCs indicated good agreement between datasets acquired on separate days. The single site long acquisition showed drift rate was reduced to 0.03 Hz/min approximately three hours after fMRI. DISCUSSION This study analyzed frequency drift data from 95 3T MRI scanners. Median levels of drift were relatively low (5-min average under 1 Hz), but the most extreme cases suffered from higher levels of drift. The extent of drift varied across scanners which both linear and nonlinear drifts were observed.
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Affiliation(s)
- Steve C N Hui
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Mark Mikkelsen
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Helge J Zöllner
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Vishwadeep Ahluwalia
- GSU/GT Center for Advanced Brain Imaging, Georgia Institute of Technology, Atlanta, GA USA
| | - Sarael Alcauter
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Queretaro, Mexico
| | - Laima Baltusis
- Center for Cognitive and Neurobiological Imaging, Stanford University, Stanford, CA USA
| | - Deborah A Barany
- Department of Kinesiology, University of Georgia, and Augusta University/University of Georgia Medical Partnership, Athens, GA USA
| | - Laura R Barlow
- Department of Radiology, Faculty of Medicine, The University of British Columbia, Vancouver, Canada
| | - Robert Becker
- Center for Innovative Psychiatry and Psychotherapy Research, Department Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jeffrey I Berman
- Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
| | - Adam Berrington
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | | | - Jakob Udby Blicher
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Wolfgang Bogner
- Department of Biomedical Imaging and Image-guided Therapy, High-Field MR Center, Medical University of Vienna, Vienna, Austria
| | - Mark S Brown
- Department of Radiology, Medical Physics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Vince D Calhoun
- Tri-Institutional Center for Translational Research in Neuroimaging and Data Science (TReNDS), Georgia State University, Georgia Institute of Technology, and Emory University, Atlanta, GA USA
| | - Ryan Castillo
- NeuRA Imaging, Neuroscience Research Australia, Randwick, Australia
| | - Kim M Cecil
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH USA
| | - Yeo Bi Choi
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH USA
| | - Winnie C W Chu
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong, China
| | - William T Clarke
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Alexander R Craven
- Department of Biological and Medical Psychology, University of Bergen, Haukeland University Hospital, Bergen, Norway
| | - Koen Cuypers
- REVAL Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek, Belgium; Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Michael Dacko
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Camilo de la Fuente-Sandoval
- Laboratory of Experimental Psychiatry & Neuropsychiatry Department, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico
| | - Patricia Desmond
- Department of Radiology, University of Melbourne/ Royal Melbourne Hospital, Melbourne, Australia
| | - Aleksandra Domagalik
- Brain Imaging Core Facility, Malopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland
| | - Julien Dumont
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, US 41 - UMS 2014 - PLBS, F-59000 Lille, France
| | - Niall W Duncan
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, Taipei, Taiwan
| | - Ulrike Dydak
- School of Health Sciences, Purdue University, West Lafayette, IN USA
| | - Katherine Dyke
- School of Psychology, University of Nottingham, Nottingham, UK
| | - David A Edmondson
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH USA
| | - Gabriele Ende
- Center for Innovative Psychiatry and Psychotherapy Research, Department Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Lars Ersland
- Department of Clinical Engineering, University of Bergen, Haukeland University Hospital, Bergen, Norway
| | | | - Alan S R Fermin
- Center for Brain, Mind and KANSEI Sciences Research, Hiroshima University, Hiroshima, Japan
| | - Antonio Ferretti
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" of Chieti-Pescara, Chieti, Italy
| | - Ariane Fillmer
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig und Berlin, Germany
| | - Tao Gong
- Department of Imaging and Nuclear Medicine, Shandong Medical Imaging Research Institute, Shandong University, Jinan, China
| | - Ian Greenhouse
- Department of Human Physiology, University of Oregon, Eugene, OR USA
| | - James T Grist
- Department of Physiology, Anatomy, and Genetics, Oxford Centre for Magnetic Resonance / Department of Radiology, The Churchill Hospital, The University of Oxford, Oxford, UK
| | - Meng Gu
- Department of Radiology, Stanford University, Stanford, CA, USA
| | - Ashley D Harris
- Department of Radiology, University of Calgary, Calgary, Canada
| | - Katarzyna Hat
- Consciousness Lab, Institute of Psychology, Jagiellonian University, Kraków, Poland
| | - Stefanie Heba
- Department of Neurology, BG University Hospital Bergmannsheil, Bochum, Germany
| | - Eva Heckova
- Department of Biomedical Imaging and Image-guided Therapy, High-Field MR Center, Medical University of Vienna, Vienna, Austria
| | - John P Hegarty
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA, USA
| | | | - Shiori Honda
- Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Aaron Jacobson
- Department of Radiology / Psychiatry, University of California San Diego, San Diego, CA USA
| | - Jacobus F A Jansen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | - Stephen J Johnston
- Psychology Department / Clinical Imaging Facility, Swansea University, Swansea, UK
| | - Christoph Juchem
- Departments of Biomedical Engineering and Radiology, Columbia University, New York, NY USA
| | - Alayar Kangarlu
- Department of Psychiatry, Columbia University Irving Medical Center/New York State Psychiatric Institute, New York, NY USA
| | - Adam B Kerr
- Center for Cognitive and Neurobiological Imaging, Stanford University, Stanford, CA USA
| | - Karl Landheer
- Departments of Biomedical Engineering and Radiology, Columbia University, New York, NY USA
| | - Thomas Lange
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Phil Lee
- Department of Radiology / Hoglund Biomedical Imaging Center, University of Kansas Medical Center, Kansas City, KS USA
| | | | - Catherine Limperopoulos
- Developing Brain Institute, Diagnostic Imaging and Radiology, Children's National Hospital, Washington, DC USA
| | - Feng Liu
- Department of Psychiatry, Columbia University Irving Medical Center/New York State Psychiatric Institute, New York, NY USA
| | - William Lloyd
- Division of Informatics, Imaging & Data Sciences, University of Manchester, Manchester, UK
| | - David J Lythgoe
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Maro G Machizawa
- Center for Brain, Mind and KANSEI Sciences Research, Hiroshima University, Hiroshima, Japan
| | - Erin L MacMillan
- Department of Radiology, Faculty of Medicine, The University of British Columbia, Vancouver, Canada; Philips Canada, Markham, ON, Canada
| | - Richard J Maddock
- Department of Psychiatry and Behavioral Sciences, University of California Davis, Imaging Research Center, Davis, CA USA
| | - Andrei V Manzhurtsev
- Department of Radiology, Clinical and Research Institute of Emergency Pediatric Surgery and Trauma, Moscow, Russia; Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Moscow, Russia
| | - María L Martinez-Gudino
- Departamento de Imágenes Cerebrales, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Jack J Miller
- Department of Physics, University of Oxford, Oxford, UK; The MR Research Centre & The PET Research Centre, Aarhus University, Aarhus, DK
| | - Heline Mirzakhanian
- Department of Radiology / Psychiatry, University of California San Diego, San Diego, CA USA
| | - Marta Moreno-Ortega
- Department of Psychiatry, Columbia University Irving Medical Center/New York State Psychiatric Institute, New York, NY USA
| | - Paul G Mullins
- Bangor Imaging Unit, Department of Psychology, Bangor University, Bangor, Wales, UK
| | - Shinichiro Nakajima
- Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Jamie Near
- Douglas Mental Health University Institute and Department of Psychiatry, McGill University, Montreal, Canada
| | | | - Wibeke Nordhøy
- NORMENT, Division of Mental Health and Addiction and Department of Diagnostic Physics, Division of Radiology and Nuclear Medicine, Oslo University Hospital / Department of Psychology, University of Oslo, Oslo, Norway
| | - Georg Oeltzschner
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Raul Osorio-Duran
- Departamento de Imágenes Cerebrales, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Maria C G Otaduy
- LIM44, Instituto e Departamento de Radiologia, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Erick H Pasaye
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Queretaro, Mexico
| | - Ronald Peeters
- Department of Imaging & Pathology, Department of Radiology, University Hospitals Leuven, KU Leuven, Leuven, Belgium
| | - Scott J Peltier
- Functional MRI Laboratory, University of Michigan, Ann Arbor, MI USA
| | - Ulrich Pilatus
- Institute of Neuroradiology, Goethe-University Frankfurt, Frankfurt, Germany
| | - Nenad Polomac
- Institute of Neuroradiology, Goethe-University Frankfurt, Frankfurt, Germany
| | - Eric C Porges
- Center for Cognitive Aging and Memory, McKnight Brain Institute, Department of Clinical and Health Psychology, College of Public Health and Health Professions. Department of Neuroscience, College of Medicine, University of Florida, Gainesville, USA
| | - Subechhya Pradhan
- Developing Brain Institute, Diagnostic Imaging and Radiology, Children's National Hospital, Washington, DC USA
| | - James Joseph Prisciandaro
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC USA
| | - Nicolaas A Puts
- Department of Forensic & Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, King's College London, London, UK
| | - Caroline D Rae
- NeuRA Imaging, Neuroscience Research Australia, Randwick, Australia
| | - Francisco Reyes-Madrigal
- Laboratory of Experimental Psychiatry & Neuropsychiatry Department, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico
| | - Timothy P L Roberts
- Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
| | - Caroline E Robertson
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH USA
| | - Jens T Rosenberg
- McKnight Brain Institute, AMRIS, University of Florida, Gainesville, FL USA
| | - Diana-Georgiana Rotaru
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Ruth L O'Gorman Tuura
- Center for MR Research, University Children's Hospital, Zurich, University of Zurich, Switzerland
| | - Muhammad G Saleh
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, USA
| | - Kristian Sandberg
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Ryan Sangill
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | | | - Anouk Schrantee
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Natalia A Semenova
- Department of Radiology, Clinical and Research Institute of Emergency Pediatric Surgery and Trauma, Moscow, Russia; Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Moscow, Russia
| | - Debra Singel
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Rouslan Sitnikov
- Clinical Neuroscience, MRI Centre, Karolinska Institute, Stockholm, Sweden
| | - Jolinda Smith
- Lewis Center for Neuroimaging, University of Oregon, Eugene, OR USA
| | - Yulu Song
- Department of Imaging and Nuclear Medicine, Shandong Medical Imaging Research Institute, Shandong University, Jinan, China
| | - Craig Stark
- Department of Neurobiology and Behavior, Facility for Imaging and Brain Research (FIBRE) & Campus Center for Neuroimaging (CCNI), School of Biological Sciences, University of California, Irvine, Irvine, CA USA
| | - Diederick Stoffers
- Spinoza Centre for Neuroimaging, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | | | - Rongwen Tain
- Department of Neurobiology and Behavior, Facility for Imaging and Brain Research (FIBRE) & Campus Center for Neuroimaging (CCNI), School of Biological Sciences, University of California, Irvine, Irvine, CA USA
| | - Costin Tanase
- Department of Psychiatry and Behavioral Sciences, University of California Davis, Imaging Research Center, Davis, CA USA
| | - Sofie Tapper
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Martin Tegenthoff
- Department of Neurology, BG University Hospital Bergmannsheil, Bochum, Germany
| | - Thomas Thiel
- Institute of Clinical Neuroscience and Medical Psychology, University Dusseldorf, Medical Faculty, Düsseldorf, Germany
| | - Marc Thioux
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Peter Truong
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, Canada
| | - Pim van Dijk
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Nolan Vella
- Medical Physics, Mater Dei Hospital, Imsida, Malta
| | - Rishma Vidyasagar
- Melbourne Dementia Research Centre, Florey Institute of Neurosciences and Mental Health, Melbourne, Australia
| | - Andrej Vovk
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Guangbin Wang
- Department of Imaging and Nuclear Medicine, Shandong Medical Imaging Research Institute, Shandong University, Jinan, China
| | - Lars T Westlye
- NORMENT, Division of Mental Health and Addiction and Department of Diagnostic Physics, Division of Radiology and Nuclear Medicine, Oslo University Hospital / Department of Psychology, University of Oslo, Oslo, Norway
| | - Timothy K Wilbur
- Department of Radiology, University of Washington, Seattle, WA USA
| | - William R Willoughby
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL USA
| | - Martin Wilson
- Centre for Human Brain Health and School of Psychology, University of Birmingham, Birmingham, UK
| | - Hans-Jörg Wittsack
- Department of Diagnostic and Interventional Radiology, University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Adam J Woods
- Center for Cognitive Aging and Memory, McKnight Brain Institute, Department of Clinical and Health Psychology, College of Public Health and Health Professions. Department of Neuroscience, College of Medicine, University of Florida, Gainesville, USA
| | - Yen-Chien Wu
- Department of Radiology, TMU-Shuang Ho Hospital, New Taipei City, Taiwan
| | - Junqian Xu
- Department of Radiology and Psychiatry, Baylor College of Medicine, Houston, USA
| | | | - David K W Yeung
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong, China
| | - Qun Zhao
- Bioimaging Research Center, Department of Physics and Astronomy, University of Georgia, Athens, GA USA
| | - Xiaopeng Zhou
- School of Health Sciences, Purdue University, West Lafayette, IN USA
| | - Gasper Zupan
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Richard A E Edden
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
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Dwork N, O'Connor D, Baron CA, Johnson EMI, Kerr AB, Pauly JM, Larson PEZ. Utilizing the Wavelet Transform's Structure in Compressed Sensing. Signal Image Video Process 2021; 15:1407-1414. [PMID: 34531930 PMCID: PMC8439112 DOI: 10.1007/s11760-021-01872-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/11/2021] [Accepted: 02/08/2021] [Indexed: 06/13/2023]
Abstract
Compressed sensing has empowered quality image reconstruction with fewer data samples than previously thought possible. These techniques rely on a sparsifying linear transformation. The Daubechies wavelet transform is commonly used for this purpose. In this work, we take advantage of the structure of this wavelet transform and identify an affine transformation that increases the sparsity of the result. After inclusion of this affine transformation, we modify the resulting optimization problem to comply with the form of the Basis Pursuit Denoising problem. Finally, we show theoretically that this yields a lower bound on the error of the reconstruction and present results where solving this modified problem yields images of higher quality for the same sampling patterns using both magnetic resonance and optical images.
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Affiliation(s)
- Nicholas Dwork
- University of California, San Francisco, Department of Radiology and Biomedical Imaging
| | - Daniel O'Connor
- Department of Mathematics and Statistics, University of San Francisco
| | | | | | - Adam B Kerr
- Stanford University, Center for Cognitive and Neurobiological Imaging
| | - John M Pauly
- Stanford University, Department of Electrical Engineering
| | - Peder E Z Larson
- University of California, San Francisco, Department of Radiology and Biomedical Imaging
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Tozzi L, Staveland B, Holt-Gosselin B, Chesnut M, Chang SE, Choi D, Shiner M, Wu H, Lerma-Usabiaga G, Sporns O, Barch DM, Gotlib IH, Hastie TJ, Kerr AB, Poldrack RA, Wandell BA, Wintermark M, Williams LM. The human connectome project for disordered emotional states: Protocol and rationale for a research domain criteria study of brain connectivity in young adult anxiety and depression. Neuroimage 2020; 214:116715. [PMID: 32147367 PMCID: PMC8597395 DOI: 10.1016/j.neuroimage.2020.116715] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/03/2020] [Indexed: 12/31/2022] Open
Abstract
Through the Human Connectome Project (HCP) our understanding of the functional connectome of the healthy brain has been dramatically accelerated. Given the pressing public health need, we must increase our understanding of how connectome dysfunctions give rise to disordered mental states. Mental disorders arising from high levels of negative emotion or from the loss of positive emotional experience affect over 400 million people globally. Such states of disordered emotion cut across multiple diagnostic categories of mood and anxiety disorders and are compounded by accompanying disruptions in cognitive function. Not surprisingly, these forms of psychopathology are the leading cause of disability worldwide. The Research Domain Criteria (RDoC) initiative spearheaded by NIMH offers a framework for characterizing the relations among connectome dysfunctions, anchored in neural circuits and phenotypic profiles of behavior and self-reported symptoms. Here, we report on our Connectomes Related to Human Disease protocol for integrating an RDoC framework with HCP protocols to characterize connectome dysfunctions in disordered emotional states, and present quality control data from a representative sample of participants. We focus on three RDoC domains and constructs most relevant to depression and anxiety: 1) loss and acute threat within the Negative Valence System (NVS) domain; 2) reward valuation and responsiveness within the Positive Valence System (PVS) domain; and 3) working memory and cognitive control within the Cognitive System (CS) domain. For 29 healthy controls, we present preliminary imaging data: functional magnetic resonance imaging collected in the resting state and in tasks matching our constructs of interest ("Emotion", "Gambling" and "Continuous Performance" tasks), as well as diffusion-weighted imaging. All functional scans demonstrated good signal-to-noise ratio. Established neural networks were robustly identified in the resting state condition by independent component analysis. Processing of negative emotional faces significantly activated the bilateral dorsolateral prefrontal and occipital cortices, fusiform gyrus and amygdalae. Reward elicited a response in the bilateral dorsolateral prefrontal, parietal and occipital cortices, and in the striatum. Working memory was associated with activation in the dorsolateral prefrontal, parietal, motor, temporal and insular cortices, in the striatum and cerebellum. Diffusion tractography showed consistent profiles of fractional anisotropy along known white matter tracts. We also show that results are comparable to those in a matched sample from the HCP Healthy Young Adult data release. These preliminary data provide the foundation for acquisition of 250 subjects who are experiencing disordered emotional states. When complete, these data will be used to develop a neurobiological model that maps connectome dysfunctions to specific behaviors and symptoms.
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Affiliation(s)
- Leonardo Tozzi
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Brooke Staveland
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | | | - Megan Chesnut
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Sarah E Chang
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - David Choi
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Melissa Shiner
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Hua Wu
- Center for Cognitive and Neurobiological Imaging, Stanford University, CA, USA
| | - Garikoitz Lerma-Usabiaga
- Psychology, Stanford University, CA, USA; BCBL. Basque Center on Cognition, Brain and Language, Donostia - San Sebastián, Gipuzkoa, Spain
| | - Olaf Sporns
- Psychological and Brain Sciences, Indiana University, IN, USA
| | - Deanna M Barch
- Psychological and Brain Sciences, Psychiatry & Radiology Washington University in St. Louis, MO, USA
| | | | | | - Adam B Kerr
- Center for Cognitive and Neurobiological Imaging, Stanford University, CA, USA; Department of Electrical Engineering, Stanford University, CA, USA
| | | | - Brian A Wandell
- Center for Cognitive and Neurobiological Imaging, Stanford University, CA, USA
| | | | - Leanne M Williams
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA; Sierra-Pacific Mental Illness Research, Education, and Clinical Center (MIRECC) Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA.
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7
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Zeng DY, Baron CA, Malavé MO, Kerr AB, Yang PC, Hu BS, Nishimura DG. Combined T 2 -preparation and multidimensional outer volume suppression for coronary artery imaging with 3D cones trajectories. Magn Reson Med 2020; 83:2221-2231. [PMID: 31691350 PMCID: PMC7047567 DOI: 10.1002/mrm.28057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 11/07/2022]
Abstract
PURPOSE To develop a modular magnetization preparation sequence for combined T2 -preparation and multidimensional outer volume suppression (OVS) for coronary artery imaging. METHODS A combined T2 -prepared 1D OVS sequence with fat saturation was defined to contain a 90°-60 180°60 composite nonselective tip-down pulse, two 180°Y hard pulses for refocusing, and a -90° spectral-spatial sinc tip-up pulse. For 2D OVS, 2 modules were concatenated, selective in X and then Y. Bloch simulations predicted robustness of the sequence to B0 and B1 inhomogeneities. The proposed sequence was compared with a T2 -prepared 2D OVS sequence proposed by Luo et al, which uses a spatially selective 2D spiral tip-up. The 2 sequences were compared in phantom studies and in vivo coronary artery imaging studies with a 3D cones trajectory. RESULTS Phantom results demonstrated superior OVS for the proposed sequence compared with the Luo sequence. In studies on 15 healthy volunteers, the proposed sequence had superior image edge profile acutance values compared with the Luo sequence for the right (P < .05) and left (P < .05) coronary arteries, suggesting superior vessel sharpness. The proposed sequence also had superior signal-to-noise ratio (P < .05) and passband-to-stopband ratio (P < .05). Reader scores and reader preference indicated superior coronary image quality of the proposed sequence for both the right (P < .05) and left (P < .05) coronary arteries. CONCLUSION The proposed sequence with concatenated 1D spatially selective tip-ups and integrated fat saturation has superior image quality and suppression compared with the Luo sequence with 2D spatially selective tip-up.
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Affiliation(s)
- David Y Zeng
- Department of Electrical Engineering, Stanford University, Stanford, California
| | - Corey A Baron
- Department of Electrical Engineering, Stanford University, Stanford, California
- Department of Medical Biophysics, Western University, London, Canada
| | - Mario O Malavé
- Department of Electrical Engineering, Stanford University, Stanford, California
| | - Adam B Kerr
- Department of Electrical Engineering, Stanford University, Stanford, California
| | - Phillip C Yang
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, California
| | - Bob S Hu
- Department of Electrical Engineering, Stanford University, Stanford, California
- Department of Cardiology, Palo Alto Medical Foundation, Palo Alto, California
| | - Dwight G Nishimura
- Department of Electrical Engineering, Stanford University, Stanford, California
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Bian W, Kerr AB, Tranvinh E, Parivash S, Zahneisen B, Han MH, Lock CB, Goubran M, Zhu K, Rutt BK, Zeineh MM. MR susceptibility contrast imaging using a 2D simultaneous multi-slice gradient-echo sequence at 7T. PLoS One 2019; 14:e0219705. [PMID: 31314813 PMCID: PMC6636815 DOI: 10.1371/journal.pone.0219705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 06/29/2019] [Indexed: 12/15/2022] Open
Abstract
Purpose To develop a 7T simultaneous multi-slice (SMS) 2D gradient-echo sequence for susceptibility contrast imaging, and to compare its quality to 3D imaging. Methods A frequency modulated and phase cycled RF pulse was designed to simultaneously excite multiple slices in multi-echo 2D gradient-echo imaging. The imaging parameters were chosen to generate images with susceptibility contrast, including T2*-weighted magnitude/phase images, susceptibility-weighted images and quantitative susceptibility/R2* maps. To compare their image quality with 3D gradient-echo imaging, both 2D and 3D imaging were performed on 11 healthy volunteers and 4 patients with multiple sclerosis (MS). The signal to noise ratio (SNR) in gray and white matter and their contrast to noise ratio (CNR) was simulated for the 2D and 3D magnitude images using parameters from the imaging. The experimental SNRs and CNRs were measured in gray/white matter and deep gray matter structures on magnitude, phase, R2* and QSM images from volunteers and the visibility of MS lesions on these images from patients was visually rated. All SNRs and CNRs were compared between the 2D and 3D imaging using a paired t-test. Results Although the 3D magnitude images still had significantly higher SNRs (by 13.0~17.6%), the 2D magnitude and QSM images generated significantly higher gray/white matter or globus pallidus/putamen contrast (by 13.3~87.5%) and significantly higher MS lesion contrast (by 5.9~17.3%). Conclusion 2D SMS gradient-echo imaging can serve as an alternative to often used 3D imaging to obtain susceptibility-contrast-weighted images, with an advantage of providing better image contrast and MS lesion sensitivity.
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Affiliation(s)
- Wei Bian
- Department of Biomedical Engineering, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China
| | - Adam B. Kerr
- Department of Electrical Engineering, Stanford University, Palo Alto, CA, United States of America
| | - Eric Tranvinh
- Department of Radiology, Stanford University, Palo Alto, CA, United States of America
| | - Sherveen Parivash
- Department of Radiology, Stanford University, Palo Alto, CA, United States of America
| | - Benjamin Zahneisen
- Department of Radiology, Stanford University, Palo Alto, CA, United States of America
| | - May H. Han
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Christopher B. Lock
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Maged Goubran
- Department of Radiology, Stanford University, Palo Alto, CA, United States of America
| | - Kongrong Zhu
- Department of Electrical Engineering, Stanford University, Palo Alto, CA, United States of America
| | - Brian K. Rutt
- Department of Radiology, Stanford University, Palo Alto, CA, United States of America
| | - Michael M. Zeineh
- Department of Radiology, Stanford University, Palo Alto, CA, United States of America
- * E-mail:
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9
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Jahanian H, Holdsworth S, Christen T, Wu H, Zhu K, Kerr AB, Middione MJ, Dougherty RF, Moseley M, Zaharchuk G. Advantages of short repetition time resting-state functional MRI enabled by simultaneous multi-slice imaging. J Neurosci Methods 2019; 311:122-132. [DOI: 10.1016/j.jneumeth.2018.09.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/17/2018] [Accepted: 09/28/2018] [Indexed: 01/15/2023]
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10
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Gibbons EK, Vasanawala SS, Pauly JM, Kerr AB. Body diffusion-weighted imaging using magnetization prepared single-shot fast spin echo and extended parallel imaging signal averaging. Magn Reson Med 2018; 79:3032-3044. [PMID: 29044721 PMCID: PMC6312718 DOI: 10.1002/mrm.26971] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 09/25/2017] [Accepted: 09/25/2017] [Indexed: 12/22/2022]
Abstract
PURPOSE This work demonstrates a magnetization prepared diffusion-weighted single-shot fast spin echo (SS-FSE) pulse sequence for the application of body imaging to improve robustness to geometric distortion. This work also proposes a scan averaging technique that is superior to magnitude averaging and is not subject to artifacts due to object phase. THEORY AND METHODS This single-shot sequence is robust against violation of the Carr-Purcell-Meiboom-Gill (CPMG) condition. This is achieved by dephasing the signal after diffusion weighting and tipping the MG component of the signal onto the longitudinal axis while the non-MG component is spoiled. The MG signal component is then excited and captured using a traditional SS-FSE sequence, although the echo needs to be recalled prior to each echo. Extended Parallel Imaging (ExtPI) averaging is used where coil sensitivities from the multiple acquisitions are concatenated into one large parallel imaging (PI) problem. The size of the PI problem is reduced by SVD-based coil compression which also provides background noise suppression. This sequence and reconstruction are evaluated in simulation, phantom scans, and in vivo abdominal clinical cases. RESULTS Simulations show that the sequence generates a stable signal throughout the echo train which leads to good image quality. This sequence is inherently low-SNR, but much of the SNR can be regained through scan averaging and the proposed ExtPI reconstruction. In vivo results show that the proposed method is able to provide diffusion encoded images while mitigating geometric distortion artifacts compared to EPI. CONCLUSION This work presents a diffusion-prepared SS-FSE sequence that is robust against the violation of the CPMG condition while providing diffusion contrast in clinical cases. Magn Reson Med 79:3032-3044, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Eric K Gibbons
- Department of Bioengineering, Stanford University, Stanford, California, USA
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | | | - John M Pauly
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Adam B Kerr
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
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11
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Chen HY, Larson PEZ, Gordon JW, Bok RA, Ferrone M, van Criekinge M, Carvajal L, Cao P, Pauly JM, Kerr AB, Park I, Slater JB, Nelson SJ, Munster PN, Aggarwal R, Kurhanewicz J, Vigneron DB. Technique development of 3D dynamic CS-EPSI for hyperpolarized 13 C pyruvate MR molecular imaging of human prostate cancer. Magn Reson Med 2018; 80:2062-2072. [PMID: 29575178 DOI: 10.1002/mrm.27179] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/23/2018] [Accepted: 02/23/2018] [Indexed: 01/29/2023]
Abstract
PURPOSE The purpose of this study was to develop a new 3D dynamic carbon-13 compressed sensing echoplanar spectroscopic imaging (EPSI) MR sequence and test it in phantoms, animal models, and then in prostate cancer patients to image the metabolic conversion of hyperpolarized [1-13 C]pyruvate to [1-13 C]lactate with whole gland coverage at high spatial and temporal resolution. METHODS A 3D dynamic compressed sensing (CS)-EPSI sequence with spectral-spatial excitation was designed to meet the required spatial coverage, time and spatial resolution, and RF limitations of the 3T MR scanner for its clinical translation for prostate cancer patient imaging. After phantom testing, animal studies were performed in rats and transgenic mice with prostate cancers. For patient studies, a GE SPINlab polarizer (GE Healthcare, Waukesha, WI) was used to produce hyperpolarized sterile GMP [1-13 C]pyruvate. 3D dynamic 13 C CS-EPSI data were acquired starting 5 s after injection throughout the gland with a spatial resolution of 0.5 cm3 , 18 time frames, 2-s temporal resolution, and 36 s total acquisition time. RESULTS Through preclinical testing, the 3D CS-EPSI sequence developed in this project was shown to provide the desired spectral, temporal, and spatial 5D HP 13 C MR data. In human studies, the 3D dynamic HP CS-EPSI approach provided first-ever simultaneously volumetric and dynamic images of the LDH-catalyzed conversion of [1-13 C]pyruvate to [1-13 C]lactate in a biopsy-proven prostate cancer patient with full gland coverage. CONCLUSION The results demonstrate the feasibility to characterize prostate cancer metabolism in animals, and now patients using this new 3D dynamic HP MR technique to measure kPL , the kinetic rate constant of [1-13 C]pyruvate to [1-13 C]lactate conversion.
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Affiliation(s)
- Hsin-Yu Chen
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Jeremy W Gordon
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Robert A Bok
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Marcus Ferrone
- Department of Clinical Pharmacy, University of California, San Francisco, California
| | - Mark van Criekinge
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Lucas Carvajal
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Peng Cao
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - John M Pauly
- Electrical Engineering, Stanford University, Stanford, California
| | - Adam B Kerr
- Electrical Engineering, Stanford University, Stanford, California
| | - Ilwoo Park
- Department of Radiology, Chonnam National University Medical School and Hospital, Gwangju, Chonnam, Korea
| | - James B Slater
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Sarah J Nelson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Pamela N Munster
- Department of Medicine, University of California, San Francisco, California
| | - Rahul Aggarwal
- Department of Medicine, University of California, San Francisco, California
| | - John Kurhanewicz
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
| | - Daniel B Vigneron
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California
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12
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Gibbons EK, Le Roux P, Vasanawala SS, Pauly JM, Kerr AB. Robust Self-Calibrating nCPMG Acquisition: Application to Body Diffusion-Weighted Imaging. IEEE Trans Med Imaging 2018; 37:200-209. [PMID: 28829307 PMCID: PMC5784776 DOI: 10.1109/tmi.2017.2741421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
This paper demonstrates a robust diffusion-weighted single-shot fast spin echo (SS-FSE) sequence in the presence of significant off-resonance, which includes a variable-density acquisition and a self-calibrated reconstruction as improvements. A non-Carr-Purcell-Meiboom-Gill (nCPMG) SS-FSE acquisition stabilizes both the main and parasitic echo families for each echo. This preserves both the in-phase and quadrature components of the magnetization throughout the echo train. However, nCPMG SS-FSE also promotes aliasing of the quadrature component, which complicates reconstruction. A new acquisition and reconstruction approach is presented here, where the field-of-view is effectively doubled, but a partial k-space and variable density sampling is used to improve scan efficiency. The technique is presented in phantom scans to validate SNR and robustness against rapidly varying object phase. In vivo healthy volunteer examples and the clinical cases are demonstrated in abdominal imaging. This new approach provides comparable SNR to previous nCPMG acquisition techniques as well as providing more uniform apparent diffusion coefficient maps in phantom scans. In vivo scans suggest that this method is more robust against motion than previous approaches. The proposed reconstruction is an improvement to the nCPMG sequence as it is auto-calibrating and is justified to accurately treat the signal model for the nCPMG SS-FSE sequence.
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13
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Gibbons EK, Le Roux P, Pauly JM, Kerr AB. Slice profile effects on nCPMG SS-FSE. Magn Reson Med 2017; 79:430-438. [PMID: 28370409 DOI: 10.1002/mrm.26694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/13/2017] [Accepted: 03/09/2017] [Indexed: 11/07/2022]
Abstract
PURPOSE To determine the effects of the RF refocusing pulse profile on the magnitude of the transverse signal smoothness throughout the echo train in non-Carr-Purcell-Meiboom-Gill (nCPMG) single-shot fast spin echo (SS-FSE) imaging and to design an RF refocusing pulse that provides improved signal stability. THEORY AND METHODS: nCPMG SS-FSE quadratic phase modulation requires sufficiently high and uniform refocusing flip angle to achieve a stable signal. Typically, refocusing pulses used in SS-FSE sequences are designed for minimum duration to minimize echo spacing and as a consequence have poor selectivity. However, delay-insensitive variable rate excitation Shinnar-Le Roux (DV-SLR) refocusing pulses can achieve both improved selectivity as well as a short duration. This class of RF pulse is compared against a traditional low time-bandwidth refocusing pulse in a nCPMG SS-FSE in simulation, phantom, and in vivo. RESULTS DV-SLR pulses achieve a more stable signal in simulation, phantom, and in vivo cases while maintaining an appropriately short duration as well as not dramatically increasing specific absorption rate (SAR) accumulation. CONCLUSION The nCPMG SS-FSE method demonstrates improved robustness when a more selective refocusing pulse is used. Refocusing pulses that use a time-varying excitation gradient can achieve this selectivity while maintaining short echo spacing. Magn Reson Med 79:430-438, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Eric K Gibbons
- Department of Bioengineering, Stanford University, Stanford, California, USA.,Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | | | - John M Pauly
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Adam B Kerr
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
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14
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Abstract
SS-FSE is a fast technique that does not suffer from off-resonance distortions to the degree that EPI does. Unlike EPI, SS-FSE is ill-suited to diffusion weighted imaging (DWI) due to the Carr-Purcell-Meiboom-Geill (CPMG) condition. Non-CPMG phase cycling does accommodate SS-FSE and DWI but places constraints on reconstruction, which are resolved here through parallel imaging. Additionally, improved echo stability can be achieved by using short duration and highly selective DIVERSE radiofrequency pulses. Here, signal-to-noise ratio (SNR) comparisons between EPI and nCPMG SS-FSE acquisitions and reconstruction techniques give similar values. Diffusion imaging with nCPMG SS-FSE gives similar SNR to an EPI acquisition, though apparent diffusion coefficient values are higher than seen with EPI. In vivo images have good image quality with little distortion. This method has the ability to capture distortion-free DWI images near areas of significant off-resonance as well as preserve adequate SNR. Parallel imaging and DIVERSE refocusing RF pulses allow shorter ETL compared to previous implementations and thus reduces phase encode direction blur and SAR accumulation.
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15
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Zhu K, Dougherty RF, Wu H, Middione MJ, Takahashi AM, Zhang T, Pauly JM, Kerr AB. Hybrid-Space SENSE Reconstruction for Simultaneous Multi-Slice MRI. IEEE Trans Med Imaging 2016; 35:1824-36. [PMID: 26915118 PMCID: PMC4988924 DOI: 10.1109/tmi.2016.2531635] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Simultaneous Multi-Slice (SMS) magnetic resonance imaging (MRI) is a rapidly evolving technique for increasing imaging speed. Controlled aliasing techniques utilize periodic undersampling patterns to help mitigate the loss in signal-to-noise ratio (SNR) in SMS MRI. To evaluate the performance of different undersampling patterns, a quantitative description of the image SNR loss is needed. Additionally, eddy current effects in echo planar imaging (EPI) lead to slice-specific Nyquist ghosting artifacts. These artifacts cannot be accurately corrected for each individual slice before or after slice-unaliasing. In this work, we propose a hybrid-space sensitivity encoding (SENSE) reconstruction framework for SMS MRI by adopting a three-dimensional representation of the SMS acquisition. Analytical SNR loss maps are derived for SMS acquisitions with arbitrary phase encoding undersampling patterns. Moreover, we propose a matrix-decoding correction method that corrects the slice-specific Nyquist ghosting artifacts in SMS EPI acquisitions. Brain images demonstrate that the proposed hybrid-space SENSE reconstruction generates images with comparable quality to commonly used split-slice-generalized autocalibrating partially parallel acquisition reconstruction. The analytical SNR loss maps agree with those calculated by a Monte Carlo based method, but require less computation time for high quality maps. The analytical maps enable a fair comparison between the performances of coherent and incoherent SMS undersampling patterns. Phantom and brain SMS EPI images show that the matrix-decoding method performs better than the single-slice and slice-averaged Nyquist ghosting correction methods under the hybrid-space SENSE reconstruction framework.
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Affiliation(s)
- Kangrong Zhu
- Electrical Engineering Department, Stanford University, Stanford, CA 94305 USA
| | - Robert F. Dougherty
- Center for Cognitive and Neurobiological Imaging, Stanford University, Stanford, CA 94305 USA
| | - Hua Wu
- Center for Cognitive and Neurobiological Imaging, Stanford University, Stanford, CA 94305 USA
| | | | - Atsushi M. Takahashi
- Athinoula A. Martinos Imaging Center at MIT, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Tao Zhang
- Electrical Engineering Department, Stanford University, Stanford, CA 94305 USA
| | - John M. Pauly
- Electrical Engineering Department, Stanford University, Stanford, CA 94305 USA
| | - Adam B. Kerr
- Electrical Engineering Department, Stanford University, Stanford, CA 94305 USA
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16
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Jordanova KV, Nishimura DG, Kerr AB. Measuring B1 distributions by B1 phase encoding. Magn Reson Med 2016; 77:229-236. [PMID: 26778689 DOI: 10.1002/mrm.26114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 11/11/2015] [Accepted: 12/12/2015] [Indexed: 11/12/2022]
Abstract
PURPOSE We propose a method to acquire B1 distribution plots by encoding in B1 instead of image space. Using this method, B1 data is acquired in a different way from traditional spatial B1 mapping, and allows for quick measurement of high dynamic range B1 data. METHODS To encode in B1, we acquire multiple projections of a slice, each along the same direction, but using a different phase sensitivity to B1. Using a convex optimization formulation, we reconstruct histograms of the B1 distribution estimates of the slice. RESULTS We verify in vivo B1 distribution measurements by comparing measured distributions to distributions calculated from reference spatial B1 maps using the Earth Mover's Distance. Phantom measurements using a surface coil show that for increased spatial B1 variations, measured B1 distributions using the proposed method more accurately estimate the distribution than a low-resolution spatial B1 map, resulting in a 37% Earth Mover's Distance decrease while using fewer measurements. CONCLUSION We propose and validate the performance of a method to acquire B1 distribution information directly without acquiring a spatial B1 map. The method may provide faster estimates of a B1 field for applications that do not require spatial B1 localization, such as the transmit gain calibration of the scanner, particularly for high dynamic B1 ranges. Magn Reson Med 77:229-236, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Kalina V Jordanova
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA
| | - Dwight G Nishimura
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA
| | - Adam B Kerr
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA
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17
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Shin PJ, Larson PE, Uecker M, Reed GD, Kerr AB, Tropp J, Ohliger MA, Nelson SJ, Pauly JM, Lustig M, Vigneron DB. Chemical shift separation with controlled aliasing for hyperpolarized (13) C metabolic imaging. Magn Reson Med 2015; 74:978-89. [PMID: 25298086 PMCID: PMC4390401 DOI: 10.1002/mrm.25473] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 08/15/2014] [Accepted: 09/05/2014] [Indexed: 12/21/2022]
Abstract
PURPOSE A chemical shift separation technique for hyperpolarized (13) C metabolic imaging with high spatial and temporal resolution was developed. Specifically, a fast three-dimensional pulse sequence and a reconstruction method were implemented to acquire signals from multiple (13) C species simultaneously with subsequent separation into individual images. THEORY AND METHODS A stack of flyback echo-planar imaging readouts and a set of multiband excitation radiofrequency pulses were designed to spatially modulate aliasing patterns of the acquired metabolite images, which translated the chemical shift separation problem into parallel imaging reconstruction problem. An eight-channel coil array was used for data acquisition and a parallel imaging method based on nonlinear inversion was developed to separate the aliased images. RESULTS Simultaneous acquisitions of pyruvate and lactate in a phantom study and in vivo rat experiments were performed. The results demonstrated successful separation of the metabolite distributions into individual images having high spatial resolution. CONCLUSION This method demonstrated the ability to provide accelerated metabolite imaging in hyperpolarized (13) C MR using multichannel coils, tailored readout, and specialized RF pulses.
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Affiliation(s)
- Peter J. Shin
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - Peder E.Z. Larson
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - Martin Uecker
- Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California, USA
| | - Galen D. Reed
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - Adam B. Kerr
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - James Tropp
- General Electric Healthcare, Fremont, California, USA
| | - Michael A. Ohliger
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Sarah J. Nelson
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - John M. Pauly
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Michael Lustig
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
- Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California, USA
| | - Daniel B. Vigneron
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
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18
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Lagemaat MW, Breukels V, Vos EK, Kerr AB, van Uden MJ, Orzada S, Bitz AK, Maas MC, Scheenen TWJ. (1)H MR spectroscopic imaging of the prostate at 7T using spectral-spatial pulses. Magn Reson Med 2015; 75:933-45. [PMID: 25943445 DOI: 10.1002/mrm.25569] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/17/2014] [Accepted: 11/17/2014] [Indexed: 12/16/2022]
Abstract
PURPOSE To assess the feasibility of prostate (1)H MR spectroscopic imaging (MRSI) using low-power spectral-spatial (SPSP) pulses at 7T, exploiting accurate spectral selection and spatial selectivity simultaneously. METHODS A double spin-echo sequence was equipped with SPSP refocusing pulses with a spectral selectivity of 1 ppm. Three-dimensional prostate (1)H-MRSI at 7T was performed with the SPSP-MRSI sequence using an 8-channel transmit array coil and an endorectal receive coil in three patients with prostate cancer and in one healthy subject. No additional water or lipid suppression pulses were used. RESULTS Prostate (1)H-MRSI could be obtained well within specific absorption rate (SAR) limits in a clinically feasible time (10 min). Next to the common citrate signals, the prostate spectra exhibited high spermine signals concealing creatine and sometimes also choline. Residual lipid signals were observed at the edges of the prostate because of limitations in spectral and spatial selectivity. CONCLUSION It is possible to perform prostate (1)H-MRSI at 7T with a SPSP-MRSI sequence while using separate transmit and receive coils. This low-SAR MRSI concept provides the opportunity to increase spatial resolution of MRSI within reasonable scan times.
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Affiliation(s)
- Miriam W Lagemaat
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Vincent Breukels
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Eline K Vos
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Adam B Kerr
- Magnetic Resonance Systems Research Lab, Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Mark J van Uden
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Stephan Orzada
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
| | - Andreas K Bitz
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany.,Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany
| | - Marnix C Maas
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Tom W J Scheenen
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands.,Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany
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Jordanova KV, Nishimura DG, Kerr AB. Lowering the B1 threshold for improved BEAR B1 mapping. Magn Reson Med 2015; 75:1262-8. [PMID: 25846905 DOI: 10.1002/mrm.25711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/02/2015] [Accepted: 03/04/2015] [Indexed: 11/06/2022]
Abstract
PURPOSE Accurate measurement of the nonuniform transmit radiofrequency field is necessary for magnetic resonance imaging applications. The radiofrequency field excitation amplitude (B1) is often obtained by acquiring a B1 map. We modify the B1 estimation using adiabatic refocusing (BEAR) method to extend its range to lower B1 magnitudes. THEORY AND METHODS The BEAR method is a phase-based B1 mapping method, wherein hyperbolic secant pulses induce a phase sensitivity to B1. The measurable B1 range is limited due to the adiabatic threshold of the pulses. We redesign the method to use flattened hyperbolic secant pulses, which have lower adiabatic thresholds. We optimize the flattened hyperbolic secant parameters to minimize phase sensitivity to frequency variations. RESULTS We validate the performance of the new method via simulation and in vivo at 3T, and show that for n ≤ 8, accurate B1 maps can be acquired using reduced nominal peak B1 values. CONCLUSION The adiabatic threshold for the BEAR method is reduced with flattened hyperbolic secant pulses, which are optimized for accurate phase-to-B1 mapping over a frequency range, and allow for lower nominal B1 values. At 3T, the nominal B1 is decreased by 52% and the sensitivity to B1 is increased by a factor of 3.8. This can improve the method's applicability for measurement of low B1.
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Affiliation(s)
- Kalina V Jordanova
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Dwight G Nishimura
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Adam B Kerr
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
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20
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Kwon KT, Kerr AB, Wu HH, Hu BS, Brittain JH, Nishimura DG. Non-contrast-enhanced peripheral angiography using a sliding interleaved cylinder acquisition. Magn Reson Med 2014; 74:727-38. [PMID: 25203505 DOI: 10.1002/mrm.25452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 08/22/2014] [Accepted: 08/25/2014] [Indexed: 11/07/2022]
Abstract
PURPOSE To develop a new sequence for non-contrast-enhanced peripheral angiography using a sliding interleaved cylinder (SLINCYL) acquisition. METHODS A venous saturation pulse was incorporated into a three-dimensional magnetization-prepared balanced steady-state free precession sequence for non-contrast-enhanced peripheral angiography to improve artery-vein contrast. The SLINCYL acquisition, which consists of a series of overlapped thin slabs for volumetric coverage similar to the original sliding interleaved ky (SLINKY) acquisition, was used to evenly distribute the venous-suppression effects over the field of view. In addition, the thin-slab-scan nature of SLINCYL and the centric-ordered sampling geometry of its readout trajectory were exploited to implement efficient fluid-suppression and parallel imaging schemes. The sequence was tested in healthy subjects and a patient. RESULTS Compared to a multiple overlapped thin slab acquisition, both SLINKY and SLINCYL suppressed the venetian blind artifacts and provided similar artery-vein contrast. However, SLINCYL achieved this with shorter scan times and less noticeable artifacts from k-space amplitude modulation than SLINKY. The fluid-suppression and parallel imaging schemes were also validated. A patient study using the SLINCYL-based sequence well identified stenoses at the superficial femoral arteries, which were also confirmed with digital subtraction angiography. CONCLUSION Non-contrast-enhanced angiography using SLINCYL can provide angiograms with improved artery-vein contrast in the lower extremities.
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Affiliation(s)
- Kie Tae Kwon
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA
| | - Adam B Kerr
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA
| | - Holden H Wu
- Department of Radiological Sciences, University of California at Los Angeles, Los Angeles, California, USA
| | - Bob S Hu
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA.,Palo Alto Medical Foundation, Palo Alto, California, USA
| | - Jean H Brittain
- Department of Radiology, University of Wisconsin-Madison, Wisconsin, USA
| | - Dwight G Nishimura
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA
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21
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Jordanova KV, Nishimura DG, Kerr AB. B1 estimation using adiabatic refocusing: BEAR. Magn Reson Med 2013; 72:1302-10. [PMID: 24272817 DOI: 10.1002/mrm.25049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/10/2013] [Accepted: 10/28/2013] [Indexed: 11/09/2022]
Abstract
PURPOSE Accurate measurement of the nonuniform transmit radiofrequency field is useful for many applications in magnetic resonance imaging, such as calibrating the scanner transmit system, evaluating coil performance, and improving image quality and quantitation. The radiofrequency field excitation amplitude (B(1)) is often obtained by acquiring a B(1) map. In this study, a new B(1) mapping method is proposed. THEORY AND METHODS The use of two adiabatic full passage pulses with different magnitudes applied as successive refocusing pulses results in a linear relationship between phase and B(1) field strength that is insensitive to the repetition time, off-resonance effects, T(1), and T(2). Using this method, B(1) mapping can be localized to a slice or three-dimensional (3D) volume, with a spin-echo acquisition that is appropriate for fast projection measurements. RESULTS This new method is shown to agree well with the Bloch-Siegert B(1) mapping method for both phantom and in vivo B(1) measurements at 1.5T, 3T, and 7T. The method's ability to acquire accurate projection B(1) measurements is also demonstrated. CONCLUSION This method's high dynamic range, ability to make fast projection measurements, and linear quantitative relationship between phase and B1 make it an ideal candidate for use in robust transmitter gain calibration.
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Affiliation(s)
- Kalina V Jordanova
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
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22
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Xing Y, Reed GD, Pauly JM, Kerr AB, Larson PEZ. Optimal variable flip angle schemes for dynamic acquisition of exchanging hyperpolarized substrates. J Magn Reson 2013; 234:75-81. [PMID: 23845910 PMCID: PMC3765634 DOI: 10.1016/j.jmr.2013.06.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 06/01/2013] [Accepted: 06/03/2013] [Indexed: 05/22/2023]
Abstract
In metabolic MRI with hyperpolarized contrast agents, the signal levels vary over time due to T1 decay, T2 decay following RF excitations, and metabolic conversion. Efficient usage of the nonrenewable hyperpolarized magnetization requires specialized RF pulse schemes. In this work, we introduce two novel variable flip angle schemes for dynamic hyperpolarized MRI in which the flip angle is varied between excitations and between metabolites. These were optimized to distribute the magnetization relatively evenly throughout the acquisition by accounting for T1 decay, prior RF excitations, and metabolic conversion. Simulation results are presented to confirm the flip angle designs and evaluate the variability of signal dynamics across typical ranges of T1 and metabolic conversion. They were implemented using multiband spectral-spatial RF pulses to independently modulate the flip angle at various chemical shift frequencies. With these schemes we observed increased SNR of [1-(13)C]lactate generated from [1-(13)C]pyruvate, particularly at later time points. This will allow for improved characterization of tissue perfusion and metabolic profiles in dynamic hyperpolarized MRI.
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Affiliation(s)
- Yan Xing
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
| | - Galen D. Reed
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
| | - John M. Pauly
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - Adam B. Kerr
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - Peder E. Z. Larson
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
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23
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Larson PEZ, Hurd RE, Kerr AB, Pauly JM, Bok RA, Kurhanewicz J, Vigneron DB. Perfusion and diffusion sensitive 13C stimulated-echo MRSI for metabolic imaging of cancer. Magn Reson Imaging 2013; 31:635-42. [PMID: 23260391 PMCID: PMC3626756 DOI: 10.1016/j.mri.2012.10.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 09/20/2012] [Accepted: 10/30/2012] [Indexed: 01/17/2023]
Abstract
Metabolic imaging with hyperpolarized [1-(13)C]-pyruvate can rapidly probe tissue metabolic profiles in vivo and has been shown to provide cancer imaging biomarkers for tumor detection, progression, and response to therapy. This technique uses a bolus injection followed by imaging within 1-2 minutes. The observed metabolites include vascular components and their generation is also influenced by cellular transport. These factors complicate image interpretation, especially since [1-(13)C]lactate, a metabolic product that is a biomarker of cancer, is also produced by red blood cells. It would be valuable to understand the distribution of metabolites between the vasculature, interstitial space, and intracellular compartments. The purpose of this study was to better understand this compartmentalization by using a perfusion and diffusion-sensitive stimulated-echo acquisition mode (STEAM) MRSI acquisition method tailored to hyperpolarized substrates. Our results in mouse models showed that among metabolites, the injected substrate (13)C-pyruvate had the largest vascular fraction overall while (13)C-alanine had the smallest vascular fraction. We observed a larger vascular fraction of pyruvate and lactate in the kidneys and liver when compared to back muscle and prostate tumor tissue. Our data suggests that (13)C-lactate in prostate tumor tissue voxels was the most abundant labeled metabolite intracellularly. This was shown in STEAM images that highlighted abnormal cancer cell metabolism and suppressed vascular (13)C metabolite signals.
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Affiliation(s)
- Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, CA 94158, USA.
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Swisher CL, Larson PEZ, Kruttwig K, Kerr AB, Hu S, Bok RA, Goga A, Pauly JM, Nelson SJ, Kurhanewicz J, Vigneron DB. Quantitative measurement of cancer metabolism using stimulated echo hyperpolarized carbon-13 MRS. Magn Reson Med 2013; 71:1-11. [PMID: 23412881 DOI: 10.1002/mrm.24634] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 11/28/2012] [Accepted: 12/19/2012] [Indexed: 01/01/2023]
Abstract
PURPOSE Magnetic resonance spectroscopy of hyperpolarized substrates allows for the observation of label exchange catalyzed by enzymes providing a powerful tool to investigate tissue metabolism and potentially kinetics in vivo. However, the accuracy of current methods to calculate kinetic parameters has been limited by T1 relaxation effects, extracellular signal contributions, and reduced precision at lower signal-to-noise ratio. THEORY AND METHODS To address these challenges, we investigated a new modeling technique using metabolic activity decomposition-stimulated echo acquisition mode. The metabolic activity decomposition-stimulated echo acquisition mode technique separates exchanging from nonexchanging metabolites providing twice the information as conventional techniques. RESULTS This allowed for accurate measurements of rates of conversion and of multiple T1 values simultaneously using a single acquisition. CONCLUSION The additional measurement of T1 values for the reaction metabolites provides further biological information about the cellular environment of the metabolites. The new technique was investigated through simulations and in vivo studies of transgenic mouse models of cancer demonstrating improved assessments of kinetic rate constants and new T1 relaxation value measurements for hyperpolarized (13) C-pyruvate, (13) C-lactate, and (13) C-alanine.
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Affiliation(s)
- Christine Leon Swisher
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, California, USA
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Lee D, Santos JM, Hu BS, Pauly JM, Kerr AB. Reducing artifacts in one-dimensional Fourier velocity encoding for fast and pulsatile flow. Magn Reson Med 2012; 68:1876-85. [PMID: 22457248 PMCID: PMC3499673 DOI: 10.1002/mrm.24212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/27/2011] [Accepted: 01/20/2012] [Indexed: 11/08/2022]
Abstract
When evaluating the severity of valvular stenosis, the peak velocity of the blood flow is routinely used to estimate the transvalvular pressure gradient. One-dimensional Fourier velocity encoding effectively detects the peak velocity with an ungated time series of spatially resolved velocity spectra in real time. However, measurement accuracy can be degraded by the pulsatile and turbulent nature of stenotic flow and the existence of spatially varying off-resonance. In this work, we investigate the feasibility of improving the peak velocity detection capability of one-dimensional Fourier velocity encoding for stenotic flow using a novel echo-shifted interleaved readout combined with a variable-density circular k-space trajectory. The shorter echo and readout times of the echo-shifted interleaved acquisitions are designed to reduce sensitivity to off-resonance. Preliminary results from limited phantom and in vivo results also indicate that some artifacts from pulsatile flow appear to be suppressed when using this trajectory compared to conventional single-shot readouts, suggesting that peak velocity detection may be improved. The efficiency of the new trajectory improves the temporal and spatial resolutions. To realize the proposed readout, a novel multipoint-traversing algorithm is introduced for flexible and automated gradient-waveform design.
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Affiliation(s)
- Daeho Lee
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA.
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26
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Larson PEZ, Kerr AB, Swisher CL, Pauly JM, Vigneron DB. A rapid method for direct detection of metabolic conversion and magnetization exchange with application to hyperpolarized substrates. J Magn Reson 2012; 225:71-80. [PMID: 23143011 PMCID: PMC3531583 DOI: 10.1016/j.jmr.2012.09.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 09/26/2012] [Accepted: 09/28/2012] [Indexed: 05/27/2023]
Abstract
In this work, we present a new MR spectroscopy approach for directly observing nuclear spins that undergo exchange, metabolic conversion, or, generally, any frequency shift during a mixing time. Unlike conventional approaches to observe these processes, such as exchange spectroscopy (EXSY), this rapid approach requires only a single encoding step and thus is readily applicable to hyperpolarized MR in which the magnetization is not replenished after T(1) decay and RF excitations. This method is based on stimulated-echoes and uses phase-sensitive detection in conjunction with precisely chosen echo times in order to separate spins generated during the mixing time from those present prior to mixing. We are calling the method Metabolic Activity Decomposition Stimulated-echo Acquisition Mode or MAD-STEAM. We have validated this approach as well as applied it in vivo to normal mice and a transgenic prostate cancer mouse model for observing pyruvate-lactate conversion, which has been shown to be elevated in numerous tumor types. In this application, it provides an improved measure of cellular metabolism by separating [1-(13)C]-lactate produced in tissue by metabolic conversion from [1-(13)C]-lactate that has flowed into the tissue or is in the blood. Generally, MAD-STEAM can be applied to any system in which spins undergo a frequency shift.
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Affiliation(s)
- Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, 1700 4th St, San Francisco, CA 94158, USA.
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Khalighi MM, Rutt BK, Kerr AB. Adiabatic RF pulse design for Bloch-Siegert B1+ mapping. Magn Reson Med 2012; 70:829-35. [PMID: 23041985 DOI: 10.1002/mrm.24507] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/09/2012] [Accepted: 09/04/2012] [Indexed: 11/08/2022]
Abstract
The Bloch-Siegert (B-S) B1+ mapping method has been shown to be fast and accurate, yet it suffers from high Specific Absorption Rate (SAR) and moderately long echo time. An adiabatic RF pulse design is introduced here for optimizing the off-resonant B-S RF pulse to achieve more B-S B1+ measurement sensitivity for a given pulse width. The extra sensitivity can be used for higher angle-to-noise ratio B1+ maps or traded off for faster scans. Using numerical simulations and phantom experiments, it is shown that a numerically optimized 2-ms adiabatic B-S pulse is 2.5 times more efficient than a conventional 6-ms Fermi-shaped B-S pulse. The adiabatic B-S pulse performance is validated in a phantom, and in vivo brain B1+ mapping at 3T and 7T are shown.
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Reed GD, Larson PEZ, Morze CV, Bok R, Lustig M, Kerr AB, Pauly JM, Kurhanewicz J, Vigneron DB. A method for simultaneous echo planar imaging of hyperpolarized ¹³C pyruvate and ¹³C lactate. J Magn Reson 2012; 217:41-7. [PMID: 22405760 PMCID: PMC3326401 DOI: 10.1016/j.jmr.2012.02.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 02/09/2012] [Accepted: 02/11/2012] [Indexed: 05/12/2023]
Abstract
A rapid echo planar imaging sequence for dynamic imaging of [1-(13)C] lactate and [1-(13)C] pyruvate simultaneously was developed. Frequency-based separation of these metabolites was achieved by spatial shifting in the phase-encoded direction with the appropriate choice of echo spacing. Suppression of the pyruvate-hydrate and alanine resonances is achieved through an optimized spectral-spatial RF waveform. Signal sampling efficiency as a function of pyruvate and lactate excitation angle was simulated using two site exchange models. Dynamic imaging is demonstrated in a transgenic mouse model, and phantom validations of the RF pulse frequency selectivity were performed.
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Affiliation(s)
- Galen D Reed
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
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Larson PEZ, Kerr AB, Reed GD, Hurd RE, Kurhanewicz J, Pauly JM, Vigneron DB. Generating super stimulated-echoes in MRI and their application to hyperpolarized C-13 diffusion metabolic imaging. IEEE Trans Med Imaging 2012; 31:265-275. [PMID: 22027366 PMCID: PMC3274664 DOI: 10.1109/tmi.2011.2168235] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Stimulated-echoes in MR can be used to provide high sensitivity to motion and flow, creating diffusion and perfusion weighting as well as T(1) contrast, but conventional approaches inherently suffer from a 50% signal loss. The super stimulated-echo, which uses a specialized radio-frequency (RF) pulse train, has been proposed in order to improve the signal while preserving motion and T(1) sensitivity. This paper presents a novel and straightforward method for designing the super stimulated-echo pulse train using inversion pulse design techniques. This method can also create adiabatic designs with an improved response to RF transmit field variations. The scheme was validated in phantom experiments and shown in vivo to improve signal-to-noise ratio (SNR). We have applied a super stimulated-echo to metabolic MRI with hyperpolarized (13)C-labeled molecules. For spectroscopic imaging of hyperpolarized agents, several repetition times are required but only a single stimulated-echo encoding is feasible, which can lead to unwanted motion blurring. To address this, a super stimulated-echo preparation scheme was used in which the diffusion weighting is terminated prior to the acquisition, and we observed a SNR increases of 60% in phantoms and 49% in vivo over a conventional stimulated-echo. Experiments following injection of hyperpolarized [1-(13)C] -pyruvate in murine transgenic cancer models have shown improved delineation for tumors since signals from metabolites within tumor tissues are retained while those from the vasculature are suppressed by the diffusion preparation scheme.
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Affiliation(s)
- Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California—San Francisco, San Francisco, CA 94158, USA.
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Lee D, Grissom WA, Lustig M, Kerr AB, Stang PP, Pauly JM. VERSE-guided numerical RF pulse design: A fast method for peak RF power control. Magn Reson Med 2012. [DOI: 10.1002/mrm.24200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Lee D, Grissom WA, Lustig M, Kerr AB, Stang PP, Pauly JM. VERSE-guided numerical RF pulse design: a fast method for peak RF power control. Magn Reson Med 2012; 67:353-62. [PMID: 22135085 PMCID: PMC3644517 DOI: 10.1002/mrm.23010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 04/09/2011] [Accepted: 04/27/2011] [Indexed: 11/09/2022]
Abstract
In parallel excitation, the computational speed of numerical radiofrequency (RF) pulse design methods is critical when subject dependencies and system nonidealities need to be incorporated on-the-fly. One important concern with optimization-based methods is high peak RF power exceeding hardware or safety limits. Hence, online controllability of the peak RF power is essential. Variable-rate selective excitation pulse reshaping is ideally suited to this problem due to its simplicity and low computational cost. In this work, we first improve the fidelity of variable-rate selective excitation implementation for discrete-time waveforms through waveform oversampling such that variable-rate selective excitation can be robustly applied to numerically designed RF pulses. Then, a variable-rate selective excitation-guided numerical RF pulse design is suggested as an online RF pulse design framework, aiming to simultaneously control peak RF power and compensate for off-resonance.
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Affiliation(s)
- Daeho Lee
- Department of Electrical Engineering, Magnetic Resonance Systems Research Laboratory, Stanford University, Stanford, California, USA.
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Khalighi MM, Rutt BK, Kerr AB. RF pulse optimization for Bloch-Siegert B ₁⁺ mapping. Magn Reson Med 2011; 68:857-62. [PMID: 22144397 DOI: 10.1002/mrm.23271] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 09/22/2011] [Accepted: 10/03/2011] [Indexed: 12/13/2022]
Abstract
The Bloch-Siegert (B-S) method of B ₁⁺ mapping has been shown to be fast and accurate, yet has high SAR and moderately long TE. These limitations can lengthen scan times and incur signal loss due to B(0) inhomogeneity, particularly at high field. The B-S method relies on applying a band-limited off-resonant B-S radiofrequency pulse to induce a B ₁⁺-dependent frequency-shift for resonant spins. A method for optimizing the B-S radiofrequency pulse is presented here, which maximizes B-S B ₁⁺ measurement sensitivity for a given SAR and T(2) . A 4-ms optimized pulse is shown to have 35% less SAR compared with the conventional 6-ms Fermi pulse while still improving B ₁⁺ map angle-to-noise ratio by 22%. The optimized pulse performance is validated both in phantom and in vivo brain imaging at 7 T.
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Grissom WA, Kerr AB, Stang P, Scott GC, Pauly JM. Minimum envelope roughness pulse design for reduced amplifier distortion in parallel excitation. Magn Reson Med 2010; 64:1432-9. [PMID: 20632401 PMCID: PMC3053148 DOI: 10.1002/mrm.22512] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 04/26/2010] [Indexed: 11/10/2022]
Abstract
Parallel excitation uses multiple transmit channels and coils, each driven by independent waveforms, to afford the pulse designer an additional spatial encoding mechanism that complements gradient encoding. In contrast to parallel reception, parallel excitation requires individual power amplifiers for each transmit channel, which can be cost prohibitive. Several groups have explored the use of low-cost power amplifiers for parallel excitation; however, such amplifiers commonly exhibit nonlinear memory effects that distort radio frequency pulses. This is especially true for pulses with rapidly varying envelopes, which are common in parallel excitation. To overcome this problem, we introduce a technique for parallel excitation pulse design that yields pulses with smoother envelopes. We demonstrate experimentally that pulses designed with the new technique suffer less amplifier distortion than unregularized pulses and pulses designed with conventional regularization.
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Affiliation(s)
- William A Grissom
- Department of Electrical Engineering, Stanford University, Stanford, California, USA.
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Larson PEZ, Hu S, Lustig M, Kerr AB, Nelson SJ, Kurhanewicz J, Pauly JM, Vigneron DB. Fast dynamic 3D MR spectroscopic imaging with compressed sensing and multiband excitation pulses for hyperpolarized 13C studies. Magn Reson Med 2010; 65:610-9. [PMID: 20939089 DOI: 10.1002/mrm.22650] [Citation(s) in RCA: 174] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 08/18/2010] [Accepted: 08/26/2010] [Indexed: 11/07/2022]
Abstract
Hyperpolarized 13C MR spectroscopic imaging can detect not only the uptake of the pre-polarized molecule but also its metabolic products in vivo, thus providing a powerful new method to study cellular metabolism. Imaging the dynamic perfusion and conversion of these metabolites provides additional tissue information but requires methods for efficient hyperpolarization usage and rapid acquisitions. In this work, we have developed a time-resolved 3D MR spectroscopic imaging method for acquiring hyperpolarized 13C data by combining compressed sensing methods for acceleration and multiband excitation pulses to efficiently use the magnetization. This method achieved a 2 sec temporal resolution with full volumetric coverage of a mouse, and metabolites were observed for up to 60 sec following injection of hyperpolarized [1-(13)C]-pyruvate. The compressed sensing acquisition used random phase encode gradient blips to create a novel random undersampling pattern tailored to dynamic MR spectroscopic imaging with sampling incoherency in four (time, frequency, and two spatial) dimensions. The reconstruction was also tailored to dynamic MR spectroscopic imaging by applying a temporal wavelet sparsifying transform to exploit the inherent temporal sparsity. Customized multiband excitation pulses were designed with a lower flip angle for the [1-(13)C]-pyruvate substrate given its higher concentration than its metabolic products ([1-(13)C]-lactate and [1-(13)C]-alanine), thus using less hyperpolarization per excitation. This approach has enabled the monitoring of perfusion and uptake of the pyruvate, and the conversion dynamics to lactate and alanine throughout a volume with high spatial and temporal resolution.
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Affiliation(s)
- Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, California 94158, USA.
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Larson PEZ, Bok R, Kerr AB, Lustig M, Hu S, Chen AP, Nelson SJ, Pauly JM, Kurhanewicz J, Vigneron DB. Investigation of tumor hyperpolarized [1-13C]-pyruvate dynamics using time-resolved multiband RF excitation echo-planar MRSI. Magn Reson Med 2010; 63:582-91. [PMID: 20187172 DOI: 10.1002/mrm.22264] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Hyperpolarized [1-(13)C]-pyruvate is an exciting new agent for the in vivo study of cellular metabolism and a potential cancer biomarker. The nature of the hyperpolarized signal poses unique challenges because of its short duration and the loss of magnetization with every excitation. In this study, we applied a novel and efficient time-resolved MR spectroscopic imaging (MRSI) method to investigate in a prostate cancer model the localized temporal dynamics of the uptake of [1-(13)C]-pyruvate and its conversion to metabolic products, specifically [1-(13)C]-lactate. This hyperpolarized (13)C method used multiband excitation pulses for efficient use of the magnetization. This study demonstrated that regions of tumor were differentially characterized from normal tissue by the lactate dynamics, where tumors showed later lactate detection and longer lactate duration that was statistically significant (P < 0.001). Compared to late-pathologic-stage tumors, early- to intermediate-stage tumors demonstrated significantly (P < 0.01) lower lactate total signal-to-noise ratio (SNR), with similar temporal dynamic parameters. Hyperpolarized pyruvate dynamics provided uptake, perfusion, and vascularization information on tumors and normal tissue. Large, heterogeneous tumors demonstrated spatially variable uptake of pyruvate and metabolic conversion that was consistent with cellularity and necrosis identified by histology. The results of this study demonstrated the potential of this new hyperpolarized MR dynamic method for improved cancer detection and characterization.
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Affiliation(s)
- Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California-San Francisco, San Francisco, California 94158, USA.
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Grissom WA, Kerr AB, Holbrook AB, Pauly JM, Butts-Pauly K. Maximum linear-phase spectral-spatial radiofrequency pulses for fat-suppressed proton resonance frequency-shift MR Thermometry. Magn Reson Med 2009; 62:1242-50. [PMID: 19780177 PMCID: PMC2795148 DOI: 10.1002/mrm.22118] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 05/28/2009] [Indexed: 12/31/2022]
Abstract
Conventional spectral-spatial pulses used for water-selective excitation in proton resonance frequency-shift MR thermometry require increased sequence length compared to shorter wideband pulses. This is because spectral-spatial pulses are longer than wideband pulses, and the echo time period starts midway through them. Therefore, for a fixed echo time, one must increase sequence length to accommodate conventional spectral-spatial pulses in proton resonance frequency-shift thermometry. We introduce improved water-selective spectral-spatial pulses for which the echo time period starts near the beginning of excitation. Instead of requiring increased sequence length, these pulses extend into the long echo time periods common to PRF sequences. The new pulses therefore alleviate the traditional tradeoff between sequence length and fat suppression. We experimentally demonstrate an 11% improvement in frame rate in a proton resonance frequency imaging sequence compared to conventional spectral-spatial excitation. We also introduce a novel spectral-spatial pulse design technique that is a hybrid of previous model- and filter-based techniques and that inherits advantages from both. We experimentally validate the pulses' performance in suppressing lipid signal and in reducing sequence length compared to conventional spectral-spatial pulses.
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Affiliation(s)
- William A Grissom
- Electrical Engineering, Stanford University, Stanford, California, USA.
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Abstract
Large-tip-angle multidimensional radio-frequency (RF) pulse design is a difficult problem, due to the nonlinear response of magnetization to applied RF at large tip-angles. In parallel excitation, multidimensional RF pulse design is further complicated by the possibility for transmit field patterns to change between subjects, requiring pulses to be designed rapidly while a subject lies in the scanner. To accelerate pulse design, we introduce a fast version of the optimal control method for large-tip-angle parallel excitation. The new method is based on a novel approach to analytically linearizing the Bloch equation about a large-tip-angle RF pulse, which results in an approximate linear model for the perturbations created by adding a small-tip-angle pulse to a large-tip-angle pulse. The linear model can be evaluated rapidly using nonuniform fast Fourier transforms, and we apply it iteratively to produce a sequence of pulse updates that improve excitation accuracy. We achieve drastic reductions in design time and memory requirements compared to conventional optimal control, while producing pulses of similar accuracy. The new method can also compensate for nonidealities such as main field inhomogeneties.
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Affiliation(s)
- William A. Grissom
- W. A. Grissom and A. B. Kerr are with the Information Systems and Radiological Sciences Laboratories, Stanford University, Stanford, CA 94305 USA (, ). D. Xu is with the Global Applied Research Lab, GE Healthcare, Waukesha, Wisconsin USA (). J. A. Fessler is with the Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122 USA (). D. C. Noll is with the Biomedical Engineering Department, The University of Michigan, Ann Arbor, MI 48109-2099 USA ()
| | - Dan Xu
- W. A. Grissom and A. B. Kerr are with the Information Systems and Radiological Sciences Laboratories, Stanford University, Stanford, CA 94305 USA (, ). D. Xu is with the Global Applied Research Lab, GE Healthcare, Waukesha, Wisconsin USA (). J. A. Fessler is with the Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122 USA (). D. C. Noll is with the Biomedical Engineering Department, The University of Michigan, Ann Arbor, MI 48109-2099 USA ()
| | - Adam B. Kerr
- W. A. Grissom and A. B. Kerr are with the Information Systems and Radiological Sciences Laboratories, Stanford University, Stanford, CA 94305 USA (, ). D. Xu is with the Global Applied Research Lab, GE Healthcare, Waukesha, Wisconsin USA (). J. A. Fessler is with the Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122 USA (). D. C. Noll is with the Biomedical Engineering Department, The University of Michigan, Ann Arbor, MI 48109-2099 USA ()
| | - Jeffrey A. Fessler
- W. A. Grissom and A. B. Kerr are with the Information Systems and Radiological Sciences Laboratories, Stanford University, Stanford, CA 94305 USA (, ). D. Xu is with the Global Applied Research Lab, GE Healthcare, Waukesha, Wisconsin USA (). J. A. Fessler is with the Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122 USA (). D. C. Noll is with the Biomedical Engineering Department, The University of Michigan, Ann Arbor, MI 48109-2099 USA ()
| | - Douglas C. Noll
- W. A. Grissom and A. B. Kerr are with the Information Systems and Radiological Sciences Laboratories, Stanford University, Stanford, CA 94305 USA (, ). D. Xu is with the Global Applied Research Lab, GE Healthcare, Waukesha, Wisconsin USA (). J. A. Fessler is with the Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109-2122 USA (). D. C. Noll is with the Biomedical Engineering Department, The University of Michigan, Ann Arbor, MI 48109-2099 USA ()
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Osorio JA, Xu D, Cunningham CH, Chen A, Kerr AB, Pauly JM, Vigneron DB, Nelson SJ. Design of cosine modulated very selective suppression pulses for MR spectroscopic imaging at 3T. Magn Reson Med 2009; 61:533-40. [PMID: 19097232 DOI: 10.1002/mrm.21842] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The advantages of using a 3 Tesla (T) scanner for MR spectroscopic imaging (MRSI) of brain tissue include improved spectral resolution and increased sensitivity. Very selective saturation (VSS) pulses are important for maximizing selectivity for PRESS MRSI and minimizing chemical shift misregistration by saturating signals from outside the selected region. Although three-dimensional (3D) PRESS MRSI is able to provide excellent quality metabolic data for patients with brain tumors and has been shown to be important for defining tumor burden, the method is currently limited by how much of the anatomic lesion can be covered within a single examination. In this study we designed and implemented cosine modulated VSS pulses that were optimized for 3T MRSI acquisitions. This provided improved coverage and suppression of unwanted lipid signals with a smaller number of pulses. The use of the improved pulse sequence was validated in volunteer studies, and in clinical 3D MRSI exams of brain tumors.
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Affiliation(s)
- Joseph A Osorio
- UCSF/UCB Joint Graduate Group in Bioengineering, San Francisco, California 94158-2532, USA.
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Lechner SM, Sipilä PT, Wiesinger F, Kerr AB, Vogel MW. Spiral imaging artifact reduction: A comparison of two k-trajectory measurement methods. J Magn Reson Imaging 2009; 29:1485-92. [DOI: 10.1002/jmri.21782] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Santos JM, Kerr AB, Lee D, McConnell M, Hu BS, Pauly JM. 232 Real-time and gated MR Doppler. J Cardiovasc Magn Reson 2008. [DOI: 10.1186/1532-429x-10-s1-a93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Larson PEZ, Kerr AB, Chen AP, Lustig MS, Zierhut ML, Hu S, Cunningham CH, Pauly JM, Kurhanewicz J, Vigneron DB. Multiband excitation pulses for hyperpolarized 13C dynamic chemical-shift imaging. J Magn Reson 2008; 194:121-7. [PMID: 18619875 PMCID: PMC3739981 DOI: 10.1016/j.jmr.2008.06.010] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 06/17/2008] [Accepted: 06/17/2008] [Indexed: 05/03/2023]
Abstract
Hyperpolarized 13C offers high signal-to-noise ratios for imaging metabolic activity in vivo, but care must be taken when designing pulse sequences because the magnetization cannot be recovered once it has decayed. It has a short lifetime, on the order of minutes, and gets used up by each RF excitation. In this paper, we present a new dynamic chemical-shift imaging method that uses specialized RF pulses designed to maintain most of the hyperpolarized substrate while providing adequate SNR for the metabolic products. These are multiband, variable flip angle, spectral-spatial RF pulses that use spectral selectivity to minimally excite the injected prepolarized 13C-pyruvate substrate. The metabolic products of lactate and alanine are excited with a larger flip angle to increase SNR. This excitation was followed by an RF amplitude insensitive double spin-echo and an echo-planar flyback spectral-spatial readout gradient. In vivo results in rats and mice are presented showing improvements over constant flip angle RF pulses. The metabolic products are observable for a longer window because the low pyruvate flip angle preserves magnetization, allowing for improved observation of spatially varying metabolic reactions.
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Affiliation(s)
- Peder E. Z. Larson
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
| | - Adam B. Kerr
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - Albert P. Chen
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
| | - Michael S. Lustig
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - Matthew L. Zierhut
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
| | - Simon Hu
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
| | - Charles H. Cunningham
- Sunnybrook Health Sciences Centre and Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - John M. Pauly
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California
| | - John Kurhanewicz
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
| | - Daniel B. Vigneron
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, California
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Affiliation(s)
- A B Kerr
- Surgical Division of a Military General Hospital
| | - H Werner
- Surgical Division of a Military General Hospital
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Abstract
PURPOSE The Magnetic resonance imaging (MRI) is an emerging technology for catheter-based imaging and interventions. Real-time MRI is a promising methodfor overcoming catheter and physiologic motion for intravascular imaging. METHODS All imaging was performed on a 1.5 T Signa MRI scanner with high-speed gradients. Multiple catheter coils were designed and constructed, including low-profile, stub-matched coils. Coil sensitivity patterns and SNR measurements were compared. Real-time imaging was performed with an interleaved spiral sequence using a dedicated workstation, providing real-time data acquisition, image reconstruction and interactive control and display. Real-time "black-blood" imaging was achieved through incorporation of off-slice saturation pulses. The imaging sequence was tested in a continuous flow phantom and then in vivo in the rabbit aorta using a 2 mm catheter coil. RESULTS The real-time intravascular imaging sequence achieved 120-440 micron resolution at up to 16 frames per second. Low-profile stub-tuned catheter coils achieved similar SNR to larger traditional coil designs. In the phantom experiments, addition of real-time black-blood saturation pulses effectively suppressed the flow signal and allowed visualization of the phantom wall. In vivo experiments clearly showed real-time intravascular imaging of the rabbit aortic wall with minimal motion artifacts and effective blood signal suppression. CONCLUSIONS Real-time imaging with low-profile coil designs provides significant enhancements to intravascular MRI.
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Affiliation(s)
- Pedro A Rivas
- Division of Cardiovascular Medicine, Stanford University School of Medicine, CA 94305-5233, USA
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Kaji S, Yang PC, Kerr AB, Tang WH, Meyer CH, Macovski A, Pauly JM, Nishimura DG, Hu BS. Rapid evaluation of left ventricular volume and mass without breath-holding using real-time interactive cardiac magnetic resonance imaging system. J Am Coll Cardiol 2001; 38:527-33. [PMID: 11499748 DOI: 10.1016/s0735-1097(01)01399-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVES The purpose of this study was to validate cardiac measurements derived from real-time cardiac magnetic resonance imaging (MRI) as compared with well-validated conventional cine MRI. BACKGROUND Although cardiac MRI provides accurate assessment of left ventricular (LV) volume and mass, most techniques have been relatively slow and required electrocardiogram (ECG) gating over many heart beats. A newly developed real-time MRI system allows continuous real-time dynamic acquisition and display without cardiac gating or breath-holding. METHODS Fourteen healthy volunteers and nine patients with heart failure underwent real-time and cine MRI in the standard short-axis orientation with a 1.5T MRI scanner. Nonbreath-holding cine MRI was performed with ECG gating and respiratory compensation. Left ventricular end-diastolic volume (LVEDV), left ventricular endsystolic volume (LVESV), ejection fraction (EF) and LV mass calculated from the images obtained by real-time MRI were compared to those obtained by cine MRI. RESULTS The total study time including localization for real-time MRI was significantly shorter than cine MRI (8.6 +/- 2.3 vs. 24.7 +/- 3.5 min, p < 0.001). Both imaging techniques yielded good quality images allowing cardiac measurements. The measurements of LVEDV, LVESV, EF and LV mass obtained with real-time MRI showed close correlation with those obtained with cine MRI (LVEDV: r = 0.985, p < 0.001; LVESV: r = 0.994, p < 0.001; EF: r = 0.975, p < 0.001; LV mass: r = 0.977, p < 0.001). CONCLUSIONS Real-time MRI provides accurate measurements of LV volume and mass in a time-efficient manner with respect to image acquisition.
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Affiliation(s)
- S Kaji
- Department of Medicine, Stanford University, California, USA
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Abstract
A real-time interactive black-blood imaging system is described. Rapid blood suppression is achieved by exciting and dephasing slabs outside the imaging slice before each imaging excitation. Sharp-profiled radio frequency saturation pulses placed close to the imaging slice provide good blood suppression, even in views containing slow through-plane flow. In vivo results indicate that this technique improves endocardial border definition during systole in real-time cardiac wall-motion studies. Phantom and animal results indicate that this technique nearly eliminates flow artifacts in real-time intravascular studies. J. Magn. Reson. Imaging 2001;13:807-812.
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Affiliation(s)
- K S Nayak
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305-9510, USA.
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Abstract
In many applications of dynamic MR imaging, only a portion of the field-of-view (FOV) exhibits considerable variations in time. In such cases, a prior knowledge of the static part of the image allows a partial-FOV reconstruction of the dynamic section using only a fraction of the raw data. This method of reconstruction generally results in higher temporal resolution, because the scan time for partial-FOV data is shorter. The fidelity of this reconstruction technique depends, among other factors, on the accuracy of the prior information of the static section. This information is usually derived from the reconstructed images at previous time frames. This data, however, is normally corrupted by the motion artifact Because the temporal frequency contents of the motion artifact is very similar to that of the dynamic section, a temporal low-pass filter can efficiently remove this artifact from the static data. The bandwidth of the filter can be obtained from the rate of variations inside and outside the dynamic area. In general, when the temporal bandwidth is not spatially uniform, a bank of low-pass filters can provide a proper suppression of the motion artifact outside the dynamic section. This reconstruction technique is adapted for spiral acquisition and is successfully applied to cardiac fluoroscopy, doubling the temporal resolution.
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Affiliation(s)
- H Sedarat
- Department of Electrical Engineering, Stanford University, California, USA.
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Abstract
A real-time interactive color flow MRI system capable of rapidly visualizing cardiac and vascular flow is described. Interleaved spiral phase contrast datasets are acquired continuously, while real-time gridding and phase differencing is used to compute density and velocity maps. These maps are then displayed using a color overlay similar to what is used by ultrasound. For cardiac applications, 6 independent images/sec are acquired with in-plane resolution of 2.4 mm over a 20 cm field of view (FOV). Sliding window reconstruction achieves display rates up to 18 images/sec. Appropriate tradeoffs are made for other applications. Flow phantom studies indicate this technique accurately measures velocities up to 2 m/sec, and accurately captures real-time velocity waveforms (comparable to continuous wave ultrasound). In vivo studies indicate this technique is useful for imaging cardiac and vascular flow, particularly valvular regurgitation. Arbitrary scan planes can be quickly localized, and flow measured in any direction.
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Affiliation(s)
- K S Nayak
- Department of Electrical Engineering, Stanford University, California 94305-9510, USA.
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48
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Yang PC, Kerr AB, Liu AC, Liang DH, Hardy C, Meyer CH, Macovski A, Pauly JM, Hu BS. New real-time interactive cardiac magnetic resonance imaging system complements echocardiography. J Am Coll Cardiol 1998; 32:2049-56. [PMID: 9857892 DOI: 10.1016/s0735-1097(98)00462-8] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES We conducted an initial clinical trial of a newly developed cardiac magnetic resonance imaging (CMRI) system. We evaluated left ventricular (LV) function in 85 patients to compare the clinical utility of the CMRI system with echocardiography, the current noninvasive gold standard. BACKGROUND Conventional CMRI systems require cardiac-gating and respiratory compensation to synthesize a single image from data acquired over multiple cardiac cycles. In contrast, the new CMRI system allows continuous real-time dynamic acquisition and display of any scan plane at 16 images/s without the need for cardiac gating or breath-holding. METHODS A conventional 1.5T Signa MRI Scanner (GE, Milwaukee, Wisconsin) was modified by the addition of an interactive workstation and a bus adapter. The new CMRI system underwent clinical trial by testing its ability to evaluate global and regional LV function. The first group (A) consisted of 31 patients with acceptable echocardiography image quality. The second group (B) consisted of 31 patients with suboptimal echocardiography image quality. The third group (C) consisted of 29 patients with severe lung disease or congenital cardiac malformation who frequently have suboptimal echo study. Two independent observers scored wall motion and image quality using the standard 16-segment model and rank-order analysis. RESULTS CMRI evaluation was complete in less than 15 min. In group A, no significant difference was found between ECHO and CMRI studies (p = NS). In group B, adequate visualization of wall segments was obtained 38% of the time using ECHO and 97% of the time using CMRI (p < 0.0001). When grouped into coronary segments, adequate visualization of at least one segment occurred in 18 of 30 patients (60%) with ECHO and in all 30 patients (100%) with CMRI (p < 0.0001). In group C, adequate visualization of the wall segments was obtained in 58% (CI 0.53-0.62) of the time using echocardiography and 99.7% (CI 0.99-1.0) of the time using CMRI (p < 0.0001). CONCLUSIONS The new CMRI system provides clinically reliable evaluation of LV function and complements suboptimal echocardiography. In comparison with the conventional CMRI, the new CMRI system significantly reduces scan time, patient discomfort and associated cost.
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Affiliation(s)
- P C Yang
- Department of Medicine, Stanford University, California 94305, USA.
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49
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Abstract
The acquisition of complete three-dimensional (3D), segmented gradient-echo data sets to visualize the coronary arteries can be both time consuming and sensitive to motion, even with use of multiple breath-holding or respiratory gating. An alternate hybrid approach is demonstrated here, in which real-time interactive imaging is first used to locate an optimal oblique coronary scan plane. Then, a limited number of contiguous slices are acquired around that plane within a breath-hold with use of two-dimensional (2D) segmented gradient-echo imaging. Dual inversion nulling is used to suppress fat and myocardium. Finally, if needed, a limited reformat of the data is performed to produce images from relatively long sections of the coronaries. This approach yields relatively rapid visualization of portions of the coronary tree. Several different methods are compared for interactively moving the scan plane.
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Affiliation(s)
- C J Hardy
- GE Corporate Research and Development, Schenectady, New York 12301, USA
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50
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Abstract
A real-time interactive MRI system capable of localizing coronary arteries and imaging arrhythmic hearts in real-time is described. Non-2DFT acquisition strategies such as spiral-interleaf, spiral-ring, and circular echo-planar imaging provide short scan times on a conventional scanner. Real-time gridding reconstruction at 8-20 images/s is achieved by distributing the reconstruction on general-purpose UNIX workstations. An X-windows application provides interactive control. A six-interleaf spiral sequence is used for cardiac imaging and can acquire six images/s. A sliding window reconstruction achieves display rates of 16-20 images/s. This allows cardiac images to be acquired in real-time, with minimal motion and flow artifacts, and without breath holding or cardiac gating. Abdominal images are acquired at over 2.5 images/s with spiral-ring or circular echo-planar sequences. Reconstruction rates are 8-10 images/s. Rapid localization in the abdomen is demonstrated with the spiral-ring acquisition, whereas peristaltic motion in the small bowel is well visualized using the circular echo-planar sequence.
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Affiliation(s)
- A B Kerr
- Department of Electrical Engineering, Stanford University, California, USA
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