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Cho J, Liao C, Tian Q, Zhang Z, Xu J, Lo WC, Poser BA, Stenger VA, Stockmann J, Setsompop K, Bilgic B. Highly accelerated EPI with wave encoding and multi-shot simultaneous multislice imaging. Magn Reson Med 2022; 88:1180-1197. [PMID: 35678236 DOI: 10.1002/mrm.29291] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 11/09/2022]
Abstract
PURPOSE To introduce wave-encoded acquisition and reconstruction techniques for highly accelerated EPI with reduced g-factor penalty and image artifacts. THEORY AND METHODS Wave-EPI involves application of sinusoidal gradients during the EPI readout, which spreads the aliasing in all spatial directions, thereby taking better advantage of 3D coil sensitivity profiles. The amount of voxel spreading that can be achieved by the wave gradients during the short EPI readout period is constrained by the slew rate of the gradient coils and peripheral nerve stimulation monitor. We propose to use a "half-cycle" sinusoidal gradient to increase the amount of voxel spreading that can be achieved while respecting the slew and stimulation constraints. Extending wave-EPI to multi-shot acquisition minimizes geometric distortion and voxel blurring at high in-plane resolutions, while structured low-rank regularization mitigates shot-to-shot phase variations. To address gradient imperfections, we propose to use different point spread functions for the k-space lines with positive and negative polarities, which are calibrated with a FLEET-based reference scan. RESULTS Wave-EPI enabled whole-brain single-shot gradient-echo (GE) and multi-shot spin-echo (SE) EPI acquisitions at high acceleration factors at 3T and was combined with g-Slider encoding to boost the SNR level in 1 mm isotropic diffusion imaging. Relative to blipped-CAIPI, wave-EPI reduced average and maximum g-factors by up to 1.21- and 1.37-fold at Rin × Rsms = 3 × 3, respectively. CONCLUSION Wave-EPI allows highly accelerated single- and multi-shot EPI with reduced g-factor and artifacts and may facilitate clinical and neuroscientific applications of EPI by improving the spatial and temporal resolution in functional and diffusion imaging.
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Affiliation(s)
- Jaejin Cho
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Congyu Liao
- Radiological Sciences Laboratory, Department of Radiology, Stanford University, Stanford, California, USA.,Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Qiyuan Tian
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA
| | - Zijing Zhang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Jinmin Xu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Wei-Ching Lo
- Siemens Medical Solutions, Boston, Massachusetts, USA
| | - Benedikt A Poser
- Maastricht Brain Imaging Center, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - V Andrew Stenger
- MR Research Program, Department of Medicine, John A. Burns School of Medicine, University of Hawai'i, Honolulu, Hawaii, USA
| | - Jason Stockmann
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Kawin Setsompop
- Radiological Sciences Laboratory, Department of Radiology, Stanford University, Stanford, California, USA.,Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Berkin Bilgic
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Rettenmeier CA, Maziero D, Stenger VA. Three dimensional radial echo planar imaging for functional MRI. Magn Reson Med 2022; 87:193-206. [PMID: 34411342 PMCID: PMC8616809 DOI: 10.1002/mrm.28980] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 02/09/2021] [Revised: 07/07/2021] [Accepted: 07/31/2021] [Indexed: 01/03/2023]
Abstract
PURPOSE To demonstrate a novel 3D radial echo planar imaging (3D REPI) sequence for flexible, rapid, and motion-robust sampling in fMRI. METHODS The 3D REPI method expands on the recently described golden angle rotated EPI trajectory using radial batched internal navigator echoes (TURBINE) approach by exploiting the unused perpendicular direction in the EPI readout to form fast analogues of rotated stack of stars or spirals trajectories that cover all 3 dimensions of k-space. An iterative conjugate gradient algorithm with SENSE reconstruction and time-segmented non-uniform fast Fourier transform (FFT) was used for parallel imaging acceleration and to account for the effects of B0 inhomogeneity. The golden angle rotation allowed for sliding window reconstruction schemes to be applied in brain BOLD fMRI experiments. RESULTS Combined whole brain visual and motor fMRI experiments were successfully carried out on a clinical 3T scanner at 2 mm isotropic and 1 × 1 × 2 mm3 resolutions using the 3D REPI design. Improved sampling characteristics and image quality were observed for twisted trajectories at the expense of prolonged readout times and off-resonance effects. The ability to correct for rigid motion correction was also demonstrated. CONCLUSIONS 3D REPI presents a flexible approach for segmented volumetric fMRI with motion correction and high in-plane spatial resolutions. Improved BOLD fMRI brain activation maps were obtained using a sliding window reconstruction.
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Affiliation(s)
- Christoph A. Rettenmeier
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA,Corresponding author: Christoph Rettenmeier, Ph.D., University of Hawaii John A. Burns School of Medicine, 1356 Lusitana Street, 7th floor, Honolulu, 96813 Hawaii, USA, , tel. +1 808 691 5163
| | - Danilo Maziero
- Department of Radiation Oncology, University of Miami, Miller School of Medicine, Sylvester Comprehensive Cancer Center, Miami, Florida
| | - V. Andrew Stenger
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
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Nakamatsu NA, Aytaç G, Mikami B, Thompson JD, Davis M, Rettenmeier C, Maziero D, Andrew Stenger V, Labrash S, Lenze S, Torigoe T, Lozanoff BK, Kaya B, Smith A, Douglas Miles J, Lee UY, Lozanoff S. Case-based radiological anatomy instruction using cadaveric MRI imaging and delivered with extended reality web technology. Eur J Radiol 2021; 146:110043. [PMID: 34844172 DOI: 10.1016/j.ejrad.2021.110043] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 09/02/2021] [Revised: 10/20/2021] [Accepted: 11/14/2021] [Indexed: 12/27/2022]
Abstract
PURPOSE Extended reality (XR) technology enhances learning in medical education. The purpose of this study was to develop and apply a case-based approach for teaching radiological anatomy utilizing XR technology for improved student exploration and engagement. METHODS The workflow consisted of MRI scanning cadavers followed by radiological, pathological, and anatomical assessment, and finally case presentation based on XR visualizations and student interaction. Case information (Subject, History, and Physical Exam) was presented to student groups who generated and recorded hypotheses using Google Forms. RESULTS Use of all components of the system was voluntary and a total of 74 students responded to the survey request (response rate = 95%). Assessment of the experience was conducted through a qualitative survey comprising four Likert scale questions (1-5, 1 lowest), three binary questions, and open-ended comments. Mean, standard deviation, and overall agreement (mean ± SD, OA) showed that students found MRI scans of cadavers to be helpful for dissections (4.14 ± 1.1, 74.3%) and provided an understanding of relevant anatomy (4.32 ± 0.9, 79.7%), while 78.4% of students used the DICOM viewer to visualize scans of cadavers. The difficulty of use was found to be average (2.90 ± 1.0, 23%). zSpace visualizations were used by 40.5% of students, generally agreeing that an understanding of spatial relationships improved as a result (3.60 ± 1.0, 43.2%). More case-based sessions were favored by 97.3% of students. CONCLUSIONS Results suggest that cadaveric MRI radiological visualization and XR technology enhance understanding of case-based anatomical dissections and encourage student exploration and engagement.
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Affiliation(s)
| | - Güneş Aytaç
- John A. Burns School of Medicine, Honolulu, HI, United States; TOBB University of Economics and Technology, School of Medicine, Ankara, Turkey
| | - Brandi Mikami
- John A. Burns School of Medicine, Honolulu, HI, United States
| | | | - McKay Davis
- UH/QMC MRI Research Center, John A. Burns School of Medicine, Honolulu, HI, United States
| | - Christoph Rettenmeier
- UH/QMC MRI Research Center, John A. Burns School of Medicine, Honolulu, HI, United States
| | - Danilo Maziero
- UH/QMC MRI Research Center, John A. Burns School of Medicine, Honolulu, HI, United States
| | - V Andrew Stenger
- UH/QMC MRI Research Center, John A. Burns School of Medicine, Honolulu, HI, United States
| | - Steven Labrash
- John A. Burns School of Medicine, Honolulu, HI, United States
| | - Stacy Lenze
- John A. Burns School of Medicine, Honolulu, HI, United States
| | - Trevor Torigoe
- John A. Burns School of Medicine, Honolulu, HI, United States
| | - Beth K Lozanoff
- John A. Burns School of Medicine, Honolulu, HI, United States
| | - Brock Kaya
- John A. Burns School of Medicine, Honolulu, HI, United States
| | - Alice Smith
- John A. Burns School of Medicine, Honolulu, HI, United States
| | - J Douglas Miles
- John A. Burns School of Medicine, Honolulu, HI, United States
| | - U-Young Lee
- John A. Burns School of Medicine, Honolulu, HI, United States; College of Medicine, The Catholic University of Korea, South Korea
| | - Scott Lozanoff
- John A. Burns School of Medicine, Honolulu, HI, United States
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Nakamatsu NA, Mikami B, Thompson JD, Davis M, Rettenmeier C, Maziero D, Stenger VA, Labrash S, Lenze S, Torigoe T, Lozanoff BK, Lee UY, Kaya B, Smith A, Miles JD, Lozanoff SK. Hypothesis Driven Gross Anatomy Learning for Brain and Cranial Cavity Dissection Using MRI Imaging of Cadavers and Delivered Utilizing XR‐Web Technology. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.04898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | - Danilo Maziero
- UH/QMC MRI Research Center John A. Burns School of Medicine
| | | | | | | | | | | | - U-Young Lee
- John A. Burns School of Medicine
- College of Medicine The Catholic University of Korea
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Rettenmeier C, Stenger VA. Radiofrequency phase encoded half-pulses in simultaneous multislice ultrashort echo time imaging. Magn Reson Med 2019; 81:3720-3733. [PMID: 30756426 DOI: 10.1002/mrm.27693] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 11/06/2022]
Abstract
PURPOSE To describe a simultaneous multislice (SMS) ultrashort echo time (UTE) imaging method using radiofrequency phase encoded half-pulses in combination with power independent of number of slices (PINS) inversion recovery (IR) pulses to generate multiple-slice images with short T2 * contrasts in less than 3 min with close to an eightfold acceleration compared with a standard 2D approach. THEORY AND METHODS Radiofrequency phase encoding is applied in an SMS (NSMS = 4) excitation scheme using "sinc" half-pulses. With the use of coil sensitivity encoding (SENSE) and controlled aliasing in parallel imaging (CAIPI) in combination with a gradient echo 2D spiral readout trajectory and IR PINS pulses for contrast enhancement a fast UTE sequence is developed. Images are obtained using a model-based reconstruction method. Sequence details and performance tests on phantoms as well as the heads of healthy volunteers at 3T are presented. RESULTS An SMS UTE sequence with an undersampling factor of 4 is developed using radiofrequency phase encoded half-pulses and PINS IR pulses which enables the acquisition of 8 slices at 0.862 mm2 resolution in less than 3-min scan time. UTE images of the head are obtained showing highlighted signal of cortical bone. Image quality and T2 contrast are comparable to the one obtained by corresponding single slice acquisitions with only minor deviations. CONCLUSIONS The method combining radiofrequency phase encoded SMS half-pulses and PINS IR pulses presents a suitable approach to SMS UTE imaging. The usage of coil sensitivity information and increased sampling density by means of interleaved slice group acquisitions allows to reduce the total scan time by a factor close to 8.
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Affiliation(s)
- Christoph Rettenmeier
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - V Andrew Stenger
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
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Rettenmeier C, Maziero D, Qian Y, Stenger VA. A circular echo planar sequence for fast volumetric fMRI. Magn Reson Med 2018; 81:1685-1698. [PMID: 30273963 DOI: 10.1002/mrm.27522] [Citation(s) in RCA: 2] [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: 03/26/2018] [Revised: 08/03/2018] [Accepted: 08/15/2018] [Indexed: 11/07/2022]
Abstract
PURPOSE To demonstrate a circular EPI (CEPI) sequence as well as a generalized EPI reconstruction for fast fMRI with parallel imaging acceleration. METHODS The CEPI acquisition was constructed using variable readout lengths and maximum ramp sampling as well as blipped-CAIPI z-gradient encoding for simultaneous multislice (SMS) and 3D volumetric imaging. A signal equation model with constant and linear phase terms was used to iteratively reconstruct images with low ghosting. Simulation, phantom, and human imaging experiments including audio/visual fMRI were performed at 3T using a 52-channel coil. RESULTS Application of CEPI gradients with duration of 27 ms covering a 22-cm FOV at a 64 × 64 pixel resolution in SMS and 3D acquisitions resulted in images with comparable quality to those of standard Cartesian EPI. With parallel imaging techniques robust detection of BOLD fMRI activation with temporal sampling down to 275 ms was possible. The high temporal resolution enabled higher activation statistics at a penalty in increased noise and residual aliasing. The un-accelerated 3D acquisition showed large temporal instability compared with a standard 2D acquisition. CONCLUSION Nonuniform sampling and generalized image reconstructions can be applied to EPI acquisitions including those with blipped-CAIPI z gradients. The same gradients can be used for either SMS or 3D acquisitions providing identical coverage.
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Affiliation(s)
- Christoph Rettenmeier
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Danilo Maziero
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Yongxian Qian
- Department of Radiology, New York University School of Medicine, New York, New York
| | - V Andrew Stenger
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
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Song H, Ruan D, Liu W, Stenger VA, Pohmann R, Fernández-Seara MA, Nair T, Jung S, Luo J, Motai Y, Ma J, Hazle JD, Gach HM. Respiratory motion prediction and prospective correction for free-breathing arterial spin-labeled perfusion MRI of the kidneys. Med Phys 2017; 44:962-973. [PMID: 28074528 DOI: 10.1002/mp.12099] [Citation(s) in RCA: 11] [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: 08/31/2016] [Revised: 12/14/2016] [Accepted: 12/27/2016] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Respiratory motion prediction using an artificial neural network (ANN) was integrated with pseudocontinuous arterial spin labeling (pCASL) MRI to allow free-breathing perfusion measurements in the kidney. In this study, we evaluated the performance of the ANN to accurately predict the location of the kidneys during image acquisition. METHODS A pencil-beam navigator was integrated with a pCASL sequence to measure lung/diaphragm motion during ANN training and the pCASL transit delay. The ANN algorithm ran concurrently in the background to predict organ location during the 0.7-s 15-slice acquisition based on the navigator data. The predictions were supplied to the pulse sequence to prospectively adjust the axial slice acquisition to match the predicted organ location. Additional navigators were acquired immediately after the multislice acquisition to assess the performance and accuracy of the ANN. The technique was tested in eight healthy volunteers. RESULTS The root-mean-square error (RMSE) and mean absolute error (MAE) for the eight volunteers were 1.91 ± 0.17 mm and 1.43 ± 0.17 mm, respectively, for the ANN. The RMSE increased with transit delay. The MAE typically increased from the first to last prediction in the image acquisition. The overshoot was 23.58% ± 3.05% using the target prediction accuracy of ± 1 mm. CONCLUSION Respiratory motion prediction with prospective motion correction was successfully demonstrated for free-breathing perfusion MRI of the kidney. The method serves as an alternative to multiple breathholds and requires minimal effort from the patient.
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Affiliation(s)
- Hao Song
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Dan Ruan
- Departments of Radiation Oncology, Biomedical Physics and Bioengineering, UCLA, Los Angeles, CA, 90095, USA
| | - Wenyang Liu
- Departments of Radiation Oncology, Biomedical Physics and Bioengineering, UCLA, Los Angeles, CA, 90095, USA
| | - V Andrew Stenger
- Department of Medicine, University of Hawai'i at Manoa, Honolulu, HI, 96813, USA
| | - Rolf Pohmann
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, 72076, Tubingen, Germany
| | | | - Tejas Nair
- DMC R&D Center, Samsung Electronics Inc., Seocho-gu, 06765, Seoul, Korea
| | - Sungkyu Jung
- Department of Statistics, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Jingqin Luo
- Department of Surgery, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - Yuichi Motai
- Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Jingfei Ma
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - John D Hazle
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - H Michael Gach
- Departments of Radiation Oncology and Radiology, Washington University, St. Louis, MO, 63110, USA
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Herbst M, Poser BA, Singh A, Deng W, Knowles B, Zaitsev M, Stenger VA, Ernst T. Motion correction for diffusion weighted SMS imaging. Magn Reson Imaging 2016; 38:33-38. [PMID: 27988191 DOI: 10.1016/j.mri.2016.12.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 12/13/2016] [Accepted: 12/13/2016] [Indexed: 10/20/2022]
Affiliation(s)
- M Herbst
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA; Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - B A Poser
- Maastricht Brain Imaging Centre, Faculty of Psychology & Neuroscience, Maastricht University, Netherlands
| | - A Singh
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - W Deng
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - B Knowles
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M Zaitsev
- Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - V A Stenger
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - T Ernst
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
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Herbst M, Deng W, Ernst T, Stenger VA. Segmented simultaneous multi-slice diffusion weighted imaging with generalized trajectories. Magn Reson Med 2016; 78:1476-1481. [PMID: 27888543 DOI: 10.1002/mrm.26545] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [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: 04/02/2016] [Revised: 10/14/2016] [Accepted: 10/18/2016] [Indexed: 11/09/2022]
Abstract
PURPOSE The purpose of this work is to develop and evaluate a single framework for the use of Cartesian and non-Cartesian segmented trajectories for rapid and robust simultaneous multislice (SMS) diffusion weighted imaging (DWI) at 3 Telsa (T). METHODS A generalized SMS approach with intrinsic phase navigation using Multiplexed Sensitivity Encoding (MUSE) was developed. Segmented blipped-controlled aliasing in parallel imaging echo planar imaging (EPI) and z-gradient modulated spiral trajectories were examined using SMS DWI scans at 3T with a 32-channel head coil. RESULTS The generalized SMS MUSE reconstruction framework was successful in significantly reducing artifacts for all trajectories. A DWI brain volume with a 67.5-mm height, 1.5-mm isotropic resolution, and 90 diffusion weightings was obtained in a scan time of 6 minutes. CONCLUSION The MUSE technique can be generalized to allow for reconstruction of both Cartesian and non-Cartesian segmented trajectories. Magn Reson Med 78:1476-1481, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Michael Herbst
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.,Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Weiran Deng
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Thomas Ernst
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - V Andrew Stenger
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
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Deng W, Zahneisen B, Stenger VA. Rotated stack-of-spirals partial acquisition for rapid volumetric parallel MRI. Magn Reson Med 2015; 76:127-35. [PMID: 26268139 DOI: 10.1002/mrm.25863] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [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: 03/02/2015] [Revised: 06/30/2015] [Accepted: 07/10/2015] [Indexed: 11/10/2022]
Abstract
PURPOSE We present a volumetric sampling method that rotates the spiral interleaves of a stack of spirals (SOSP) trajectory for reduced aliasing artifacts using parallel imaging with undersampling. METHODS The aliasing pattern in an undersampled SOSP acquisition was modified by consecutively rotating spiral interleaves in each phase-encoding plane. This allows a sampling scheme with a high reduction factor when using a volumetric multireceiver array. Phantom and in vivo brain images at a resolution of 1 × 1 × 2 mm(3) were acquired at 3T using a 32-channel coil. Images reconstructed with a reduction factor of 16 were compared for aliasing artifacts and geometry factor (g-factor). RESULTS Phantom and in vivo brain image results revealed that the rotated SOSP acquisition with a reduction factor of 16 produces images with reduced aliasing and lower g-factors than images acquired without rotation. CONCLUSION The proposed rotated SOSP sampling method is a highly efficient way to maximize the encoding power of volumetric receiver arrays in parallel imaging and is applicable to rapid volumetric scanning, including susceptibility-weighted imaging and functional MRI. Magn Reson Med 76:127-135, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Weiran Deng
- University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii, USA
| | - Benjamin Zahneisen
- University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii, USA
| | - V Andrew Stenger
- University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii, USA
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Anderson RJ, Poser BA, Stenger VA. Simultaneous multislice spectral-spatial excitations for reduced signal loss susceptibility artifact in BOLD functional MRI. Magn Reson Med 2014; 72:1342-52. [PMID: 24338863 PMCID: PMC4058096 DOI: 10.1002/mrm.25050] [Citation(s) in RCA: 8] [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: 07/15/2013] [Revised: 10/25/2013] [Accepted: 10/28/2013] [Indexed: 11/08/2022]
Abstract
PURPOSE Simultaneous multislice (SMS) imaging can significantly increase image acquisition rates and improve temporal resolution and contrast in gradient-echo blood oxygen level-dependent (BOLD) functional MRI (fMRI) experiments. Through-plane signal loss due to B(0) inhomogeneities at air-tissue interfaces limits fMRI of structures near the nasal cavity and ear canals. This study implemented spectral-spatial (SPSP) radiofrequency pulses for reduced through-plane signal loss across multiple simultaneously excited slices. THEORY AND METHODS Multiband (MB) and power independent of number of slices (PINS) methods are combined with SPSP excitation for signal loss compensation in slice-accelerated human brain imaging. Nine simultaneous slices of 5-mm thickness and 20 mm apart were excited using standard MB radiofrequency pulses and the proposed SPSP-SMS pulses, yielding coverage of 36 slices in four shots with 350-ms volume pulse repetition time. The pulses were compared in breath-hold fMRI at 3T. RESULTS The SPSP-SMS pulses recovered ∼45% of voxels with signal loss in standard SMS images. Activation in areas of signal recovery increased by 26.4% using a 12.6-ms SPSP-MB pulse and 20.3% using a 12.1-ms SPSP-PINS pulse. CONCLUSIONS It is demonstrated that SPSP-SMS pulses can improve BOLD sensitivity in areas of signal loss across simultaneous multiple slices.
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Affiliation(s)
- Robert J. Anderson
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Benedikt A. Poser
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - V. Andrew Stenger
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
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Sharma A, Bammer R, Stenger VA, Grissom WA. Low peak power multiband spokes pulses for B1 (+) inhomogeneity-compensated simultaneous multislice excitation in high field MRI. Magn Reson Med 2014; 74:747-55. [PMID: 25203620 DOI: 10.1002/mrm.25455] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [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: 03/03/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 11/11/2022]
Abstract
PURPOSE To design low peak and integrated power simultaneous multislice excitation radiofrequency pulses with transmit field inhomogeneity compensation in high field MRI. THEORY AND METHODS The "interleaved greedy and local optimization" algorithm for small-tip-angle spokes pulses is extended to design multiband (MB) spokes pulses that simultaneously excite multiple slices, with independent spokes weight optimization for each slice. The peak power of the pulses is controlled using a slice phase optimization technique. Simulations were performed at 7T to compare the peak power of optimized MB spokes pulses to unoptimized pulses, and to compare the proposed slice-independent spokes weight optimization to a joint approach. In vivo experiments were performed at 7T to validate the pulse's function and compare them to conventional MB pulses. RESULTS Simulations showed that the peak power-minimized pulses had lower peak power than unregularized and integrated power-regularized pulses, and that the slice-independent spokes weight optimization consistently produced lower flip angle inhomogeneity and lower peak and integrated power pulses. In the brain imaging experiments, the MB spokes pulses showed significant improvement in excitation flip angle and subsequently signal homogeneity compared to conventional MB pulses. CONCLUSION The proposed MB spokes pulses improve flip angle homogeneity in simultaneous multislice acquisitions at ultrahigh field, with minimal increase in integrated and peak radiofrequency power.
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Affiliation(s)
- Anuj Sharma
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Roland Bammer
- Department of Radiology, Stanford University, Stanford, California, USA
| | - V Andrew Stenger
- Department of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - William A Grissom
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology, Vanderbilt University, Nashville, Tennessee, USA
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Zahneisen B, Poser BA, Ernst T, Stenger VA. Three-dimensional Fourier encoding of simultaneously excited slices: generalized acquisition and reconstruction framework. Magn Reson Med 2013; 71:2071-81. [PMID: 23878075 DOI: 10.1002/mrm.24875] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [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: 12/03/2012] [Revised: 05/24/2013] [Accepted: 06/15/2013] [Indexed: 11/09/2022]
Abstract
PURPOSE Simultaneous multislice (SMS) acquisitions have recently received much attention as a means of increasing single-shot imaging speed. SMS acquisitions combine the advantages of single-shot sampling and acceleration along the slice dimension which was previously limited to three-dimensional (3D) volumetric acquisitions. A two-dimensional description of SMS sampling and reconstruction has become established in the literature. Here, we present a more general 3D Fourier encoding and reconstruction formalism for SMS acquisitions that can easily be applied to non-Cartesian SMS acquisitions. THEORY AND METHODS An "SMS 3D" k-space is defined in which the field of view along the slice select direction is equal to the number of excited slices times their separation. In this picture, SMS acceleration can be viewed as an undersampling of SMS 3D k-space that can be freely distributed between the in-plane and slice directions as both are effective phase-encoding directions. RESULTS Use of the SMS 3D k-space picture is demonstrated in phantom and in vivo brain acquisitions including data obtained with blipped-controlled aliasing in parallel imaging sampling. SMS sensitivity encoding reconstruction is demonstrated as well as non-Cartesian SMS imaging using blipped spiral trajectories. CONCLUSIONS The full framework of reconstruction methods can be applied to SMS acquisitions by employing a 3D k-space approach. The blipped-controlled aliasing in parallel imaging method can be viewed as a special case of undersampling an SMS 3D k-space. The extension of SMS methods to non-Cartesian 3D sampling and reconstruction is straightforward.
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Affiliation(s)
- Benjamin Zahneisen
- Department of Medicine, University of Hawaii, John A. Burns School of Medicine, Honolulu, Hawaii, USA
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14
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Poser BA, Anderson RJ, Guérin B, Setsompop K, Deng W, Mareyam A, Serano P, Wald LL, Stenger VA. Simultaneous multislice excitation by parallel transmission. Magn Reson Med 2013; 71:1416-27. [PMID: 23716365 DOI: 10.1002/mrm.24791] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [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: 08/16/2012] [Revised: 04/09/2013] [Accepted: 04/10/2013] [Indexed: 11/11/2022]
Abstract
PURPOSE A technique is described for simultaneous multislice (SMS) excitation using radiofrequency (RF) parallel transmission (pTX). METHODS Spatially distinct slices are simultaneously excited by applying different RF frequencies on groups of elements of a multichannel transmit array. The localized transmit sensitivities of the coil geometry are thereby exploited to reduce RF power. The method is capable of achieving SMS-excitation using single-slice RF pulses, or multiband pulses. SMS-pTX is demonstrated using eight-channel parallel RF transmission on a dual-ring pTX coil at 3 T. The effect on B(1)(+) homogeneity and specific absorption rate (SAR) is evaluated experimentally and by simulations. Slice-GRAPPA reconstruction was used for separation of the collapsed slice signals. RESULTS Phantom and in vivo brain data acquired with fast low-angle shot (FLASH) and blipped-controlled aliasing results in higher acceleration (CAIPIRINHA) echo-planar imaging are presented at SMS excitation factors of two, four, and six. We also show that with our pTX coil design, slice placement, and binary division of transmitters, SMS-pTX excitations can achieve the same mean flip angles excitations at ∼30% lower RF power than a conventional SMS approach with multiband RF pulses. CONCLUSION The proposed SMS-pTX allows SMS excitations at reduced RF power by exploiting the local B(1)(+) sensitivities of suitable multielement pTX arrays.
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Affiliation(s)
- Benedikt A Poser
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
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15
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Yang C, Poser B, Deng W, Stenger VA. Spectral decomposition of susceptibility artifacts for spectral-spatial radiofrequency pulse design. Magn Reson Med 2012; 68:1905-10. [PMID: 22334396 PMCID: PMC3355209 DOI: 10.1002/mrm.24208] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [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: 09/12/2011] [Revised: 12/14/2011] [Accepted: 01/19/2012] [Indexed: 11/08/2022]
Abstract
Susceptibility induced signal loss is a limitation in gradient echo functional MRI. The through-plane artifact in axial slices is particularly problematic due to the inferior position of air cavities in the brain. Spectral-spatial radiofrequency pulses have recently been shown to reduce signal loss in a single excitation. The pulses were successfully demonstrated assuming a linear relationship between susceptibility gradient and frequency, however, the exact frequency and spatial distribution of the susceptibility gradient in the brain is unknown. We present a spiral spectroscopic imaging sequence with a time-shifted radiofrequency pulse that can spectrally decompose the through-plane susceptibility gradient for spectral-spatial radiofrequency pulse design. Maps of the through-plane susceptibility gradient as a function of frequency were generated for the human brain at 3T. We found that the linear relationship holds well for the whole brain with an optimal slope of -1.0 μT/m/Hz.
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Affiliation(s)
- Cungeng Yang
- Department of Medicine, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii
| | - Benedikt Poser
- Department of Medicine, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii
| | - Weiran Deng
- Department of Medicine, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii
| | - V. Andrew Stenger
- Department of Medicine, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii
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16
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Poser BA, Barth M, Goa PE, Deng W, Stenger VA. Single-shot echo-planar imaging with Nyquist ghost compensation: interleaved dual echo with acceleration (IDEA) echo-planar imaging (EPI). Magn Reson Med 2012; 69:37-47. [PMID: 22411762 DOI: 10.1002/mrm.24222] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 12/28/2011] [Accepted: 01/30/2012] [Indexed: 11/12/2022]
Abstract
Echo planar imaging (EPI) is most commonly used for blood oxygen level-dependent fMRI, owing to its sensitivity and acquisition speed. A major problem with EPI is Nyquist (N/2) ghosting, most notably at high field. EPI data are acquired under an oscillating readout gradient and hence vulnerable to gradient imperfections such as eddy current delays and off-resonance effects, as these cause inconsistencies between odd and even k-space lines after time reversal. We propose a straightforward and pragmatic method herein termed "interleaved dual echo with acceleration (IDEA) EPI": two k-spaces (echoes) are acquired under the positive and negative readout lobes, respectively, by performing phase encoding blips only before alternate readout gradients. From these two k-spaces, two almost entirely ghost free images per shot can be constructed, without need for phase correction. The doubled echo train length can be compensated by parallel imaging and/or partial Fourier acquisition. The two k-spaces can either be complex averaged during reconstruction, which results in near-perfect cancellation of residual phase errors, or reconstructed into separate images. We demonstrate the efficacy of IDEA EPI and show phantom and in vivo images at both 3 T and 7 T.
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Affiliation(s)
- Benedikt A Poser
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
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17
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Deng W, Yang C, Stenger VA. Accelerated multidimensional radiofrequency pulse design for parallel transmission using concurrent computation on multiple graphics processing units. Magn Reson Med 2011; 65:363-9. [PMID: 21264929 PMCID: PMC3069537 DOI: 10.1002/mrm.22690] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [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: 03/15/2010] [Revised: 07/09/2010] [Accepted: 09/24/2010] [Indexed: 01/30/2023]
Abstract
Multidimensional radiofrequency (RF) pulses are of current interest because of their promise for improving high-field imaging and for optimizing parallel transmission methods. One major drawback is that the computation time of numerically designed multidimensional RF pulses increases rapidly with their resolution and number of transmitters. This is critical because the construction of multidimensional RF pulses often needs to be in real time. The use of graphics processing units for computations is a recent approach for accelerating image reconstruction applications. We propose the use of graphics processing units for the design of multidimensional RF pulses including the utilization of parallel transmitters. Using a desktop computer with four NVIDIA Tesla C1060 computing processors, we found acceleration factors on the order of 20 for standard eight-transmitter two-dimensional spiral RF pulses with a 64 × 64 excitation resolution and a 10-μsec dwell time. We also show that even greater acceleration factors can be achieved for more complex RF pulses.
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Affiliation(s)
- Weiran Deng
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
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18
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Yang C, Deng W, Stenger VA. Simple analytical dual-band spectral-spatial RF pulses for B(1) + and susceptibility artifact reduction in gradient echo MRI. Magn Reson Med 2011; 65:370-6. [PMID: 21264930 PMCID: PMC3065027 DOI: 10.1002/mrm.22725] [Citation(s) in RCA: 11] [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: 05/21/2010] [Revised: 10/14/2010] [Accepted: 10/17/2010] [Indexed: 11/09/2022]
Abstract
Susceptibility artifacts and transmission radio frequency (RF) field (B(1) +) inhomogeneity are major limitations in high-field gradient echo MRI. Previously proposed numerical 2D spectral-spatial RF pulses have been shown to be promising for reducing the through-plane signal loss susceptibility artifact by incorporating a frequency-dependent through-plane phase correction. This method has recently been extended to 4D spectral-spatial RF pulse designs for reducing B(1) + inhomogeneity as well as the signal loss. In this manuscript, we present simple analytical pulse designs for constructing 2D and 4D spectral-spatial RF pulses as an alternative to the numerical approaches. The 2D pulse capable of exciting slices with reduced signal loss and is lipid suppressing. The 4D pulse simultaneously corrects signal loss as well as the B(1) + inhomogeneity from a body coil transmitter. The pulses are demonstrated with simulations and with gradient echo phantom and brain images at 3T using a standard RF body coil. The pulses were observed to work well for multiple slices and several volunteers.
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Affiliation(s)
| | | | - V. Andrew Stenger
- Department of Medicine, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii
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19
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Keating B, Deng W, Roddey JC, White N, Dale A, Stenger VA, Ernst T. Prospective motion correction for single-voxel 1H MR spectroscopy. Magn Reson Med 2011; 64:672-9. [PMID: 20806374 DOI: 10.1002/mrm.22448] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Head motion during (1)H MR spectroscopy acquisitions may compromise the quality and reliability of in vivo metabolite measurements. Therefore, a three-plane image-based motion-tracking module was integrated into a single-voxel (1)H MR spectroscopy (point-resolved spectroscopy) sequence. A series of three orthogonal spiral navigator images was acquired immediately prior to the MR spectroscopy water suppression module in order to estimate head motion. By applying the appropriate rotations and translations, the MR spectroscopy voxel position can be updated such that it remains stationary with respect to the brain. Frequency and phase corrections were applied during postprocessing to reduce line width and restore coherent averaging. Spectra acquired during intentional head motion in 11 volunteers demonstrate reduced lipid contamination and increased spectral reproducibility when motion correction is applied.
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Affiliation(s)
- Brian Keating
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96813-2427, USA.
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20
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Yang C, Deng W, Alagappan V, Wald LL, Stenger VA. Four-dimensional spectral-spatial RF pulses for simultaneous correction of B1+ inhomogeneity and susceptibility artifacts in T2*-weighted MRI. Magn Reson Med 2010; 64:1-8. [PMID: 20577982 PMCID: PMC3040071 DOI: 10.1002/mrm.22471] [Citation(s) in RCA: 20] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 03/03/2010] [Indexed: 11/10/2022]
Abstract
Susceptibility artifacts and excitation radiofrequency field B(1)+ inhomogeneity are major limitations in high-field MRI. Parallel transmission methods are promising for reducing artifacts in high-field applications. In particular, three-dimensional RF pulses have been shown to be useful for reducing B(1)+ inhomogeneity using multiple transmitters due to their ability to spatially shape the slice profile. Recently, two-dimensional spectral-spatial pulses have been demonstrated to be effective for reducing the signal loss susceptibility artifact by incorporating a frequency-dependent through-plane phase correction. We present the use of four-dimensional spectral-spatial RF pulses for simultaneous B(1)+ and through-plane signal loss susceptibility artifact compensation. The method is demonstrated with simulations and in T(2)*-weighted human brain images at 3 T, using a four-channel parallel transmission system. Parallel transmission was used to reduce the in-plane excitation resolution to improve the slice-selection resolution between two different pulse designs. Both pulses were observed to improve B(1)+ homogeneity and reduce the signal loss artifact in multiple slice locations and several human volunteers.
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Affiliation(s)
- Cungeng Yang
- Department of Medicine, John A. Burns School of Medicine, Honolulu, Hawaii
| | - Weiran Deng
- Department of Medicine, John A. Burns School of Medicine, Honolulu, Hawaii
| | | | - Lawrence L. Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts
| | - V. Andrew Stenger
- Department of Medicine, John A. Burns School of Medicine, Honolulu, Hawaii
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21
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Abstract
Three-dimensional spatial-spectral radiofrequency pulses using a stack-of-spirals trajectory can achieve two-dimensional spatial localization and one-dimensional spectral selection simultaneously. These pulses are useful, for example, in reduced field-of-view applications that also require frequency specificity such as lipid imaging. A limitation of the pulse design is that the length of the spiral trajectory is fixed by the frequency separation of lipid and water. This restricts the highest possible excitation resolution of the spatial profile over a given field of excitation. In this work, we examine the use of periodically rotated variable-density spirals to increase the spatial excitation resolution without changing the frequency selectivity. Variable-density spirals are used to undersample the high spatial frequencies such that higher excitation resolutions can be obtained with a small expense in increased aliasing of the slice profile. The periodic rotation of the spiral trajectories reduces the impact of the undersampling by distributing the aliasing in the frequency domain. The technique is demonstrated with simulations, phantom studies, and imaging human leg muscle at 3 T. It was found in the human study that the spatial excitation resolution could be improved from 6 x 6 to 8 x 8 (matrix size over a fixed field of view) while decreasing aliasing by approximately 40-60%.
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Affiliation(s)
- Weiran Deng
- Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96813-2427, USA.
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22
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Deng W, Nakama H, Chang L, Haning W, Stenger VA. Evaluation of the Inhibitory Circuit of Methamphetamine Users using Functional MRI with a Go-NoGo Task. Neuroimage 2009. [DOI: 10.1016/s1053-8119(09)70046-1] [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: 12/01/2022] Open
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23
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Deng W, Chang L, Nakama H, Fein G, Stenger VA. Increased Saliency to Rewards and Losses with Blunted Responses to Risks in Methamphetamine Users using the Balloon-Analogue-Risk-Task (BART). Neuroimage 2009. [DOI: 10.1016/s1053-8119(09)70374-x] [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: 10/20/2022] Open
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24
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Deng W, Yang C, Alagappan V, Wald LL, Boada FE, Stenger VA. Simultaneous z-shim method for reducing susceptibility artifacts with multiple transmitters. Magn Reson Med 2009; 61:255-9. [PMID: 19165881 PMCID: PMC2714643 DOI: 10.1002/mrm.21870] [Citation(s) in RCA: 22] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 10/01/2008] [Indexed: 11/10/2022]
Abstract
The signal loss susceptibility artifact is a major limitation in gradient-echo MRI applications. Various methods, including z-shim techniques and multidimensional tailored radio frequency (RF) pulses, have been proposed to mitigate the through-plane signal loss artifact, which is dominant in axial slices above the sinus region. Unfortunately, z-shim techniques require multiple steps and multidimensional RF methods are complex, with long pulse lengths. Parallel transmission methods were recently shown to be promising for improving B1 inhomogeneity and reducing the specific absorption rate. In this work, a novel method using time-shifted slice-select RF pulses is presented for reducing the through-plane signal loss artifact in parallel transmission applications. A simultaneous z-shim is obtained by concurrently applying unique time-shifted pulses on each transmitter. The method is shown to reduce the signal loss susceptibility artifact in gradient-echo images using a four-channel parallel transmission system at 3T.
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Affiliation(s)
- Weiran Deng
- UH-QMC Magnetic Resonance Research Center, Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96813-2427, USA.
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25
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Ursu S, Clark KA, Aizenstein HJ, Stenger VA, Carter CS. Conflict-related activity in the caudal anterior cingulate cortex in the absence of awareness. Biol Psychol 2008; 80:279-86. [PMID: 19026710 DOI: 10.1016/j.biopsycho.2008.10.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 09/03/2008] [Accepted: 10/21/2008] [Indexed: 12/30/2022]
Abstract
The caudal anterior cingulate cortex (cACC) is thought to be involved in performance monitoring, as conflict and error-related activity frequently co-localize in this area. Recent results suggest that these effects may be differentially modulated by awareness. To clarify the role of awareness in performance monitoring by the cACC, we used rapid event-related fMRI to examine the cACC activity while subjects performed a dual task: a delayed recognition task and a serial response task (SRT) with an implicit probabilistic learning rule (i.e. the stimulus location followed a probabilistic sequence of which the subjects were unaware). Task performance confirmed that the location sequence was learned implicitly. Even though we found no evidence of awareness for the presence of the sequence, imaging data revealed increased cACC activity during correct trials which violated the sequence (high-conflict), relative to trials when stimuli followed the sequence (low conflict). Errors made with awareness also activated the same brain region. These results suggest that the performance monitoring function of the cACC extends beyond detection of errors made with or without awareness, and involves detection of multiple responses even when they are outside of awareness.
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Affiliation(s)
- Stefan Ursu
- Department of Psychiatry, University of California, Davis, Sacramento, CA 95817, USA.
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26
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Van Horn JD, Bandettini PA, Cheng K, Egan GF, Stenger VA, Strother S, Toga AW. New Horizons for the Next Era of Human Brain Imaging, Cognitive, and Behavioral Research: Pacific Rim Interactivity. Brain Imaging Behav 2008; 2:227-231. [PMID: 20169011 DOI: 10.1007/s11682-008-9045-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Beginning in the 1990's, substantial advances have been made in the ability to image the living human brain. Functional MRI, PET, and other modalities have been developed to provide a rich means for assessing brain function and structure across spatial and temporal dimensions. Such methods are now the preferred means to examine the brain in vivo, with several thousand articles now appearing in the literature each year. The next era of human brain imaging is upon us now as technological developments reach a level where data can be processed quickly and combined with other biological information to provide fundamentally new applications and insights. This new era will involve and require the collaborative participation of leading research groups from around the world to share information and expertise for understanding observed effects and synthesizing these into new knowledge. One particular community that is gaining in its prominence in the field is that of the Pacific Rim, whose collective research efforts present an important corpus of research effort into brain structure and function. The Pacific Rim represents an important collection of researchers interested in the greater sharing of ideas. In this special issue of Brain Imaging and Behavior, we focus on emerging areas of research that utilize brain imaging methodology, and discuss how current developments are driving the expansion of functional imaging research. Moreover, we focus on the robust interaction of researchers from around the Pacific Rim whose collaborations are significantly shaping the future of brain imaging.
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Affiliation(s)
- John Darrell Van Horn
- Laboratory of Neuro Imaging (LONI), University of California Los Angeles (USA), 635 Charles E. Young Drive SW, Suite 225, Los Angeles, CA 90095 USA
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Ursu S, Clark KA, Stenger VA, Carter CS. Distinguishing expected negative outcomes from preparatory control in the human orbitofrontal cortex. Brain Res 2008; 1227:110-9. [PMID: 18602375 DOI: 10.1016/j.brainres.2008.06.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 05/19/2008] [Accepted: 06/04/2008] [Indexed: 11/26/2022]
Abstract
The human orbitofrontal cortex (OFC) plays a critical role in adapting behavior according to the context provided by expected outcomes of actions. However, several aspects of this function are still poorly understood. In particular, it is unclear to what degree any subdivisions of the OFC are specifically engaged when negatively valenced outcomes are expected, and to what extent such areas might be involved in preparatory active control of behavior. We examined these issues in two complementary functional magnetic resonance imaging (fMRI) studies in which we simultaneously and independently manipulated monetary incentives for correct performance, and demands for active preparation of cognitive control. In both experiments, preparation for performance was associated with lateral PFC activity in response to high incentives, regardless of their valence, as well as in response to increased task demands. In contrast, areas of the OFC centered around the lateral orbital sulcus responded maximally to negatively perceived prospects, even when such prospects were associated with decreases in preparatory cognitive control. These results provide direct support for theoretical models which posit that the OFC contributes to behavioral regulation by representing the value of anticipated outcomes, but does not implement active control aimed at avoiding or pursuing outcomes. Furthermore, they provide additional converging evidence that the lateral OFC is involved in representing specifically the affective impact of anticipated negative outcomes.
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Affiliation(s)
- Stefan Ursu
- Department of Psychiatry, University of California-Davis, Sacramento, CA 95817, USA.
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28
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Abstract
Parallel transmitter techniques are a promising approach for reducing transmitter B1 inhomogeneity due to the potential for adjusting the spatial excitation profile with independent RF pulses. These techniques may be further improved with transmit sensitivity encoding (SENSE) methods because the sensitivity information in pulse design provides an excitation that is inherently compensated for transmitter B1 inhomogeneity. This paper presents a proof of this concept using transmit SENSE 3D tailored RF pulses designed for small flip angles. An eight-channel receiver coil was used to mimic parallel transmission for brain imaging at 3T. The transmit SENSE pulses were based on the fast-k(z) design and produced 5-mm-thick slices at a flip angle of 30 degrees with only a 4.3-ms pulse length. It was found that the transmit SENSE pulses produced more homogeneous images than those obtained from the complex sum of images from all receivers excited with a standard RF pulse.
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Affiliation(s)
| | - Chun-Yu Yip
- University of Michigan Departments of Electrical Engineering and Computer Science
| | | | - Douglas C. Noll
- University of Michigan Departments of Electrical Engineering and Computer Science
- University of Michigan Department of Biomedical Engineering
| | - Fernando E. Boada
- University of Pittsburgh, Department of Bioengineering
- University of Pittsburgh Department of Radiology
| | - V. Andrew Stenger
- University of Hawaii Department of Medicine
- Corresponding Author: V. Andrew Stenger, Ph.D., UH-QMC Magnetic Resonance Research Center, University of Hawaii John A. Burns School of Medicine Department of Medicine, 1356 Lusitana Street, 7 Floor, Honolulu, HI 96813-2427, USA, Tel: (+1) 808-585-5159, Fax: (+1) 808-585-5160,
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Stenger VA, Giurgi MS, Boada FE, Noll DC. Excitation UNFOLD (XUNFOLD) to improve the temporal resolution of multishot tailored RF pulses. Magn Reson Med 2006; 56:692-7. [PMID: 16894575 PMCID: PMC3050053 DOI: 10.1002/mrm.21000] [Citation(s) in RCA: 5] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Accepted: 05/16/2006] [Indexed: 01/23/2023]
Abstract
An extension of the "UNaliasing by Fourier encoding the Overlaps using the temporaL Dimension" (UNFOLD) method to the excitation domain (XUNFOLD) is presented to improve the temporal resolution of multishot tailored RF (TRF) pulses. Multishot three-dimensional TRF pulses were designed to produce a time series of images with periodically aliased excitation profiles. The XUNFOLD method is shown to remove the excitation profile aliasing from the dynamic imaging data by filtering in the temporal frequency dimension. The technique is demonstrated to improve the temporal resolution of simulated functional MRI (fMRI) activation in a time series of brain images.
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Affiliation(s)
- V Andrew Stenger
- Department of Medicine, University of Hawaii, Honolulu, Hawaii 96813, USA.
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Aizenstein HJ, Butters MA, Clark KA, Figurski JL, Andrew Stenger V, Nebes RD, Reynolds CF, Carter CS. Prefrontal and striatal activation in elderly subjects during concurrent implicit and explicit sequence learning. Neurobiol Aging 2006; 27:741-51. [PMID: 15935517 DOI: 10.1016/j.neurobiolaging.2005.03.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [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: 05/27/2004] [Revised: 03/02/2005] [Accepted: 03/09/2005] [Indexed: 11/27/2022]
Abstract
Decreased function in the prefrontal cortex (PFC) is regarded as a primary mechanism of cognitive aging. However, despite a strong association between the prefrontal cortex and the neostriatum, the role of the neostriatum in cognitive aging is less certain. In the current study, event-related functional MRI was used to distinguish the cognitive contributions of neostriatal and prefrontal function in elderly versus young subjects. Twenty healthy subjects, 9 elderly (mean age 67.6 years), and 11 young (mean age 22 years) performed a concurrent implicit and explicit sequence learning task while undergoing functional MR imaging. Both groups showed learning in both the implicit and explicit task conditions. Relative to the young subjects, the elderly subjects showed decreased activation in the left PFC during both implicit and explicit learning, decreased activation in the right putamen during implicit learning, and increased activation in the right PFC during explicit learning. Our results support the theory that changes in a network of brain regions, including the dorsolateral prefrontal cortex and the striatum, are related to cognitive aging. Moreover, these changes are observed during an implicit task, and thus do not seem to be mediated by awareness.
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Affiliation(s)
- Howard J Aizenstein
- Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Department of Psychiatry, 3811 O'Hara Street, Pittsburgh, PA 15213, USA. aizen+@pitt.edu
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Saekho S, Yip CY, Noll DC, Boada FE, Stenger VA. Fast-kz three-dimensional tailored radiofrequency pulse for reduced B1 inhomogeneity. Magn Reson Med 2006; 55:719-24. [PMID: 16526012 PMCID: PMC3076290 DOI: 10.1002/mrm.20840] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [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: 08/19/2005] [Accepted: 12/19/2005] [Indexed: 11/09/2022]
Abstract
This article presents a small-flip-angle, three-dimensional tailored RF pulse that excites thin slices with an adjustable quadratic in-plane spatial variation. The quadratic spatial variation helps to compensate for the loss in image uniformity using a volume coil at 3 T due to the wavelike properties of the RF field. The pulse is based on a novel "fast-kz" design that uses a series of slice-select subpulses along kz and phase encoding "blips" along kx-ky. The method is demonstrated by acquiring a series of 5-mm-thick T2-weighted images of the human brain at 3 T using pulses 4.8 ms in length with a 45 degrees flip angle.
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Affiliation(s)
- Suwit Saekho
- Chiangmai University, Associated Medical Sciences
| | - Chun-yu Yip
- University of Michigan Department of Electrical Engineering and Computer Science
| | - Douglas C. Noll
- University of Michigan Department of Electrical Engineering and Computer Science
- University of Michigan Departments of Biomedical Engineering
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Abstract
Parallel excitation has been introduced as a means of accelerating multidimensional, spatially-selective excitation using multiple transmit coils, each driven by a unique RF pulse. Previous approaches to RF pulse design in parallel excitation were either formulated in the frequency domain or restricted to echo-planar trajectories, or both. This paper presents an approach that is formulated as a quadratic optimization problem in the spatial domain and allows the use of arbitrary k-space trajectories. Compared to frequency domain approaches, the new design method has some important advantages. It allows for the specification of a region of interest (ROI), which improves excitation accuracy at high speedup factors. It allows for magnetic field inhomogeneity compensation during excitation. Regularization may be used to control integrated and peak pulse power. The effects of Bloch equation nonlinearity on the large-tip-angle excitation error of RF pulses designed with the method are investigated, and the utility of Tikhonov regularization in mitigating this error is demonstrated.
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Affiliation(s)
- William Grissom
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2108, USA.
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Kerns JG, Cohen JD, MacDonald AW, Johnson MK, Stenger VA, Aizenstein H, Carter CS. Decreased conflict- and error-related activity in the anterior cingulate cortex in subjects with schizophrenia. Am J Psychiatry 2005; 162:1833-9. [PMID: 16199829 DOI: 10.1176/appi.ajp.162.10.1833] [Citation(s) in RCA: 230] [Impact Index Per Article: 12.1] [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: 01/03/2023]
Abstract
OBJECTIVE People with schizophrenia have exhibited reduced functional activity in the anterior cingulate cortex during the performance of many types of cognitive tasks and during the commission of errors. According to conflict theory, the anterior cingulate cortex is involved in the monitoring of response conflict, acting as a signal for a need for greater cognitive control. This study examined whether impaired conflict monitoring in people with schizophrenia could underlie reduced anterior cingulate activity during both correct task performance and error-related activity. METHOD Functional activity in the anterior cingulate of 13 schizophrenia patients and 13 healthy comparison subjects was investigated by using event-related fMRI and a Stroop task that allowed simultaneous examination of activity during both conflict (incongruent trials) and error (commission of error trials). RESULTS In the presence of comparable reaction time measures for conflict as well as comparable error rates, the schizophrenia subjects showed both decreased conflict- and error-related activity in the same region of the anterior cingulate cortex. Moreover, those with schizophrenia did not exhibit significant post-conflict or post-error behavioral adjustments. CONCLUSIONS Concurrently reduced conflict- and error-related activity in the anterior cingulate cortex along with reduced trial-to-trial adjustments in performance has not previously been reported in schizophrenia. The current results suggest that impaired conflict monitoring by the anterior cingulate cortex might play an important role in contributing to cognitive control deficits in patients with schizophrenia.
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Affiliation(s)
- John G Kerns
- UC Davis Imaging Research Center, University of California-Davis, 4701 X Street, Sacramento, CA 95817, USA
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Aizenstein HJ, Butters MA, Figurski JL, Stenger VA, Reynolds CF, Carter CS. Prefrontal and striatal activation during sequence learning in geriatric depression. Biol Psychiatry 2005; 58:290-6. [PMID: 16018981 DOI: 10.1016/j.biopsych.2005.04.023] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [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] [Received: 08/31/2004] [Revised: 03/29/2005] [Accepted: 04/13/2005] [Indexed: 11/15/2022]
Abstract
BACKGROUND Frontostriatal dysfunction is a primary hypothesis for the neurocognitive changes of depression in late life. The aim of the present study was to test this hypothesis with the use of functional magnetic resonance imaging (fMRI) tasks that are known to engage the prefrontal and neostriatal cognitive circuits. METHODS Twenty-three elderly subjects (mean age, 69.9 years) participated: 11 subjects with a current major depressive episode and 12 nondepressed elderly control subjects. Subjects underwent fMRI while performing a concurrent implicit and explicit sequence learning task. Region of interest (ROI)-based analyses were conducted, focusing on the dorsal anterior cingulate cortex, the dorsolateral prefrontal cortex, and the neostriatum. RESULTS As expected, both the control and depressed subjects learned the sequence during both implicit and explicit conditions. During explicit learning, decreased prefrontal activation was found in the depressed subjects, along with increased striatal activation. The increased striatal activity in the depressed subjects was due to increased activity on the trials that violated the sequence. During implicit learning, no significant differences were found between the groups in the identified ROIs. CONCLUSIONS The increased striatal activation on trials that violated the sequence demonstrates a greater response to negative feedback for depressed compared with control subjects. Our observations of significant differences in both prefrontal and striatal regions in the depressed elderly subjects relative to elderly control subjects supports the frontostriatal dysfunction hypothesis of late-life depression.
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Affiliation(s)
- Howard J Aizenstein
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. aizen+@pitt.edu
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Holmes AJ, MacDonald A, Carter CS, Barch DM, Andrew Stenger V, Cohen JD. Prefrontal functioning during context processing in schizophrenia and major depression: an event-related fMRI study. Schizophr Res 2005; 76:199-206. [PMID: 15949653 DOI: 10.1016/j.schres.2005.01.021] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [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] [Received: 04/09/2004] [Revised: 01/24/2005] [Accepted: 01/26/2005] [Indexed: 11/28/2022]
Abstract
Patients with schizophrenia frequently demonstrate hypofrontality in tasks that require executive processing; however questions still remain as to whether prefrontal cortex dysfunctions are specific to schizophrenia, or a general feature of major psychopathology. Context processing is conceptualized as an executive function associated with attention and working memory processes. Impairment in the ability of patients with schizophrenia to represent and maintain context information has been previously reported in a number of studies. To examine the question of the specificity of a context processing deficit to schizophrenia, we used functional MRI and an expectancy AX continuous performance task designed to assess context processing in a group of healthy controls (n=9), depressed patient controls (n=10), and patients with schizophrenia (n=7). The behavioral performance was consistent with a context processing deficit in patients with schizophrenia, but not those with depression. The imaging data replicate previous results in showing abnormal activity in the right middle frontal gyrus (BA9) in schizophrenia patients related to context processing.
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Affiliation(s)
- Avram J Holmes
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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MacDonald AW, Carter CS, Kerns JG, Ursu S, Barch DM, Holmes AJ, Stenger VA, Cohen JD. Specificity of prefrontal dysfunction and context processing deficits to schizophrenia in never-medicated patients with first-episode psychosis. Am J Psychiatry 2005; 162:475-84. [PMID: 15741464 DOI: 10.1176/appi.ajp.162.3.475] [Citation(s) in RCA: 252] [Impact Index Per Article: 13.3] [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: 11/30/2022]
Abstract
OBJECTIVE Context processing is a cognitive construct associated with activity in the middle frontal gyrus. Schizophrenia-related deficits in context processing tasks have been associated with prefrontal cortical dysfunction. This study evaluated whether prefrontal cortical dysfunction related to context processing occurred in first-episode, never-medicated schizophrenia patients, whether this dysfunction also occurred in patients with nonschizophrenia psychosis, and whether this dysfunction was related to psychotic symptom expression. METHOD A modified version of the AX continuous performance task was conducted during event-related functional magnetic resonance imaging in 18 never-medicated, first-episode schizophrenia patients, 12 never-medicated patients with first-episode nonschizophrenia psychosis, and 28 comparison participants without psychiatric disorder. RESULTS In-scanner measures of errors and interference reaction time showed that the schizophrenia patients had a specific deficit in context processing. Trials with greater context processing demands corresponded to activity in the middle frontal gyrus (Brodmann's area 9) in the comparison subjects and in the patients with nonschizophrenia psychosis, but not in the schizophrenia patients. Individual differences in prefrontal cortical dysfunction were associated with context processing measures and disorganization symptoms. The schizophrenia patients also showed increased activity in the anterior (Brodmann's area 10) and inferior prefrontal cortices (Brodmann's area 45/46) when they were maintaining context over a delay. CONCLUSIONS Prefrontal dysfunctions related to context processing were found only in schizophrenia patients early in the course of the illness, and these dysfunctions were related to disorganization symptoms. Instead of using context processing during a continuous performance task, schizophrenia patients may use an inefficient encoding and retrieval strategy.
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Affiliation(s)
- Angus W MacDonald
- Department of Psychology, University of Minnesota, N219 Elliott Hall, 75 E. River Rd., Minneapolis, MN 55455, USA.
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Sohn MH, Goode A, Stenger VA, Jung KJ, Carter CS, Anderson JR. An information-processing model of three cortical regions: evidence in episodic memory retrieval. Neuroimage 2005; 25:21-33. [PMID: 15734340 DOI: 10.1016/j.neuroimage.2004.11.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [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: 12/11/2003] [Revised: 10/25/2004] [Accepted: 11/01/2004] [Indexed: 10/25/2022] Open
Abstract
ACT-R (Anderson, J.R., et al., 2003. An information-processing model of the BOLD response in symbol manipulation tasks. Psychon. Bull. Rev. 10, 241-261) relates the inferior dorso-lateral prefrontal cortex to a retrieval buffer that holds information retrieved from memory and the posterior parietal cortex to an imaginal buffer that holds problem representations. Because the number of changes in a problem representation is not necessarily correlated with retrieval difficulties, it is possible to dissociate prefrontal-parietal activations. In two fMRI experiments, we examined this dissociation using the fan effect paradigm. Experiment 1 compared a recognition task, in which representation requirement remains the same regardless of retrieval difficulty, with a recall task, in which both representation and retrieval loads increase with retrieval difficulty. In the recognition task, the prefrontal activation revealed a fan effect but not the parietal activation. In the recall task, both regions revealed fan effects. In Experiment 2, we compared visually presented stimuli and aurally presented stimuli using the recognition task. While only the prefrontal region revealed the fan effect, the activation patterns in the prefrontal and the parietal region did not differ by stimulus presentation modality. In general, these results provide support for the prefrontal-parietal dissociation in terms of retrieval and representation and the modality-independent nature of the information processed by these regions. Using ACT-R, we also provide computational models that explain patterns of fMRI responses in these two areas during recognition and recall.
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Affiliation(s)
- Myeong-Ho Sohn
- Department of Psychology, Carnegie Mellon University, 342C Baker Hall, Pittsburgh, PA 15213, USA.
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Saekho S, Boada FE, Noll DC, Stenger VA. Small tip angle three-dimensional tailored radiofrequency slab-select pulse for reduced B1 inhomogeneity at 3 T. Magn Reson Med 2005; 53:479-84. [PMID: 15678525 PMCID: PMC4120772 DOI: 10.1002/mrm.20358] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [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: 05/11/2004] [Accepted: 08/30/2004] [Indexed: 11/10/2022]
Abstract
This work presents a small tip-angle 3D tailored RF slab-select pulse for reducing the B1 field inhomogeneity at 3T. The compensated slice profile was determined from a B1 inhomogeneity map. SNR improvement and degree of artifact reduction were evaluated in a NiCl2 doped phantom and human brains. The technique was found to reduce inhomogeneities as large as 30% of the peak image magnitude in all three spatial directions in the brain using a standard head coil.
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Affiliation(s)
- Suwit Saekho
- University of Pittsburgh Department of Bioengineering
| | - Fernando E. Boada
- University of Pittsburgh Department of Bioengineering
- University of Pittsburgh Department of Radiology
| | - Douglas C. Noll
- University of Michigan Departments of Biomedical Engineering and Radiology
| | - V. Andrew Stenger
- University of Pittsburgh Department of Bioengineering
- University of Pittsburgh Department of Radiology
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Abstract
Current standard sensitivity-encoded parallel imaging (SENSE) utilizes a fully sampled low-resolution reference scan to estimate the coil sensitivities. This reference scan adds scan time and may introduce misregistration artifacts. The purpose of this study was to investigate the feasibility of estimating the coil sensitivities for spiral SENSE directly from an undersampled k-space center. The limited spatial frequencies of the coil sensitivities, and the undersampling beyond the Nyquist radius cause image artifacts. A point spread function (PSF) analysis and experiments on both phantoms and humans identified an optimal radius for the k-space center by minimizing these image artifacts. The preliminary data indicate that self-calibrated SENSE is as accurate as standard SENSE, which uses a fully sampled reference scan.
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Affiliation(s)
- Yongxian Qian
- Department of Radiology, University of Pittsburgh, PA, USA
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van Veen V, Holroyd CB, Cohen JD, Stenger VA, Carter CS. Errors without conflict: Implications for performance monitoring theories of anterior cingulate cortex. Brain Cogn 2004; 56:267-76. [PMID: 15518940 DOI: 10.1016/j.bandc.2004.06.007] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.0] [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] [Accepted: 06/16/2004] [Indexed: 11/21/2022]
Abstract
Recent theories of the neural basis of performance monitoring have emphasized a central role for the anterior cingulate cortex (ACC). Replicating an earlier event-related potential (ERP) study, which showed an error feedback negativity that was modeled as having an ACC generator, we used event-related fMRI to investigate whether the ACC would differentiate between correct and incorrect feedback stimuli in a time estimation task. The design controlled for response conflict and frequency and expectancy effects. Although participants in the current study adjusted their performance following error feedback, we did not observe error feedback-evoked ACC activity. In contrast, we did observe ACC activity while the same subjects performed the Stroop task, in which an area of the ACC activated during both conflict and error trials. These findings are inconsistent with previous dipole models of the error feedback negativity, and suggest the ACC may not be involved in the generation of this ERP component. These results question involvement of the ACC in the detection of errors per se when controlling for conflict.
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Zhu H, Buck DG, Zhang Z, Zhang H, Wang P, Stenger VA, Prince MR, Wang Y. High temporal and spatial resolution 4D MRA using spiral data sampling and sliding window reconstruction. Magn Reson Med 2004; 52:14-8. [PMID: 15236361 DOI: 10.1002/mrm.20167] [Citation(s) in RCA: 28] [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] [Indexed: 11/05/2022]
Abstract
Contrast-enhanced magnetic resonance angiography (CE-MRA) requires high spatial resolution to demonstrate detailed vasculature and high temporal resolution to capture the contrast bolus. Sparse bright voxels in MRA permit substantial undersampling in MRI data acquisition, allowing simultaneous high temporal and spatial resolution. We developed a time-resolved 3D MRA technique using the efficient spiral sampling trajectory, and performed off-resonance corrections using inhomogeneity field maps. View sharing and sliding window reconstruction were utilized to generate high temporal resolution. High-resolution 3D angiograms were generated at 1-2 s per frame, with a 5-8 ml gadolinium dose, in patients with vascular disease.
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Affiliation(s)
- He Zhu
- Department of Radiology, University of Pittsburg, Pittsburgh, Pennsylvania 15213, USA
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Sohn MH, Goode A, Koedinger KR, Stenger VA, Fissell K, Carter CS, Anderson JR. Behavioral equivalence, but not neural equivalence--neural evidence of alternative strategies in mathematical thinking. Nat Neurosci 2004; 7:1193-4. [PMID: 15475949 DOI: 10.1038/nn1337] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [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: 07/19/2004] [Accepted: 09/09/2004] [Indexed: 11/10/2022]
Abstract
In a functional magnetic resonance imaging study, we investigated how people solve mathematically equivalent problems presented in two alternative formats: verbal, story format or symbolic, equation format. Although representation format had no effect on behavior, anterior prefrontal activation was greater in the story condition and posterior parietal activation was greater in the equation condition. These results show that there exist alternative neural pathways that implement different and yet equally efficient problem-solving strategies.
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Affiliation(s)
- Myeong-Ho Sohn
- Department of Psychology, Carnegie-Mellon University, Pittsburgh, Pennsylvania, USA.
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Derbyshire SWG, Whalley MG, Stenger VA, Oakley DA. Cerebral activation during hypnotically induced and imagined pain. Neuroimage 2004; 23:392-401. [PMID: 15325387 DOI: 10.1016/j.neuroimage.2004.04.033] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Revised: 02/24/2004] [Accepted: 04/28/2004] [Indexed: 11/15/2022] Open
Abstract
The continuing absence of an identifiable physical cause for disorders such as chronic low back pain, atypical facial pain, or fibromyalgia, is a source of ongoing controversy and frustration among pain physicians and researchers. Aberrant cerebral activity is widely believed to be involved in such disorders, but formal demonstration of the brain independently generating painful experiences is lacking. Here we identify brain areas directly involved in the generation of pain using hypnotic suggestion to create an experience of pain in the absence of any noxious stimulus. In contrast with imagined pain, functional magnetic resonance imaging (fMRI) revealed significant changes during this hypnotically induced (HI) pain experience within the thalamus and anterior cingulate (ACC), insula, prefrontal, and parietal cortices. These findings compare well with the activation patterns during pain from nociceptive sources and provide the first direct experimental evidence in humans linking specific neural activity with the immediate generation of a pain experience.
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Affiliation(s)
- Stuart W G Derbyshire
- Department of Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA.
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Abstract
Several previous studies have compared the blood oxygen level-dependent (BOLD) hemodynamic response (HDR) in healthy elderly subjects to the HDR in young subjects. Some studies have found a relative decreased amplitude in the elderly in the visual cortex, whereas other studies have found the elderly HDR amplitude in the visual cortex to be nearly identical to that in young subjects. A possible explanation for the different findings is that the peak voxel HDR is similar between the groups, but that the HDR in the group-averaged region-of-interest (ROI) is "washed out" by the inclusion of less significant voxels (due to a smaller extent of activation in the elderly) or by the inclusion of negative-peaking voxels. We tested this hypothesis using event-related functional magnetic resonance imaging (fMRI ). While undergoing fMRI, subjects performed a simple visual and motor task, pressing with their index fingers in response to visual presentation of the word tap. Data from 18 subjects, 8 young and 10 elderly, were analyzed. For each subject, a visual and a motor ROI was selected by choosing the most significant positive voxels within the anatomically defined ROI. This individual subject approach excluded both low-significance and negative-peaking voxels. Similar peaks were found for the elderly and the young subjects in both motor and visual regions and a more sustained BOLD response was found for the elderly in both regions. Additionally, as predicted, a greater percentage of voxels with a negative HDR was found for the elderly in the visual region; this finding was also replicated in our reanalysis of an independent fMRI and aging study from the fMRI Data Center. Functional neuroimaging observations of negative HDRs in visual areas have been interpreted as the effect of unconstrained processing during rest. Our results suggest that the elderly may have more unconstrained visual processing during the rest condition in the scanner. The observation that the group differences in the BOLD response are sensitive to voxel selection (e.g., inclusion of low-significance and/or negative voxels) underscores the importance of ROI selection criteria in the interpretation of fMRI studies using elderly populations.
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Kerns JG, Cohen JD, Stenger VA, Carter CS. Prefrontal Cortex Guides Context-Appropriate Responding during Language Production. Neuron 2004; 43:283-91. [PMID: 15260963 DOI: 10.1016/j.neuron.2004.06.032] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2003] [Revised: 05/03/2004] [Accepted: 06/23/2004] [Indexed: 11/15/2022]
Abstract
Although language processing is thought to frequently require cognitive control, little is known about the cognitive and neural basis of the control of language. Here, we demonstrate that processing of context by the PFC plays an important role in the control of language comprehension and production. Using a missing letter paradigm and fMRI, we found that increased activation in the PFC (but not in posterior regions), while encoding and maintaining context information, predicted context-appropriate responses. Furthermore, greater selection demands increased activity during responding in the same regions engaged during the encoding and maintenance of context. Overall, as in other cognitive task domains, these results suggest that PFC context processing plays an important role in the control of language.
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Affiliation(s)
- John G Kerns
- Department of Psychological Sciences, University of Missouri-Columbia, 65211, USA
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Abstract
Abstract
This research tests a model of the computational role of three cortical regions in tasks like algebra equation solving. The model assumes that there is a left parietal region-of-interest (ROI) where the problem expression is represented and transformed, a left prefrontal ROI where information for solving the task is retrieved, and a motor ROI where hand movements to produce the answer are programmed. A functional magnetic resonance imaging (fMRI) study of an abstract symbolmanipulation task was performed to articulate the roles of these three regions. Participants learned to associate words with instructions for transforming strings of letters. The study manipulated the need to retrieve these instructions, the need to transform the strings, and whether there was a delay between calculation of the answer and the output of the answer. As predicted, the left parietal ROI mainly reflected the need for a transformation and the left prefrontal ROI the need for retrieval. Homologous right ROIs showed similar but weaker responses. Neither the prefrontal nor the parietal ROIs responded to delay, but the motor ROI did respond to delay, implying motor rehearsal over the delay. Except for the motor ROI, these patterns of activity did not vary with response hand. In an ACT-R model, it was shown that the activity of an imaginal buffer predicted the blood oxygen level-dependent (BOLD) response of the parietal ROI, the activity of a retrieval buffer predicted the response of the prefrontal ROI, and the activity of a manual buffer predicted the response of the motor ROI.
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Affiliation(s)
- John R Anderson
- Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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Goodpaster BH, Stenger VA, Boada F, McKolanis T, Davis D, Ross R, Kelley DE. Skeletal muscle lipid concentration quantified by magnetic resonance imaging. Am J Clin Nutr 2004; 79:748-54. [PMID: 15113711 DOI: 10.1093/ajcn/79.5.748] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [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] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Skeletal muscle lipid is associated with obesity and type 2 diabetes and may be altered by diet, physical activity, and weight loss. OBJECTIVE We explored the utility of magnetic resonance imaging (MRI) for quantifying the lipid concentration of muscle tissue in vivo. DESIGN Fat-selective MR images of the lower leg were taken in 8 normal-weight [body mass index (in kg/m(2)) < or = 24.9] and 8 obese (body mass index > 29.9) subjects to obtain spatial maps of lipid signal intensity within muscle tissue. Fast-spiral-sequence (echo time = 5.6-13.8 ms, repetition time = 1 s, 8 interleaves) MRI scans were conducted at 3.0 T by using an extremity transmit-receive coil. Lipid concentrations within muscle were determined from manually drawn regions of interest in the tibialis anterior (TA), soleus, and medial head of the gastrocnemius (MHG) muscle groups. RESULTS There was extremely good agreement (mean R(2) = 0.985) between the fat signal intensity and the actual lipid concentration of standards containing 2.5, 5.0, and 10.0 g lipid/dL, which were placed on the subject's leg during each scan. The lipid content of both the soleus (2.99 +/- 0.37 g/dL) and the MHG (3.80 +/- 0.68 g/dL) was higher (P < 0.05) than that of the TA (1.83 +/- 0.28 g/dL). Lipid content was more than two-fold higher (P < 0.05) in the MHG of obese subjects (5.48 +/- 1.18 g/dL) than in the MHG of normal-weight subjects (2.54 +/- 0.47 g/dL), but did not differ significantly in the TA or soleus. CONCLUSIONS MRI can be used to quantify lipid within human muscle tissue. MRI can also be used to detect differences in muscle lipid content among various muscle groups and between normal-weight and obese subjects.
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Affiliation(s)
- Bret H Goodpaster
- Department of Medicine, 809 North MUH, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA.
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Abstract
Motivation is a complex process that leads to completion or avoidance of a behavior. Past research strongly implicates the basal ganglia in a circuit integral for the control of motivation. Specifically, the human striatum has been shown to process reward information, differentiating between monetary rewards and punishments in recent neuroimaging experiments. It is unclear, however, how the dorsal striatum, particularly the caudate nucleus, responds to changes in the motivational context of a task. Using an event-related design, where participants were given positive and negative feedback upon guessing the value of an unknown card, we manipulated the motivational context of the task by dividing trials into periods of high incentive (where visual feedback indicated monetary rewards and punishments) and low incentive (where visual feedback indicated only accuracy). We found that activity in the caudate nucleus was strongly influenced by the different incentive periods. The hemodynamic response was characterized by a larger rise at the onset of trials and larger differences between positive and negative feedback during periods of high incentive. These results suggest that changes in motivation are capable of modulating basal ganglia activity, and further support an important role for the caudate nucleus in affective processing.
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Affiliation(s)
- M R Delgado
- Department of Psychology, New York University, New York, NY 10003, USA.
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Qin Y, Carter CS, Silk EM, Stenger VA, Fissell K, Goode A, Anderson JR. The change of the brain activation patterns as children learn algebra equation solving. Proc Natl Acad Sci U S A 2004; 101:5686-91. [PMID: 15064407 PMCID: PMC397478 DOI: 10.1073/pnas.0401227101] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In a brain imaging study of children learning algebra, it is shown that the same regions are active in children solving equations as are active in experienced adults solving equations. As with adults, practice in symbol manipulation produces a reduced activation in prefrontal cortex area. However, unlike adults, practice seems also to produce a decrease in a parietal area that is holding an image of the equation. This finding suggests that adolescents' brain responses are more plastic and change more with practice. These results are integrated in a cognitive model that predicts both the behavioral and brain imaging results.
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Affiliation(s)
- Yulin Qin
- Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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Abstract
Conflict monitoring by the anterior cingulate cortex (ACC) has been posited to signal a need for greater cognitive control, producing neural and behavioral adjustments. However, the very occurrence of behavioral adjustments after conflict has been questioned, along with suggestions that there is no direct evidence of ACC conflict-related activity predicting subsequent neural or behavioral adjustments in control. Using the Stroop color-naming task and controlling for repetition effects, we demonstrate that ACC conflict-related activity predicts both greater prefrontal cortex activity and adjustments in behavior, supporting a role of ACC conflict monitoring in the engagement of cognitive control.
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Affiliation(s)
- John G Kerns
- Department of Psychological Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA
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