NeuroImage (Nov 2021)
Frequency drift in MR spectroscopy at 3T
- Steve C.N. Hui,
- Mark Mikkelsen,
- Helge J. Zöllner,
- Vishwadeep Ahluwalia,
- Sarael Alcauter,
- Laima Baltusis,
- Deborah A. Barany,
- Laura R. Barlow,
- Robert Becker,
- Jeffrey I. Berman,
- Adam Berrington,
- Pallab K. Bhattacharyya,
- Jakob Udby Blicher,
- Wolfgang Bogner,
- Mark S. Brown,
- Vince D. Calhoun,
- Ryan Castillo,
- Kim M. Cecil,
- Yeo Bi Choi,
- Winnie C.W. Chu,
- William T. Clarke,
- Alexander R. Craven,
- Koen Cuypers,
- Michael Dacko,
- Camilo de la Fuente-Sandoval,
- Patricia Desmond,
- Aleksandra Domagalik,
- Julien Dumont,
- Niall W. Duncan,
- Ulrike Dydak,
- Katherine Dyke,
- David A. Edmondson,
- Gabriele Ende,
- Lars Ersland,
- C. John Evans,
- Alan S.R. Fermin,
- Antonio Ferretti,
- Ariane Fillmer,
- Tao Gong,
- Ian Greenhouse,
- James T. Grist,
- Meng Gu,
- Ashley D. Harris,
- Katarzyna Hat,
- Stefanie Heba,
- Eva Heckova,
- John P. Hegarty, II,
- Kirstin-Friederike Heise,
- Shiori Honda,
- Aaron Jacobson,
- Jacobus F.A. Jansen,
- Christopher W. Jenkins,
- Stephen J. Johnston,
- Christoph Juchem,
- Alayar Kangarlu,
- Adam B. Kerr,
- Karl Landheer,
- Thomas Lange,
- Phil Lee,
- Swati Rane Levendovszky,
- Catherine Limperopoulos,
- Feng Liu,
- William Lloyd,
- David J. Lythgoe,
- Maro G. Machizawa,
- Erin L. MacMillan,
- Richard J. Maddock,
- Andrei V. Manzhurtsev,
- María L. Martinez-Gudino,
- Jack J. Miller,
- Heline Mirzakhanian,
- Marta Moreno-Ortega,
- Paul G. Mullins,
- Shinichiro Nakajima,
- Jamie Near,
- Ralph Noeske,
- Wibeke Nordhøy,
- Georg Oeltzschner,
- Raul Osorio-Duran,
- Maria C.G. Otaduy,
- Erick H. Pasaye,
- Ronald Peeters,
- Scott J. Peltier,
- Ulrich Pilatus,
- Nenad Polomac,
- Eric C. Porges,
- Subechhya Pradhan,
- James Joseph Prisciandaro,
- Nicolaas A Puts,
- Caroline D. Rae,
- Francisco Reyes-Madrigal,
- Timothy P.L. Roberts,
- Caroline E. Robertson,
- Jens T. Rosenberg,
- Diana-Georgiana Rotaru,
- Ruth L O'Gorman Tuura,
- Muhammad G. Saleh,
- Kristian Sandberg,
- Ryan Sangill,
- Keith Schembri,
- Anouk Schrantee,
- Natalia A. Semenova,
- Debra Singel,
- Rouslan Sitnikov,
- Jolinda Smith,
- Yulu Song,
- Craig Stark,
- Diederick Stoffers,
- Stephan P. Swinnen,
- Rongwen Tain,
- Costin Tanase,
- Sofie Tapper,
- Martin Tegenthoff,
- Thomas Thiel,
- Marc Thioux,
- Peter Truong,
- Pim van Dijk,
- Nolan Vella,
- Rishma Vidyasagar,
- Andrej Vovk,
- Guangbin Wang,
- Lars T. Westlye,
- Timothy K. Wilbur,
- William R. Willoughby,
- Martin Wilson,
- Hans-Jörg Wittsack,
- Adam J. Woods,
- Yen-Chien Wu,
- Junqian Xu,
- Maria Yanez Lopez,
- David K.W. Yeung,
- Qun Zhao,
- Xiaopeng Zhou,
- Gasper Zupan,
- Richard A.E. Edden
Affiliations
- 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
- Pallab K. Bhattacharyya
- Imaging Institute, The Cleveland Clinic, Cleveland, OH USA
- 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
- C. John Evans
- CUBRIC, Cardiff university, Cardiff, Wales, UK
- 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, II
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA, USA
- Kirstin-Friederike Heise
- Department of Movement Sciences, KU Leuven, Leuven, Belgium
- 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
- Christopher W. Jenkins
- CUBRIC, Cardiff university, Cardiff, Wales, UK
- 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
- Swati Rane Levendovszky
- Department of Radiology, University of Washington, Seattle, WA 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
- Ralph Noeske
- GE Healthcare, Berlin, Germany
- 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
- Keith Schembri
- Medical Physics, Mater Dei Hospital, Imsida, Malta
- 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
- Stephan P. Swinnen
- Department of Movement Sciences, KU Leuven, Leuven, Belgium
- 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
- Maria Yanez Lopez
- Perinatal Imaging & Health, King's College London, London, UK
- 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; Corresponding author. Division of Neuroradiology, Park 367H, The Johns Hopkins University School of Medicine, 600 N Wolfe St, Baltimore, MD 21287, USA.
- Journal volume & issue
-
Vol. 241
p. 118430
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.
