51
|
Kim KH, Park SH. Artificial neural network for suppression of banding artifacts in balanced steady-state free precession MRI. Magn Reson Imaging 2017; 37:139-146. [DOI: 10.1016/j.mri.2016.11.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 11/25/2016] [Indexed: 11/29/2022]
|
52
|
Slawig A, Wech T, Ratz V, Tran-Gia J, Neubauer H, Bley T, Köstler H. Multifrequency reconstruction for frequency-modulated bSSFP. Magn Reson Med 2017; 78:2226-2235. [DOI: 10.1002/mrm.26630] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/02/2016] [Accepted: 01/09/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Anne Slawig
- Department of Diagnostic and Interventional Radiology; University of Würzburg; Würzburg Germany
| | - Tobias Wech
- Department of Diagnostic and Interventional Radiology; University of Würzburg; Würzburg Germany
| | - Valentin Ratz
- Department of Diagnostic and Interventional Radiology; University of Würzburg; Würzburg Germany
| | - Johannes Tran-Gia
- Department of Diagnostic and Interventional Radiology; University of Würzburg; Würzburg Germany
- Department of Nuclear Medicine; University of Würzburg; Würzburg Germany
| | - Henning Neubauer
- Department of Diagnostic and Interventional Radiology; University of Würzburg; Würzburg Germany
| | - Thorsten Bley
- Department of Diagnostic and Interventional Radiology; University of Würzburg; Würzburg Germany
| | - Herbert Köstler
- Department of Diagnostic and Interventional Radiology; University of Würzburg; Würzburg Germany
| |
Collapse
|
53
|
Ilicak E, Senel LK, Biyik E, Çukur T. Profile-encoding reconstruction for multiple-acquisition balanced steady-state free precession imaging. Magn Reson Med 2016; 78:1316-1329. [DOI: 10.1002/mrm.26507] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 09/02/2016] [Accepted: 09/21/2016] [Indexed: 11/12/2022]
Affiliation(s)
- Efe Ilicak
- Department of Electrical and Electronics Engineering; Bilkent University; Ankara Turkey
- National Magnetic Resonance Research Center (UMRAM); Bilkent University; Ankara Turkey
| | - Lutfi Kerem Senel
- Department of Electrical and Electronics Engineering; Bilkent University; Ankara Turkey
| | - Erdem Biyik
- Department of Electrical and Electronics Engineering; Bilkent University; Ankara Turkey
| | - Tolga Çukur
- Department of Electrical and Electronics Engineering; Bilkent University; Ankara Turkey
- National Magnetic Resonance Research Center (UMRAM); Bilkent University; Ankara Turkey
- Neuroscience Program, Graduate School of Engineering and Science; Bilkent University; Ankara Turkey
| |
Collapse
|
54
|
Abstract
The emergence of newer pharmacotherapeutic agents and surgical cartilage resurfacing techniques is driving the need for imaging modalities capable of early, accurate, and reproducible lesion detection. Magnetic resonance imaging (MRI) has emerged as a noninvasive tool for direct 2-dimensional (2D) and 3-dimensional (3D) assessment of the articular cartilage in both clinical and research settings. MRI has largely overcome the shortcomings of the current gold standard, radiography, by allowing for the detection of preclinical disease and subtle early abnormalities prior to the onset of radiographic disease, when damage is still reversible. Current MRI techniques are either morphological (2D/3D qualitative and quantitative techniques) or compositional (matrix-assessment techniques that detect macromolecular changes prior to morphological changes). MRI is evolving as a complete answer to our cartilage-imaging requirements of lesion description, treatment planning, and outcome measurement as well as in various research settings.
Collapse
Affiliation(s)
- Shaafiya Ashraf
- Government Medical College, Srinagar, Jammu and Kashmir, India
| | - Adnan Zahoor
- Government Medical College, Srinagar, Jammu and Kashmir, India.,Government Bone and Joint Hospital, Srinagar, Jammu and Kashmir, India
| |
Collapse
|
55
|
Hoff MN, Andre JB, Xiang Q. Combined geometric and algebraic solutions for removal of bSSFP banding artifacts with performance comparisons. Magn Reson Med 2016; 77:644-654. [DOI: 10.1002/mrm.26150] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 12/22/2015] [Accepted: 01/14/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Michael N. Hoff
- Department of RadiologyUniversity of WashingtonSeattle Washington USA
| | - Jalal B. Andre
- Department of RadiologyUniversity of WashingtonSeattle Washington USA
| | - Qing‐San Xiang
- Department of Physics & AstronomyUniversity of British ColumbiaVancouver BC Canada
- Department of RadiologyUniversity of British ColumbiaVancouver BC Canada
| |
Collapse
|
56
|
Fast isotropic banding-free bSSFP imaging using 3D dynamically phase-cycled radial bSSFP (3D DYPR-SSFP). Z Med Phys 2016; 26:63-74. [DOI: 10.1016/j.zemedi.2015.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/23/2015] [Accepted: 05/10/2015] [Indexed: 11/21/2022]
|
57
|
Gurler N, Ider YZ. Gradient-based electrical conductivity imaging using MR phase. Magn Reson Med 2016; 77:137-150. [PMID: 26762771 DOI: 10.1002/mrm.26097] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 11/27/2015] [Accepted: 11/27/2015] [Indexed: 11/07/2022]
Abstract
PURPOSE To develop a fast, practically applicable, and boundary artifact free electrical conductivity imaging method that does not use transceive phase assumption, and that is more robust against the noise. THEORY Starting from the Maxwell's equations, a new electrical conductivity imaging method that is based solely on the MR transceive phase has been proposed. Different from the previous phase based electrical properties tomography (EPT) method, a new formulation was derived by including the gradients of the conductivity into the equations. METHODS The governing partial differential equation, which is in the form of a convection-reaction-diffusion equation, was solved using a three-dimensional finite-difference scheme. To evaluate the performance of the proposed method numerical simulations, phantom and in vivo human experiments have been conducted at 3T. RESULTS Simulation and experimental results of the proposed method and the conventional phase-based EPT method were illustrated to show the superiority of the proposed method over the conventional method, especially in the transition regions and under noisy data. CONCLUSION With the contributions of the proposed method to the phase-based EPT approach, a fast and reliable electrical conductivity imaging appears to be feasible, which is promising for clinical diagnoses and local SAR estimation. Magn Reson Med 77:137-150, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Necip Gurler
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
| | - Yusuf Ziya Ider
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
| |
Collapse
|
58
|
Wang Y, Shao X, Martin T, Moeller S, Yacoub E, Wang DJJ. Phase-cycled simultaneous multislice balanced SSFP imaging with CAIPIRINHA for efficient banding reduction. Magn Reson Med 2015; 76:1764-1774. [PMID: 26667600 DOI: 10.1002/mrm.26076] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/13/2015] [Accepted: 11/13/2015] [Indexed: 11/08/2022]
Abstract
PURPOSE To present a time-efficient technique for banding reduction in balanced steady-state free precession (bSSFP) imaging using phase-cycled simultaneous multislice (SMS) acquisition with CAIPIRINHA (controlled aliasing in parallel imaging results in higher acceleration). THEORY The proposed technique exploits the inherent phase modulation of SMS imaging with CAIPIRINHA to acquire multiple phase-cycled images, which can be combined for efficient banding reduction within the same scan time of a single-band bSSFP scan. METHODS Bloch equation simulation, phantom and in vivo brain, abdominal and cardiac imaging experiments were performed on healthy volunteers at 3T using multi-channel head and body array coils with SMS acceleration factors of two to four. The performance of banding reduction was quantitatively evaluated based on the percent ripple of signal distribution and signal-to-noise ratio (SNR) efficiency in both phantom and human studies. RESULTS The banding artifact was successfully removed or suppressed using phase-cycled SMS bSSFP imaging across SMS factors of two to four. The performance of banding reduction improved with higher SMS factors along with increased SNR efficiency. CONCLUSION Phase-cycled SMS bSSFP with CAIPIRINHA is a promising technique for efficient band reduction in bSSFP without prolonged scan time. Further evaluation of this technique in clinical applications is warranted. Magn Reson Med 76:1764-1774, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
Collapse
Affiliation(s)
- Yi Wang
- Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, USA
| | - Xingfeng Shao
- Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, USA
| | - Thomas Martin
- Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, USA
| | - Steen Moeller
- Center of Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Essa Yacoub
- Center of Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA
| | - Danny J J Wang
- Laboratory of FMRI Technology (LOFT), Department of Neurology, University of California Los Angeles, Los Angeles, California, USA
| |
Collapse
|
59
|
Xiang QS, Hoff MN. Banding artifact removal for bSSFP imaging with an elliptical signal model. Magn Reson Med 2015; 71:927-33. [PMID: 24436006 DOI: 10.1002/mrm.25098] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PURPOSE Balanced steady-state free precession (bSSFP) imaging has broad clinical applications by virtue of its high time efficiency and desirable contrast. Unfortunately, banding artifact is often seen as a result of signal modulation due to B0 inhomogeneity. This study aims to develop an effective method for banding artifact suppression. METHODS bSSFP is analyzed with an elliptical signal model. A simple analytical "Geometric-Solution" (GS) is presented to demodulate the signal from B0 inhomogeneity dependence with phase-cycled bSSFP data from both a computer simulation and experiments using phantom and human subjects. RESULTS The proposed algorithm is able to remove banding artifacts completely. It also compares favorably with the complex sum (CS), which is considered one of the more efficient methods for banding artifact correction. CONCLUSION Using an elliptical signal model, an analytical solution to the bSSFP banding problem has been found and demonstrated with simulation as well as phantom and in vivo experiments.
Collapse
Affiliation(s)
- Qing-San Xiang
- Department of Radiology, University of British Columbia, Vancouver, Canada; Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
| | | |
Collapse
|
60
|
Ribot EJ, Wecker D, Trotier AJ, Dallaudière B, Lefrançois W, Thiaudière E, Franconi JM, Miraux S. Water Selective Imaging and bSSFP Banding Artifact Correction in Humans and Small Animals at 3T and 7T, Respectively. PLoS One 2015; 10:e0139249. [PMID: 26426849 PMCID: PMC4591352 DOI: 10.1371/journal.pone.0139249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 09/09/2015] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION The purpose of this paper is to develop an easy method to generate both fat signal and banding artifact free 3D balanced Steady State Free Precession (bSSFP) images at high magnetic field. METHODS In order to suppress fat signal and bSSFP banding artifacts, two or four images were acquired with the excitation frequency of the water-selective binomial radiofrequency pulse set On Resonance or shifted by a maximum of 3/4TR. Mice and human volunteers were imaged at 7 T and 3 T, respectively to perform whole-body and musculoskeletal imaging. "Sum-Of-Square" reconstruction was performed and combined or not with parallel imaging. RESULTS The frequency selectivity of 1-2-3-2-1 or 1-3-3-1 binomial pulses was preserved after (3/4TR) frequency shifting. Consequently, whole body small animal 3D imaging was performed at 7 T and enabled visualization of small structures within adipose tissue like lymph nodes. In parallel, this method allowed 3D musculoskeletal imaging in humans with high spatial resolution at 3 T. The combination with parallel imaging allowed the acquisition of knee images with ~500 μm resolution images in less than 2 min. In addition, ankles, full head coverage and legs of volunteers were imaged, demonstrating the possible application of the method also for large FOV. CONCLUSION In conclusion, this robust method can be applied in small animals and humans at high magnetic fields. The high SNR and tissue contrast obtained in short acquisition times allows to prescribe bSSFP sequence for several preclinical and clinical applications.
Collapse
Affiliation(s)
- Emeline J. Ribot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France
- * E-mail:
| | | | - Aurélien J. Trotier
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France
| | - Benjamin Dallaudière
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France
| | - William Lefrançois
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France
| | - Eric Thiaudière
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France
| | - Jean-Michel Franconi
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France
| | - Sylvain Miraux
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France
| |
Collapse
|
61
|
Ridder DA, Wenzel J, Müller K, Töllner K, Tong XK, Assmann JC, Stroobants S, Weber T, Niturad C, Fischer L, Lembrich B, Wolburg H, Grand'Maison M, Papadopoulos P, Korpos E, Truchetet F, Rades D, Sorokin LM, Schmidt-Supprian M, Bedell BJ, Pasparakis M, Balschun D, D'Hooge R, Löscher W, Hamel E, Schwaninger M. Brain endothelial TAK1 and NEMO safeguard the neurovascular unit. ACTA ACUST UNITED AC 2015; 212:1529-49. [PMID: 26347470 PMCID: PMC4577837 DOI: 10.1084/jem.20150165] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 08/07/2015] [Indexed: 12/25/2022]
Abstract
Ridder et al. show that deletion of NEMO, a component of NF-kB signaling, in brain endothelial cells results in increased cerebral vascular permeability and endothelial cell death, and recapitulates the neurological symptoms observed in the genetic disease incontinentia pigmenti. Inactivating mutations of the NF-κB essential modulator (NEMO), a key component of NF-κB signaling, cause the genetic disease incontinentia pigmenti (IP). This leads to severe neurological symptoms, but the mechanisms underlying brain involvement were unclear. Here, we show that selectively deleting Nemo or the upstream kinase Tak1 in brain endothelial cells resulted in death of endothelial cells, a rarefaction of brain microvessels, cerebral hypoperfusion, a disrupted blood–brain barrier (BBB), and epileptic seizures. TAK1 and NEMO protected the BBB by activating the transcription factor NF-κB and stabilizing the tight junction protein occludin. They also prevented brain endothelial cell death in a NF-κB–independent manner by reducing oxidative damage. Our data identify crucial functions of inflammatory TAK1–NEMO signaling in protecting the brain endothelium and maintaining normal brain function, thus explaining the neurological symptoms associated with IP.
Collapse
Affiliation(s)
- Dirk A Ridder
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Jan Wenzel
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany German Research Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Lübeck/Kiel, 23562 Lübeck, Germany
| | - Kristin Müller
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Kathrin Töllner
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany Center for Systems Neuroscience, 30559 Hannover, Germany
| | - Xin-Kang Tong
- Montreal Neurological Institute, McGill University, Montreal QC H3A 0G4, Canada
| | - Julian C Assmann
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Stijn Stroobants
- Laboratory of Biological Psychology, KU Leuven, 3000 Leuven, Belgium
| | - Tobias Weber
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Cristina Niturad
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Lisanne Fischer
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Beate Lembrich
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Hartwig Wolburg
- Institute of Pathology and Neuropathology, University Hospital Tübingen, 72076 Tübingen, Germany
| | | | | | - Eva Korpos
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany
| | | | - Dirk Rades
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany
| | - Lydia M Sorokin
- Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany
| | - Marc Schmidt-Supprian
- Department of Hematology and Oncology, Klinikum rechts der Isar, Technische Universität München, 81675 Munich, Germany
| | - Barry J Bedell
- Montreal Neurological Institute, McGill University, Montreal QC H3A 0G4, Canada
| | | | - Detlef Balschun
- Laboratory of Biological Psychology, KU Leuven, 3000 Leuven, Belgium
| | - Rudi D'Hooge
- Laboratory of Biological Psychology, KU Leuven, 3000 Leuven, Belgium
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany Center for Systems Neuroscience, 30559 Hannover, Germany
| | - Edith Hamel
- Montreal Neurological Institute, McGill University, Montreal QC H3A 0G4, Canada
| | - Markus Schwaninger
- Institute of Experimental and Clinical Pharmacology and Toxicology and Department of Radiation Oncology, University of Lübeck, 23562 Lübeck, Germany German Research Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Lübeck/Kiel, 23562 Lübeck, Germany
| |
Collapse
|
62
|
Park SH, Han PK, Choi SH. Physiological and Functional Magnetic Resonance Imaging Using Balanced Steady-state Free Precession. Korean J Radiol 2015; 16:550-9. [PMID: 25995684 PMCID: PMC4435985 DOI: 10.3348/kjr.2015.16.3.550] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 02/05/2015] [Indexed: 12/01/2022] Open
Abstract
Balanced steady-state free precession (bSSFP) is a highly efficient pulse sequence that is known to provide the highest signal-to-noise ratio per unit time. Recently, bSSFP is getting increasingly popular in both the research and clinical communities. This review will be focusing on the application of the bSSFP technique in the context of probing the physiological and functional information. In the first part of this review, the basic principles of bSSFP are briefly covered. Afterwards, recent developments related to the application of bSSFP, in terms of physiological and functional imaging, are introduced and reviewed. Despite its long development history, bSSFP is still a promising technique that has many potential benefits for obtaining high-resolution physiological and functional images.
Collapse
Affiliation(s)
- Sung-Hong Park
- Magnetic Resonance Imaging Lab, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
| | - Paul Kyu Han
- Magnetic Resonance Imaging Lab, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
| | - Seung Hong Choi
- Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea
| |
Collapse
|
63
|
Han M, Chiba K, Banerjee S, Carballido-Gamio J, Krug R. Variable flip angle three-dimensional fast spin-echo sequence combined with outer volume suppression for imaging trabecular bone structure of the proximal femur. J Magn Reson Imaging 2015; 41:1300-10. [PMID: 24956149 PMCID: PMC4275424 DOI: 10.1002/jmri.24673] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND To demonstrate the feasibility of using a variable flip angle three-dimensional fast spin-echo (3D VFA-FSE) sequence combined with outer volume suppression for imaging trabecular bone structure at the proximal femur in vivo at 3 Tesla. METHODS The 3D VFA-FSE acquisition was optimized to minimize blurring and to provide high signal-to-noise ratio (SNR) from bone marrow. Outer volume suppression was achieved by applying three quadratic-phase radio-frequency pulses. The SNR and trabecular bone structures from 3D VFA-FSE were compared with those from previously demonstrated multiple-acquisition 3D balanced steady-state free precision (bSSFP) using theoretical simulations, ex vivo experiments, and in vivo experiments. RESULTS Our simulation demonstrated that 3D VFA-FSE can provide at least 35% higher SNR than 3D bSSFP, which was confirmed by the ex vivo and in vivo experiments. The ex vivo experiments demonstrated a good correlation and agreement between bone structural paramters obtained with the two sequences. The proposed sequence depicted trabecular bone structure at the proxiaml femur in vivo well without visible suppression artifacts and provided a mean SNR of 11.0. CONCLUSION The 3D VFA-FSE sequence combined with outer volume suppression can depict the trabecular bone structure of the proximal femur in vivo with minimal blurring and high SNR efficiency.
Collapse
Affiliation(s)
- Misung Han
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA
| | - Ko Chiba
- Department of Orthopaedic Surgery, Nagasaki University School of Medicine, Nagasaki, Japan
| | | | - Julio Carballido-Gamio
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA
| | - Roland Krug
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA
| |
Collapse
|
64
|
Çukur T. Spectrally selective imaging with wideband balanced steady-state free precession MRI. Magn Reson Med 2015; 75:1132-41. [PMID: 25846631 DOI: 10.1002/mrm.25700] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 01/26/2015] [Accepted: 02/25/2015] [Indexed: 11/10/2022]
Abstract
PURPOSE Unwanted, bright fat signals in balanced steady-state free precession sequences are commonly suppressed using spectral shaping. Here, a new spectral-shaping method is proposed to significantly improve the uniformity of stopband suppression without compromising the level of passband signals. METHODS The proposed method combines binomial-pattern excitation pulses with a wideband balanced steady-state free precession sequence kernel. It thereby increases the frequency separation between the centers of pass and stopbands by π radians, enabling improved water-fat contrast. Simulations were performed to find the optimal flip angles and subpulse spacing for the binomial pulses that maximize contrast and signal efficiency. RESULTS Comparisons with a conventional binomial balanced steady-state free precession sequence were performed in simulations as well as phantom and in vivo experiments at 1.5 T and 3 T. Enhanced fat suppression is demonstrated in vivo with an average improvement of 58% in blood-fat and 68% in muscle-fat contrast (P < 0.001, Wilcoxon signed-rank test). CONCLUSION The proposed binomial wideband balanced steady-state free precession method is a promising candidate for spectrally selective imaging with enhanced reliability against field inhomogeneities.
Collapse
Affiliation(s)
- Tolga Çukur
- Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey.,National Magnetic Resonance Research Center, Bilkent University, Ankara, Turkey
| |
Collapse
|
65
|
Cukur T. Accelerated phase-cycled SSFP imaging with compressed sensing. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:107-115. [PMID: 25134078 DOI: 10.1109/tmi.2014.2346814] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Balanced steady-state free precession (SSFP) imaging suffers from irrecoverable signal losses, known as banding artifacts, in regions of large B0 field inhomogeneity. A common solution is to acquire multiple phase-cycled images each with a different frequency sensitivity, such that the location of banding artifacts are shifted in space. These images are then combined to alleviate signal loss across the entire field-of-view. Although high levels of artifact suppression are viable using a large number of images, this is a time costly process that limits clinical utility. Here, we propose to accelerate individual acquisitions such that the overall scan time is equal to that of a single SSFP acquisition. Aliasing artifacts and noise are minimized by using a variable-density random sampling pattern in k-space, and by generating disjoint sampling patterns for separate acquisitions. A sparsity-enforcing method is then used for image reconstruction. Demonstrations on realistic brain phantom images, and in vivo brain and knee images are provided. In all cases, the proposed technique enables robust SSFP imaging in the presence of field inhomogeneities without prolonging scan times.
Collapse
|
66
|
Diwoky C, Liebmann D, Neumayer B, Reinisch A, Knoll F, Strunk D, Stollberger R. Positive contrast of SPIO-labeled cells by off-resonant reconstruction of 3D radial half-echo bSSFP. NMR IN BIOMEDICINE 2015; 28:79-88. [PMID: 25379657 DOI: 10.1002/nbm.3229] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 10/02/2014] [Accepted: 10/03/2014] [Indexed: 06/04/2023]
Abstract
This article describes a new acquisition and reconstruction concept for positive contrast imaging of cells labeled with superparamagnetic iron oxides (SPIOs). Overcoming the limitations of a negative contrast representation as gained with gradient echo and fully balanced steady state (bSSFP), the proposed method delivers a spatially localized contrast with high cellular sensitivity not accomplished by other positive contrast methods. Employing a 3D radial bSSFP pulse sequence with half-echo sampling, positive cellular contrast is gained by adding artificial global frequency offsets to each half-echo before image reconstruction. The new contrast regime is highlighted with numerical intravoxel simulations including the point-spread function for 3D half-echo acquisitions. Furthermore, the new method is validated on the basis of in vitro cell phantom measurements on a clinical MRI platform, where the measured contrast-to-noise ratio (CNR) of the new approach exceeds even the negative contrast of bSSFP. Finally, an in vivo proof of principle study based on a mouse model with a clear depiction of labeled cells within a subcutaneous cell islet containing a cell density as low as 7 cells/mm(3) is presented. The resultant isotropic images show robustness to motion and a high CNR, in addition to an enhanced specificity due to the positive contrast of SPIO-labeled cells.
Collapse
Affiliation(s)
- Clemens Diwoky
- Institute of Medical Engineering, Graz University of Technology, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | | | | | | | | | | | | |
Collapse
|
67
|
Ultrahigh-resolution imaging of the human brain with phase-cycled balanced steady-state free precession at 7 T. Invest Radiol 2014; 49:278-89. [PMID: 24473366 DOI: 10.1097/rli.0000000000000015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVES The objectives of this study were to acquire ultra-high resolution images of the brain using balanced steady-state free precession (bSSFP) at 7 T and to identify the potential utility of this sequence. MATERIALS AND METHODS Eight volunteers participated in this study after providing informed consent. Each volunteer was scanned with 8 phase cycles of bSSFP at 0.4-mm isotropic resolution using 0.5 number of excitations and 2-dimensional parallel acceleration of 1.75 × 1.75. Each phase cycle required 5 minutes of scanning, with pauses between the phase cycles allowing short periods of rest. The individual phase cycles were aligned and then averaged. The same volunteers underwent scanning using 3-dimensional (3D) multiecho gradient recalled echo at 0.8-mm isotropic resolution, 3D Cube T2 at 0.7-mm isotropic resolution, and thin-section coronal oblique T2-weighted fast spin echo at 0.22 × 0.22 × 2.0-mm resolution for comparison. Two neuroradiologists assessed image quality and potential research and clinical utility. RESULTS The volunteers generally tolerated the scan sessions well, and composite high-resolution bSSFP images were produced for each volunteer. Rater analysis demonstrated that bSSFP had a superior 3D visualization of the microarchitecture of the hippocampus, very good contrast to delineate the borders of the subthalamic nucleus, and relatively good B1 homogeneity throughout. In addition to an excellent visualization of the cerebellum, subtle details of the brain and skull base anatomy were also easier to identify on the bSSFP images, including the line of Gennari, membrane of Liliequist, and cranial nerves. Balanced steady-state free precession had a strong iron contrast similar to or better than the comparison sequences. However, cortical gray-white contrast was significantly better with Cube T2 and T2-weighted fast spin echo. CONCLUSIONS Balanced steady-state free precession can facilitate ultrahigh-resolution imaging of the brain. Although total imaging times are long, the individually short phase cycles can be acquired separately, improving examination tolerability. These images may be beneficial for studies of the hippocampus, iron-containing structures such as the subthalamic nucleus and line of Gennari, and the basal cisterns and their contents.
Collapse
|
68
|
Comparison between balanced steady-state free precession and standard spoiled gradient echo magnetization transfer ratio imaging in multiple sclerosis: methodical and clinical considerations. Neuroimage 2014; 108:87-94. [PMID: 25536494 DOI: 10.1016/j.neuroimage.2014.12.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 12/12/2014] [Accepted: 12/16/2014] [Indexed: 11/22/2022] Open
Abstract
Different pathological processes like demyelination and axonal loss can alter the magnetisation transfer ratio (MTR) in brain tissue. The standard method to measure this effect is to scan the respective tissue twice, one with and one without a specific saturation pulse. A major drawback of this technique based on spoiled gradient echo (GRE) sequences relates to its long acquisition time due to the saturation pulses. Recently, an alternative concept for MT imaging based on balanced steady state free precession (bSSFP) has been proposed. Modification of the duration of the radiofrequency pulses for imaging allows scanning MT sensitive and non-sensitive images. The steady-state character of bSSFP with high intrinsic signal-to-noise ratio (SNR) allows three-dimensional (3D) whole brain MTR at high spatial resolution within short and thus clinically feasible acquisition times. In the present study, both bSSFP-MT and 2D GRE-MT imaging were used in a cohort of 31 patients with multiple sclerosis (MS) to characterize different normal appearing (NA) and pathological brain structures. Under the constraint of identical SNR and scan time, a 3.4 times higher voxel size could be achieved with bSSFP. This increased resolution allowed a more accurate delineation of the different brain structures, especially of cortex, hippocampus and MS lesions. In a multiple linear regression model, we found an association between MTR of cortical lesions and a clinical measure of disability (r= -0.407, p=0.035) in the bSSFP dataset only. The different relaxation weighting of the base images (T2/T1 in bSSFP, proton density in GRE) had no effects besides a larger spreading of the MTR values of the different NA structures. This was demonstrated by the nearly perfect linearity between the NA matter MTR of both techniques as well as in the absolute MTR differences between NA matter and the respective lesions.
Collapse
|
69
|
Abele TA, Besachio DA, Quigley EP, Gurgel RK, Shelton C, Harnsberger HR, Wiggins RH. Diagnostic accuracy of screening MR imaging using unenhanced axial CISS and coronal T2WI for detection of small internal auditory canal lesions. AJNR Am J Neuroradiol 2014; 35:2366-70. [PMID: 25034778 DOI: 10.3174/ajnr.a4041] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE While enhanced T1WI is considered the "gold standard" for detection of internal auditory canal pathology, unenhanced fluid-sensitive sequences have shown high sensitivity for lesion identification. Our purpose was to evaluate the diagnostic accuracy of an unenhanced MR imaging protocol using axial CISS and coronal T2WI for detection of small (10 mm or less) internal auditory canal lesions. MATERIALS AND METHODS Twenty-three patients with small internal auditory canal lesions and 13 patients without lesions who had undergone MR imaging using the screening protocol and confirmatory gadolinium-enhanced thin section T1WI were identified. Two blinded neuroradiologists retrospectively evaluated all examinations using 1) only axial CISS, 2) only coronal T2WI, and 3) axial and coronal sequences together. Accuracy, specificity, sensitivity, and interobserver agreement were assessed. RESULTS Median maximum lesion dimension was 4 mm (range, 2-10 mm). Accuracy, specificity, and sensitivity for axial CISS alone were 0.94, 0.96, and 0.91 for observer 1 and 0.94, 0.92, and 1.00 for observer 2. The data for the coronal T2WI sequence only were 0.94, 0.96, and 0.91 for observer 1, and 0.99, 1.00, and 0.96 for observer 2. Using axial and coronal sequences, the data were 0.97, 0.96, and 1.00 for observer 1, and 0.99, 0.98, and 1.00 for observer 2. κ coefficients were 0.84 for the axial sequence only, 0.90 for coronal only, and 0.91 for axial and coronal both. CONCLUSIONS Screening noncontrast MR imaging using a combination of axial CISS and coronal T2WI sequences can detect small internal auditory canal lesions with 100% sensitivity and excellent interobserver agreement.
Collapse
Affiliation(s)
- T A Abele
- From the Departments of Radiology (T.A.A., E.P.Q., H.R.H., R.H.W.)
| | - D A Besachio
- Department of Radiology (D.A.B.), Naval Medical Center Portsmouth, Portsmouth, Virginia
| | - E P Quigley
- From the Departments of Radiology (T.A.A., E.P.Q., H.R.H., R.H.W.)
| | - R K Gurgel
- Division of Otolaryngology-Head and Neck Surgery (R.K.G., C.S., R.H.W.), University of Utah, Salt Lake City, Utah
| | - C Shelton
- Division of Otolaryngology-Head and Neck Surgery (R.K.G., C.S., R.H.W.), University of Utah, Salt Lake City, Utah
| | - H R Harnsberger
- From the Departments of Radiology (T.A.A., E.P.Q., H.R.H., R.H.W.)
| | - R H Wiggins
- From the Departments of Radiology (T.A.A., E.P.Q., H.R.H., R.H.W.) Biomedical Informatics (R.H.W.) Division of Otolaryngology-Head and Neck Surgery (R.K.G., C.S., R.H.W.), University of Utah, Salt Lake City, Utah
| |
Collapse
|
70
|
Quist B, Hargreaves BA, Daniel BL, Saranathan M. Balanced SSFP Dixon imaging with banding-artifact reduction at 3 Tesla. Magn Reson Med 2014; 74:706-15. [PMID: 25227766 DOI: 10.1002/mrm.25449] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 01/10/2023]
Abstract
PURPOSE To develop a three-dimensional (3D) balanced steady-state free-precession (bSSFP) two-point Dixon method with banding-artifact suppression to offer robust high-resolution 3D bright-fluid imaging. METHODS A complex sum reconstruction that combines phase-cycled bSSFP images acquired at specific echo times for robust fat/water separation without banding was investigated and compared with a magnitude-based method. Bloch simulations using both single-peak and multiple-peak fat models were performed to predict the performance of these methods for a wide range of echo times and repetition times. The quality and degree of fat/water separation was evaluated in both simulations and using in vivo imaging. RESULTS Simulations predicted that both effective banding-artifact suppression and substantial improvements in fat/water separation are possible at echo times that are different from conventional echo times, enabling improved spatial resolution. Comparisons between various echo times and repetition times in vivo validated the improved fat/water separation and effective banding-artifact removal predicted by the simulations. CONCLUSION The proposed complex sum Dixon 3D bSSFP method is able to effectively separate fat and water at different sets of echo times, while removing banding-artifacts, providing a fast, high-resolution, T2 -like sequence without blurring.
Collapse
Affiliation(s)
- Brady Quist
- Department of Radiology, Stanford University, Stanford, California, USA.,Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | | | - Bruce L Daniel
- Department of Radiology, Stanford University, Stanford, California, USA
| | | |
Collapse
|
71
|
Sun H, Fessler JA, Noll DC, Nielsen JF. Strategies for improved 3D small-tip fast recovery imaging. Magn Reson Med 2014; 72:389-98. [PMID: 24127132 PMCID: PMC4428120 DOI: 10.1002/mrm.24947] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 08/15/2013] [Accepted: 08/19/2013] [Indexed: 11/06/2022]
Abstract
PURPOSE Small-tip fast recovery (STFR) imaging is a recently proposed steady-state sequence that has similar image contrast as balanced steady-state free precession but has the potential to simultaneously remove banding artifacts and transient fluctuation. STFR relies on a "tip-up" radiofrequency (RF) pulse tailored to the accumulated phase during the free precession (data acquisition) interval, designed to bring spins back to the longitudinal axis, thereby preserving transverse magnetization as longitudinal magnetization for the next pulse repetition time. We recently proposed an RF-spoiled STFR sequence suitable for thin slab imaging, however, in many applications, e.g., functional magnetic resonance imaging or isotropic-resolution structural imaging, three-dimensional (3D) steady-state imaging is desirable. Unfortunately, 3D STFR imaging is challenging due to the need for 3D tailored RF pulses. Here, we propose new strategies for improved 3D STFR imaging, based on (i) unspoiled imaging, and (ii) joint design of nonslice-selective tip-down/tip-up RF pulses. THEORY AND METHODS We derive an analytic signal model for the proposed unspoiled STFR sequence, and propose two strategies for designing the 3D tailored tip-down/tip-up RF pulses. We validate the analytic results using phantom and in vivo imaging experiments. RESULTS Our analytic model and imaging experiments demonstrate that the proposed unspoiled STFR sequence is less sensitive to tip-up excitation error compared to the corresponding spoiled sequence, and may, therefore, be an attractive candidate for 3D imaging. The proposed "joint" RF pulse design method, in which we formulate the tip-down/tip-up RF pulse design task as a magnitude least squares problem, produces modest improvement over a simpler "Separate" design approach. Using the proposed unspoiled sequence and joint RF pulse design, we demonstrate proof-of-principle 3D STFR brain images with balanced steady-state free precession-like signal properties but with reduced banding. CONCLUSION Using the proposed unspoiled sequence and joint RF pulse design, STFR brain images in a 3D region of interest with balanced steady-state free precession-like signal properties but with reduced banding can be obtained.
Collapse
Affiliation(s)
- Hao Sun
- Departments of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
| | - Jeffrey A. Fessler
- Departments of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
- Departments of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Douglas C. Noll
- Departments of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Jon-Fredrik Nielsen
- Departments of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
72
|
Ribot EJ, Duriez TJ, Trotier AJ, Thiaudiere E, Franconi JM, Miraux S. Self-gated bSSFP sequences to detect iron-labeled cancer cells and/or metastases in vivo in mouse liver at 7 Tesla. J Magn Reson Imaging 2014; 41:1413-21. [DOI: 10.1002/jmri.24688] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 06/09/2014] [Accepted: 06/09/2014] [Indexed: 02/03/2023] Open
Affiliation(s)
- Emeline J. Ribot
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS-Université Bordeaux; France
| | - Tom J. Duriez
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS-Université Bordeaux; France
| | - Aurélien J. Trotier
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS-Université Bordeaux; France
| | - Eric Thiaudiere
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS-Université Bordeaux; France
| | - Jean-Michel Franconi
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS-Université Bordeaux; France
| | - Sylvain Miraux
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS-Université Bordeaux; France
| |
Collapse
|
73
|
Benkert T, Bartsch AJ, Blaimer M, Jakob PM, Breuer FA. Generating multiple contrasts using single-shot radial T1 sensitive and insensitive steady-state imaging. Magn Reson Med 2014; 73:2129-41. [PMID: 24975241 DOI: 10.1002/mrm.25337] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/07/2014] [Accepted: 06/05/2014] [Indexed: 11/11/2022]
Abstract
PURPOSE Recently, the (Resolution Enhanced-) T1 insensitive steady-state imaging (TOSSI) approach has been proposed for the fast acquisition of T2 -weighted images. This has been achieved by balanced steady-state free precession (bSSFP) imaging between unequally spaced inversion pulses. The purpose of this work is to present an extension of this technique, considerably increasing both the efficiency and possibilities of TOSSI. THEORY AND METHODS A radial trajectory in combination with an appropriate view-sharing reconstruction is used. Because each projection traverses the contrast defining k-space center, several different contrasts can be extracted from a single-shot measurement. These contrasts include various T2 -weightings and T2 /T1 -weighting if an even number of inversion pulses is used, while an odd number allow the generation of several images with predefined tissue types cancelled. RESULTS The approach is validated for brain and abdominal imaging at 3.0 Tesla. Results are compared with RE-TOSSI, bSSFP, and turbo spin-echo images and are shown to provide similar contrasts in a fraction of scan time. Furthermore, the potential utility of the approach is illustrated by images obtained from a brain tumor patient. CONCLUSION Radial T1 sensitive and insensitive steady-state imaging is able to generate multiple contrasts out of one single-shot measurement in a short scan time.
Collapse
Affiliation(s)
- Thomas Benkert
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany
| | - Andreas J Bartsch
- Department of Neuroradiology, University of Heidelberg, Heidelberg, Germany.,Department of Neuroradiology, University of Würzburg, Würzburg, Germany.,FMRIB Centre, University of Oxford, Oxford, United Kingdom
| | - Martin Blaimer
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany
| | - Peter M Jakob
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany.,Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany
| | - Felix A Breuer
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany
| |
Collapse
|
74
|
Moraes TB, Santos PM, Magon CJ, Colnago LA. Suppression of spectral anomalies in SSFP-NMR signal by the Krylov Basis Diagonalization Method. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 243:74-80. [PMID: 24747788 DOI: 10.1016/j.jmr.2014.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 03/11/2014] [Accepted: 03/14/2014] [Indexed: 06/03/2023]
Abstract
Krylov Basis Diagonalization Method (KBDM) is a numerical procedure used to fit time domain signals as a sum of exponentially damped sinusoids. In this work KBDM is used as an alternative spectral analysis tool, complimentary to Fourier transform. We report results obtained from (13)C Nuclear Magnetic Resonance (NMR) by Steady State Free Precession (SSFP) measurements in brucine, C23H26N2O4. Results lead to the conclusion that the KBDM can be successfully applied, mainly because it is not influenced by truncation or phase anomalies, as observed in the Fourier transform spectra.
Collapse
Affiliation(s)
- Tiago Bueno Moraes
- Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São-carlense 400, São Carlos, SP 13566-590, Brazil; Embrapa Instrumentação, Rua XV de Novembro 1452, São Carlos, SP 13560-970, Brazil
| | | | - Claudio Jose Magon
- Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São-carlense 400, São Carlos, SP 13566-590, Brazil.
| | - Luiz Alberto Colnago
- Embrapa Instrumentação, Rua XV de Novembro 1452, São Carlos, SP 13560-970, Brazil
| |
Collapse
|
75
|
Ingle RR, Santos JM, Overall WR, McConnell MV, Hu BS, Nishimura DG. Self-gated fat-suppressed cardiac cine MRI. Magn Reson Med 2014; 73:1764-74. [PMID: 24806049 DOI: 10.1002/mrm.25291] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 04/15/2014] [Accepted: 04/23/2014] [Indexed: 11/08/2022]
Abstract
PURPOSE To develop a self-gated alternating repetition time balanced steady-state free precession (ATR-SSFP) pulse sequence for fat-suppressed cardiac cine imaging. METHODS Cardiac gating is computed retrospectively using acquired magnetic resonance self-gating data, enabling cine imaging without the need for electrocardiogram (ECG) gating. Modification of the slice-select rephasing gradients of an ATR-SSFP sequence enables the acquisition of a one-dimensional self-gating readout during the unused short repetition time (TR). Self-gating readouts are acquired during every TR of segmented, breath-held cardiac scans. A template-matching algorithm is designed to compute cardiac trigger points from the self-gating signals, and these trigger points are used for retrospective cine reconstruction. The proposed approach is compared with ECG-gated ATR-SSFP and balanced steady-state free precession in 10 volunteers and five patients. RESULTS The difference of ECG and self-gating trigger times has a variability of 13 ± 11 ms (mean ± SD). Qualitative reviewer scoring and ranking indicate no statistically significant differences (P > 0.05) between self-gated and ECG-gated ATR-SSFP images. Quantitative blood-myocardial border sharpness is not significantly different among self-gated ATR-SSFP ( 0.61±0.15 mm -1), ECG-gated ATR-SSFP ( 0.61±0.15 mm -1), or conventional ECG-gated balanced steady-state free precession cine MRI ( 0.59±0.15 mm -1). CONCLUSION The proposed self-gated ATR-SSFP sequence enables fat-suppressed cardiac cine imaging at 1.5 T without the need for ECG gating and without decreasing the imaging efficiency of ATR-SSFP.
Collapse
Affiliation(s)
- R Reeve Ingle
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | | | | | | | | | | |
Collapse
|
76
|
Peng X, Ying L, Liu Q, Zhu Y, Liu Y, Qu X, Liu X, Zheng H, Liang D. Incorporating reference in parallel imaging and compressed sensing. Magn Reson Med 2014; 73:1490-504. [PMID: 24771404 DOI: 10.1002/mrm.25272] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 04/09/2014] [Accepted: 04/09/2014] [Indexed: 12/15/2022]
Abstract
PURPOSE To develop a new compressed sensing parallel imaging technique called READ-PICS that can effectively incorporate prior information from a reference scan for MR image reconstruction from highly undersampled multichannel measurements. METHODS READ-PICS incorporates information from a high-spatial-resolution reference prior using the generalized series model, to achieve increased image sparsity and mitigated noise amplification simultaneously. To further improve the ill-conditioning of the parallel imaging system, an annular area in the central residual k-space is used for calibration. Additionally, the mixed L1-L2 norm of the coefficients from the prior component and residual component is used to enforce joint sparsity. RESULTS The evaluations on parametric imaging and multiscan experiment demonstrate superior performance of READ-PICS in terms of detail preservation and noise suppression compared to state-of-the-art technique, L1-Iterative self-consistent parallel imaging reconstruction, and prescan required method, correlation imaging. CONCLUSIONS The proposed method can significantly increase signal sparsity and improve the ill-conditioning of the parallel imaging system using reference adaptive regularization. This technique can be easily adapted to other imaging applications where multiple images need to be acquired sequentially and a reference prior is also available.
Collapse
Affiliation(s)
- Xi Peng
- Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Shenzhen, Guangdong, 518055, China; Beijing Center for Mathematics and Information Interdisciplinary Sciences, Beijing, 100048, China; Shenzhen Key Laboratory for MRI, Chinese Academy of Sciences, Shenzhen, Guangdong, 518055, China
| | | | | | | | | | | | | | | | | |
Collapse
|
77
|
Benkert T, Ehses P, Blaimer M, Jakob PM, Breuer FA. Dynamically phase-cycled radial balanced SSFP imaging for efficient banding removal. Magn Reson Med 2014; 73:182-94. [PMID: 24478187 DOI: 10.1002/mrm.25113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 12/09/2013] [Accepted: 12/12/2013] [Indexed: 11/07/2022]
Abstract
PURPOSE Balanced steady-state free precession (bSSFP) imaging suffers from banding artifacts due to its inherent sensitivity to inhomogeneities in the main magnetic field. These artifacts can be removed by the acquisition of multiple images at different frequency offsets. However, conventional phase-cycling is hindered by a long scan time. The purpose of this work is to present a novel approach for efficient banding removal in bSSFP imaging. THEORY AND METHODS To this end, the phase-cycle during a single-shot radial acquisition of an image was dynamically changed. Thus, each projection is acquired with a different frequency offset. Using conventional radial gridding, an artifact-free image can be reconstructed out of this dataset. RESULTS The approach is validated at clinical field strength [3.0 Tesla (T)] as well as at ultrahigh field (9.4T). Robust elimination of banding artifacts was obtained for different imaging regions, including brain imaging at ultrahigh field with an in-plane resolution of 0.25 × 0.25 mm(2). Besides banding artifact-free imaging, the applicability of the proposed technique for fat-water separation is demonstrated. CONCLUSION Dynamically phase-cycled radial bSSFP has the potential for banding-free bSSFP imaging in a short scan time, in the presence of severe field inhomogeneities and at high resolution.
Collapse
Affiliation(s)
- Thomas Benkert
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany
| | - Philipp Ehses
- Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany.,High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Martin Blaimer
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany
| | - Peter M Jakob
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany.,Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany
| | - Felix A Breuer
- Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany
| |
Collapse
|
78
|
Björk M, Ingle RR, Gudmundson E, Stoica P, Nishimura DG, Barral JK. Parameter estimation approach to banding artifact reduction in balanced steady-state free precession. Magn Reson Med 2013; 72:880-92. [PMID: 24166591 DOI: 10.1002/mrm.24986] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 08/13/2013] [Accepted: 09/02/2013] [Indexed: 11/11/2022]
Abstract
PURPOSE The balanced steady-state free precession (bSSFP) pulse sequence has shown to be of great interest due to its high signal-to-noise ratio efficiency. However, bSSFP images often suffer from banding artifacts due to off-resonance effects, which we aim to minimize in this article. METHODS We present a general and fast two-step algorithm for 1) estimating the unknowns in the bSSFP signal model from multiple phase-cycled acquisitions, and 2) reconstructing band-free images. The first step, linearization for off-resonance estimation (LORE), solves the nonlinear problem approximately by a robust linear approach. The second step applies a Gauss-Newton algorithm, initialized by LORE, to minimize the nonlinear least squares criterion. We name the full algorithm LORE-GN. RESULTS We derive the Cramér-Rao bound, a theoretical lower bound of the variance for any unbiased estimator, and show that LORE-GN is statistically efficient. Furthermore, we show that simultaneous estimation of T1 and T2 from phase-cycled bSSFP is difficult, since the Cramér-Rao bound is high at common signal-to-noise ratio. Using simulated, phantom, and in vivo data, we illustrate the band-reduction capabilities of LORE-GN compared to other techniques, such as sum-of-squares. CONCLUSION Using LORE-GN we can successfully minimize banding artifacts in bSSFP.
Collapse
Affiliation(s)
- Marcus Björk
- Department of Information Technology, Uppsala University, Uppsala, Sweden
| | | | | | | | | | | |
Collapse
|
79
|
Rosas H, Kijowski R. Volumetric magnetic resonance imaging of the musculoskeletal system. Semin Roentgenol 2013; 48:140-7. [PMID: 23452461 DOI: 10.1053/j.ro.2012.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Humberto Rosas
- Department of Radiology, Musculoskeletal Division, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-3252, USA.
| | | |
Collapse
|
80
|
Cortical atrophy and hypoperfusion in a transgenic mouse model of Alzheimer's disease. Neurobiol Aging 2013; 34:1644-52. [DOI: 10.1016/j.neurobiolaging.2012.11.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 11/24/2012] [Accepted: 11/26/2012] [Indexed: 01/24/2023]
|
81
|
Grand'Maison M, Zehntner SP, Ho MK, Hébert F, Wood A, Carbonell F, Zijdenbos AP, Hamel E, Bedell BJ. Early cortical thickness changes predict β-amyloid deposition in a mouse model of Alzheimer's disease. Neurobiol Dis 2013; 54:59-67. [DOI: 10.1016/j.nbd.2013.02.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/31/2013] [Accepted: 02/19/2013] [Indexed: 12/15/2022] Open
|
82
|
Pelot NA, Bowen CV. Quantification of superparamagnetic iron oxide using inversion recovery balanced steady-state free precession. Magn Reson Imaging 2013; 31:953-60. [PMID: 23601361 DOI: 10.1016/j.mri.2013.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 02/19/2013] [Accepted: 03/09/2013] [Indexed: 11/29/2022]
Abstract
Cellular and molecular MRI trafficking studies using superparamagnetic iron oxide (SPIO) have greatly improved non-invasive investigations of disease progression and drug efficacy, but thus far, these studies have largely been restricted to qualitative assessment of hypo- or hyperintense areas near SPIO. In this work, SPIO quantification using inversion recovery balanced steady-state free precession (IR-bSSFP) was demonstrated at 3T by extracting R2 values from a monoexponential model (P. Schmitt et al., 2004). A low flip angle was shown to reduce the apparent recovery rate of the IR-bSSFP time course, thus extending the dynamic range of quantification. However, low flip angle acquisitions preclude the use of traditional methods for combining RF phase-cycled images to reduce banding artifacts arising from off-resonance due to B0 inhomogeneity. To achieve R2 quantification of SPIO, we present a new algorithm applicable to low flip angle IR-bSSFP acquisitions that is specifically designed to identify on-resonance acquisitions. We demonstrate in this work, using both theoretical and empirical methods, that the smallest estimated R2 from multiple RF phase-cycled acquisitions correspond well to the on-resonance time course. Using this novel minimum R2 algorithm, homogeneous R2 maps and linear R2 calibration curves were created up to 100μg(Fe)/mL with 20° flip angles, despite substantial B0 inhomogeneity. In addition, we have shown this technique to be feasible for pre-clinical research: the minimum R2 algorithm was resistant to off-resonance in a single slice mouse R2 map, whereas maximum intensity projection resulted in banding artifacts and overestimated R2 values. With the application of recent advances in accelerated acquisitions, IR-bSSFP has the potential to quantify SPIO in vivo, thus providing important information for oncology, immunology, and regenerative medicine MRI studies.
Collapse
Affiliation(s)
- Nicole A Pelot
- Department of Biomedical Engineering, Duke University, Room 136 Hudson Hall, Box 90281, Durham, NC 27708-0281, USA.
| | | |
Collapse
|
83
|
Nielsen JF, Yoon D, Noll DC. Small-tip fast recovery imaging using non-slice-selective tailored tip-up pulses and radiofrequency-spoiling. Magn Reson Med 2013; 69:657-66. [PMID: 22511367 PMCID: PMC3408566 DOI: 10.1002/mrm.24289] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 03/06/2012] [Accepted: 03/16/2012] [Indexed: 11/10/2022]
Abstract
Small-tip fast recovery (STFR) imaging is a new steady-state imaging sequence that is a potential alternative to balanced steady-state free precession. Under ideal imaging conditions, STFR may provide comparable signal-to-noise ratio and image contrast as balanced steady-state free precession, but without signal variations due to resonance offset. STFR relies on a tailored "tip-up," or "fast recovery," radiofrequency pulse to align the spins with the longitudinal axis after each data readout segment. The design of the tip-up pulse is based on the acquisition of a separate off-resonance (B0) map. Unfortunately, the design of fast (a few ms) slice- or slab-selective radiofrequency pulses that accurately tailor the excitation pattern to the local B0 inhomogeneity over the entire imaging volume remains a challenging and unsolved problem. We introduce a novel implementation of STFR imaging based on "non-slice-selective" tip-up pulses, which simplifies the radiofrequency pulse design problem significantly. Out-of-slice magnetization pathways are suppressed using radiofrequency-spoiling. Brain images obtained with this technique show excellent gray/white matter contrast, and point to the possibility of rapid steady-state T(2)/T(1) -weighted imaging with intrinsic suppression of cerebrospinal fluid, through-plane vessel signal, and off-resonance artifacts. In the future, we expect STFR imaging to benefit significantly from parallel excitation hardware and high-order gradient shim systems.
Collapse
Affiliation(s)
- Jon-Fredrik Nielsen
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
| | | | | |
Collapse
|
84
|
Hargreaves BA. Rapid gradient-echo imaging. J Magn Reson Imaging 2012; 36:1300-13. [PMID: 23097185 DOI: 10.1002/jmri.23742] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 05/24/2012] [Indexed: 11/07/2022] Open
Abstract
Gradient-echo sequences are widely used in magnetic resonance imaging (MRI) for numerous applications ranging from angiography to perfusion to functional MRI. Compared with spin-echo techniques, the very short repetition times of gradient-echo methods enable very rapid 2D and 3D imaging, but also lead to complicated "steady states." Signal and contrast behavior can be described graphically and mathematically, and depends strongly on the type of spoiling: fully balanced (no spoiling), gradient spoiling, or radiofrequency (RF)-spoiling. These spoiling options trade off between high signal and pure T(1) contrast, while the flip angle also affects image contrast in all cases, both of which can be demonstrated theoretically and in image examples. As with spin-echo sequences, magnetization preparation can be added to gradient-echo sequences to alter image contrast. Gradient-echo sequences are widely used for numerous applications such as 3D perfusion imaging, functional MRI, cardiac imaging, and MR angiography.
Collapse
Affiliation(s)
- Brian A Hargreaves
- Department of Radiology, Stanford University, Stanford, California, USA.
| |
Collapse
|
85
|
Mikami T, Minamida Y, Akiyama Y, Wanibuchi M, Sugino T, Houkin K, Mikuni N. Microvascular decompression for hemifacial spasm associated with the vertebral artery. Neurosurg Rev 2012; 36:303-8; discussion 308-9. [DOI: 10.1007/s10143-012-0425-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 06/19/2012] [Accepted: 07/29/2012] [Indexed: 10/27/2022]
|
86
|
Miller KL. FMRI using balanced steady-state free precession (SSFP). Neuroimage 2012; 62:713-9. [PMID: 22036996 PMCID: PMC3398389 DOI: 10.1016/j.neuroimage.2011.10.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 10/11/2011] [Accepted: 10/12/2011] [Indexed: 10/26/2022] Open
Abstract
Steady-state free precession (SSFP) is a highly-efficient MRI pulse sequence that has been a fairly recent arrival in the functional MRI realm. Several methods for using balanced SSFP to detect the BOLD signal have been proposed to date and will be discussed in this review. After a brief introduction to the general properties of SSFP, this review describes the quite different approaches of transition-band and pass-band SSFP in terms of functional contrast mechanism. It then discusses the potential advantages of these techniques, followed by their challenges and shortcomings. Finally, it gives an overview of some applications considered to date and the author's perspective on where these techniques are headed. In the spirit of this special issue, the author also includes some of the personal history underlying her own explorations in this area.
Collapse
|
87
|
Ribot EJ, Foster PJ. In vivo MRI discrimination between live and lysed iron-labelled cells using balanced steady state free precession. Eur Radiol 2012; 22:2027-34. [DOI: 10.1007/s00330-012-2435-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 01/26/2012] [Accepted: 02/11/2012] [Indexed: 11/30/2022]
|
88
|
Chan DD, Neu CP. Transient and microscale deformations and strains measured under exogenous loading by noninvasive magnetic resonance. PLoS One 2012; 7:e33463. [PMID: 22448245 PMCID: PMC3308970 DOI: 10.1371/journal.pone.0033463] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Accepted: 02/13/2012] [Indexed: 11/18/2022] Open
Abstract
Characterization of spatiotemporal deformation dynamics and material properties requires non-destructive methods to visualize mechanics of materials and biological tissues. Displacement-encoded magnetic resonance imaging (MRI) has emerged as a noninvasive and non-destructive technique used to quantify deformation and strains. However, the techniques are not yet applicable to a broad range of materials and load-bearing tissues. In this paper, we visualize transient and internal material deformation through the novel synchrony of external mechanical loading with rapid displacement-encoded MRI. We achieved deformation measurements in silicone gel materials with a spatial resolution of 100 µm and a temporal resolution (of 2.25 ms), set by the repetition time (TR) of the rapid MRI acquisition. Displacement and strain precisions after smoothing were 11 µm and 0.1%, respectively, approaching cellular length scales. Short (1/2 TR) echo times enabled visualization of in situ deformation in a human tibiofemoral joint, inclusive of multiple variable T(2) biomaterials. Moreover, the MRI acquisitions achieved a fivefold improvement in imaging time over previous technology, setting the stage for mechanical imaging in vivo. Our results provide a general approach for noninvasive and non-destructive measurement, at high spatial and temporal resolution, of the dynamic mechanical response of a broad range of load-bearing materials and biological tissues.
Collapse
Affiliation(s)
| | - Corey P. Neu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
| |
Collapse
|
89
|
Lu L, Erokwu B, Lee G, Gulani V, Griswold MA, Dell KM, Flask CA. Diffusion-prepared fast imaging with steady-state free precession (DP-FISP): a rapid diffusion MRI technique at 7 T. Magn Reson Med 2011; 68:868-73. [PMID: 22139974 DOI: 10.1002/mrm.23287] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 10/11/2011] [Accepted: 10/14/2011] [Indexed: 01/17/2023]
Abstract
Diffusion MRI is a useful imaging technique with many clinical applications. Many diffusion MRI studies have utilized echo-planar imaging (EPI) acquisition techniques. In this study, we have developed a rapid diffusion-prepared fast imaging with steady-state free precession MRI acquisition for a preclinical 7T scanner providing diffusion-weighted images in less than 500 ms and diffusion tensor imaging assessments in ∼1 min with minimal image artifacts in comparison with EPI. Phantom apparent diffusion coefficient (ADC) and fractional anisotropy (FA) assessments obtained from the diffusion-prepared fast imaging with steady-state free precession (DP-FISP) acquisition resulted in good agreement with EPI and spin echo diffusion methods. The mean apparent diffusion coefficient was 2.0 × 10(-3) mm(2) /s, 1.90 × 10(-3) mm(2) /s, and 1.97 × 10(-3) mm(2) /s for DP-FISP, diffusion-weighted spin echo, and diffusion-weighted EPI, respectively. The mean fractional anisotropy was 0.073, 0.072, and 0.070 for diffusion-prepared fast imaging with steady-state free precession, diffusion-weighted spin echo, and diffusion-weighted EPI, respectively. Initial in vivo studies show reasonable ADC values in a normal mouse brain and polycystic rat kidneys.
Collapse
Affiliation(s)
- Lan Lu
- Department of Radiology, Case Western Reserve University, Cleveland, Ohio, USA
| | | | | | | | | | | | | |
Collapse
|
90
|
Quist B, Hargreaves BA, Cukur T, Morrell GR, Gold GE, Bangerter NK. Simultaneous fat suppression and band reduction with large-angle multiple-acquisition balanced steady-state free precession. Magn Reson Med 2011; 67:1004-12. [PMID: 22038883 DOI: 10.1002/mrm.23076] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Revised: 05/01/2011] [Accepted: 06/08/2011] [Indexed: 01/13/2023]
Abstract
Balanced steady-state free precession (bSSFP) MRI is a rapid and signal-to-noise ratio-efficient imaging method, but suffers from characteristic bands of signal loss in regions of large field inhomogeneity. Several methods have been developed to reduce the severity of these banding artifacts, typically involving the acquisition of multiple bSSFP datasets (and the accompanying increase in scan time). Fat suppression with bSSFP is also challenging; most existing methods require an additional increase in scan time, and some are incompatible with bSSFP band-reduction techniques. This work was motivated by the need for both robust fat suppression and band reduction in the presence of field inhomogeneity when using bSSFP for flow-independent peripheral angiography. The large flip angles used in this application to improve vessel conspicuity and contrast lead to specific absorption rate considerations, longer repetition times, and increased severity of banding artifacts. In this work, a novel method that simultaneously suppresses fat and reduces bSSFP banding artifact with the acquisition of only two phase-cycled bSSFP datasets is presented. A weighted sum of the two bSSFP acquisitions is taken on a voxel-by-voxel basis, effectively synthesizing an off-resonance profile at each voxel that puts fat in the stop band while keeping water in the pass band. The technique exploits the near-sinusoidal shape of the bSSFP off-resonance spectrum for many tissues at large (>50°) flip angles.
Collapse
Affiliation(s)
- Brady Quist
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT, USA
| | | | | | | | | | | |
Collapse
|
91
|
Ingle RR, Cukur T, Nishimura DG. The central signal singularity phenomenon in balanced SSFP and its application to positive-contrast imaging. Magn Reson Med 2011; 67:1673-83. [PMID: 22025426 DOI: 10.1002/mrm.23156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 07/20/2011] [Accepted: 07/26/2011] [Indexed: 11/06/2022]
Abstract
Small perturbations of steady-state sequence parameters can induce very large spectral profile deviations that are localized to specific off-resonant frequencies, denoted critical frequencies. Although, a small number of studies have previously considered the use of these highly specific modulations for MR angiography and elastography, many potential applications still remain to be explored. An analysis of this phenomenon using a linear systems technique and a geometric magnetization trajectory technique shows that the critical frequencies correspond to singularities in the steady-state signal equation. An interleaved acquisition combined with a complex difference technique yields a spectral profile containing sharp peaks interleaved with wide stopbands, while a complex sum technique yields a spectral profile similar to that of balanced steady-state free precession. Simulations and phantom experiments are used to demonstrate a novel application of this technique for positive-contrast imaging of superparamagnetic iron-oxide nanoparticles. The technique is shown to yield images with high levels of positive contrast and good water and fat background suppression. The technique can also simultaneously yield images with contrast similar to balanced steady-state free precession.
Collapse
Affiliation(s)
- R Reeve Ingle
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA.
| | | | | |
Collapse
|
92
|
Buračas GT, Jung Y, Lee J, Buxton RB, Wong EC, Liu TT. On multiple alternating steady states induced by periodic spin phase perturbation waveforms. Magn Reson Med 2011; 67:1412-8. [PMID: 21826730 DOI: 10.1002/mrm.23105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 05/29/2011] [Accepted: 06/25/2011] [Indexed: 11/09/2022]
Abstract
Direct measurement of neural currents by means of MRI can potentially open a high temporal resolution (10-100 ms) window applicable for monitoring dynamics of neuronal activity without loss of the high spatial resolution afforded by MRI. Previously, we have shown that the alternating balanced steady state imaging affords high sensitivity to weak periodic currents owing to its amplification of periodic spin phase perturbations. This technique, however, requires precise synchronization of such perturbations to the radiofrequency pulses. Herein, we extend alternating balanced steady state imaging to multiple balanced alternating steady states for estimation of neural current waveforms. Simulations and phantom experiments show that the off-resonance profile of the multiple alternating steady state signal carries information about the frequency content of driving waveforms. In addition, the method is less sensitive than alternating balanced steady state to precise waveform timing relative to radiofrequency pulses. Thus, multiple alternating steady state technique is potentially applicable to MR imaging of the waveforms of periodic neuronal activity.
Collapse
Affiliation(s)
- Giedrius T Buračas
- Center for Functional MRI, Department of Radiology, University of California, San Diego, La Jolla, California 92037, USA.
| | | | | | | | | | | |
Collapse
|
93
|
Ribot EJ, Martinez-Santiesteban FM, Simedrea C, Steeg PS, Chambers AF, Rutt BK, Foster PJ. In vivo single scan detection of both iron-labeled cells and breast cancer metastases in the mouse brain using balanced steady-state free precession imaging at 1.5 T. J Magn Reson Imaging 2011; 34:231-8. [PMID: 21698713 PMCID: PMC3501681 DOI: 10.1002/jmri.22593] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
PURPOSE To simultaneously detect iron-labeled cancer cells and brain tumors in vivo in one scan, the balanced steady-state free precession (b-SSFP) imaging sequence was optimized at 1.5 T on mice developing brain metastases subsequent to the injection of micron-sized iron oxide particle-labeled human breast cancer cells. MATERIALS AND METHODS b-SSFP sequence parameters (repetition time, flip angle, and receiver bandwidth) were varied and the signal-to-noise ratio, contrast between the brain and tumors, and the number of detected iron-labeled cells were evaluated. RESULTS Optimal b-SSFP images were acquired with a 26 msec repetition time, 35° flip angle, and bandwidth of ±21 kHz. b-SSFP images were compared with T(2) -weighted 2D fast spin echo (FSE) and 3D spoiled gradient recalled echo (SPGR) images. The mean tumor-brain contrast-to-noise ratio and the ability to detect iron-labeled cells were the highest in the b-SSFP images. CONCLUSION A single b-SSFP scan can be used to visualize both iron-labeled cells and brain metastases.
Collapse
Affiliation(s)
- Emeline J. Ribot
- Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | | | | | - Patricia S. Steeg
- Women’s Cancers Section, Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Ann F. Chambers
- London Regional Cancer Program, London, ON, Canada
- Department of Medical Biophysics, University of Western Ontario, London, ON, Canada
| | - Brian K. Rutt
- Richard M. Lucas Center for Imaging, Radiology Department, Stanford University, Stanford, California, USA
| | - Paula J. Foster
- Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
- Department of Medical Biophysics, University of Western Ontario, London, ON, Canada
| |
Collapse
|
94
|
Strickland CD, Kijowski R. Morphologic Imaging of Articular Cartilage. Magn Reson Imaging Clin N Am 2011; 19:229-48. [DOI: 10.1016/j.mric.2011.02.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
95
|
Mallett CL, Foster PJ. Optimization of the balanced steady state free precession (bSSFP) pulse sequence for magnetic resonance imaging of the mouse prostate at 3T. PLoS One 2011; 6:e18361. [PMID: 21494660 PMCID: PMC3072967 DOI: 10.1371/journal.pone.0018361] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 03/03/2011] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION MRI can be used to non-invasively monitor tumour growth and response to treatment in mouse models of prostate cancer, particularly for longitudinal studies of orthotopically-implanted models. We have optimized the balanced steady-state free precession (bSSFP) pulse sequence for mouse prostate imaging. METHODS Phase cycling, excitations, flip angle and receiver bandwidth parameters were optimized for signal to noise ratio and contrast to noise ratio of the prostate. The optimized bSSFP sequence was compared to T1- and T2-weighted spin echo sequences. RESULTS SNR and CNR increased with flip angle. As bandwidth increased, SNR, CNR and artifacts such as chemical shift decreased. The final optimized sequence was 4 PC, 2 NEX, FA 50°, BW ±62.5 kHz and took 14-26 minutes with 200 µm isotropic resolution. The SNR efficiency of the bSSFP images was higher than for T1WSE and T2WSE. CNR was highest for T1WSE, followed closely by bSSFP, with the T2WSE having the lowest CNR. With the bSSFP images the whole body and organs of interest including renal, iliac, inguinal and popliteal lymph nodes were visible. CONCLUSION We were able to obtain fast, high-resolution, high CNR images of the healthy mouse prostate with an optimized bSSFP sequence.
Collapse
Affiliation(s)
- Christiane L Mallett
- Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada.
| | | |
Collapse
|
96
|
Folkesson J, Goldenstein J, Carballido-Gamio J, Kazakia G, Burghardt AJ, Rodriguez A, Krug R, de Papp AE, Link TM, Majumdar S. Longitudinal evaluation of the effects of alendronate on MRI bone microarchitecture in postmenopausal osteopenic women. Bone 2011; 48:611-21. [PMID: 21059422 PMCID: PMC4461063 DOI: 10.1016/j.bone.2010.10.179] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Revised: 10/28/2010] [Accepted: 10/28/2010] [Indexed: 11/24/2022]
Abstract
UNLABELLED We evaluated longitudinal effects of alendronate on MRI-based trabecular bone structure parameters derived from dual thresholding and fuzzy clustering (BE-FCM) trabecular bone segmentation. Treatment effects were observed in the distal tibia after 24 months. The BE-FCM method increased correlations to HR-pQCT-based parameters. INTRODUCTION High-resolution magnetic resonance imaging (MRI) allows for non-invasive bone microarchitecture analysis. The goal of this study was to examine the potential of MRI-based trabecular bone structure parameters to monitor effects of alendronate in humans in vivo, and to compare the results to HR-pQCT and DXA measurements. MATERIALS AND METHODS Postmenopausal osteopenic women were divided into alendronate treatment and control groups, and imaged at baseline, 12 months, and 24 months (n = 52 at baseline) using 3T MRI, HR-pQCT, and DXA. Image acquisition sites included distal tibia (MRI and HR-pQCT), distal radius (MRI, DXA, and HR-pQCT), and the proximal femur (MRI and DXA). Two different regions of interest were evaluated. One contained the trabecular bone region within the entire MRI acquisition, and the second contained a subregion matched to the region contained in the HR-pQCT acquisition. The trabecular bone was segmented using two different methods; dual thresholding and BE-FCM. Trabecular bone structure parameters included bone volume fraction (BV/TV), number (Tb.N), spacing (Tb.Sp), and thickness (Tb.Th), along with seven geodesic topological analysis (GTA) parameters. Longitudinal changes and correlations to HR-pQCT and DXA measurements were evaluated. RESULTS Apparent Tb.N and four GTA parameters showed treatment effects (p < 0.05) in the distal tibia after 24 months in the entire MRI region using BE-FCM, as well as Tb.N using dual thresholding. No treatment effects after 24 months were observed in the HR-pQCT or in MRI analysis for the HR-pQCT-matched regions. Apparent BV/TV and Tb.N from BE-FCM had significantly higher correlations to HR-pQCT values compared to those derived from thresholding. CONCLUSIONS This study demonstrates the influence of computational methods and region of interest definitions on measurements of trabecular bone structure, and the feasibility of MRI-based quantification of longitudinal changes in bone microarchitecture due to bisphosphonate therapy. The results suggest that there may be a need to reevaluate the current standard HR-pQCT region definition for increased treatment sensitivity.
Collapse
Affiliation(s)
- Jenny Folkesson
- Musculoskeletal Quantitative Imaging Research Group (MQIR), Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
97
|
Hu P, Stoeck CT, Smink J, Peters DC, Ngo L, Goddu B, Kissinger KV, Goepfert LA, Chan J, Hauser TH, Rofsky NM, Manning WJ, Nezafat R. Noncontrast SSFP pulmonary vein magnetic resonance angiography: impact of off-resonance and flow. J Magn Reson Imaging 2011; 32:1255-61. [PMID: 21031533 DOI: 10.1002/jmri.22356] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To investigate pulmonary vein (PV) off-resonance and blood flow as causes of signal void artifacts in noncontrast steady-state-free-precession (SSFP) PV magnetic resonance angiography (MRA). MATERIALS AND METHODS PV blood off-resonance was measured on 11 healthy adult subjects and 10 atrial fibrillation (AF) patients. Noncontrast PV MRA was performed using a 3D slab-selective SSFP sequence at 1.5T on seven healthy subjects with signal profile shifts of 0-125 Hz. The time-resolved blood flow velocity of the PVs was measured on five healthy subjects. The impact of flow was studied on six healthy subjects, on whom SSFP PV MRA was acquired twice with the electrocardiogram (ECG) trigger delay corresponding to low and high flow, respectively. RESULTS The PV off-resonances were 97 ± 27 Hz, 65 ± 20 Hz, 74 ± 25 Hz, and 52 ± 17 Hz for right inferior, left inferior, right superior, and left superior PVs, respectively, on healthy subjects, and 74 ± 20 Hz, 38 ± 9 Hz, 51 ± 20 Hz, and 28 ± 11 Hz on AF patients (P<0.01 for all). The off-resonance caused severe signal voids in the PVs. Signal acquired during mid-diastole with high PV flow caused additional signal voids in the left atrium, which was reduced by setting the ECG trigger delay to late-diastole. CONCLUSION PV off-resonance and flow causes signal void artifacts in noncontrast 3D slab-selective SSFP PV MRA.
Collapse
Affiliation(s)
- Peng Hu
- Department of Medicine (Cardiology Division), Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
98
|
Gloor M, Scheffler K, Bieri O. Intrascanner and interscanner variability of magnetization transfer-sensitized balanced steady-state free precession imaging. Magn Reson Med 2010; 65:1112-7. [DOI: 10.1002/mrm.22694] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 07/26/2010] [Accepted: 09/24/2010] [Indexed: 11/11/2022]
|
99
|
Lee J, Fukunaga M, Duyn JH. Improving contrast to noise ratio of resonance frequency contrast images (phase images) using balanced steady-state free precession. Neuroimage 2010; 54:2779-88. [PMID: 21040793 DOI: 10.1016/j.neuroimage.2010.10.071] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 10/20/2010] [Accepted: 10/23/2010] [Indexed: 11/29/2022] Open
Abstract
Recent MRI studies have exploited subtle magnetic susceptibility differences between brain tissues to improve anatomical contrast and resolution. These susceptibility differences lead to resonance frequency shifts which can be visualized by reconstructing the signal phase in conventional gradient echo (GRE) acquisition techniques. In this work, a method is proposed to improve the contrast to noise ratio per unit time (CNR efficiency) of anatomical MRI based on resonance frequency contrast. The method, based on the balanced steady-state free precession (bSSFP) MRI acquisition technique, was evaluated in its ability to generate contrast between gray and white matter in human brain at 3T and 7T. The results show substantially improved CNR efficiency of bSSFP phase images (2.85±0.21 times at 3 T and 1.71±0.11 times at 7 T) compared to the GRE data in a limited spatial area. This limited spatial coverage is attributed to the sensitivity of bSSFP to macroscopic B(0) inhomogeneities. With this CNR improvement, high resolution bSSFP phase images (resolution=0.3×0.3×2 mm(3), acquisition time=10min) acquired at 3T had sufficient CNR to allow the visualization of cortical laminar structures in invivo human primary visual cortex. Practical application of the proposed method may require improvement of B(0) homogeneity and stability by additional preparatory scans and/or compensation schemes such as respiration and drift compensation. Without these additions, the CNR benefits of the method may be limited to studies at low field or limited regions of interest.
Collapse
Affiliation(s)
- Jongho Lee
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1065, USA.
| | | | | |
Collapse
|
100
|
Gloor M, Scheffler K, Bieri O. Nonbalanced SSFP-based quantitative magnetization transfer imaging. Magn Reson Med 2010; 64:149-56. [PMID: 20572130 DOI: 10.1002/mrm.22331] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The previously reported concept for quantitative magnetization transfer (MT) imaging using balanced steady-state free precession (SSFP) is applied to nonbalanced SSFP sequences. This offers the possibility to derive quantitative MT parameters of targets with high-susceptibility variations such as the musculoskeletal system, where balanced SSFP suffers from off-resonance-related signal loss. In the first part of this work, an extended SSFP free induction decay (SSFP-FID) signal equation is derived based on a binary spin-bath model. Based on this new description, quantitative MT parameters such as the fractional pool size, magnetization exchange rate, and relaxation times can be assessed. In the second part of this work, MT model parameters are derived from an ex vivo muscle sample, in vivo human femoral muscle, and in vivo human patellar cartilage. Motion sensitivity issues are discussed and results from two-pool SSFP-FID are compared to results from two-pool balanced SSFP and common quantitative MT models. In summary, this work demonstrates that SSFP-FID allows for quantitative MT imaging of targets with high-susceptibility variations within short acquisition times.
Collapse
Affiliation(s)
- Monika Gloor
- Division of Radiological Physics, Department of Medical Radiology, University of Basel Hospital, Basel, Switzerland.
| | | | | |
Collapse
|