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Kim SE, Roberts JA, Kholmovski EG, Hitchcock Y, Anzai Y. T1 mapping for Head and Neck Cancer Patients undergoing Chemoradiotherapy: Feasibility of 3D Stack of Star Imaging. Magn Reson Imaging 2024; 112:38-46. [PMID: 38604349 PMCID: PMC11303096 DOI: 10.1016/j.mri.2024.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 03/27/2024] [Accepted: 04/05/2024] [Indexed: 04/13/2024]
Abstract
BACKGROUND Measuring tissue oxygen concentration is crucial in understanding the pathophysiological process of hypoxia in head and neck cancer (HNC) and its significant role in cancer biology. This study aimed to determine the feasibility of T1 mapping using a variable flip angle (VFA) technique with stack of stars (SOS) trajectory sampling in HNC patients undergoing chemoradiotherapy (CRT). METHODS To evaluate the ability of SOS acquisition to detect T1, a phantom study was conducted and compared to conventional Cartesian acquisition (CART). Additionally, four newly diagnosed patients were recruited and underwent two scans each at baseline and inter-treatment. The repeatability of SOS and CART acquisitions was assessed by comparing the T1 measurements of CSF from the baseline and intra-treatment MRI studies. The changes in ∆T1 of the tumors during air and oxygen inhalation between baseline and inter-treatment scans were also evaluated. RESULTS Our study found that the 3D VFA SOS sequence was effective in reducing motion artifacts compared to the conventional VFA sequence with CART sampling and the same scan time, as demonstrated by the results from the phantom and patient studies. In terms of repeatability, no significant correlation was observed between the variability in ΔT1 measurements of CSF obtained from SOS T1 maps. The SOS ΔT1 measurements showed higher consistency, as evidenced by the ICC values ranging from 0.52 to 0.92. The ∆T1 measurements on the primary tumors increased after the first CRT (p<0.05) for all patients who showed a positive treatment response, except for one patient (0.05 CONCLUSION The 3D VFA SOS sequence is a feasible and reliable method for T1 mapping in HNC patients undergoing CRT. The use of this technique could potentially aid in the assessment of treatment response and contribute to improving patient outcomes.
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Affiliation(s)
- Seong-Eun Kim
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT, USA.
| | - John A Roberts
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT, USA
| | - Eugene G Kholmovski
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Ying Hitchcock
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT, USA
| | - Yoshimi Anzai
- Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT, USA
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Nie Y, Lu N, Liao L, Liu Z, Gu A, Huang X, Tie C, Liu H, Huang Z, Xie G. Black-Blood Magnetization Prepared 2 Rapid Acquisition Gradient Echoes: A Fast and Three-Dimensional MR Black-Blood T 1 Mapping Technique for Quantitative Assessment of Atherosclerosis and Venous Thrombosis. J Magn Reson Imaging 2024; 60:1148-1162. [PMID: 38009385 DOI: 10.1002/jmri.29156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/28/2023] Open
Abstract
BACKGROUND Blood flow signals may be a confounder in quantifying T1 values of plaque or thrombus and how to realize black-blood T1 mapping remains a challenge task. PURPOSE To develop a fast and three-dimensional black-blood T1 mapping technique for quantitative assessment of atherosclerosis and venous thrombosis. STUDY TYPE Sequence development and optimization via phantoms and volunteers as well as pilot prospective. PHANTOM AND SUBJECTS Numerical simulations, a standard phantom, 8 healthy volunteers (mean age, 22 ± 1 years; 5 males), and 19 patients (mean age, 57 ± 14 years; 13 males) with atherosclerosis or venous thrombosis. FIELD STRENGTH/SEQUENCE 3T/inversion recovery spin-echo sequence (IR-SE), magnetization prepared 2 rapid acquisition gradient echoes (MP2RAGE), and black-blood prepared MP2RAGE (BB-MP2RAGE). ASSESSMENT The black-blood preparation (i.e., delay alternating with nutation for tailored excitation, DANTE) was incorporated into MP2RAGE for black-blood T1 mapping. The BB-MP2RAGE was optimized numerically based on the Bloch equation, and then the phantom study was performed to verify the accuracy of T1 mapping by BB-MP2RAGE against IR-SE and MP2RAGE. Preliminary clinical validation was prospectively performed to assess the flow suppression effect and its potential application in plaque and thrombosis identification. STATISTICAL TESTS Pearson correlation test, Bland-Altman analysis, paired t-test, and intraclass correlation coefficient. A P value <0.05 indicates a statistically significant difference. RESULTS Phantom experiments showed comparable accuracy of T1 maps by BB-MP2RAGE with IR-SE and MP2RAGE (all r2 > 0.99); Compared to MP2RAGE, BB-MP2RAGE effectively nulled the blood flow signals, and had a significant improvement in contrast-to-noise ratio between static tissue and blood (250.5 ± 66.6 vs. 91.9 ± 35.9). BB-MP2RAGE can quantify plaque or thrombus T1 relaxation time with blood flow signal suppression. DATA CONCLUSION Accurate T1 mapping with sufficient blood flow suppression was achieved by BB-MP2RAGE. BB-MP2RAGE has the potential to quantitatively characterize atherosclerosis and venous thrombosis. LEVEL OF EVIDENCE 1 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Yuhui Nie
- School of Biomedical Engineering, The Sixth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
| | - Na Lu
- School of Biomedical Engineering, The Sixth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Liping Liao
- Department of Radiology, The First People's Hospital of Qinzhou, Qinzhou, China
| | - Zeping Liu
- School of Biomedical Engineering, The Sixth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Anyan Gu
- School of Biomedical Engineering, The Sixth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Xin Huang
- School of Biomedical Engineering, The Sixth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Changjun Tie
- Paul C. Lauterbur Imaging Center, Shenzhen Institutes Advanced Technology, Shenzhen, Guangdong, China
| | - Hongyan Liu
- School of Biomedical Engineering, The Sixth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Zehe Huang
- Department of Radiology, The First People's Hospital of Qinzhou, Qinzhou, China
| | - Guoxi Xie
- School of Biomedical Engineering, The Sixth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, China
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Haacke EM, Xu Q, Kokeny P, Gharabaghi S, Chen Y, Wu B, Liu Y, He N, Yan F. Strategically Acquired Gradient Echo (STAGE) Imaging, part IV: Constrained Reconstruction of White Noise (CROWN) Processing as a Means to Improve Signal-to-Noise in STAGE Imaging at 3 Tesla. Magn Reson Imaging 2024; 107:55-68. [PMID: 38181834 DOI: 10.1016/j.mri.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/30/2023] [Accepted: 01/01/2024] [Indexed: 01/07/2024]
Abstract
Increasing the signal-to-noise ratio (SNR) has always been of critical importance for magnetic resonance imaging. Although increasing field strength provides a linear increase in SNR, it is more and more costly as field strength increases. Therefore, there is a major effort today to use signal processing methods to improve SNR since it is more efficient and economical. There are a variety of methods to improve SNR such as averaging the data at the expense of imaging time, or collecting the data with a lower resolution, all of these methods, including imaging processing methods, usually come at the expense of loss of image detail or image blurring. Therefore, we developed a new mathematical approach called CROWN (Constrained Reconstruction of White Noise) to enhance SNR without loss of structural detail and without affecting scanning time. In this study, we introduced and tested the concept behind CROWN specifically for STAGE (strategically acquired gradient echo) imaging. The concept itself is presented first, followed by simulations to demonstrate its theoretical effectiveness. Then the SNR improvement on proton spin density (PSD) and R2⁎ maps was investigated using brain STAGE data acquired from 10 healthy controls (HCs) and 10 patients with Parkinson's disease (PD). For the PSD and R2* maps, the SNR and CNR between white matter and gray matter were improved by a factor of 1.87 ± 0.50 and 1.72 ± 0.88, respectively. The white matter hyperintensity lesions in PD patients were more clearly defined after CROWN processing. Using these improved maps, simulated images for any repeat time, echo time or flip angle can be created with improved SNR. The potential applications of this technology are to trade off the increased SNR for higher resolution images and/or faster imaging.
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Affiliation(s)
- E Mark Haacke
- SpinTech MRI, Bingham Farms, MI 48025, United States of America; Wayne State University, Department of Neurology, Detroit, MI 48201, United States of America; Wayne State University, Department of Radiology, Detroit, MI 48201, United States of America; Zhuyan Limited, Shanghai, China.
| | - Qiuyun Xu
- SpinTech MRI, Bingham Farms, MI 48025, United States of America
| | - Paul Kokeny
- SpinTech MRI, Bingham Farms, MI 48025, United States of America
| | - Sara Gharabaghi
- SpinTech MRI, Bingham Farms, MI 48025, United States of America
| | - Yongsheng Chen
- Wayne State University, Department of Neurology, Detroit, MI 48201, United States of America
| | - Bo Wu
- Zhuyan Limited, Shanghai, China
| | - Yu Liu
- Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Department of Radiology, Shanghai, China
| | - Naying He
- Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Department of Radiology, Shanghai, China
| | - Fuhua Yan
- Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Department of Radiology, Shanghai, China
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Swago S, Wilson NE, Elliott MA, Reddy Nanga RP, Reddy R, Witschey WR. Quantification of NAD + T 1 and T 2 relaxation times using downfield 1 H MRS at 7 T in human brain in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.27.582276. [PMID: 38464048 PMCID: PMC10925302 DOI: 10.1101/2024.02.27.582276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Introduction The purpose of this study was to use a single-slice spectrally-selective sequence to measure T 1 and T 2 relaxation times of NAD + proton resonances in the downfield 1 H MRS spectrum in human brain at 7 T in vivo and assess the propagation of relaxation time uncertainty in NAD + quantification. Methods Downfield spectra from 7 healthy volunteers were acquired at multiple echo times in all subjects to measure T 2 relaxation, and saturation recovery data were to measure T 1 relaxation. The downfield acquisition used a spectrally-selective 90° sinc pulse for excitation centered at 9.1 ppm with a bandwidth of 2 ppm, followed by a 180° spatially-selective Shinnar-Le Roux refocusing pulse for localization. For the multiple echo experiment, spectra were collected with echo times ranging from 13 to 33 ms. For the saturation recovery experiment, saturation was performed prior to excitation using the same spectrally-selective sinc pulse as was used for excitation. Saturation delay times (TS) ranged from 100 to 600 ms. Uncertainty propagation analysis was performed analytically and with Monte Carlo simulation. Results The mean ± standard deviation of T 1 relaxation times of the H2, H6, and H4 protons were 152.7 ± 16.6, 163.6 ± 22.3, and 169.9 ± 11.2 ms, respectively. The mean ± standard deviation of T 2 relaxation times of the H2, H6, and H4 protons were 32.5 ± 7.0, 27.4 ± 5.2, and 38.1 ± 11.7 ms, respectively. The mean R 2 of the H2 and H6 T 1 fits were 0.98. The mean R 2 of the H4 proton T 1 fit was 0.96. The mean R 2 of the T 2 fits of the H2 and H4 proton resonances were 0.98, while the mean R 2 of the T 2 fits of the H4 proton was 0.93. The relative uncertainty in NAD + concentration due to relaxation time uncertainty was 8.5%-11%. Conclusion Using downfield spectrally-selective spectroscopy with single-slice localization, we found NAD + T 1 and T 2 relaxation times to be approximately 162 ms and 32 ms respectively in the human brain in vivo at 7 T.
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Wallstein N, Müller R, Pampel A, Möller HE. Radiation damping at clinical field strength: Characterization and compensation in quantitative measurements. Magn Reson Med 2024; 91:1239-1253. [PMID: 38010072 DOI: 10.1002/mrm.29934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/03/2023] [Accepted: 10/24/2023] [Indexed: 11/29/2023]
Abstract
PURPOSE In any MR experiment, the bulk magnetization acts on itself, caused by the induced current in the RF receiver circuit that generates an oscillating damping field. This effect, known as "radiation damping" (RD), is usually weak and, therefore, unconsidered in MRI, but can affect quantitative studies performed with dedicated coils that provide a high SNR. The current work examined RD in a setup for investigations of small tissue specimens including a quantitative characterization of the spin-coil system. THEORY AND METHODS A custom-made Helmholtz coil (radius and spacing 16 mm) was interfaced to a transmit-receive (Tx/Rx) switch with integrated passive feedback for modulation or suppression of RD similar to preamplifier decoupling. Pulse sequences included pulse-width arrays to demonstrate the absence/ presence of RD and difference techniques employing gradient pulses or composite RF pulses to quantify RD effects during free precession and transmission, respectively. Experiments were performed at 3T in small samples of MnCl2 solution. RESULTS Significant RD effects may impact RF pulse application and evolution periods. Effective damping time constants were comparable to typical T2 * times or echo spacings in multi-echo sequences. Measurements of the phase relation showed that deviations from the commonly assumed 90° angle between the damping field and the transverse magnetization may occur. CONCLUSION Radiation damping may affect the accuracy of quantitative MR measurements performed with dedicated RF coils. Efficient mitigation can be achieved hardware-based or by appropriate consideration in the pulse sequence.
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Affiliation(s)
- Niklas Wallstein
- Nuclear Magnetic Resonance Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Roland Müller
- Nuclear Magnetic Resonance Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - André Pampel
- Nuclear Magnetic Resonance Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Harald E Möller
- Nuclear Magnetic Resonance Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Faculty of Physics and Earth Sciences, Felix Bloch Institute for Solid State Physics, Leipzig University, Leipzig, Germany
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Sirucek L, Zoelch N, Schweinhardt P. Improving magnetic resonance spectroscopy in the brainstem periaqueductal gray using spectral registration. Magn Reson Med 2024; 91:28-38. [PMID: 37800387 DOI: 10.1002/mrm.29832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/08/2023] [Accepted: 07/31/2023] [Indexed: 10/07/2023]
Abstract
PURPOSE Functional understanding of the periaqueductal gray (PAG), a clinically relevant brainstem region, can be advanced using 1 H-MRS. However, the PAG's small size and high levels of physiological noise are methodologically challenging. This study aimed to (1) improve 1 H-MRS quality in the PAG using spectral registration for frequency and phase error correction; (2) investigate whether spectral registration is particularly useful in cases of greater head motion; and (3) examine metabolite quantification using literature-based or individual-based water relaxation times. METHODS Spectra were acquired in 33 healthy volunteers (50.1 years, SD = 17.19, 18 females) on a 3 T Philipps MR system using a point-resolved spectroscopy (PRESS) sequence optimized with very selective saturation pulses (OVERPRESS) and voxel-based flip angle calibration (effective volume of interest size: 8.8 × 10.2 × 12.2 mm3 ). Spectra were fitted using LCModel and SNR, NAA peak linewidths and Cramér-Rao lower bounds (CRLBs) were measured after spectral registration and after minimal frequency alignment. RESULTS Spectral registration improved SNR by 5% (p = 0.026, median value post-correction: 18.0) and spectral linewidth by 23% (p < 0.001, 4.3 Hz), and reduced the metabolites' CRLBs by 1% to 15% (p < 0.026). Correlational analyses revealed smaller SNR improvements with greater head motion (p = 0.010) recorded using a markerless motion tracking system. Higher metabolite concentrations were detected using individual-based compared to literature-based water relaxation times (p < 0.001). CONCLUSION This study demonstrates high-quality 1 H-MRS acquisition in the PAG using spectral registration. This shows promise for future 1 H-MRS studies in the PAG and possibly other clinically relevant brain regions with similar methodological challenges.
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Affiliation(s)
- Laura Sirucek
- Department of Chiropractic Medicine, Integrative Spinal Research Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland
| | - Niklaus Zoelch
- Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
- Department of Psychiatry, Psychotherapy, and Psychosomatics, Psychiatric University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Petra Schweinhardt
- Department of Chiropractic Medicine, Integrative Spinal Research Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland
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Mahmoudi N, Dadak M, Bronzlik P, Maudsley AA, Sheriff S, Lanfermann H, Ding XQ. Microstructural and Metabolic Changes in Normal Aging Human Brain Studied with Combined Whole-Brain MR Spectroscopic Imaging and Quantitative MR Imaging. Clin Neuroradiol 2023; 33:993-1005. [PMID: 37336867 PMCID: PMC10654209 DOI: 10.1007/s00062-023-01300-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/27/2023] [Indexed: 06/21/2023]
Abstract
PURPOSE This study aimed to detect age-related brain metabolic and microstructural changes in healthy human brains by the use of whole-brain proton magnetic resonance spectroscopic imaging (1H‑MRSI) and quantitative MR imaging (qMRI). METHODS In this study, 60 healthy participants with evenly distributed ages (between 21 and 69 years) and sex underwent MRI examinations at 3T including whole-brain 1H‑MRSI. The concentrations of the metabolites N‑acetylaspartate (NAA), choline-containing compounds (Cho), total creatine and phosphocreatine (tCr), glutamine and glutamate (Glx), and myo-inositol (mI), as well as the brain relaxation times T2, T2' and T1 were measured in 12 regions of interest (ROI) in each hemisphere. Correlations between measured parameters and age were estimated with linear regression analysis and Pearson's correlation test. RESULTS Significant age-related changes of brain regional metabolite concentrations and tissue relaxation times were found: NAA decreased in eight of twelve ROIs, Cho increased in three ROIs, tCr in four ROIs, and mI in three ROIs. Glx displayed a significant decrease in one ROI and an increase in another ROI. T1 increased in four ROIs and T2 in one ROI, while T2' decreased in two ROIs. A negative correlation of tCr concentrations with T2' relaxation time was found in one ROI as well as the positive correlations of age-related T1 relaxation time with concentrations of tCr, mI, Glx and Cho in another ROI. CONCLUSION Normal aging in human brain is associated with coexistent brain regional metabolic alterations and microstructural changes, which may be related to age-related decline in cognitive, affective and psychomotor domains of life in the older population.
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Affiliation(s)
- N Mahmoudi
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany.
| | - M Dadak
- Department of Diagnostic and Interventional Radiology and Neuroradiology, St. Vincenz Hospital Paderborn, Paderborn, Germany
| | - P Bronzlik
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - A A Maudsley
- Department of Radiology, University of Miami School of Medicine, Miami, FL, USA
| | - S Sheriff
- Department of Radiology, University of Miami School of Medicine, Miami, FL, USA
| | - H Lanfermann
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - X-Q Ding
- Institute of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
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Powell E, Dickie BR, Ohene Y, Maskery M, Parker GJM, Parkes LM. Blood-brain barrier water exchange measurements using contrast-enhanced ASL. NMR IN BIOMEDICINE 2023; 36:e5009. [PMID: 37666494 PMCID: PMC10909569 DOI: 10.1002/nbm.5009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 05/17/2023] [Accepted: 06/30/2023] [Indexed: 09/06/2023]
Abstract
A technique for quantifying regional blood-brain barrier (BBB) water exchange rates using contrast-enhanced arterial spin labelling (CE-ASL) is presented and evaluated in simulations and in vivo. The two-compartment ASL model describes the water exchange rate from blood to tissue,k b , but to estimatek b in practice it is necessary to separate the intra- and extravascular signals. This is challenging in standard ASL data owing to the small difference inT 1 values. Here, a gadolinium-based contrast agent is used to increase thisT 1 difference and enable the signal components to be disentangled. The optimal post-contrast bloodT 1 (T 1 , b post ) at 3 T was determined in a sensitivity analysis, and the accuracy and precision of the method quantified using Monte Carlo simulations. Proof-of-concept data were acquired in six healthy volunteers (five female, age range 24-46 years). The sensitivity analysis identified the optimalT 1 , b post at 3 T as 0.8 s. Simulations showed thatk b could be estimated in individual cortical regions with a relative error ϵ < 1 % and coefficient of variation CoV = 30 %; however, a high dependence on bloodT 1 was also observed. In volunteer data, mean parameter values in grey matter were: arterial transit timet A = 1 . 15 ± 0 . 49 s, cerebral blood flow f = 58 . 0 ± 14 . 3 mL blood/min/100 mL tissue and water exchange ratek b = 2 . 32 ± 2 . 49 s-1 . CE-ASL can provide regional BBB water exchange rate estimates; however, the clinical utility of the technique is dependent on the achievable accuracy of measuredT 1 values.
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Affiliation(s)
- Elizabeth Powell
- Centre for Medical Image Computing, Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Ben R. Dickie
- Division of Informatics, Imaging and Data Sciences, School of Health Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
- Geoffrey Jefferson Brain Research CentreUniversity of Manchester, Manchester Academic Health Science CentreManchesterUK
| | - Yolanda Ohene
- Geoffrey Jefferson Brain Research CentreUniversity of Manchester, Manchester Academic Health Science CentreManchesterUK
- Division of Psychology, Communication and Human Neuroscience, School of Health Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
| | - Mark Maskery
- Department of NeurologyLancashire Teaching Hospitals NHS Foundation TrustPrestonUK
| | - Geoff J. M. Parker
- Centre for Medical Image Computing, Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- Queen Square MS Centre, Institute of NeurologyUniversity College LondonLondonUK
- Bioxydyn LimitedManchesterUnited Kingdom
| | - Laura M. Parkes
- Geoffrey Jefferson Brain Research CentreUniversity of Manchester, Manchester Academic Health Science CentreManchesterUK
- Division of Psychology, Communication and Human Neuroscience, School of Health Sciences, Faculty of Biology, Medicine and HealthUniversity of ManchesterManchesterUK
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Tanasescu R, Mougin O, Chou IJ, Al-Radaideh A, Jerca OP, Lim SY, Gowland P, Constantinescu CS. Natalizumab Treatment for Relapsing Multiple Sclerosis Stabilises Normal-Appearing White Matter Microstructure: A One-Year Prospective Ultra-High-Field Quantitative Imaging Study. Brain Sci 2023; 13:1464. [PMID: 37891832 PMCID: PMC10605806 DOI: 10.3390/brainsci13101464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 09/24/2023] [Accepted: 10/14/2023] [Indexed: 10/29/2023] Open
Abstract
(1) Background: Natalizumab dramatically reduces relapses and MRI inflammatory activity (new lesions and enhancing lesions) in multiple sclerosis (MS). Chemical exchange saturation transfer (CEST) MRI can explore brain tissue in vivo with high resolution and sensitivity. We investigated if natalizumab can prevent microstructural tissue damage progression measured with MRI at ultra-high field (7 Tesla) over the first year of treatment. (2) Methods: In this one-year prospective longitudinal study, patients with active relapsing-remitting MS were assessed clinically and scanned at ultra-high-field MRI at the time of their first natalizumab infusion, at 6 and 12 months, with quantitative imaging aimed to detect microstructural changes in the normal-appearing white matter (NAWM), including sequences sensitive to magnetisation transfer (MT) effects from amide proton transfer (MTRAPT) and the nuclear Overhauser effect (MTRNOE). (3) Results: 12 patients were recruited, and 10 patients completed the study. The difference in the T1 relaxation times at month 6 and month 12 of natalizumab treatment was not significant, suggesting the lack of accumulation of tissue damage, while improvements were seen in MTR (MTRAPT and MTRNOE measures) at month 12, suggesting a tissue repair effect. This paralleled the expected lack of clinical and radiological worsening of conventional MRI measures of disease activity (new lesions or gadolinium-enhancing lesions). (4) Conclusion: Natalizumab prevents microstructural brain damage and has effects suggesting an improved white matter microstructure measured at ultra-high field during the first year of treatment.
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Affiliation(s)
- Radu Tanasescu
- Academic Unit of Mental Health and Clinical Neurosciences, Section of Clinical Neurology, University of Nottingham, Nottingham NG7 2UH, UK
- Department of Neurology, Nottingham Centre for MS and Neuroinflammation, Nottingham University Hospitals NHS Trust, Nottingham NG5 1PB, UK
| | - Olivier Mougin
- Sir Peter Mansfield Imaging Centre, School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2QL, UK; (O.M.)
| | - I-Jun Chou
- Academic Unit of Mental Health and Clinical Neurosciences, Section of Clinical Neurology, University of Nottingham, Nottingham NG7 2UH, UK
- Chang Gung Memorial Hospital, Linko Branch, Taoyuan 333, Taiwan
| | - Ali Al-Radaideh
- Sir Peter Mansfield Imaging Centre, School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2QL, UK; (O.M.)
- Department of Medical Imaging, Faculty of Applied Medical Sciences, The Hashemite University, Zarqa 13133, Jordan
- Department of Medical Radiography, College of Health Sciences, University of Doha for Science and Technology, Doha 24449, Qatar
| | - Oltita P. Jerca
- Academic Unit of Mental Health and Clinical Neurosciences, Section of Clinical Neurology, University of Nottingham, Nottingham NG7 2UH, UK
- Medizinisches Zentrum Harz, 38820 Halberstadt, Germany
| | - Su-Yin Lim
- Academic Unit of Mental Health and Clinical Neurosciences, Section of Clinical Neurology, University of Nottingham, Nottingham NG7 2UH, UK
- School of Medicine, Faculty of Health and Medical Sciences, Taylor’s University, Subang Jaya 47500, Malaysia
| | - Penny Gowland
- Sir Peter Mansfield Imaging Centre, School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2QL, UK; (O.M.)
| | - Cris S. Constantinescu
- Academic Unit of Mental Health and Clinical Neurosciences, Section of Clinical Neurology, University of Nottingham, Nottingham NG7 2UH, UK
- Department of Neurology, Nottingham Centre for MS and Neuroinflammation, Nottingham University Hospitals NHS Trust, Nottingham NG5 1PB, UK
- Cooper Neurological Institute, Cooper Medical School of Rowan University, Camden, NJ 08013, USA
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Beaumont J, Fripp J, Raniga P, Acosta O, Ferre JC, McMahon K, Trinder J, Kober T, Gambarota G. Multi T1-weighted contrast imaging and T1 mapping with compressed sensing FLAWS at 3 T. MAGMA (NEW YORK, N.Y.) 2023; 36:823-836. [PMID: 36847989 DOI: 10.1007/s10334-023-01071-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/26/2023] [Accepted: 02/10/2023] [Indexed: 03/01/2023]
Abstract
OBJECTIVE The Fluid And White matter Suppression (FLAWS) MRI sequence provides multiple T1-weighted contrasts of the brain in a single acquisition. However, the FLAWS acquisition time is approximately 8 min with a standard GRAPPA 3 acceleration factor at 3 T. This study aims at reducing the FLAWS acquisition time by providing a new sequence optimization based on a Cartesian phyllotaxis k-space undersampling and a compressed sensing (CS) reconstruction. This study also aims at showing that T1 mapping can be performed with FLAWS at 3 T. MATERIALS AND METHODS The CS FLAWS parameters were determined using a method based on a profit function maximization under constraints. The FLAWS optimization and T1 mapping were assessed with in-silico, in-vitro and in-vivo (10 healthy volunteers) experiments conducted at 3 T. RESULTS In-silico, in-vitro and in-vivo experiments showed that the proposed CS FLAWS optimization allows the acquisition time of a 1 mm-isotropic full-brain scan to be reduced from [Formula: see text] to [Formula: see text] without decreasing image quality. In addition, these experiments demonstrate that T1 mapping can be performed with FLAWS at 3 T. DISCUSSION The results obtained in this study suggest that the recent advances in FLAWS imaging allow to perform multiple T1-weighted contrast imaging and T1 mapping in a single [Formula: see text] sequence acquisition.
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Affiliation(s)
- Jeremy Beaumont
- Univ Rennes, CRLCC Eugene Marquis, Inserm, LTSI-UMR1099, LTSI, Campus de Beaulieu, Université de Rennes 1, 35042, Rennes, France.
- The Australian e-Health Research Centre, CSIRO, Brisbane, QLD, Australia.
| | - Jurgen Fripp
- The Australian e-Health Research Centre, CSIRO, Brisbane, QLD, Australia
| | - Parnesh Raniga
- The Australian e-Health Research Centre, CSIRO, Brisbane, QLD, Australia
| | - Oscar Acosta
- Univ Rennes, CRLCC Eugene Marquis, Inserm, LTSI-UMR1099, LTSI, Campus de Beaulieu, Université de Rennes 1, 35042, Rennes, France
| | - Jean-Christophe Ferre
- Univ Rennes, Inria, CNRS, Inserm, IRISA, EMPENN ERL U-1228, Rennes, France
- Department of Neuroradiology, CHU Rennes, Rennes, France
| | - Katie McMahon
- School of Clinical Sciences, Centre for Biomedical Technologies, Queensland University of Technology (QUT), Brisbane, QLD, Australia
- Herston Imaging Research Facility, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
| | - Julie Trinder
- The Australian e-Health Research Centre, CSIRO, Brisbane, QLD, Australia
| | - Tobias Kober
- Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland
- Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- LTS5, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Giulio Gambarota
- Univ Rennes, CRLCC Eugene Marquis, Inserm, LTSI-UMR1099, LTSI, Campus de Beaulieu, Université de Rennes 1, 35042, Rennes, France
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11
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To XV, Donnelly P, Maclachlan L, Mahady K, Apellaniz EM, Cumming P, Winter C, Nasrallah F. Anti-inflammatory interleukin 1 receptor antagonist concentration in plasma correlates with blood-brain barrier integrity in the primary lesion area in traumatic brain injury patients. Brain Behav Immun Health 2023; 31:100653. [PMID: 37415924 PMCID: PMC10320227 DOI: 10.1016/j.bbih.2023.100653] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/06/2023] [Accepted: 06/11/2023] [Indexed: 07/08/2023] Open
Abstract
Purpose Blood-brain barrier (BBB) dysregulation and pro-inflammatory signalling molecules are secondary factors that have been associated with injury severity and long-term clinical outcome following traumatic brain injury (TBI). However, the association between BBB permeability and inflammation is unknown in human TBI patients. In this study, we investigated whether BBI integrity as measured by Dynamic Contrast-Enhanced (DCE) Magnetic Resonance Imaging (MRI) correlates with plasma levels of immunological markers following TBI. Methods Thirty-two TBI patients recruited from a neurosurgical unit were included in the study. Structural three-dimensional T1-weighted and DCE-MRI images were acquired on a 3T MRI at the earliest opportunity once the participant was sufficiently stable after patient admission to hospital. Blood sampling was performed on the same day as the MRI. The location and extents of the haemorrhagic and contusional lesions were identified. Immunological biomarkers were quantified from the participants' plasma using a multiplex immunoassay. Demographic and clinical information, including age and Glasgow Coma Scale (GCS) were also collected and the immunological biomarker profiles were compared across controls and the TBI severity sub-groups. Contrast agent leakiness through blood-brain barriers (BBB) in the contusional lesions were assessed by fitting DCE-MRI using Patlak model and BBB leakiness characteristics of the participants were correlated with the immunological biomarker profiles. Results TBI patients showed reduced plasma levels of interleukin (IL)-1β, IFN-γ, IL-13, and chemokine (C-C motif) ligands (CCL)2 compared to controls and significantly higher levels of platelet-derived growth factor (PDGF-BB), IL-6, and IL-8. BBB leakiness of the contusional lesions did not significantly differ across different TBI severity sub-groups. IL-1ra levels significantly and positively correlated with the contusional lesion's BBB integrity as measured with DCE-MRI via an exponential curve relationship. Discussion This is the first study to combine DCE-MRI with plasma markers of inflammation in acute TBI patients. Our finding that plasma levels of the anti-inflammatory cytokine IL-1ra correlated negatively with increased leakiness of the BBB.
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Affiliation(s)
- Xuan Vinh To
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Patrick Donnelly
- Department of Neurosurgery, Royal Brisbane and Women's Hospital, Brisbane, Australia
| | - Liam Maclachlan
- Department of Neurosurgery, Royal Brisbane and Women's Hospital, Brisbane, Australia
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia
| | - Kate Mahady
- Department of Radiology, Royal Brisbane and Women's Hospital, Brisbane, Australia
| | | | - Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
| | - Craig Winter
- Department of Neurosurgery, Royal Brisbane and Women's Hospital, Brisbane, Australia
- Faculty of Medicine, University of Queensland, Brisbane, Australia
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Australia
| | - Fatima Nasrallah
- Department of Neurosurgery, Royal Brisbane and Women's Hospital, Brisbane, Australia
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Motovilova E, Aronowitz E, Vincent J, Shin J, Tan ET, Robb F, Taracila V, Sneag DB, Dyke JP, Winkler SA. Silicone-based materials with tailored MR relaxation characteristics for use in reduced coil visibility and in tissue-mimicking phantom design. Med Phys 2023; 50:3498-3510. [PMID: 36737839 PMCID: PMC10272082 DOI: 10.1002/mp.16255] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 12/24/2022] [Accepted: 01/15/2023] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The development of materials with tailored signal intensity in MR imaging is critically important both for the reduction of signal from non-tissue hardware, as well as for the construction of tissue-mimicking phantoms. Silicone-based phantoms are becoming more popular due to their structural stability, stretchability, longer shelf life, and ease of handling, as well as for their application in dynamic imaging of physiology in motion. Moreover, silicone can be also used for the design of stretchable receive radio-frequency (RF) coils. PURPOSE Fabrication of materials with tailored signal intensity for MRI requires knowledge of precise T1 and T2 relaxation times of the materials used. In order to increase the range of possible relaxation times, silicone materials can be doped with gadolinium (Gd). In this work, we aim to systematically evaluate relaxation properties of Gd-doped silicone material at a broad range of Gd concentrations and at three clinically relevant magnetic field strengths (1.5 T, 3 T, and 7 T). We apply the findings for rendering silicone substrates of stretchable receive RF coils less visible in MRI. Moreover, we demonstrate early stage proof-of-concept applicability in tissue-mimicking phantom development. MATERIALS AND METHODS Ten samples of pure and Gd-doped Ecoflex silicone polymer samples were prepared with various Gd volume ratios ranging from 1:5000 to 1:10, and studied using 1.5 T and 3 T clinical and 7 T preclinical scanners. T1 and T2 relaxation times of each sample were derived by fitting the data to Bloch signal intensity equations. A receive coil made from Gd-doped Ecoflex silicone polymer was fabricated and evaluated in vitro at 3 T. RESULTS With the addition of a Gd-based contrast agent, it is possible to significantly change T2 relaxation times of Ecoflex silicone polymer (from 213 ms to 20 ms at 1.5 T; from 135 ms to 17 ms at 3 T; and from 111.4 ms to 17.2 ms at 7 T). T1 relaxation time is less affected by the introduction of the contrast agent (changes from 608 ms to 579 ms; from 802.5 ms to 713 ms at 3 T; from 1276 ms to 979 ms at 7 T). First results also indicate that liver, pancreas, and white matter tissues can potentially be closely mimicked using this phantom preparation technique. Gd-doping reduces the appearance of the silicone-based coil substrate during the MR scan by up to 81%. CONCLUSIONS Gd-based contrast agents can be effectively used to create Ecoflex silicone polymer-based phantoms with tailored T2 relaxation properties. The relative low cost, ease of preparation, stretchability, mechanical stability, and long shelf life of Ecoflex silicone polymer all make it a good candidate for "MR invisible" coil development and bears promise for tissue-mimicking phantom development applicability.
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Affiliation(s)
- Elizaveta Motovilova
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
- Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | - Eric Aronowitz
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | | | - James Shin
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
| | - Ek Tsoon Tan
- Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | | | | | - Darryl B. Sneag
- Department of Radiology, Hospital for Special Surgery, New York, New York, USA
| | - Jonathan P. Dyke
- Department of Radiology, Weill Cornell Medicine, New York, New York, USA
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13
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Shao X, Zhao C, Shou Q, St Lawrence KS, Wang DJJ. Quantification of blood-brain barrier water exchange and permeability with multidelay diffusion-weighted pseudo-continuous arterial spin labeling. Magn Reson Med 2023; 89:1990-2004. [PMID: 36622951 PMCID: PMC10079266 DOI: 10.1002/mrm.29581] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/22/2022] [Accepted: 12/26/2022] [Indexed: 01/11/2023]
Abstract
PURPOSE To present a pulse sequence and mathematical models for quantification of blood-brain barrier water exchange and permeability. METHODS Motion-compensated diffusion-weighted (MCDW) gradient-and-spin echo (GRASE) pseudo-continuous arterial spin labeling (pCASL) sequence was proposed to acquire intravascular/extravascular perfusion signals from five postlabeling delays (PLDs, 1590-2790 ms). Experiments were performed on 11 healthy subjects at 3 T. A comprehensive set of perfusion and permeability parameters including cerebral blood flow (CBF), capillary transit time (τc ), and water exchange rate (kw ) were quantified, and permeability surface area product (PSw ), total extraction fraction (Ew ), and capillary volume (Vc ) were derived simultaneously by a three-compartment single-pass approximation (SPA) model on group-averaged data. With information (i.e., Vc and τc ) obtained from three-compartment SPA modeling, a simplified linear regression of logarithm (LRL) approach was proposed for individual kw quantification, and Ew and PSw can be estimated from long PLD (2490/2790 ms) signals. MCDW-pCASL was compared with a previously developed diffusion-prepared (DP) pCASL sequence, which calculates kw by a two-compartment SPA model from PLD = 1800 ms signals, to evaluate the improvements. RESULTS Using three-compartment SPA modeling, group-averaged CBF = 51.5/36.8 ml/100 g/min, kw = 126.3/106.7 min-1 , PSw = 151.6/93.8 ml/100 g/min, Ew = 94.7/92.2%, τc = 1409.2/1431.8 ms, and Vc = 1.2/0.9 ml/100 g in gray/white matter, respectively. Temporal SNR of MCDW-pCASL perfusion signals increased 3-fold, and individual kw maps calculated by the LRL method achieved higher spatial resolution (3.5 mm3 isotropic) as compared with DP pCASL (3.5 × 3.5 × 8 mm3 ). CONCLUSION MCDW-pCASL allows visualization of intravascular/extravascular ASL signals across multiple PLDs. The three-compartment SPA model provides a comprehensive measurement of blood-brain barrier water dynamics from group-averaged data, and a simplified LRL method was proposed for individual kw quantification.
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Affiliation(s)
- Xingfeng Shao
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Chenyang Zhao
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Qinyang Shou
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Keith S St Lawrence
- Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Danny JJ Wang
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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Veeraiah P, Jansen JFA. Multinuclear Magnetic Resonance Spectroscopy at Ultra-High-Field: Assessing Human Cerebral Metabolism in Healthy and Diseased States. Metabolites 2023; 13:metabo13040577. [PMID: 37110235 PMCID: PMC10143499 DOI: 10.3390/metabo13040577] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/06/2023] [Accepted: 04/17/2023] [Indexed: 04/29/2023] Open
Abstract
The brain is a highly energetic organ. Although the brain can consume metabolic substrates, such as lactate, glycogen, and ketone bodies, the energy metabolism in a healthy adult brain mainly relies on glucose provided via blood. The cerebral metabolism of glucose produces energy and a wide variety of intermediate metabolites. Since cerebral metabolic alterations have been repeatedly implicated in several brain disorders, understanding changes in metabolite levels and corresponding cell-specific neurotransmitter fluxes through different substrate utilization may highlight the underlying mechanisms that can be exploited to diagnose or treat various brain disorders. Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure tissue metabolism in vivo. 1H-MRS is widely applied in research at clinical field strengths (≤3T) to measure mostly high abundant metabolites. In addition, X-nuclei MRS including, 13C, 2H, 17O, and 31P, are also very promising. Exploiting the higher sensitivity at ultra-high-field (>4T; UHF) strengths enables obtaining unique insights into different aspects of the substrate metabolism towards measuring cell-specific metabolic fluxes in vivo. This review provides an overview about the potential role of multinuclear MRS (1H, 13C, 2H, 17O, and 31P) at UHF to assess the cerebral metabolism and the metabolic insights obtained by applying these techniques in both healthy and diseased states.
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Affiliation(s)
- Pandichelvam Veeraiah
- Scannexus (Ultra-High-Field MRI Center), 6229 EV Maastricht, The Netherlands
- Faculty of Health Medicine and Life Sciences, Maastricht University, 6229 ER Maastricht, The Netherlands
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
| | - Jacobus F A Jansen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
- School for Mental Health and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
- Department of Electrical Engineering, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands
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15
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Reynolds LA, Morris SR, Vavasour IM, Barlow L, Laule C, MacKay AL, Michal CA. Nonaqueous magnetization following adiabatic and selective pulses in brain: T1 and cross-relaxation dynamics. NMR IN BIOMEDICINE 2023:e4936. [PMID: 36973767 DOI: 10.1002/nbm.4936] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/03/2023] [Accepted: 03/20/2023] [Indexed: 06/18/2023]
Abstract
Inversion pulses are commonly employed in MRI for T 1 $$ {T}_1 $$ -weighted contrast and relaxation measurements. In the brain, it is often assumed that adiabatic pulses saturate the nonaqueous magnetization. We investigated this assumption using solid-state NMR to monitor the nonaqueous signal directly following adiabatic inversion and compared this with signals following hard and soft inversion pulses. The effects of the different preparations on relaxation dynamics were explored. Inversion recovery experiments were performed on ex vivo bovine and porcine brains using 360-MHz (8.4 T) and 200-MHz (4.7 T) NMR spectrometers, respectively, using broadband rectangular, adiabatic, and sinc inversion pulses as well as a long rectangular saturation pulse. Analogous human brain MRI experiments were performed at 3 T using single-slice echo-planar imaging. Relaxation data were fitted by mono- and biexponential decay models. Further fitting analysis was performed using only two inversion delay times. Adiabatic and sinc inversion left much of the nonaqueous magnetization along B 0 $$ {B}_0 $$ and resulted in biexponential relaxation. Saturation of both aqueous and nonaqueous magnetization components led to effectively monoexponential T 1 $$ {T}_1 $$ relaxation. Typical adiabatic inversion pulses do not, as has been widely assumed, saturate the nonaqueous proton magnetization in white matter. Unequal magnetization states in aqueous and nonaqueous 1 H reservoirs prepared by soft and adiabatic pulses result in biexponential T 1 $$ {T}_1 $$ relaxation. Both pools must be prepared in the same magnetization state (e.g., saturated or inverted) in order to observe consistent monoexponential relaxation.
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Affiliation(s)
- Luke A Reynolds
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
| | - Sarah R Morris
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Department of Radiology, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, Blusson Spinal Cord Centre, University of British Columbia, Vancouver, BC, Canada
| | - Irene M Vavasour
- Department of Radiology, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, Blusson Spinal Cord Centre, University of British Columbia, Vancouver, BC, Canada
- UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Laura Barlow
- UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Cornelia Laule
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Department of Radiology, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, Blusson Spinal Cord Centre, University of British Columbia, Vancouver, BC, Canada
- Department of Pathology & Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Alex L MacKay
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
- Department of Radiology, University of British Columbia, Vancouver, BC, Canada
- UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Carl A Michal
- Department of Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada
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16
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Tao S, Zhou X, Lin C, Patel V, Westerhold EM, Middlebrooks EH. Optimization of MP2RAGE T1 mapping with radial view-ordering for deep brain stimulation targeting at 7 T MRI. Magn Reson Imaging 2023; 100:55-63. [PMID: 36924805 DOI: 10.1016/j.mri.2023.03.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/28/2023] [Accepted: 03/12/2023] [Indexed: 03/15/2023]
Abstract
PURPOSE Deep brain stimulation (DBS) is an effective treatment of various neurological disorders. Due to higher intrinsic signal, 7 T MRI can potentially improve delineation of DBS targets. However, the severe RF transmit field (B1+) inhomogeneity at 7 T can compromise the image contrast of traditional single-contrast sequences for DBS targeting, leading to sub-optimal target visualization. The Magnetization Prepared 2 Rapid Acquisition Gradient Echo (MP2RAGE)-based T1 mapping provides an alternative to the traditional single-contrast techniques by allowing retrospective synthesis of images at arbitrary inversion times to aid in visualization of various DBS targets. With this approach, optimization of sequence parameters to create T1 maps with low noise and low quantification bias is critical, as these characteristics directly affect the noise and uniformity of the synthetic images. In this work, we perform sequence optimization for MP2RAGE-based T1 mapping using a radial view-ordering technique to improve image quality, and demonstrate the clinical utility of T1 mapping approach for DBS targeting. METHODS We first introduce a systematic sequence optimization framework for 7 T MP2RAGE T1 mapping by formulating it into a constrained, multi-dimensional optimization process considering the effect of B1+ inhomogeneity on image noise, T1 quantification bias, and image blurring. With this framework, we investigate the use of radial view-order approach for T1 mapping, in lieu of the conventional linear view-ordering. Bloch's equation-based simulations were performed to compare the T1 maps generated using different approaches. Images of healthy volunteer and patients were acquired on a clinical 7 T MRI scanner for validation and to demonstrate the utility of T1 mapping for DBS targeting. RESULTS Numerical experiments demonstrated that the proposed framework allowed optimization of image SNR in T1 maps while controlling the quantification bias and image blurring, therefore facilitating the selection of optimal sequence parameters for visualizing DBS targets. The optimized sequence using radial view-ordering offered 40-60% noise reduction compared to the linear view-ordering. The improvement of SNR was confirmed in the in vivo examples. Clinical images showed that the synthetic images generated from the optimized T1 maps allowed clear visualization of DBS targets. CONCLUSION We demonstrated the optimization of MP2RAGE T1 mapping with radial view-ordering technique for DBS targeting at 7 T and showed that the optimized sequence allows retrospective generation of synthetic inversion time images commonly utilized in DBS targeting, such as fast gray matter acquisition T1 inversion recovery (FGATIR) and edge-enhancing gradient echo (EDGE) sequences.
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Affiliation(s)
- Shengzhen Tao
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA.
| | - Xiangzhi Zhou
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | - Chen Lin
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | - Vishal Patel
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | | | - Erik H Middlebrooks
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA; Department of Neurosurgery, Mayo Clinic, Jacksonville, FL, USA
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Manuel TJ, Sigona MK, Phipps MA, Kusunose J, Luo H, Yang PF, Newton AT, Gore JC, Grissom W, Chen LM, Caskey CF. Small volume blood-brain barrier opening in macaques with a 1 MHz ultrasound phased array. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.02.530815. [PMID: 36909495 PMCID: PMC10002751 DOI: 10.1101/2023.03.02.530815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Focused ultrasound blood-brain barrier (BBB) opening is a promising tool for targeted delivery of therapeutic agents into the brain. The volume of opening determines the extent of therapeutic administration and sets a lower bound on the size of targets which can be selectively treated. We tested a custom 1 MHz array transducer optimized for cortical regions in the macaque brain with the goal of achieving small volume openings. We integrated this device into a magnetic resonance image guided focused ultrasound system and demonstrated twelve instances of small volume BBB opening with average opening volumes of 59 ± 37 mm 3 and 184 ± 2 mm 3 in cortical and subcortical targets, respectively. We developed real-time cavitation monitoring using a passive cavitation detector embedded in the array and characterized its performance on a bench-top flow phantom mimicking transcranial BBB opening procedures. We monitored cavitation during in-vivo procedures and compared cavitation metrics against opening volumes and safety outcomes measured with FLAIR and susceptibility weighted MR imaging. Our findings show small BBB opening at cortical targets in macaques and characterize the safe pressure range for 1 MHz BBB opening. Additionally, we used subject-specific simulations to investigate variance in measured opening volumes and found high correlation (R 2 = 0.8577) between simulation predictions and observed measurements. Simulations suggest the threshold for 1 MHz BBB opening was 0.53 MPa. This system enables BBB opening for drug delivery and gene therapy to be targeted to more specific brain regions.
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Fuderer M, van der Heide O, Liu H, van den Berg CAT, Sbrizzi A. Efficient performance analysis and optimization of transient-state sequences for multiparametric magnetic resonance imaging. NMR IN BIOMEDICINE 2023; 36:e4864. [PMID: 36321222 PMCID: PMC10078474 DOI: 10.1002/nbm.4864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/11/2022] [Accepted: 10/30/2022] [Indexed: 06/16/2023]
Abstract
In transient-state multiparametric MRI sequences such as Magnetic Resonance Spin TomogrAphy in Time-domain (MR-STAT), MR fingerprinting, or hybrid-state imaging, the flip angle pattern of the RF excitation varies over the sequence. This gives considerable freedom to choose an optimal pattern of flip angles. For pragmatic reasons, most optimization methodologies choose for a single-voxel approach (i.e., without taking the spatial encoding scheme into account). Particularly in MR-STAT, the context of spatial encoding is important. In the current study, we present a methodology, called BLock Analysis of a K-space-domain Jacobian (BLAKJac), which is sufficiently fast to optimize a sequence in the context of a predetermined phase-encoding pattern. Based on MR-STAT acquisitions and reconstructions, we show that sequences optimized using BLAKJac are more reliable in terms of actually achieved precision than conventional single-voxel-optimized sequences. In addition, BLAKJac provides analytical tools that give insights into the performance of the sequence in a very limited computation time. Our experiments are based on MR-STAT, but the theory is equally valid for other transient-state multiparametric methods.
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Affiliation(s)
- Miha Fuderer
- Radiotherapy, Imaging DivisionUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Oscar van der Heide
- Radiotherapy, Imaging DivisionUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Hongyan Liu
- Radiotherapy, Imaging DivisionUniversity Medical Center UtrechtUtrechtthe Netherlands
| | | | - Alessandro Sbrizzi
- Radiotherapy, Imaging DivisionUniversity Medical Center UtrechtUtrechtthe Netherlands
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Zhang Y, Huang P, Wang X, Xu Q, Liu Y, Jin Z, Li Y, Cheng Z, Tang R, Chen S, He N, Yan F, Haacke EM. Visualizing the deep cerebellar nuclei using quantitative susceptibility mapping: An application in healthy controls, Parkinson's disease patients and essential tremor patients. Hum Brain Mapp 2023; 44:1810-1824. [PMID: 36502376 PMCID: PMC9921226 DOI: 10.1002/hbm.26178] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 10/20/2022] [Accepted: 11/27/2022] [Indexed: 12/14/2022] Open
Abstract
The visualization and identification of the deep cerebellar nuclei (DCN) (dentate [DN], interposed [IN] and fastigial nuclei [FN]) are particularly challenging. We aimed to visualize the DCN using quantitative susceptibility mapping (QSM), predict the contrast differences between QSM and T2* weighted imaging, and compare the DCN volume and susceptibility in movement disorder populations and healthy controls (HCs). Seventy-one Parkinson's disease (PD) patients, 39 essential tremor patients, and 80 HCs were enrolled. The PD patients were subdivided into tremor dominant (TD) and postural instability/gait difficulty (PIGD) groups. A 3D strategically acquired gradient echo MR imaging protocol was used for each subject to obtain the QSM data. Regions of interest were drawn manually on the QSM data to calculate the volume and susceptibility. Correlation analysis between the susceptibility and either age or volume was performed and the intergroup differences of the volume and magnetic susceptibility in all the DCN structures were evaluated. For the most part, all the DCN structures were clearly visualized on the QSM data. The susceptibility increased as a function of volume for both the HC group and disease groups in the DN and IN (p < .001) but not the FN (p = .74). Only the volume of the FN in the TD-PD group was higher than that in the HCs (p = .012), otherwise, the volume and susceptibility among these four groups did not differ significantly. In conclusion, QSM provides clear visualization of the DCN structures. The results for the volume and susceptibility of the DCN can be used as baseline references in future studies of movement disorders.
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Affiliation(s)
- Youmin Zhang
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Pei Huang
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xinhui Wang
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiuyun Xu
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, USA
| | - Yu Liu
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhijia Jin
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Li
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zenghui Cheng
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Rongbiao Tang
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shengdi Chen
- Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Naying He
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fuhua Yan
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - E Mark Haacke
- Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Biomedical Engineering, Wayne State University, Detroit, Michigan, USA.,Department of Radiology, Wayne State University, Detroit, Michigan, USA
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20
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Uhlig M, Reinelt JD, Lauckner ME, Kumral D, Schaare HL, Mildner T, Babayan A, Möller HE, Engert V, Villringer A, Gaebler M. Rapid volumetric brain changes after acute psychosocial stress. Neuroimage 2023; 265:119760. [PMID: 36427754 DOI: 10.1016/j.neuroimage.2022.119760] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 11/14/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
Stress is an important trigger for brain plasticity: Acute stress can rapidly affect brain activity and functional connectivity, and chronic or pathological stress has been associated with structural brain changes. Measures of structural magnetic resonance imaging (MRI) can be modified by short-term motor learning or visual stimulation, suggesting that they also capture rapid brain changes. Here, we investigated volumetric brain changes (together with changes in T1 relaxation rate and cerebral blood flow) after acute stress in humans as well as their relation to psychophysiological stress measures. Sixty-seven healthy men (25.8±2.7 years) completed a standardized psychosocial laboratory stressor (Trier Social Stress Test) or a control version while blood, saliva, heart rate, and psychometrics were sampled. Structural MRI (T1 mapping / MP2RAGE sequence) at 3T was acquired 45 min before and 90 min after intervention onset. Grey matter volume (GMV) changes were analysed using voxel-based morphometry. Associations with endocrine, autonomic, and subjective stress measures were tested with linear models. We found significant group-by-time interactions in several brain clusters including anterior/mid-cingulate cortices and bilateral insula: GMV was increased in the stress group relative to the control group, in which several clusters showed a GMV decrease. We found a significant group-by-time interaction for cerebral blood flow, and a main effect of time for T1 values (longitudinal relaxation time). In addition, GMV changes were significantly associated with state anxiety and heart rate variability changes. Such rapid GMV changes assessed with VBM may be induced by local tissue adaptations to changes in energy demand following neural activity. Our findings suggest that endogenous brain changes are counteracted by acute psychosocial stress, which emphasizes the importance of considering homeodynamic processes and generally highlights the influence of stress on the brain.
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Affiliation(s)
- Marie Uhlig
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; International Max Planck Research School NeuroCom, Leipzig, Germany.
| | - Janis D Reinelt
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Mark E Lauckner
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Independent Research Group "Adaptive Memory", Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Medical Faculty of Leipzig University, Leipzig, Germany
| | - Deniz Kumral
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Institute of Psychology, Neuropsychology, University of Freiburg, Freiburg im Breisgau, Germany
| | - H Lina Schaare
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Otto Hahn Group "Cognitive Neurogenetics", Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Institute of Neuroscience and Medicine (INM-7: Brain and Behaviour), Research Centre Jülich, Germany
| | - Toralf Mildner
- NMR Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Anahit Babayan
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; MindBrainBody Institute at the Berlin School of Mind and Brain, Faculty of Philosophy, Humboldt-Universität zu Berlin, Berlin, German
| | - Harald E Möller
- NMR Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Veronika Engert
- Institute of Psychosocial Medicine, Psychotherapy and Psychooncology, Jena University Hospital, Friedrich-Schiller University, Jena, Germany; Independent Research Group "Social Stress and Family Health", Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Arno Villringer
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; MindBrainBody Institute at the Berlin School of Mind and Brain, Faculty of Philosophy, Humboldt-Universität zu Berlin, Berlin, German
| | - Michael Gaebler
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; MindBrainBody Institute at the Berlin School of Mind and Brain, Faculty of Philosophy, Humboldt-Universität zu Berlin, Berlin, German
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21
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Kilian D, Kilian W, Troia A, Nguyen TD, Ittermann B, Zilberti L, Gelinsky M. 3D Extrusion Printing of Biphasic Anthropomorphic Brain Phantoms Mimicking MR Relaxation Times Based on Alginate-Agarose-Carrageenan Blends. ACS APPLIED MATERIALS & INTERFACES 2022; 14:48397-48415. [PMID: 36270624 PMCID: PMC9634698 DOI: 10.1021/acsami.2c12872] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
The availability of adapted phantoms mimicking different body parts is fundamental to establishing the stability and reliability of magnetic resonance imaging (MRI) methods. The primary purpose of such phantoms is the mimicking of physiologically relevant, contrast-creating relaxation times T1 and T2. For the head, frequently examined by MRI, an anthropomorphic design of brain phantoms would imply the discrimination of gray matter and white matter (WM) within defined, spatially distributed compartments. Multichannel extrusion printing allows the layer-by-layer fabrication of multiple pastelike materials in a spatially defined manner with a predefined shape. In this study, the advantages of this method are used to fabricate biphasic brain phantoms mimicking MR relaxation times and anthropomorphic geometry. The printable ink was based on purely naturally derived polymers: alginate as a calcium-cross-linkable gelling agent, agarose, ι-carrageenan, and GdCl3 in different concentrations (0-280 μmol kg-1) as the paramagnetic component. The suggested inks (e.g., 3Alg-1Agar-6Car) fulfilled the requirements of viscoelastic behavior and printability of large constructs (>150 mL). The microstructure and distribution of GdCl3 were assessed by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX). In closely monitored steps of technological development and characterization, from monophasic and biphasic samples as printable inks and cross-linked gels, we describe the construction of large-scale phantom models whose relaxation times were characterized and checked for stability over time.
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Affiliation(s)
- David Kilian
- Centre
for Translational Bone, Joint and Soft Tissue Research, Faculty of
Medicine Carl Gustav Carus, Technische Universität
Dresden (TUD), Dresden01307, Germany
| | - Wolfgang Kilian
- Physikalisch-Technische
Bundesanstalt (PTB), Berlin10587, Germany
| | - Adriano Troia
- Istituto
Nazionale di Ricerca Metrologica (INRiM), Turin10135, Italy
| | - Thanh-Duc Nguyen
- Centre
for Translational Bone, Joint and Soft Tissue Research, Faculty of
Medicine Carl Gustav Carus, Technische Universität
Dresden (TUD), Dresden01307, Germany
| | - Bernd Ittermann
- Physikalisch-Technische
Bundesanstalt (PTB), Berlin10587, Germany
| | - Luca Zilberti
- Istituto
Nazionale di Ricerca Metrologica (INRiM), Turin10135, Italy
| | - Michael Gelinsky
- Centre
for Translational Bone, Joint and Soft Tissue Research, Faculty of
Medicine Carl Gustav Carus, Technische Universität
Dresden (TUD), Dresden01307, Germany
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22
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Meng L, Zhao X, Guo J, Lu L, Cheng M, Xing Q, Shang H, Wang K, Zhang B, Lei D, Zhang X. Evaluation of the differentiation of benign and malignant breast lesions using synthetic relaxometry and the Kaiser score. Front Oncol 2022; 12:964078. [PMID: 36303839 PMCID: PMC9595598 DOI: 10.3389/fonc.2022.964078] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/26/2022] [Indexed: 12/24/2022] Open
Abstract
Objective To investigate whether there is added value of quantitative parameters from synthetic magnetic resonance imaging (SyMRI) as a complement to the Kaiser score (KS) to differentiate benign and malignant breast lesions. Materials and methods In this single-institution study, 122 patients who underwent breast MRI from March 2020 to May 2021 were retrospectively analyzed. SyMRI and dynamic contrast-enhanced MRI were performed using a 3.0-T system. Two experienced radiologists independently assigned the KS and measured the quantitative values of T1 relaxation time (T1), T2 relaxation time (T2), and proton density (PD) from SyMRI. Pathology was regarded as the gold standard. The diagnostic values were compared using the appropriate statistical tests. Results There were 122 lesions (86 malignant and 36 benign) in 122 women. The T1 value was identified as the only independent factor for the differentiation of malignant and benign lesions. The diagnostic accuracy of incorporating the T1 into the KS protocol (T1+KS) was 95.1% and 92.1% for all lesions (ALL) and The American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) category 4 lesions, respectively, which was significantly higher than that of either T1 (ALL: 82.8%, P = 0.0001; BI-RADS 4: 78.9%, P = 0.002) or KS (ALL: 90.2%, P = 0.031; BI-RADS 4: 84.2%, P = 0.031) alone. The sensitivity and specificity of T1+KS were also higher than those of the T1 or KS alone. The combined diagnosis could have avoided another 15.6% biopsies compared with using KS alone. Conclusions Incorporating T1 into the KS protocol improved both the sensitivity and specificity to differentiate benign and malignant breast lesions, thus avoiding unnecessary invasive procedures.
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Affiliation(s)
- Lingsong Meng
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Xin Zhao
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jinxia Guo
- General Electric (GE) Healthcare, MR Research China, Beijing, China
| | - Lin Lu
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Meiying Cheng
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Qingna Xing
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Honglei Shang
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Kaiyu Wang
- General Electric (GE) Healthcare, MR Research China, Beijing, China
| | - Bohao Zhang
- Henan Key Laboratory of Child Brain Injury, Institute of Neuroscience and the Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Dongmei Lei
- Department of Pathology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiaoan Zhang
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- *Correspondence: Xiaoan Zhang,
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23
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Tomer O, Barazany D, Baratz Z, Tsarfaty G, Assaf Y. In vivo measurements of lamination patterns in the human cortex. Hum Brain Mapp 2022; 43:2861-2868. [PMID: 35274794 PMCID: PMC9120563 DOI: 10.1002/hbm.25821] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 02/06/2022] [Accepted: 02/16/2022] [Indexed: 11/22/2022] Open
Abstract
The laminar composition of the cerebral cortex is tightly connected to the development and connectivity of the brain, as well as to function and pathology. Although most of the research on the cortical layers is done with the aid of ex vivo histology, there have been recent attempts to use magnetic resonance imaging (MRI) with potential in vivo applications. However, the high-resolution MRI technology and protocols required for such studies are neither common nor practical. In this article, we present a clinically feasible method for assessing the laminar properties of the human cortex using standard pulse sequence available on any common MRI scanner. Using a series of low-resolution inversion recovery (IR) MRI scans allows us to calculate multiple T1 relaxation time constants for each voxel. Based on the whole-brain T1 -distribution, we identify six different gray matter T1 populations and their variation across the cortex. Based on this, we show age-related differences in these population and demonstrate that this method is able to capture the difference in laminar composition across varying brain areas. We also provide comparison to ex vivo high-resolution MRI scans. We show that this method is feasible for the estimation of layer variability across large population cohorts, which can lead to research into the links between the cortical layers and function, behavior and pathologies that was heretofore unexplorable.
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Affiliation(s)
- Omri Tomer
- Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
| | - Daniel Barazany
- The Strauss Center for Computational NeuroimagingTel Aviv UniversityTel AvivIsrael
| | - Zvi Baratz
- Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
| | - Galia Tsarfaty
- Division of Diagnostic Imaging, Sheba Medical Center, Tel‐Hashomer, Affiliated to the Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Yaniv Assaf
- Sagol School of NeuroscienceTel Aviv UniversityTel AvivIsrael
- The Strauss Center for Computational NeuroimagingTel Aviv UniversityTel AvivIsrael
- School of Neurobiology, Biochemistry and Biophysics, Faculty of Life ScienceTel Aviv UniversityTel AvivIsrael
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24
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Ordidge R, Blunck Y, Glarin R, Moffat B, Johnston L. Ultrahigh field brain magnetic resonance imaging using semiadiabatic radiofrequency pulses. NMR IN BIOMEDICINE 2022; 35:e4672. [PMID: 34970797 DOI: 10.1002/nbm.4672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 11/29/2021] [Accepted: 12/02/2021] [Indexed: 06/14/2023]
Abstract
Great attention is being paid to solving, or mitigating, the technical problems associated with MRI at ultrahigh field strengths of 7 T and higher. This paper explores the use of the semiadiabatic spin-echo (SA-SE) pulse sequence, which uses semiadiabatic radiofrequency (RF) pulses to remove and/or mitigate the effects of the nonuniform B1 excitation field and B0 inhomogeneity associated with the electromagnetic properties of the human brain. A semiadiabatic RF pulse version of the recently published serial transmit excitation pulse (STEP) RF pulse sequence is also presented that now incorporates semiadiabatic pulses, henceforth is called SA-STEP. As demonstrated by computer simulation, and confirmed using head imaging, both techniques can produce multislice SE MR imaging at 7 T. These new methods use relatively low RF power and achieve good coverage of the human brain in a single scan.
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Affiliation(s)
- Roger Ordidge
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Yasmin Blunck
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Rebecca Glarin
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Bradford Moffat
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Leigh Johnston
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
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25
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Bollmann S, Mattern H, Bernier M, Robinson SD, Park DJ, Speck O, Polimeni JR. Imaging of the pial arterial vasculature of the human brain in vivo using high-resolution 7T time-of-flight angiography. eLife 2022; 11:71186. [PMID: 35486089 PMCID: PMC9150892 DOI: 10.7554/elife.71186] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 04/28/2022] [Indexed: 11/30/2022] Open
Abstract
The pial arterial vasculature of the human brain is the only blood supply to the neocortex, but quantitative data on the morphology and topology of these mesoscopic arteries (diameter 50–300 µm) remains scarce. Because it is commonly assumed that blood flow velocities in these vessels are prohibitively slow, non-invasive time-of-flight magnetic resonance angiography (TOF-MRA)—which is well suited to high 3D imaging resolutions—has not been applied to imaging the pial arteries. Here, we provide a theoretical framework that outlines how TOF-MRA can visualize small pial arteries in vivo, by employing extremely small voxels at the size of individual vessels. We then provide evidence for this theory by imaging the pial arteries at 140 µm isotropic resolution using a 7 Tesla (T) magnetic resonance imaging (MRI) scanner and prospective motion correction, and show that pial arteries one voxel width in diameter can be detected. We conclude that imaging pial arteries is not limited by slow blood flow, but instead by achievable image resolution. This study represents the first targeted, comprehensive account of imaging pial arteries in vivo in the human brain. This ultra-high-resolution angiography will enable the characterization of pial vascular anatomy across the brain to investigate patterns of blood supply and relationships between vascular and functional architecture.
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Affiliation(s)
- Saskia Bollmann
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Hendrik Mattern
- Department of Biomedical Magnetic Resonance, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Michaël Bernier
- Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, United States
| | - Simon D Robinson
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | - Daniel J Park
- Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, United States
| | - Oliver Speck
- German Center for Neurodegenerative Diseases, Magdeburg, Germany
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26
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Wenger E, Polk SE, Kleemeyer MM, Weiskopf N, Bodammer NC, Lindenberger U, Brandmaier AM. Reliability of quantitative multiparameter maps is high for magnetization transfer and proton density but attenuated for R 1 and R 2 * in healthy young adults. Hum Brain Mapp 2022; 43:3585-3603. [PMID: 35397153 PMCID: PMC9248308 DOI: 10.1002/hbm.25870] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 03/07/2022] [Accepted: 03/23/2022] [Indexed: 11/24/2022] Open
Abstract
We investigate the reliability of individual differences of four quantities measured by magnetic resonance imaging‐based multiparameter mapping (MPM): magnetization transfer saturation (MT), proton density (PD), longitudinal relaxation rate (R1), and effective transverse relaxation rate (R2*). Four MPM datasets, two on each of two consecutive days, were acquired in healthy young adults. On Day 1, no repositioning occurred and on Day 2, participants were repositioned between MPM datasets. Using intraclass correlation effect decomposition (ICED), we assessed the contributions of session‐specific, day‐specific, and residual sources of measurement error. For whole‐brain gray and white matter, all four MPM parameters showed high reproducibility and high reliability, as indexed by the coefficient of variation (CoV) and the intraclass correlation (ICC). However, MT, PD, R1, and R2* differed markedly in the extent to which reliability varied across brain regions. MT and PD showed high reliability in almost all regions. In contrast, R1 and R2* showed low reliability in some regions outside the basal ganglia, such that the sum of the measurement error estimates in our structural equation model was higher than estimates of between‐person differences. In addition, in this sample of healthy young adults, the four MPM parameters showed very little variability over four measurements but differed in how well they could assess between‐person differences. We conclude that R1 and R2* might carry only limited person‐specific information in some regions of the brain in healthy young adults, and, by implication, might be of restricted utility for studying associations to between‐person differences in behavior in those regions.
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Affiliation(s)
- Elisabeth Wenger
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Sarah E Polk
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Maike M Kleemeyer
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Nikolaus Weiskopf
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, UK.,Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth Sciences, Leipzig University, Leipzig, Germany
| | - Nils C Bodammer
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
| | - Ulman Lindenberger
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.,Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin, Germany
| | - Andreas M Brandmaier
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.,Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin, Germany.,Department of Psychology, MSB Medical School Berlin, Berlin, Germany
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27
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Berg RC, Leutritz T, Weiskopf N, Preibisch C. Multi-parameter quantitative mapping of R1, R2*, PD, and MTsat is reproducible when accelerated with Compressed SENSE. Neuroimage 2022; 253:119092. [PMID: 35288281 DOI: 10.1016/j.neuroimage.2022.119092] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 10/18/2022] Open
Abstract
Multi-parameter mapping (MPM) magnetic resonance imaging (MRI) provides quantitative estimates of the longitudinal and effective transverse relaxation rates R1 and R2*, proton density (PD), and magnetization transfer saturation (MTsat). Thereby, MPM enables better comparability across sites and time than conventional weighted MRI. However, for MPM, several contrasts must be acquired, resulting in prolonged measurement durations and thus preventing MPM's application in clinical routines. State-of-the-art imaging acceleration techniques such as Compressed SENSE (CS), a combination of compressed sensing and sensitivity encoding, can be used to reduce the scan time of MPM. However, the accuracy and precision of the resulting quantitative parameter maps have not been systematically evaluated. In this study, we therefore investigated the effect of CS acceleration on the fidelity and reproducibility of MPM acquisitions. In five healthy volunteers and in a phantom, we compared MPM metrics acquired without imaging acceleration, with the standard acceleration (SENSE factor 2.5), and with Compressed SENSE with acceleration factors 4 and 6 using a 32-channel head coil. We evaluated the reproducibility and repeatability of accelerated MPM using data from three scan sessions in gray and white matter volumes-of-interest (VOIs). Accelerated MPM provided precise and accurate quantitative parameter maps. For most parameters, the results of the CS-accelerated protocols correlated more strongly with the non-accelerated protocol than the standard SENSE-accelerated protocols. Furthermore, for most VOIs and contrasts, coefficients of variation were lower when calculated from data acquired with different imaging accelerations within a single scan session than from data acquired in different scan sessions. These results suggest that MPM with Compressed SENSE acceleration factors up to at least 6 yields reproducible quantitative parameter maps that are highly comparable to those acquired without imaging acceleration. Compressed SENSE can thus be used to considerably reduce the scan duration of R1, R2*, PD, and MTsat mapping, and is highly promising for clinical applications of MPM.
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Affiliation(s)
- Ronja C Berg
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Neurology, Munich, Germany.
| | - Tobias Leutritz
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurophysics, Leipzig, Germany.
| | - Nikolaus Weiskopf
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurophysics, Leipzig, Germany; Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth Sciences, Leipzig University, Leipzig, Germany.
| | - Christine Preibisch
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Neurology, Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Munich, Germany.
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28
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Tao S, Zhou X, Westerhold EM, Middlebrooks EH, Lin C. Optimization of fast gray matter acquisition T1 inversion recovery (FGATIR) on 7T MRI for deep brain stimulation targeting. Neuroimage 2022; 252:119043. [PMID: 35235838 DOI: 10.1016/j.neuroimage.2022.119043] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/24/2022] [Accepted: 02/26/2022] [Indexed: 10/19/2022] Open
Abstract
Deep brain stimulation (DBS) is an increasingly utilized treatment for multiple neurological disorders. Continued improvements in DBS outcome are, in part, related to increasing ability to directly visualize stimulation targets by MRI. However, it is challenging to image DBS targets with conventional MRI techniques due to limited contrast. Fast Gray Matter Acquisition T1 Inversion Recovery (FGATIR) is a commonly used MRI sequence that improves visualization of several key DBS targets by suppressing white matter (WM) signal to better reveal deep-brain gray matter (GM) structures. Due to increased signal level at high field strength, application of FGATIR on 7T MRI may allow higher spatial resolution and better DBS targeting accuracy. However, successful utilization of FGATIR requires meticulous sequence optimization involving multiple parameters to maximize GM signal while suppressing WM. This is further complicated by the transmit RF field (B1+) inhomogeneity on 7T, which can cause severe contrast degradation. In this work, we introduce a systematic approach to optimize FGATIR and to improve visualization of thalamic DBS targets on 7T. FGATIR optimization is cast into a constrained optimization problem whose objective function and constraints are designed to maximize the GM-WM contrast-to-noise ratio (CNR) while accounting for B1+ inhomogeneity. This approach allows a systematic search for optimal parameters across the multi-dimensional parametric space while limiting the negative effect of B1+ variation. Bloch equation simulations were performed to solve the proposed optimization problem and to compare the sequence derived from this method against the sequence optimized without considering B1+ inhomogeneity. The results showed that this approach can improve GM-WM CNR in the presence of B1+ inhomogeneity, especially in some high relative B1+ areas where several key thalamic DBS targets are located. Additionally, in vivo images were acquired on a clinical 7T MRI to further validate this approach. Severe contrast degradation in the thalamus was observed when B1+ effect was not considered in sequence optimization, while the proposed approach yielded improved image contrast in the thalamus with key DBS targets well-defined. These results demonstrated that the proposed method allowed optimization of FGATIR on 7T to better visualize thalamic DBS targets, which may lead to improved DBS targeting accuracy as well as treatment outcome.
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Affiliation(s)
- Shengzhen Tao
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA.
| | - Xiangzhi Zhou
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | | | | | - Chen Lin
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
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29
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Olsson H, Andersen M, Kadhim M, Helms G. MP3RAGE: Simultaneous mapping of T 1 and B 1 + in human brain at 7T. Magn Reson Med 2022; 87:2637-2649. [PMID: 35037283 DOI: 10.1002/mrm.29151] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 12/03/2021] [Accepted: 12/20/2021] [Indexed: 12/19/2022]
Abstract
PURPOSE To map T1 and the local flip angle ( B 1 + ) in human brain using a single MP3RAGE sequence with 3 rapid acquisitions of gradient echoes (RAGEs). THEORY AND METHODS A third RAGE with a relatively high flip angle was appended to an MP2RAGE sequence. Through curve fitting and a rational approximation for small flip angles and short TR, closed form solutions for T1 and B 1 + were derived. The influence of different k-space encoding schemes on precision and whether edge enhancement artifacts could be reduced with a saturation pulse applied prior to the third RAGE were explored. Validation of T1 estimates was performed using single-slice inversion recovery (IR) and a subsequent region-of-interest-based comparison, whereas validation of B 1 + was performed using a whole brain pixelwise comparison to a DREAM flip angle mapping protocol. Lastly, MP3RAGE was compared to T1 -mapping by MP2RAGE with separate B 1 + correction. RESULTS Whole brain maps of T1 and B 1 + at 1 mm isotropic resolution were obtained with MP3RAGE in 06:37 min. A linear-reverse centric-reverse centric phase-encoding order of the 3 RAGEs improved precision, and artifacts were successfully reduced with the saturation pulse. Estimations of T1 and B 1 + deviated +2.5 ± 3.1% and -1.7 ± 8.6% from their respective references. CONCLUSION T1 and B 1 + can be mapped simultaneously using MP3RAGE. The approach can be thought of as combining MP2RAGE with a dual flip angle T1 -mapping protocol. Both maps can be solved for analytically and will be inherently co-registered at the high resolution associated with MPRAGE.
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Affiliation(s)
- Hampus Olsson
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Mads Andersen
- Philips Healthcare, Copenhagen, Denmark.,Lund University Bioimaging Center, Lund University, Lund, Sweden
| | - Mustafa Kadhim
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Gunther Helms
- Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden
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30
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Jamárik J, Vojtíšek L, Churová V, Kašpárek T, Schwarz D. Identification of Laminar Composition in Cerebral Cortex Using Low-Resolution Magnetic Resonance Images and Trust Region Optimization Algorithm. Diagnostics (Basel) 2021; 12:diagnostics12010024. [PMID: 35054191 PMCID: PMC8774564 DOI: 10.3390/diagnostics12010024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/13/2021] [Accepted: 12/20/2021] [Indexed: 11/16/2022] Open
Abstract
Pathological changes in the cortical lamina can cause several mental disorders. Visualization of these changes in vivo would enhance their diagnostics. Recently a framework for visualizing cortical structures by magnetic resonance imaging (MRI) has emerged. This is based on mathematical modeling of multi-component T1 relaxation at the sub-voxel level. This work proposes a new approach for their estimation. The approach is validated using simulated data. Sixteen MRI experiments were carried out on healthy volunteers. A modified echo-planar imaging (EPI) sequence was used to acquire 105 individual volumes. Data simulating the images were created, serving as the ground truth. The model was fitted to the data using a modified Trust Region algorithm. In single voxel experiments, the estimation accuracy of the T1 relaxation times depended on the number of optimization starting points and the level of noise. A single starting point resulted in a mean percentage error (MPE) of 6.1%, while 100 starting points resulted in a perfect fit. The MPE was <5% for the signal-to-noise ratio (SNR) ≥ 38 dB. Concerning multiple voxel experiments, the MPE was <5% for all components. Estimation of T1 relaxation times can be achieved using the modified algorithm with MPE < 5%.
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Affiliation(s)
- Jakub Jamárik
- Department of Psychiatry, Faculty of Medicine, Masaryk University, 625 00 Brno, Czech Republic; (J.J.); (T.K.)
| | - Lubomír Vojtíšek
- Neuroscience Centre, Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic;
| | - Vendula Churová
- Department of Simulation Medicine, Institute of Biostatistics and Analyses, Faculty of Medicine, Masaryk University, 625 00 Brno, Czech Republic;
| | - Tomáš Kašpárek
- Department of Psychiatry, Faculty of Medicine, Masaryk University, 625 00 Brno, Czech Republic; (J.J.); (T.K.)
| | - Daniel Schwarz
- Department of Simulation Medicine, Institute of Biostatistics and Analyses, Faculty of Medicine, Masaryk University, 625 00 Brno, Czech Republic;
- Correspondence:
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31
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Brun G, Testud B, Girard OM, Lehmann P, de Rochefort L, Besson P, Massire A, Ridley B, Girard N, Guye M, Ranjeva JP, Le Troter A. Automatic segmentation of Deep Grey Nuclei using a high-resolution 7T MRI Atlas - quantification of T1 values in healthy volunteers. Eur J Neurosci 2021; 55:438-460. [PMID: 34939245 DOI: 10.1111/ejn.15575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 11/30/2022]
Abstract
We present a new consensus atlas of deep grey nuclei obtained by shape-based averaging of manual segmentation of two experienced neuroradiologists and optimized from 7T MP2RAGE images acquired at (0.6mm)3 in 60 healthy subjects. A group-wise normalization method was used to build a high-contrast and high-resolution T1 -weighted brain template (0.5mm)3 using data from 30 out of the 60 controls. Delineation of 24 deep grey nuclei per hemisphere, including the claustrum and twelve thalamic nuclei, was then performed by two expert neuroradiologists and reviewed by a third neuroradiologist according to tissue contrast and external references based on the Morel atlas. Corresponding deep grey matter structures were also extracted from the Morel and CIT168 atlases. The data-derived, Morel and CIT168 atlases were all applied at the individual level using non-linear registration to fit the subject reference and to extract absolute mean quantitative T1 values derived from the 3D-MP2RAGE volumes, after correction for residual B1 + biases. Three metrics (The Dice and the volumetric similarity coefficients, and a novel Hausdorff distance) were used to estimate the inter-rater agreement of manual MRI segmentation and inter-atlas variability, and these metrics were measured to quantify biases due to image registration and their impact on the measurements of the quantitative T1 values was highlighted. This represents a fully-automated segmentation process permitting the extraction of unbiased normative T1 values in a population of young healthy controls as a reference for characterizing subtle structural alterations of deep grey nuclei relevant to a range of neurological diseases.
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Affiliation(s)
- Gilles Brun
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, Service de Neuroradiologie, Marseille, France
| | - Benoit Testud
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, Service de Neuroradiologie, Marseille, France
| | - Olivier M Girard
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
| | - Pierre Lehmann
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, Service de Neuroradiologie, Marseille, France
| | - Ludovic de Rochefort
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
| | - Pierre Besson
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
| | - Aurélien Massire
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
| | - Ben Ridley
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France.,IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italia
| | - Nadine Girard
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, Service de Neuroradiologie, Marseille, France
| | - Maxime Guye
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
| | - Jean-Philippe Ranjeva
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
| | - Arnaud Le Troter
- Aix Marseille Univ, CNRS, CRMBM, Marseille, France.,AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
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Slator PJ, Palombo M, Miller KL, Westin C, Laun F, Kim D, Haldar JP, Benjamini D, Lemberskiy G, de Almeida Martins JP, Hutter J. Combined diffusion-relaxometry microstructure imaging: Current status and future prospects. Magn Reson Med 2021; 86:2987-3011. [PMID: 34411331 PMCID: PMC8568657 DOI: 10.1002/mrm.28963] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 06/25/2021] [Accepted: 07/20/2021] [Indexed: 12/15/2022]
Abstract
Microstructure imaging seeks to noninvasively measure and map microscopic tissue features by pairing mathematical modeling with tailored MRI protocols. This article reviews an emerging paradigm that has the potential to provide a more detailed assessment of tissue microstructure-combined diffusion-relaxometry imaging. Combined diffusion-relaxometry acquisitions vary multiple MR contrast encodings-such as b-value, gradient direction, inversion time, and echo time-in a multidimensional acquisition space. When paired with suitable analysis techniques, this enables quantification of correlations and coupling between multiple MR parameters-such as diffusivity, T 1 , T 2 , and T 2 ∗ . This opens the possibility of disentangling multiple tissue compartments (within voxels) that are indistinguishable with single-contrast scans, enabling a new generation of microstructural maps with improved biological sensitivity and specificity.
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Affiliation(s)
- Paddy J. Slator
- Centre for Medical Image ComputingDepartment of Computer ScienceUniversity College LondonLondonUK
| | - Marco Palombo
- Centre for Medical Image ComputingDepartment of Computer ScienceUniversity College LondonLondonUK
| | - Karla L. Miller
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Carl‐Fredrik Westin
- Department of RadiologyBrigham and Women’s HospitalHarvard Medical SchoolBostonMAUSA
| | - Frederik Laun
- Institute of RadiologyUniversity Hospital ErlangenFriedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU)ErlangenGermany
| | - Daeun Kim
- Ming Hsieh Department of Electrical and Computer EngineeringUniversity of Southern CaliforniaLos AngelesCAUSA
- Signal and Image Processing InstituteUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Justin P. Haldar
- Ming Hsieh Department of Electrical and Computer EngineeringUniversity of Southern CaliforniaLos AngelesCAUSA
- Signal and Image Processing InstituteUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Dan Benjamini
- The Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentBethesdaMDUSA
- The Center for Neuroscience and Regenerative MedicineUniformed Service University of the Health SciencesBethesdaMDUSA
| | | | - Joao P. de Almeida Martins
- Division of Physical Chemistry, Department of ChemistryLund UniversityLundSweden
- Department of Radiology and Nuclear MedicineSt. Olav’s University HospitalTrondheimNorway
| | - Jana Hutter
- Centre for Biomedical EngineeringSchool of Biomedical Engineering and ImagingKing’s College LondonLondonUK
- Centre for the Developing BrainSchool of Biomedical Engineering and ImagingKing’s College LondonLondonUK
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33
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Schick F, Pieper CC, Kupczyk P, Almansour H, Keller G, Springer F, Mürtz P, Endler C, Sprinkart AM, Kaufmann S, Herrmann J, Attenberger UI. 1.5 vs 3 Tesla Magnetic Resonance Imaging: A Review of Favorite Clinical Applications for Both Field Strengths-Part 1. Invest Radiol 2021; 56:680-691. [PMID: 34324464 DOI: 10.1097/rli.0000000000000812] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
ABSTRACT Whole-body magnetic resonance imaging (MRI) systems with a field strength of 3 T have been offered by all leading manufacturers for approximately 2 decades and are increasingly used in clinical diagnostics despite higher costs. Technologically, MRI systems operating at 3 T have reached a high standard in recent years, as well as the 1.5-T devices that have been in use for a longer time. For modern MRI systems with 3 T, more complexity is required, especially for the magnet and the radiofrequency (RF) system (with multichannel transmission). Many clinical applications benefit greatly from the higher field strength due to the higher signal yield (eg, imaging of the brain or extremities), but there are also applications where the disadvantages of 3 T might outweigh the advantages (eg, lung imaging or examinations in the presence of implants). This review describes some technical features of modern 1.5-T and 3-T whole-body MRI systems, and reports on the experience of using both types of devices in different clinical settings, with all sections written by specialist radiologists in the respective fields.This first part of the review includes an overview of the general physicotechnical aspects of both field strengths and elaborates the special conditions of diffusion imaging. Many relevant aspects in the application areas of musculoskeletal imaging, abdominal imaging, and prostate diagnostics are discussed.
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Affiliation(s)
- Fritz Schick
- From the Section of Experimental Radiology, Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen
| | | | - Patrick Kupczyk
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Haidara Almansour
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Gabriel Keller
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Fabian Springer
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Petra Mürtz
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Christoph Endler
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Alois M Sprinkart
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
| | - Sascha Kaufmann
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Judith Herrmann
- Department of Radiology, Diagnostic, and Interventional Radiology, University of Tübingen, Tübingen, Germany
| | - Ulrike I Attenberger
- Clinic for Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn
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Vis G, Nilsson M, Westin CF, Szczepankiewicz F. Accuracy and precision in super-resolution MRI: Enabling spherical tensor diffusion encoding at ultra-high b-values and high resolution. Neuroimage 2021; 245:118673. [PMID: 34688898 PMCID: PMC9272945 DOI: 10.1016/j.neuroimage.2021.118673] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 10/13/2021] [Accepted: 10/20/2021] [Indexed: 12/31/2022] Open
Abstract
Diffusion MRI (dMRI) can probe the tissue microstructure but suffers from low signal-to-noise ratio (SNR) whenever high resolution is combined with high diffusion encoding strengths. Low SNR leads to poor precision as well as poor accuracy of the diffusion-weighted signal; the latter is caused by the rectified noise floor and can be observed as a positive bias in magnitude signal. Super-resolution techniques may facilitate a beneficial tradeoff between bias and resolution by allowing acquisition at low spatial resolution and high SNR, whereafter high spatial resolution is recovered by image reconstruction. In this work, we describe a super-resolution reconstruction framework for dMRI and investigate its performance with respect to signal accuracy and precision. Using phantom experiments and numerical simulations, we show that the super-resolution approach improves accuracy by facilitating a more beneficial trade-off between spatial resolution and diffusion encoding strength before the noise floor affects the signal. By contrast, precision is shown to have a less straightforward dependency on acquisition, reconstruction, and intrinsic tissue parameters. Indeed, we find a gain in precision from super-resolution reconstruction is substantial only when some spatial resolution is sacrificed. Finally, we deployed super-resolution reconstruction in a healthy brain for the challenging combination of spherical b-tensor encoding at ultra-high b-values and high spatial resolution—a configuration that produces a unique contrast that emphasizes tissue in which diffusion is restricted in all directions. This demonstration showcased that super-resolution reconstruction enables a vastly superior image contrast compared to conventional imaging, facilitating investigations that would otherwise have prohibitively low SNR, resolution or require non-conventional MRI hardware.
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Affiliation(s)
- Geraline Vis
- Department of Diagnostic Radiology, Clinical Sciences Lund, Lund University, Lund, Sweden.
| | - Markus Nilsson
- Department of Diagnostic Radiology, Clinical Sciences Lund, Lund University, Lund, Sweden.
| | - Carl-Fredrik Westin
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
| | - Filip Szczepankiewicz
- Department of Diagnostic Radiology, Clinical Sciences Lund, Lund University, Lund, Sweden; Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
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Forodighasemabadi A, Rasoanandrianina H, El Mendili MM, Guye M, Callot V. An optimized MP2RAGE sequence for studying both brain and cervical spinal cord in a single acquisition at 3T. Magn Reson Imaging 2021; 84:18-26. [PMID: 34517015 DOI: 10.1016/j.mri.2021.08.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 11/30/2022]
Abstract
Magnetization Prepared 2 Rapid Acquisition Gradient Echo (MP2RAGE) is a T1 mapping technique that has been used broadly on brain and recently on cervical spinal cord (cSC). The growing interest for combined investigation of brain and SC in numerous pathologies of the central nervous system such as multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and traumatic injuries, now brings about the need for optimization with regards to this specific investigation. This implies large spatial coverage with high spatial resolution and short acquisition time, high CNR and low B1+ sensitivity, as well as high reproducibility and robust post-processing tools for T1 quantification in different regions of brain and SC. In this work, a dedicated protocol (referred to as Pr-BSC) has been optimized for simultaneous brain and cSC T1 MP2RAGE acquisition at 3T. After computer simulation optimization, the protocol was applied for in vivo validation experiments and compared to previously published state of the art protocols focusing on either the brain (Pr-B) or the cSC (Pr-SC). Reproducibility and in-ROI standard deviations were assessed on healthy volunteers in the perspective of future clinical use. The mean T1 values, obtained by the Pr-BSC, in brain white, gray and deep gray matters were: (mean ± in-ROI SD) 792 ± 27 ms, 1339 ± 139 ms and 1136 ± 88 ms, respectively. In cSC, T1 values for white matter corticospinal, posterior sensory, lateral sensory and rubro/reticulospinal tracts were 902 ± 41 ms, 920 ± 35 ms, 903 ± 46 ms, 891 ± 41 ms, respectively, and 954 ± 32 ms for anterior and intermediate gray matter. The Pr-BSC protocol showed excellent agreement with previously proposed Pr-B on brain and Pr-SC on cSC, with very high inter-scan reproducibility (coefficients of variation of 0.52 ± 0.36% and 1.12 ± 0.62% on brain and cSC, respectively). This optimized protocol covering both brain and cSC with a sub-millimetric isotropic spatial resolution in one acquisition of less than 8 min, opens up great perspectives for clinical applications focusing on degenerative tissue such as encountered in MS and ALS.
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Affiliation(s)
- Arash Forodighasemabadi
- Aix-Marseille Univ, CNRS, CRMBM, Marseille, France; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France; Aix-Marseille Univ, Université Gustave Eiffel, LBA, Marseille, France; iLab-Spine International Associated Laboratory, Marseille-Montreal, France, Canada
| | - Henitsoa Rasoanandrianina
- Aix-Marseille Univ, CNRS, CRMBM, Marseille, France; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France; Aix-Marseille Univ, Université Gustave Eiffel, LBA, Marseille, France; iLab-Spine International Associated Laboratory, Marseille-Montreal, France, Canada
| | - Mohamed Mounir El Mendili
- Aix-Marseille Univ, CNRS, CRMBM, Marseille, France; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France
| | - Maxime Guye
- Aix-Marseille Univ, CNRS, CRMBM, Marseille, France; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France
| | - Virginie Callot
- Aix-Marseille Univ, CNRS, CRMBM, Marseille, France; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France; iLab-Spine International Associated Laboratory, Marseille-Montreal, France, Canada.
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Radiofrequency Bias Correction of Magnetization Prepared Rapid Gradient Echo MRI at 7.0 Tesla Using an External Reference in a Sequential Protocol. Tomography 2021; 7:434-451. [PMID: 34564300 PMCID: PMC8482199 DOI: 10.3390/tomography7030038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/27/2021] [Accepted: 09/09/2021] [Indexed: 11/16/2022] Open
Abstract
At field strengths of 7 T and above, T1-weighted imaging of human brain suffers increasingly from radiofrequency (RF) B1 inhomogeneities. The well-known MP2RAGE (magnetization prepared two rapid acquisition gradient echoes) sequence provides a solution but may not be readily available for all MR systems. Here, we describe the implementation and evaluation of a sequential protocol to obtain normalized magnetization prepared rapid gradient echo (MPRAGE) images at 0.7, 0.8, or 0.9-mm isotropic spatial resolution. Optimization focused on the reference gradient-recalled echo (GRE) that was used for normalization of the MPRAGE. A good compromise between white-gray matter contrast and the signal-to-noise ratio (SNR) was reached at a flip angle of 3° and total scan time was reduced by increasing the reference voxel size by a factor of 8 relative to the MPRAGE resolution. The average intra-subject coefficient-of-variation (CV) in segmented white matter (WM) was 7.9 ± 3.3% after normalization, compared to 20 ± 8.4% before. The corresponding inter-subject average CV in WM was 7.6 ± 7.6% and 13 ± 7.8%. Maps of T1 derived from forward signal modelling showed no obvious bias after correction by a separately acquired flip angle map. To conclude, a non-interleaved acquisition for normalization of MPRAGE offers a simple alternative to MP2RAGE to obtain semi-quantitative purely T1-weighted images. These images can be converted to T1 maps, analogously to the established MP2RAGE approach. Scan time can be reduced by increasing the reference voxel size which has only a miniscule effect on image quality.
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Eckstein K, Bachrata B, Hangel G, Widhalm G, Enzinger C, Barth M, Trattnig S, Robinson SD. Improved susceptibility weighted imaging at ultra-high field using bipolar multi-echo acquisition and optimized image processing: CLEAR-SWI. Neuroimage 2021; 237:118175. [PMID: 34000407 PMCID: PMC7612087 DOI: 10.1016/j.neuroimage.2021.118175] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/28/2021] [Accepted: 05/13/2021] [Indexed: 02/07/2023] Open
Abstract
Purpose Susceptibility Weighted Imaging (SWI) has become established in the clinical investigation of stroke, microbleeds, tumor vascularization, calcification and iron deposition, but suffers from a number of shortcomings and artefacts. The goal of this study was to reduce the sensitivity of SWI to strong B1 and B0 inhomogeneities at ultra-high field to generate homogeneous images with increased contrast and free of common artefacts. All steps in SWI processing have been addressed −coil combination, phase unwrapping, image combination over echoes, phase filtering and homogeneity correction −and applied to an efficient bipolar multi-echo acquisition to substantially improve the quality of SWI. Principal results Our findings regarding the optimal individual processing steps lead us to propose a Contrast-weighted, Laplace-unwrapped, bipolar multi-Echo, ASPIRE-combined, homogeneous, improved Resolution SWI, or CLEAR-SWI. CLEAR-SWI was compared to two other multi-echo SWI methods and standard, single-echo SWI with the same acquisition time at 7 T in 10 healthy volunteers and with single-echo SWI in 13 patients with brain tumors. CLEAR-SWI had improved contrast-to-noise and homogeneity, reduced signal dropout and was not compromised by the artefacts which affected standard SWI in 10 out of 13 cases close to tumors (as assessed by expert raters), as well as generating T2* maps and phase images which can be used for Quantitative Susceptibility Mapping. In a comparison with other multi-echo SWI methods, CLEAR-SWI had the fewest artefacts, highest SNR and generally higher contrast-to-noise. Major conclusions CLEAR-SWI eliminates the artefacts common in standard, single-echo SWI, reduces signal dropouts and improves image homogeneity and contrast-to-noise. Applied clinically, in a study of brain tumor patients, CLEAR-SWI was free of the artefacts which affected standard, single-echo SWI.
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Affiliation(s)
- Korbinian Eckstein
- High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Beata Bachrata
- High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Karl Landsteiner Institute for Clinical Molecular MR in Musculoskeletal Imaging, Vienna, Austria
| | - Gilbert Hangel
- High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - Georg Widhalm
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | | | - Markus Barth
- School of Information Technology and Electrical Engineering, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, Brisbane, Australia
| | - Siegfried Trattnig
- High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Karl Landsteiner Institute for Clinical Molecular MR in Musculoskeletal Imaging, Vienna, Austria
| | - Simon Daniel Robinson
- High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Karl Landsteiner Institute for Clinical Molecular MR in Musculoskeletal Imaging, Vienna, Austria; Department of Neurology, Medical University of Graz, Graz, Austria; Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
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Woletz M, Roat S, Hummer A, Tik M, Windischberger C. Technical Note: Human tissue-equivalent MRI phantom preparation for 3 and 7 Tesla. Med Phys 2021; 48:4387-4394. [PMID: 34018625 DOI: 10.1002/mp.14986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 03/31/2021] [Accepted: 05/07/2021] [Indexed: 12/22/2022] Open
Abstract
PURPOSE While test objects (phantoms) in magnetic resonance imaging (MRI) are crucial for sequence development, protocol validation, and quality control, studies on the preparation of phantoms have been scarce, particularly at fields exceeding 3 Tesla. Here, we present a framework for the preparation of phantoms with well-defined T1 and T2 times at 3 and 7 Tesla. METHODS Phantoms with varying concentrations of agarose and Gd-DTPA were prepared and measured at 3 and 7 Tesla using T1 and T2 mapping techniques. An empirical, polynomial model was constructed that best represents the data at both field strengths, enabling the preparation of new phantoms with specified combinations of both T1 and T2 . Instructions for three different tissue types (brain gray matter, brain white matter, and renal cortex) are presented and validated. RESULTS T1 times in the samples ranged from 698 to 2820 ms and from 695 to 2906 ms, whereas T2 times ranged from 39 to 227 ms and from 34 to 235 ms for 3 and 7 Tesla scans, respectively. Models for both relaxation times used six parameters to represent the data with an adjusted R² of 0.998 and 0.997 for T1 and T2 , respectively. CONCLUSION Based on the equations derived from the current study, it is now possible to obtain accurate weight specifications for a test object with desired T1 and T2 relaxation times. This will spare researchers the laborious task of trail-and-error approaches in test object preparation attempts.
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Affiliation(s)
- Michael Woletz
- High-field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
| | - Sigrun Roat
- High-field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
| | - Allan Hummer
- High-field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
| | - Martin Tik
- High-field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
| | - Christian Windischberger
- High-field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, 1090, Austria
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Oliveira ÍAF, Roos T, Dumoulin SO, Siero JCW, van der Zwaag W. Can 7T MPRAGE match MP2RAGE for gray-white matter contrast? Neuroimage 2021; 240:118384. [PMID: 34265419 DOI: 10.1016/j.neuroimage.2021.118384] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/25/2021] [Accepted: 07/08/2021] [Indexed: 10/20/2022] Open
Abstract
Ultra-High Field (UHF) MRI provides a significant increase in Signal-to-Noise Ratio (SNR) and gains in contrast weighting in several functional and structural acquisitions. Unfortunately, an increase in field strength also induces non-uniformities in the transmit field (B1+) that can compromise image contrast non-uniformly. The MPRAGE is one of the most common T1 weighted (T1w) image acquisitions for structural imaging. It provides excellent contrast between gray and white matter and is widely used for brain segmentation. At 7T, the signal non-uniformities tend to complicate this and therefore, the self-bias-field corrected MP2RAGE is often used there. In both MPRAGE and MP2RAGE, more homogeneous image contrast can be achieved with adiabatic pulses, like the TR-FOCI inversion pulse, or special pulse design on parallel transmission systems, like Universal Pulses (UP). In the present study, we investigate different strategies to improve the bias-field for MPRAGE at 7T, comparing the contrast and GM/WM segmentability against MP2RAGE. The higher temporal efficiency of MPRAGE combined with the potential of the user-friendly UPs was the primary motivation for this MPRAGE-MP2RAGE comparison. We acquired MPRAGE data in six volunteers, adding a k-space shutter to reduce scan time, a kt-point UP approach for homogeneous signal excitation, and a TR-FOCI pulse for homogeneous inversion. Our results show remarkable signal contrast improvement throughout the brain, including regions of low B1+ such as the cerebellum. The improvements in the MPRAGE were largest following the introduction of the UPs. In addition to the CNR, both SNR and GM/WM segmentability were also assessed. Among the MPRAGEs, the combined strategy (UP + TR-FOCI) yielded highest SNR and showed highest spatial similarity between GM segments to the MP2RAGE. Interestingly, the distance between gray and white matter peaks in the intensity histograms did not increase, as better pulses and higher SNR especially benefitted the (cerebellar) gray matter. Overall, the gray-white matter contrast from MP2RAGE is higher, with higher CNR and higher intensity peak distances, even when scaled to scan time. Hence, the extra acquisition time for MP2RAGE is justified by the improved segmentability.
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Affiliation(s)
- Ícaro A F Oliveira
- Spinoza Centre for Neuroimaging, Amsterdam, the Netherlands; Experimental and Applied Psychology, VU University, Amsterdam, the Netherlands.
| | - Thomas Roos
- Spinoza Centre for Neuroimaging, Amsterdam, the Netherlands
| | - Serge O Dumoulin
- Spinoza Centre for Neuroimaging, Amsterdam, the Netherlands; Experimental and Applied Psychology, VU University, Amsterdam, the Netherlands; Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, the Netherlands
| | - Jeroen C W Siero
- Spinoza Centre for Neuroimaging, Amsterdam, the Netherlands; Radiology, Utrecht Center for Image Sciences, University Medical Center Utrecht, Utrecht, the Netherlands
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Duan W, Sehrawat P, Balachandrasekaran A, Bhumkar AB, Boraste PB, Becker JT, Kuller LH, Lopez OL, Gach HM, Dai W. Cerebral Blood Flow Is Associated with Diagnostic Class and Cognitive Decline in Alzheimer's Disease. J Alzheimers Dis 2021; 76:1103-1120. [PMID: 32597803 DOI: 10.3233/jad-200034] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Reliable cerebral blood flow (CBF) biomarkers using a noninvasive imaging technique are sought to facilitate early diagnosis and intervention in early Alzheimer's disease (AD). OBJECTIVE We aim to identify brain regions in which CBF values are affected and related to cognitive decline in early AD using a large cohort. METHODS Perfusion MRIs using continuous arterial spin labeling were acquired at 1.5 T in 58 normal controls (NC), 50 mild cognitive impairments (MCI), and 40 AD subjects from the Cardiovascular Health Study Cognition Study. Regional absolute CBF and normalized CBF (nCBF) values, without and with correction of partial volume effects, were compared across three groups. Association between regional CBF values and Modified Mini-Mental State Examination (3MSE) were investigated by multiple linear regression analyses adjusted for cardiovascular risk factors. RESULTS After correcting for partial volume effects and cardiovascular risk factors, ADs exhibited decreased nCBF with the strongest reduction in the bilateral posterior cingulate & precuneus region (p < 0.001) compared to NCs, and the strongest reduction in the bilateral superior medial frontal region (p < 0.001) compared to MCIs. MCIs exhibited the strongest nCBF decrease in the left hippocampus and nCBF increase in the right inferior frontal and insular region. The 3MSE scores within the symptomatic subjects were significantly associated with nCBF in the bilateral posterior and middle cingulate and parietal (p < 0.001), bilateral superior medial frontal (p < 0.001), bilateral temporoparietal (p < 0.02), and right hippocampus (p = 0.02) regions. CONCLUSION Noninvasive perfusion MRI can detect functional changes across diagnostic class and serve as a staging biomarker of cognitive status.
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Affiliation(s)
- Wenna Duan
- Department of Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | - Parshant Sehrawat
- Department of Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | | | - Ashish B Bhumkar
- Department of Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | - Paresh B Boraste
- Department of Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | - James T Becker
- Departments of Psychiatry, Psychology, and Neurology, University of Pittsburgh, PA, USA
| | - Lewis H Kuller
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Oscar L Lopez
- Departments of Neurology and Psychiatry, University of Pittsburgh, PA, USA
| | - H Michael Gach
- Departments of Radiation Oncology, Radiology, and Biomedical Engineering, Washington University, Saint Louis, MO, USA
| | - Weiying Dai
- Department of Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
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Calusi S, Arilli C, Mussi E, Puggelli L, Farnesi D, Casati M, Compagnucci A, Marrazzo L, Talamonti C, Zani M, Pallotta S. In phantom evaluation of targeting accuracy in MRI-based brain radiosurgery. Phys Med 2021; 85:158-164. [PMID: 34015617 DOI: 10.1016/j.ejmp.2021.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/06/2021] [Accepted: 05/08/2021] [Indexed: 01/21/2023] Open
Abstract
PURPOSE To determine the targeting accuracy of brain radiosurgery when planning procedures employing different MRI and MRI + CT combinations are adopted. MATERIALS AND METHOD A new phantom, the BrainTool, has been designed and realized to test image co-registration and targeting accuracy in a realistic anatomical situation. The phantom was created with a 3D printer and materials that mimic realistic brain MRI and CT contrast using a model extracted from a synthetic MRI study of a human brain. Eight markers distributed within the BrainTool provide for assessment of the accuracy of image registrations while two cavities that host an ionization chamber are used to perform targeting accuracy measurements with an iterative cross-scan method. Two procedures employing 1.5 T MRI-only or a combination of MRI (taken with 1.5 T or 3 T scanners) and CT to carry out Gamma Knife treatments were investigated. As distortions can impact targeting accuracy, MR images were preliminary evaluated to assess image deformation extent using GammaTool phantom. RESULTS MR images taken with both scanners showed average and maximum distortion of 0.3 mm and 1 mm respectively. The marker distances in co-registered images resulted below 0.5 mm for both MRI scans. The targeting mismatches obtained were 0.8 mm, 1.0 mm and 1.2 mm for MRI-only and MRI + CT (1,5T and 3 T), respectively. CONCLUSIONS Procedures using a combination of MR and CT images provide targeting accuracies comparable to those of MRI-only procedures. The BrainTool proved to be a suitable tool for carrying out co-registration and targeting accuracy of Gamma Knife brain radiosurgery treatments.
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Affiliation(s)
- S Calusi
- Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Italy; National Institute of Nuclear Physics, Florence, Italy.
| | - C Arilli
- Medical Physics Unit, AOU Careggi, Florence, Italy
| | - E Mussi
- Department of Industrial Engineering, University of Florence, Italy
| | - L Puggelli
- Department of Industrial Engineering, University of Florence, Italy
| | - D Farnesi
- CNR-IFAC, Institute of Applied Physics "N. Carrara", Florence, Italy
| | - M Casati
- Medical Physics Unit, AOU Careggi, Florence, Italy
| | | | - L Marrazzo
- Medical Physics Unit, AOU Careggi, Florence, Italy
| | - C Talamonti
- Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Italy; National Institute of Nuclear Physics, Florence, Italy; Medical Physics Unit, AOU Careggi, Florence, Italy
| | - M Zani
- Medical Physics Unit, AOU Careggi, Florence, Italy
| | - S Pallotta
- Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Italy; National Institute of Nuclear Physics, Florence, Italy; Medical Physics Unit, AOU Careggi, Florence, Italy
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Duan W, Zhou GD, Balachandrasekaran A, Bhumkar AB, Boraste PB, Becker JT, Kuller LH, Lopez OL, Gach HM, Dai W. Cerebral Blood Flow Predicts Conversion of Mild Cognitive Impairment into Alzheimer's Disease and Cognitive Decline: An Arterial Spin Labeling Follow-up Study. J Alzheimers Dis 2021; 82:293-305. [PMID: 34024834 DOI: 10.3233/jad-210199] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND This is the first longitudinal study to assess regional cerebral blood flow (rCBF) changes during the progression from normal control (NC) through mild cognitive impairment (MCI) and Alzheimer's disease (AD). OBJECTIVE We aim to determine if perfusion MRI biomarkers, derived from our prior cross-sectional study, can predict the onset and cognitive decline of AD. METHODS Perfusion MRIs using arterial spin labeling (ASL) were acquired in 15 stable-NC, 14 NC-to-MCI, 16 stable-MCI, and 18 MCI/AD-to-AD participants from the Cardiovascular Health Study (CHS) cognition study. Group comparisons, predictions of AD conversion and time to conversion, and Modified Mini-Mental State Examination (3MSE) from rCBF were performed. RESULTS Compared to the stable-NC group: 1) the stable-MCI group exhibited rCBF decreases in the right temporoparietal (p = 0.00010) and right inferior frontal and insula (p = 0.0094) regions; and 2) the MCI/AD-to-AD group exhibited rCBF decreases in the bilateral temporoparietal regions (p = 0.00062 and 0.0035). Compared to the NC-to-MCI group, the stable-MCI group exhibited a rCBF decrease in the right hippocampus region (p = 0.0053). The baseline rCBF values in the posterior cingulate cortex (PCC) (p = 0.0043), bilateral superior medial frontal regions (BSMF) (p = 0.012), and left inferior frontal (p = 0.010) regions predicted the 3MSE scores for all the participants at follow-up. The baseline rCBF in the PCC and BSMF regions predicted the conversion and time to conversion from MCI to AD (p < 0.05; not significant after multiple corrections). CONCLUSION We demonstrated the feasibility of ASL in detecting rCBF changes in the typical AD-affected regions and the predictive value of baseline rCBF on AD conversion and cognitive decline.
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Affiliation(s)
- Wenna Duan
- Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | - Grace D Zhou
- Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | | | - Ashish B Bhumkar
- Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | - Paresh B Boraste
- Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
| | - James T Becker
- Psychiatry, Psychology, and Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lewis H Kuller
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Oscar L Lopez
- Neurology and Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - H Michael Gach
- Radiation Oncology, Radiology, and Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO, USA
| | - Weiying Dai
- Computer Science, State University of New York at Binghamton, Binghamton, NY, USA
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Shin DJ, Choi SH, Yoo RE, Kang KM, Yun TJ, Kim JH, Sohn CH, Jo SW, Lee EJ. Application of T1 Map Information Based on Synthetic MRI for Dynamic Contrast-Enhanced Imaging: A Comparison Study with the Fixed Baseline T1 Value Method. Korean J Radiol 2021; 22:1352-1368. [PMID: 33987992 PMCID: PMC8316777 DOI: 10.3348/kjr.2020.1201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/13/2020] [Accepted: 12/31/2020] [Indexed: 11/17/2022] Open
Abstract
Objective For an accurate dynamic contrast-enhanced (DCE) MRI analysis, exact baseline T1 mapping is critical. The purpose of this study was to compare the pharmacokinetic parameters of DCE MRI using synthetic MRI with those using fixed baseline T1 values. Materials and Methods This retrospective study included 102 patients who underwent both DCE and synthetic brain MRI. Two methods were set for the baseline T1: one using the fixed value and the other using the T1 map from synthetic MRI. The volume transfer constant (Ktrans), volume of the vascular plasma space (vp), and the volume of the extravascular extracellular space (ve) were compared between the two methods. The interclass correlation coefficients and the Bland-Altman method were used to assess the reliability. Results In normal-appearing frontal white matter (WM), the mean values of Ktrans, ve, and vp were significantly higher in the fixed value method than in the T1 map method. In the normal-appearing occipital WM, the mean values of ve and vp were significantly higher in the fixed value method. In the putamen and head of the caudate nucleus, the mean values of Ktrans, ve, and vp were significantly lower in the fixed value method. In addition, the T1 map method showed comparable interobserver agreements with the fixed baseline T1 value method. Conclusion The T1 map method using synthetic MRI may be useful for reflecting individual differences and reliable measurements in clinical applications of DCE MRI.
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Affiliation(s)
- Dong Jae Shin
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Seung Hong Choi
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.,Center for Nanoparticle Research, Institute for Basic Science, Seoul, Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul, Korea.
| | - Roh Eul Yoo
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Koung Mi Kang
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Tae Jin Yun
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Ji Hoon Kim
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Chul Ho Sohn
- Department of Radiology, Seoul National University College of Medicine, Seoul, Korea
| | - Sang Won Jo
- Department of Radiology, Hallym University Dongtan Sacred Heart Hospital, Hwaseong, Korea
| | - Eun Jung Lee
- Department of Radiology, Human Medical Imaging & Intervention Center, Seoul, Korea
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Kashyap S, Ivanov D, Havlicek M, Huber L, Poser BA, Uludağ K. Sub-millimetre resolution laminar fMRI using Arterial Spin Labelling in humans at 7 T. PLoS One 2021; 16:e0250504. [PMID: 33901230 PMCID: PMC8075193 DOI: 10.1371/journal.pone.0250504] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 04/07/2021] [Indexed: 12/02/2022] Open
Abstract
Laminar fMRI at ultra-high magnetic field strength is typically carried out using the Blood Oxygenation Level-Dependent (BOLD) contrast. Despite its unrivalled sensitivity to detecting activation, the BOLD contrast is limited in its spatial specificity due to signals stemming from intra-cortical ascending and pial veins. Alternatively, regional changes in perfusion (i.e., cerebral blood flow through tissue) are colocalised to neuronal activation, which can be non-invasively measured using Arterial Spin Labelling (ASL) MRI. In addition, ASL provides a quantitative marker of neuronal activation in terms of perfusion signal, which is simultaneously acquired along with the BOLD signal. However, ASL for laminar imaging is challenging due to the lower SNR of the perfusion signal and higher RF power deposition i.e., specific absorption rate (SAR) of ASL sequences. In the present study, we present for the first time in humans, isotropic sub-millimetre spatial resolution functional perfusion images using Flow-sensitive Alternating Inversion Recovery (FAIR) ASL with a 3D-EPI readout at 7 T. We show that robust statistical activation maps can be obtained with perfusion-weighting in a single session. We observed the characteristic BOLD amplitude increase towards the superficial laminae, and, in apparent discrepancy, the relative perfusion profile shows a decrease of the amplitude and the absolute perfusion profile a much smaller increase towards the cortical surface. Considering the draining vein effect on the BOLD signal using model-based spatial “convolution”, we show that the empirically measured perfusion and BOLD profiles are, in fact, consistent with each other. This study demonstrates that laminar perfusion fMRI in humans is feasible at 7 T and that caution must be exercised when interpreting BOLD signal laminar profiles as direct representation of the cortical distribution of neuronal activity.
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Affiliation(s)
- Sriranga Kashyap
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
- Maastricht Brain Imaging Centre (M-BIC), Maastricht University, Maastricht, The Netherlands
- * E-mail: (SK); (DI)
| | - Dimo Ivanov
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
- Maastricht Brain Imaging Centre (M-BIC), Maastricht University, Maastricht, The Netherlands
- * E-mail: (SK); (DI)
| | - Martin Havlicek
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Laurentius Huber
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
- Maastricht Brain Imaging Centre (M-BIC), Maastricht University, Maastricht, The Netherlands
| | - Benedikt A. Poser
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands
- Maastricht Brain Imaging Centre (M-BIC), Maastricht University, Maastricht, The Netherlands
| | - Kâmil Uludağ
- Center for Neuroscience Imaging Research, Institute for Basic Science, Sungkyunkwan University, Suwon, South Korea
- Department of Biomedical Engineering, N Center, Sungkyunkwan University, Suwon, South Korea
- Techna Institute & Koerner Scientist in MR Imaging, University Health Network, Toronto, Canada
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Sanchez Panchuelo RM, Mougin O, Turner R, Francis ST. Quantitative T1 mapping using multi-slice multi-shot inversion recovery EPI. Neuroimage 2021; 234:117976. [PMID: 33781969 PMCID: PMC8204273 DOI: 10.1016/j.neuroimage.2021.117976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 02/27/2021] [Accepted: 03/13/2021] [Indexed: 11/12/2022] Open
Abstract
An efficient multi-slice inversion–recovery EPI (MS-IR-EPI) sequence for fast, high spatial resolution, quantitative T1 mapping is presented, using a segmented simultaneous multi-slice acquisition, combined with slice order shifting across multiple acquisitions. The segmented acquisition minimises the effective TE and readout duration compared to a single-shot EPI scheme, reducing geometric distortions to provide high quality T1 maps with a narrow point-spread function. The precision and repeatability of MS-IR-EPI T1 measurements are assessed using both T1-calibrated and T2-calibrated ISMRM/NIST phantom spheres at 3 and 7 T and compared with single slice IR and MP2RAGE methods. Magnetization transfer (MT) effects of the spectrally-selective fat-suppression (FS) pulses required for in vivo imaging are shown to shorten the measured in-vivo T1 values. We model the effect of these fat suppression pulses on T1 measurements and show that the model can remove their MT contribution from the measured T1, thus providing accurate T1 quantification. High spatial resolution T1 maps of the human brain generated with MS-IR-EPI at 7 T are compared with those generated with the widely implemented MP2RAGE sequence. Our MS-IR-EPI sequence provides high SNR per unit time and sharper T1 maps than MP2RAGE, demonstrating the potential for ultra-high resolution T1 mapping and the improved discrimination of functionally relevant cortical areas in the human brain.
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Affiliation(s)
- Rosa M Sanchez Panchuelo
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom; NIHR Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, United Kingdom.
| | - Olivier Mougin
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
| | - Robert Turner
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom; Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Susan T Francis
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom; NIHR Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, United Kingdom
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Corbin N, Callaghan MF. Imperfect spoiling in variable flip angle T 1 mapping at 7T: Quantifying and minimizing impact. Magn Reson Med 2021; 86:693-708. [PMID: 33645814 PMCID: PMC8436769 DOI: 10.1002/mrm.28720] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 01/15/2021] [Accepted: 01/17/2021] [Indexed: 02/06/2023]
Abstract
Purpose The variable flip angle (VFA) approach to T1 mapping assumes perfectly spoiled transverse magnetisation at the end of each repetition time (TR). Despite radiofrequency (RF) and gradient spoiling, this condition is rarely met, leading to erroneous T1 estimates (T1app). Theoretical corrections can be applied but make assumptions about tissue properties, for example, a global T2 time. Here, we investigate the effect of imperfect spoiling at 7T and the interaction between the RF and gradient spoiling conditions, additionally accounting for diffusion. We provide guidance on the optimal approach to maximise the accuracy of the T1 estimate in the context of 3D multi‐echo acquisitions. Methods The impact of the spoiling regime was investigated through numerical simulations, phantom and invivo experiments. Results The predicted dependence of T1app on tissue properties, system settings, and spoiling conditions was observed in both phantom and in vivo experiments. Diffusion effects modulated the dependence of T1app on both B1+ efficiency and T2 times. Conclusion Error in T1app can be minimized by using an RF spoiling increment and gradient spoiler moment combination that minimizes T2‐dependence and safeguards image quality. Although the diffusion effect was comparatively small at 7T, correction factors accounting for this effect are recommended. Click here for author‐reader discussions
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Affiliation(s)
- Nadège Corbin
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Martina F Callaghan
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
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Kleban E, Gowland P, Bowtell R. Probing the myelin water compartment with a saturation-recovery, multi-echo gradient-recalled echo sequence. Magn Reson Med 2021; 86:167-181. [PMID: 33576521 DOI: 10.1002/mrm.28695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/24/2020] [Accepted: 01/04/2021] [Indexed: 12/17/2022]
Abstract
PURPOSE To investigate the effect of varying levels of T 1 -weighting on the evolution of the complex signal from white matter in a multi-echo gradient-recalled echo (mGRE) saturation-recovery sequence. THEORY AND METHODS Analysis of the complex signal evolution in an mGRE sequence allows the contributions from short- and long- T 2 ∗ components to be separated, thus providing a measure of the relative strength of signals from the myelin water, and the external and intra-axonal compartments. Here we evaluated the effect of different levels of T 1 -weighting on these signals, expecting that the previously reported, short T 1 of the myelin water would lead to a relative enhancement of the myelin water signal in the presence of signal saturation. Complex, saturation-recovery mGRE data from the splenium of the corpus callosum from 5 healthy volunteers were preprocessed using a frequency difference mapping (FDM) approach and analyzed using the 3-pool model of complex signal evolution in white matter. RESULTS An increase in the apparent T 1 as a function of echo time was demonstrated, but this increase was an order of magnitude smaller than that expected from previously reported myelin water T 1 -values. This suggests the presence of magnetization transfer and exchange effects which counteract the T 1 -weighting. CONCLUSION Variation of the B 1 + amplitude in a saturation-recovery mGRE sequence can be used to modulate the relative strength of signals from the different compartments in white matter, but the modulation is less than predicted from previously reported T 1 -values.
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Affiliation(s)
- Elena Kleban
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK.,Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK
| | - Penny Gowland
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Richard Bowtell
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
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Wiggermann V, MacKay AL, Rauscher A, Helms G. In vivo investigation of the multi-exponential T 2 decay in human white matter at 7 T: Implications for myelin water imaging at UHF. NMR IN BIOMEDICINE 2021; 34:e4429. [PMID: 33118238 DOI: 10.1002/nbm.4429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 08/23/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
INTRODUCTION Multi-component T2 mapping using a gradient- and spin-echo (GraSE) acquisition has become standard for myelin water imaging at 3 T. Higher magnetic field strengths promise signal-to-noise ratio benefits but face specific absorption rate limits and shortened T2 times. This study investigates compartmental T2 times in vivo and addresses advantages and challenges of multi-component T2 mapping at 7 T. METHODS We acquired 3D multi-echo GraSE data in seven healthy adults at 7 T, with three subjects also scanned at 3 T. Stimulated echoes arising from B1+ inhomogeneities were accounted for by the extended phase graph (EPG) algorithm. We used the computed T2 distributions to determine T2 times that identify different water pools and assessed signal-to-noise and fit-to-noise characteristics of the signal estimation. We compared short T2 fractions and T2 properties of the intermediate water pool at 3 T and 7 T. RESULTS Flip angle mapping confirmed that EPG accurately determined the larger B1+ inhomogeneity at 7 T. Multi-component T2 analysis demonstrated shortened T2 times at 7 T compared with 3 T. Fit-to-noise and signal-to-noise ratios were improved at 7 T but depended on B1+ homogeneity. Adjusting the shortest T2 to 8 ms and the T2 threshold that separates different water compartments to 20 ms yielded short T2 fractions at 7 T that conformed to 3 T data. Short T2 fractions in myelin-rich white matter regions were lower at 7 T than at 3 T, and higher in iron-rich structures. DISCUSSION Adjusting the T2 compartment boundaries was required due to the shorter T2 relaxation times at 7 T. Shorter echo spacing would better sample the fast decaying signal but would increase peripheral nerve stimulation. Multi-channel transmission will improve T2 measurements at 7 T. CONCLUSION We used a multi-echo 3D GraSE sequence to characterize the multi-exponential T2 decay at 7 T. We adapted T2 parameters for evaluation of the short T2 fraction. Obtained 7 T multi-component T2 maps were in good agreement with 3 T data.
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Affiliation(s)
- Vanessa Wiggermann
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, Canada
- UBC MRI Research Centre, University of British Columbia, Vancouver, Canada
| | - Alexander L MacKay
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- UBC MRI Research Centre, University of British Columbia, Vancouver, Canada
- Department of Radiology, University of British Columbia, Vancouver, Canada
| | - Alexander Rauscher
- Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, Canada
- UBC MRI Research Centre, University of British Columbia, Vancouver, Canada
- BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Gunther Helms
- Medical Radiation Physics, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
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Ordidge R, Cleary J, Glarin R, Blunck Y, Farquharson S, Moffat B. Ultra-high-field MRI using composite RF (STEP) pulses. NMR IN BIOMEDICINE 2021; 34:e4445. [PMID: 33205505 DOI: 10.1002/nbm.4445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
Ultra-high field MRI offers many opportunities to expand the applications of MRI. In order for this to be realized, the technical problems associated with MRI at field strengths of 7 T and greater need to be solved or mitigated. This paper explores the use of new variations of composite RF pulses, named serial transmit excitation pulses (STEP), in contrast to parallel pulse techniques, in order to remove and/or mitigate the effects of non-uniform B1 excitation fields associated with the subject (eg the human brain). Several techniques based on STEP sequences are introduced and their application to human brain imaging is presented and evaluated.
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Affiliation(s)
- Roger Ordidge
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Jon Cleary
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Rebecca Glarin
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Yasmin Blunck
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
| | - Shawna Farquharson
- Florey Institute for Neuroscience and Mental Health, Melbourne, Australia
| | - Bradford Moffat
- Melbourne Brain Centre Imaging Unit, University of Melbourne, Australia
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Wang K, Shao X, Yan L, Ma SJ, Jin J, Wang DJJ. Optimization of adiabatic pulses for pulsed arterial spin labeling at 7 tesla: Comparison with pseudo-continuous arterial spin labeling. Magn Reson Med 2021; 85:3227-3240. [PMID: 33427349 DOI: 10.1002/mrm.28661] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 12/05/2020] [Accepted: 12/08/2020] [Indexed: 11/05/2022]
Abstract
PURPOSE To optimize and evaluate adiabatic pulses for pulsed arterial spin labeling at ultrahigh field 7 tesla. METHODS Four common adiabatic inversion pulses, including hyperbolic secant, wideband uniform rate smooth truncation, frequency offset corrected inversion, and time-resampled frequency offset corrected inversion pulses, were optimized based on a custom-defined loss function that included labeling efficiency and inversion band uniformity. The optimized pulses were implemented in flow-sensitive alternating inversion recovery sequences and tested on phantom and 11 healthy volunteers with 2 constraints: 1) specific absorption rate normalized; and 2) equal peak RF amplitude, respectively. A pseudo-continuous arterial spin labeling sequence was implemented for comparison. Quantitative metrics such as perfusion and relative labeling efficiency versus residual tissue signal were calculated. RESULTS Among the 4 pulses, the wideband uniform rate smooth truncation pulse yielded the lowest loss in simulation and achieved a good balance between labeling efficiency and residual tissue signal from both phantom and in vivo experiments. Wideband uniform rate smooth truncation-pulsed arterial spin labeling showed significantly higher relative labeling efficiency compared to the other sequences (P < .01), whereas the perfusion signal was increased by 40% when the highest B 1 + amplitude was used. The 4 pulsed arterial spin labeling sequences yielded comparable perfusion signals compared to pseudo-continuous arterial spin labeling but with less than half the specific absorption rate. CONCLUSION Optimized wideband uniform rate smooth truncation pulse with the highest B 1 + amplitude allowed was recommended for 7 tesla pulsed arterial spin labeling.
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Affiliation(s)
- Kai Wang
- Laboratory of FMRI Technology (LOFT), USC Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Xingfeng Shao
- Laboratory of FMRI Technology (LOFT), USC Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Lirong Yan
- Laboratory of FMRI Technology (LOFT), USC Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.,Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Samantha J Ma
- Laboratory of FMRI Technology (LOFT), USC Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.,Siemens Medical Solutions USA, Inc., Los Angeles, California, USA
| | - Jin Jin
- Laboratory of FMRI Technology (LOFT), USC Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.,Siemens Healthcare Pty Ltd, Brisbane, Australia
| | - Danny J J Wang
- Laboratory of FMRI Technology (LOFT), USC Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.,Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
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