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Boonsuth R, Battiston M, Grussu F, Samlidou CM, Calvi A, Samson RS, Gandini Wheeler-Kingshott CAM, Yiannakas MC. Feasibility of in vivo multi-parametric quantitative magnetic resonance imaging of the healthy sciatic nerve with a unified signal readout protocol. Sci Rep 2023; 13:6565. [PMID: 37085693 PMCID: PMC10121559 DOI: 10.1038/s41598-023-33618-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 04/15/2023] [Indexed: 04/23/2023] Open
Abstract
Magnetic resonance neurography (MRN) has been used successfully over the years to investigate the peripheral nervous system (PNS) because it allows early detection and precise localisation of neural tissue damage. However, studies demonstrating the feasibility of combining MRN with multi-parametric quantitative magnetic resonance imaging (qMRI) methods, which provide more specific information related to nerve tissue composition and microstructural organisation, can be invaluable. The translation of emerging qMRI methods previously validated in the central nervous system to the PNS offers real potential to characterise in patients in vivo the underlying pathophysiological mechanisms involved in a plethora of conditions of the PNS. The aim of this study was to assess the feasibility of combining MRN with qMRI to measure diffusion, magnetisation transfer and relaxation properties of the healthy sciatic nerve in vivo using a unified signal readout protocol. The reproducibility of the multi-parametric qMRI protocol as well as normative qMRI measures in the healthy sciatic nerve are reported. The findings presented herein pave the way to the practical implementation of joint MRN-qMRI in future studies of pathological conditions affecting the PNS.
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Affiliation(s)
- Ratthaporn Boonsuth
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK.
- Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.
| | - Marco Battiston
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Francesco Grussu
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Christina Maria Samlidou
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Alberto Calvi
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
- Laboratory of Advanced Imaging in Neuroimmunological Diseases, Center of Neuroimmunology, Hospital Clinic Barcelona, Fundació Clinic Per a La Recerca Biomedica, Barcelona, Spain
| | - Rebecca S Samson
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Claudia A M Gandini Wheeler-Kingshott
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
- Brain Connectivity Research Centre, IRCCS Mondino Foundation, Pavia, Italy
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Marios C Yiannakas
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
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Menon RG, Sharafi A, Muccio M, Smith T, Kister I, Ge Y, Regatte RR. Three-dimensional multi-parameter brain mapping using MR fingerprinting. RESEARCH SQUARE 2023:rs.3.rs-2675278. [PMID: 36993561 PMCID: PMC10055680 DOI: 10.21203/rs.3.rs-2675278/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
The purpose of this study was to develop and test a 3D multi-parameter MR fingerprinting (MRF) method for brain imaging applications. The subject cohort included 5 healthy volunteers, repeatability tests done on 2 healthy volunteers and tested on two multiple sclerosis (MS) patients. A 3D-MRF imaging technique capable of quantifying T1, T2 and T1ρ was used. The imaging sequence was tested in standardized phantoms and 3D-MRF brain imaging with multiple shots (1, 2 and 4) in healthy human volunteers and MS patients. Quantitative parametric maps for T1, T2, T1ρ, were generated. Mean gray matter (GM) and white matter (WM) ROIs were compared for each mapping technique, Bland-Altman plots and intra-class correlation coefficient (ICC) were used to assess repeatability and Student T-tests were used to compare results in MS patients. Standardized phantom studies demonstrated excellent agreement with reference T1/T2/T1ρ mapping techniques. This study demonstrates that the 3D-MRF technique is able to simultaneously quantify T1, T2 and T1ρ for tissue property characterization in a clinically feasible scan time. This multi-parametric approach offers increased potential to detect and differentiate brain lesions and to better test imaging biomarker hypotheses for several neurological diseases, including MS.
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Affiliation(s)
| | | | | | - Tyler Smith
- New York University Grossman School of Medicine
| | - Ilya Kister
- New York University Grossman School of Medicine
| | - Yulin Ge
- New York University Grossman School of Medicine
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Bowley TY, Lagutina IV, Francis C, Sivakumar S, Selwyn RG, Taylor E, Guo Y, Fahy BN, Tawfik B, Marchetti D. The RPL/RPS gene signature of melanoma CTCs associates with brain metastasis. CANCER RESEARCH COMMUNICATIONS 2022; 2:1436-1448. [PMID: 36407834 PMCID: PMC9668078 DOI: 10.1158/2767-9764.crc-22-0337] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Melanoma brain metastasis (MBM) is linked to poor prognosis and low overall survival. We hypothesized that melanoma circulating tumor cells (CTCs) possess a gene signature significantly expressed and associated with MBM. Employing a multi-pronged approach, we provide first-time evidence identifying a common CTC gene signature for ribosomal protein large/small subunits (RPL/RPS) which associate with MBM onset and progression. Experimental strategies involved capturing, transcriptional profiling and interrogating CTCs, either directly isolated from blood of melanoma patients at distinct stages of MBM progression or from CTC-driven MBM in experimental animals. Second, we developed the first Magnetic Resonance Imaging (MRI) CTC-derived MBM xenograft model (MRI-MBM CDX) to discriminate MBM spatial and temporal growth, recreating MBM clinical presentation and progression. Third, we performed the comprehensive transcriptional profiling of MRI-MBM CDXs, along with longitudinal monitoring of CTCs from CDXs possessing/not possessing MBM. Our findings suggest that enhanced ribosomal protein content/ribogenesis may contribute to MBM onset. Since ribosome modifications drive tumor progression and metastatic development by remodeling CTC translational events, overexpression of the CTC RPL/RPS gene signature could be implicated in MBM development. Collectively, this study provides important insights for relevance of the CTC RPL/RPS gene signature in MBM, and identify potential targets for therapeutic intervention to improve patient care for melanoma patients diagnosed with or at high-risk of developing MBM.
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Affiliation(s)
- Tetiana Y. Bowley
- Division of Molecular Medicine, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Irina V. Lagutina
- Animal Models Shared Resource, The University of New Mexico Comprehensive Cancer Center, Albuquerque, New Mexico
| | - Carol Francis
- Division of Molecular Medicine, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Sinduja Sivakumar
- Division of Molecular Medicine, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Reed G. Selwyn
- Department of Radiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Erik Taylor
- Department of Radiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Yan Guo
- Division of Molecular Medicine, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Bridget N. Fahy
- Division of Surgical Oncology and Palliative Medicine, University of New Mexico Comprehensive Cancer Center, Albuquerque, New Mexico
| | - Bernard Tawfik
- Division of Hematology and Oncology, Department of Internal Medicine, University of New Mexico Comprehensive Cancer Center, Albuquerque, New Mexico
| | - Dario Marchetti
- Division of Molecular Medicine, Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
- Corresponding Author: Dario Marchetti, University of New Mexico Health Sciences Center, CRF, 915 Camino de Salud, Albuquerque, NM, 87131. Phone: 505-272-7937; E-mail:
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Wakayama T, Ueyama T, Imai F, Kimura A, Fujiwara H. Quantitative assessment of regional lung ventilation in emphysematous mice using hyperpolarized 129Xe MRI with a continuous flow hyperpolarizing system. Magn Reson Imaging 2022; 92:88-95. [PMID: 35654279 DOI: 10.1016/j.mri.2022.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 10/18/2022]
Abstract
BACKGROUND Lung ventilation function in small animals can be assessed by using hyperpolarized gas MRI. For these experiments a free breathing protocol is generally preferred to mechanical ventilation as mechanical ventilation can often lead to ventilation lung injury, while the need to maintain a gas reservoir may lead to a partial reduction of the polarization. PURPOSE To evaluate regional lung ventilation of mice by a simple but fast method under free breathing and give evidence for effectiveness with an elastase instilled emphysematous mice. ANIMAL MODEL Emphysematous mice. MATERIALS AND METHODS A Look-Locker based saturation recovery sequence was developed for continuous flow hyperpolarized (CF-HP) 129Xe gas experiments, and the apparent gas-exchange rate, k', was measured by the analysis of the saturation recovery curve. RESULTS In mice with elastase-induced mild emphysema, reductions of 15-30% in k' values were observed as the results of lesion-induced changes in the lung. DATA CONCLUSION The proposed method was applied to an emphysematous model mice and ventilation dysfunctions have been approved as a definite decrease in k' values, supporting the usefulness for a non-invasive assessment of the lung functions in preclinical study by the CF-HP 129Xe experiments.
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Affiliation(s)
- Tetsuya Wakayama
- Department of Medical Physics and Engineering, Area of Medical Imaging Technology and Science, Division of Health Sciences, Graduate of School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tsuyoshi Ueyama
- Department of Medical Physics and Engineering, Area of Medical Imaging Technology and Science, Division of Health Sciences, Graduate of School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Fumito Imai
- Department of Medical Physics and Engineering, Area of Medical Imaging Technology and Science, Division of Health Sciences, Graduate of School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Atsuomi Kimura
- Department of Medical Physics and Engineering, Area of Medical Imaging Technology and Science, Division of Health Sciences, Graduate of School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hideaki Fujiwara
- Department of Medical Physics and Engineering, Area of Medical Imaging Technology and Science, Division of Health Sciences, Graduate of School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Han PK, Marin T, Djebra Y, Landes V, Zhuo Y, El Fakhri G, Ma C. Free-breathing 3D cardiac T 1 mapping with transmit B 1 correction at 3T. Magn Reson Med 2021; 87:1832-1845. [PMID: 34812547 DOI: 10.1002/mrm.29097] [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: 07/13/2021] [Revised: 10/12/2021] [Accepted: 11/05/2021] [Indexed: 12/22/2022]
Abstract
PURPOSE To develop a cardiac T1 mapping method for free-breathing 3D T1 mapping of the whole heart at 3 T with transmit B1 ( B 1 + ) correction. METHODS A free-breathing, electrocardiogram-gated inversion-recovery sequence with spoiled gradient-echo readout was developed and optimized for cardiac T1 mapping at 3 T. High-frame-rate dynamic images were reconstructed from sparse (k,t)-space data acquired along a stack-of-stars trajectory using a subspace-based method for accelerated imaging. Joint T1 and flip-angle estimation was performed in T1 mapping to improve its robustness to B 1 + inhomogeneity. Subject-specific timing of data acquisition was used in the estimation to account for natural heart-rate variations during the imaging experiment. RESULTS Simulations showed that accuracy and precision of T1 mapping can be improved with joint T1 and flip-angle estimation and optimized electrocardiogram-gated spoiled gradient echo-based inversion-recovery acquisition scheme. The phantom study showed good agreement between the T1 maps from the proposed method and the reference method. Three-dimensional cardiac T1 maps (40 slices) were obtained at a 1.9-mm in-plane and 4.5-mm through-plane spatial resolution from healthy subjects (n = 6) with an average imaging time of 14.2 ± 1.6 minutes (heartbeat rate: 64.2 ± 7.1 bpm), showing myocardial T1 values comparable to those obtained from modified Look-Locker inversion recovery. The proposed method generated B 1 + maps with spatially smooth variation showing 21%-32% and 11%-15% variations across the septal-lateral and inferior-anterior regions of the myocardium in the left ventricle. CONCLUSION The proposed method allows free-breathing 3D T1 mapping of the whole heart with transmit B1 correction in a practical imaging time.
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Affiliation(s)
- Paul Kyu Han
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Thibault Marin
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Yanis Djebra
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA.,LTCI, Télécom Paris, Institut Polytechnique de Paris, France
| | | | - Yue Zhuo
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Chao Ma
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA
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Khajehim M, Christen T, Tam F, Graham SJ. Streamlined magnetic resonance fingerprinting: Fast whole-brain coverage with deep-learning based parameter estimation. Neuroimage 2021; 238:118237. [PMID: 34091035 DOI: 10.1016/j.neuroimage.2021.118237] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/26/2021] [Accepted: 06/02/2021] [Indexed: 01/02/2023] Open
Abstract
Magnetic resonance fingerprinting (MRF) is a quantitative MRI (qMRI) framework that provides simultaneous estimates of multiple relaxation parameters as well as metrics of field inhomogeneity in a single acquisition. However, current challenges exist in the forms of (1) scan time; (2) need for custom image reconstruction; (3) large dictionary sizes; (4) long dictionary-matching time. This study aims to introduce a novel streamlined magnetic-resonance fingerprinting (sMRF) framework based on a single-shot echo-planar imaging (EPI) sequence to simultaneously estimate tissue T1, T2, and T2* with integrated B1+ correction. Encouraged by recent work on EPI-based MRF, we developed a method that combines spin-echo EPI with gradient-echo EPI to achieve T2 in addition to T1 and T2* quantification. To this design, we add simultaneous multi-slice (SMS) acceleration to enable full-brain coverage in a few minutes. Moreover, in the parameter-estimation step, we use deep learning to train a deep neural network (DNN) to accelerate the estimation process by orders of magnitude. Notably, due to the high image quality of the EPI scans, the training process can rely simply on Bloch-simulated data. The DNN also removes the need for storing large dictionaries. Phantom scans along with in-vivo multi-slice scans from seven healthy volunteers were acquired with resolutions of 1.1×1.1×3 mm3 and 1.7×1.7×3 mm3, and the results were validated against ground truth measurements. Excellent correspondence was found between our T1, T2, and T2* estimates and results obtained from standard approaches. In the phantom scan, a strong linear relationship (R = 1-1.04, R2>0.96) was found for all parameter estimates, with a particularly high agreement for T2 estimation (R2>0.99). Similar findings are reported for the in-vivo human data for all of our parameter estimates. Incorporation of DNN results in a reduction of parameter estimation time on the order of 1000 x and a reduction in storage requirements on the order of 2500 x while achieving highly similar results as conventional dictionary matching (%differences of 7.4 ± 0.4%, 3.6 ± 0.3% and 6.0 ± 0.4% error in T1, T2, and T2* estimation). Thus, sMRF has the potential to be the method of choice for future MRF studies by providing ease of implementation, fast whole-brain coverage, and ultra-fast T1/T2/T2* estimation.
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Affiliation(s)
- Mahdi Khajehim
- Department of Medical Biophysics, University of Toronto, 101 College St Suite 15-701, Toronto, ON M5G 1L7, Canada.
| | - Thomas Christen
- Grenoble Institute of Neuroscience, Inserm, Grenoble, France
| | - Fred Tam
- Hurvitz Brain Sciences Research Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Simon J Graham
- Department of Medical Biophysics, University of Toronto, 101 College St Suite 15-701, Toronto, ON M5G 1L7, Canada; Hurvitz Brain Sciences Research Program, Sunnybrook Research Institute, Toronto, ON, Canada
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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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Claeser R, Zimmermann M, Shah NJ. Sub-millimeter T 1 mapping of rapidly relaxing compartments with gradient delay corrected spiral TAPIR and compressed sensing at 3T. Magn Reson Med 2019; 82:1288-1300. [PMID: 31148282 DOI: 10.1002/mrm.27797] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 04/10/2019] [Accepted: 04/12/2019] [Indexed: 11/09/2022]
Abstract
PURPOSE The TAPIR sequence is an accurate and efficient method for T1 mapping. It combines a slice-interleaving Look-Locker read-out with an acquisition of multiple k-space lines in 1 shot. Whereas the acquisition of multiple lines per excitation increases imaging speed, the corresponding increase in TR and TE is detrimental to the T1 fitting performance. This is especially problematic for substances exhibiting rapid T2 * relaxation (e.g., myelin water). METHODS The T1 fitting performance of TAPIR is enhanced by using an interleaved spiral read-out with shorter TE and TR. Furthermore, an improvement to a method for fast gradient delay estimation is presented. Whereas previous methods assume the gradient delay to be stationary, the presented approach corrects the spiral k-space trajectory by using a polynomial fit of the measured gradient delays. RESULTS Gradient delay artifacts are largely eliminated, requiring very little additional scanning time. The sampling efficiency of the spiral read-out allows for a significant reduction of the acquisition time in comparison to Cartesian TAPIR. Spiral TAPIR enables the sampling of more slices and an accurate measurement of rapidly relaxing compartments. Over a wide T1 range (448-3115 ms), spiral TAPIR reduces the mean fitting error from -2.5% to -0.1%. Combining 50% undersampling with the shorter TR of spiral TAPIR, an increase in imaging speed by a factor of up to 3.3 was achieved. CONCLUSION Using a spiral read-out trajectory, the established TAPIR sequence enables measurement of rapidly relaxing T1 compartments, while improving T1 mapping performance and imaging speed.
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Affiliation(s)
- Robert Claeser
- Institute of Neuroscience and Medicine 4 (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - Markus Zimmermann
- Institute of Neuroscience and Medicine 4 (INM-4), Forschungszentrum Jülich, Jülich, Germany
| | - N Jon Shah
- Institute of Neuroscience and Medicine 4 (INM-4), Forschungszentrum Jülich, Jülich, Germany.,Institute of Neuroscience and Medicine 11 (INM-11), Forschungszentrum Jülich, Jülich, Germany.,Jülich Aachen Research Alliance (JARA-BRAIN), Translational Medicine, Aachen, Germany.,Department of Neurology, RWTH Aachen University, Aachen, Germany
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9
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How to choose the right MR sequence for your research question at 7 T and above? Neuroimage 2018; 168:119-140. [DOI: 10.1016/j.neuroimage.2017.04.044] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 12/29/2022] Open
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Kabadi SJ, Fatterpekar GM, Anzai Y, Mogen J, Hagiwara M, Patel SH. Dynamic Contrast-Enhanced MR Imaging in Head and Neck Cancer. Magn Reson Imaging Clin N Am 2018; 26:135-149. [DOI: 10.1016/j.mric.2017.08.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Nezafat M, Ramos IT, Henningsson M, Protti A, Basha T, Botnar RM. Improved segmented modified Look-Locker inversion recovery T1 mapping sequence in mice. PLoS One 2017; 12:e0187621. [PMID: 29121086 PMCID: PMC5679534 DOI: 10.1371/journal.pone.0187621] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 10/04/2017] [Indexed: 12/02/2022] Open
Abstract
Object To develop and evaluate a 2D modified Look-Locker (MOLLI) for high-resolution T1 mapping in mice using a 3T MRI scanner. Materials and methods To allow high-resolution T1 mapping in mice at high heart rates a multi-shot ECG-triggered 2D MOLLI sequence was developed. In the proposed T1 mapping sequence the optimal number of sampling points and pause cardiac cycles following an initial adiabatic inversion pulse was investigated in a phantom. Seven native control and eight mice, 3 days post myocardial infarction (MI) after administration of gadolinium were scanned. Two experienced readers graded the visual T1 map quality. Results In T1 phantoms, there were no significant differences (<0.4% error) between 12, 15 and 20 pause cardiac cycles (p = 0.1, 0.2 and 0.6 respectively) for 8 acquisition cardiac cycles for 600bpm in comparison to the conventional inversion recovery spin echo T1 mapping sequence for short T1’s (<600 ms). Subsequently, all in-vivo scans were performed with 8 data acquisitions and 12 pause cardiac cycles to minimize scan time. The mean native T1 value of myocardium in control animal was 820.5±52 ms. The post-contrast T1 measured 3 days after MI in scar was 264±59 ms and in healthy myocardium was 512±62 ms. The Bland-Altman analysis revealed mean difference of only -1.06% of infarct size percentage between T1 maps and LGE. Conclusions A multi-shot 2D MOLLI sequence has been presented that allows reliable measurement of high spatial resolution T1 maps in mice for heart rates up to 600bpm.
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Affiliation(s)
- Maryam Nezafat
- Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| | - Isabel T. Ramos
- Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
| | - Markus Henningsson
- Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
| | - Andrea Protti
- Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
| | - Tamer Basha
- Cairo University, Biomedical Engineering Department, Giza, Egypt
| | - René M. Botnar
- Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
- Pontificia Universidad Católica de Chile, Escuela de Ingeniería, Santiago, Chile
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Battiston M, Schneider T, Prados F, Grussu F, Yiannakas MC, Ourselin S, Gandini Wheeler-Kingshott CAM, Samson RS. Fast and reproducible in vivo T 1 mapping of the human cervical spinal cord. Magn Reson Med 2017; 79:2142-2148. [PMID: 28736946 DOI: 10.1002/mrm.26852] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 12/16/2022]
Abstract
PURPOSE To develop a fast and robust method for measuring T1 in the whole cervical spinal cord in vivo, and to assess its reproducibility. METHODS A spatially nonselective adiabatic inversion pulse is combined with zonally oblique-magnified multislice echo-planar imaging to produce a reduced field-of-view inversion-recovery echo-planar imaging protocol. Multi- inversion time data are obtained by cycling slice order throughout sequence repetitions. Measurement of T1 is performed using 12 inversion times for a total protocol duration of 7 min. Reproducibility of regional T1 estimates is assessed in a scan-rescan experiment on five heathy subjects. RESULTS Regional mean (standard deviation) T1 was: 1108.5 (±77.2) ms for left lateral column, 1110.1 (±83.2) ms for right lateral column, 1150.4 (±102.6) ms for dorsal column, and 1136.4 (±90.8) ms for gray matter. Regional T1 estimates showed good correlation between sessions (Pearson correlation coefficient = 0.89 (P value < 0.01); mean difference = 2 ms, 95% confidence interval ± 20 ms); and high reproducibility (intersession coefficient of variation approximately 1% in all the regions considered, intraclass correlation coefficient = 0.88 (P value < 0.01, confidence interval 0.71-0.95)). CONCLUSIONS T1 estimates in the cervical spinal cord are reproducible using inversion-recovery zonally oblique-magnified multislice echo-planar imaging. The short acquisition time and large coverage of this method paves the way for accurate T1 mapping for various spinal cord pathologies. Magn Reson Med 79:2142-2148, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Marco Battiston
- NMR Research Unit, Queen Square MS Center, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, United Kingdom
| | | | - Ferran Prados
- NMR Research Unit, Queen Square MS Center, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, United Kingdom.,Translational Imaging Group, Center for Medical Image Computing, Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Francesco Grussu
- NMR Research Unit, Queen Square MS Center, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, United Kingdom
| | - Marios C Yiannakas
- NMR Research Unit, Queen Square MS Center, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, United Kingdom
| | - Sebastien Ourselin
- Translational Imaging Group, Center for Medical Image Computing, Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Claudia A M Gandini Wheeler-Kingshott
- NMR Research Unit, Queen Square MS Center, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, United Kingdom.,Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.,Brain MRI 3T Mondino Research Center, C. Mondino National Neurological Institute, Pavia, Italy
| | - Rebecca S Samson
- NMR Research Unit, Queen Square MS Center, Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, United Kingdom
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Hamilton-Craig CR, Strudwick MW, Galloway GJ. T1 Mapping for Myocardial Fibrosis by Cardiac Magnetic Resonance Relaxometry-A Comprehensive Technical Review. Front Cardiovasc Med 2017; 3:49. [PMID: 28361053 PMCID: PMC5352660 DOI: 10.3389/fcvm.2016.00049] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 11/24/2016] [Indexed: 11/13/2022] Open
Abstract
Cardiac magnetic resonance (CMR) imaging has been widely used to assess myocardial perfusion and scar and is the non-invasive gold standard for identification of focal myocardial fibrosis. However, the late gadolinium enhancement technique is limited in its accuracy for absolute quantification and assessment of diffuse myocardial fibrosis by technical and pathophysiological features. CMR relaxometry, incorporating T1 mapping, has emerged as an accurate, reproducible, highly sensitive, and quantitative technique for the assessment of diffuse myocardial fibrosis in a number of disease states. We comprehensively review the physics behind CMR relaxometry, the evidence base, and the clinical applications of this emerging technique.
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Affiliation(s)
- Christian R Hamilton-Craig
- Centre for Advanced Imaging, University of Queensland, Brisbane, QLD, Australia; The Prince Charles Hospital, Brisbane, QLD, Australia
| | - Mark W Strudwick
- Medical Imaging and Radiation Science, Monash University , Clayton, VIC , Australia
| | - Graham J Galloway
- Centre for Advanced Imaging, University of Queensland, Brisbane, QLD, Australia; Translational Research Institute, Brisbane, QLD, Australia
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14
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Hayashi N, Yarita K, Sakata K, Motegi S, Nagase H, Ujita K, Ogura A, Ogura T, Shimada T, Tsushima Y. Optimization method of MRI scan parameters of a double inversion recovery sequence using a T1 map and a developed analysis algorithm. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2017; 25:803-812. [PMID: 28506023 DOI: 10.3233/xst-16243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
BACKGROUND Optimizing scan parameters for double inversion recovery (DIR) sequences remains difficult. OBJECTIVE To evaluate a new method for optimizing DIR sequence scan parameters using T1 mapping and a newly developed analysis algorithm. METHODS Twelve healthy volunteers underwent T1 mapping and DIR magnetic resonance imaging. The following steps were used for image optimization including: 1) measurement of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) T1 values to create a T1 map; 2) calculation of optimized scan parameters by using a developed analysis algorithm; 3) performance assessment of DIR magnetic resonance imaging by using the calculated optimized imaging parameters. Additionally, we used scan parameters from previous studies to obtain DIR images in order to evaluate our new method. The contrast between GM and suppressed tissues was compared between these images and those obtained using the optimized parameters. RESULTS Using our optimization method, WM and CSF regions were suppressed uniformly for all scan conditions. The contrast was significantly higher in images obtained using this optimization method compared to those obtained using previously published parameters (p < 0.01). CONCLUSIONS It is possible to obtain superior DIR images by using an optimization method that involves T1 mapping and a newly developed analysis algorithm.
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Affiliation(s)
- Norio Hayashi
- Department of Radiological Technology, Gunma Prefectural College of Health Sciences, Maebashi, Japan
| | - Kazuma Yarita
- Department of Radiology, Gunma University Hospital, Maebashi, Japan
| | - Kozue Sakata
- Department of Radiology, IMS Ohta Chuo General Hospital, Ohta, Japan
| | | | - Hiroyuki Nagase
- Department of Radiology, Maebashi Red Cross Hospital, Maebashi, Japan
| | - Kouichi Ujita
- Department of Radiology, Gunma University Hospital, Maebashi, Japan
| | - Akio Ogura
- Department of Radiological Technology, Gunma Prefectural College of Health Sciences, Maebashi, Japan
| | - Toshihiro Ogura
- Department of Radiological Technology, Gunma Prefectural College of Health Sciences, Maebashi, Japan
| | - Takehiro Shimada
- Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yoshito Tsushima
- Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
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Lauzon ML, McCreary CR, Frayne R. Multislice T1 -prepared 2D single-shot EPI: analysis of a clinical T1 mapping method unbiased by B0 or B1 inhomogeneity. NMR IN BIOMEDICINE 2016; 29:1056-1069. [PMID: 27331861 DOI: 10.1002/nbm.3566] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 06/06/2023]
Abstract
Quantitative MR imaging is as sensitive in detecting lesions as qualitative imaging, but it is potentially more specific in differentiating disease. T1 mapping in particular might help to assess acute ischemic stroke, multiple sclerosis, epilepsy and Alzheimer's disease better. Thus, a rapid and robust clinical technique is vital. In 1990, Ordidge and colleagues developed the multislice T1 -prepared two-dimensional (2D) single-shot echo planar imaging technique. Subsequent studies demonstrated its clinical viability, but none performed an in-depth analysis of the strengths and advantages of this T1 mapping method. Herein, theoretical and experimental evidence shows that the technique accounts for 2D slice profile effects and is unbiased by B0 or B1 inhomogeneity. This is verified explicitly by varying the linear shims, the T1 preparation flip angle and the excitation flip angle. Furthermore, it is shown that the repetition time (and hence scan time) can be reduced without a loss of T1 accuracy. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- M Louis Lauzon
- Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada
- Depts of Radiology and Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Cheryl R McCreary
- Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada
- Depts of Radiology and Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Richard Frayne
- Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada
- Depts of Radiology and Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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16
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Guo Y, Zhou IY, Chan ST, Wang Y, Mandeville ET, Igarashi T, Lo EH, Ji X, Sun PZ. pH-sensitive MRI demarcates graded tissue acidification during acute stroke - pH specificity enhancement with magnetization transfer and relaxation-normalized amide proton transfer (APT) MRI. Neuroimage 2016; 141:242-249. [PMID: 27444569 DOI: 10.1016/j.neuroimage.2016.07.025] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 07/06/2016] [Accepted: 07/11/2016] [Indexed: 11/26/2022] Open
Abstract
pH-sensitive amide proton transfer (APT) MRI provides a surrogate metabolic biomarker that complements the widely-used perfusion and diffusion imaging. However, the endogenous APT MRI is often calculated using the asymmetry analysis (MTRasym), which is susceptible to an inhomogeneous shift due to concomitant semisolid magnetization transfer (MT) and nuclear overhauser (NOE) effects. Although the intact brain tissue has little pH variation, white and gray matter appears distinct in the MTRasym image. Herein we showed that the heterogeneous MTRasym shift not related to pH highly correlates with MT ratio (MTR) and longitudinal relaxation rate (R1w), which can be reasonably corrected using the multiple regression analysis. Because there are relatively small MT and R1w changes during acute stroke, we postulate that magnetization transfer and relaxation-normalized APT (MRAPT) analysis increases MRI specificity to acidosis over the routine MTRasym image, hence facilitates ischemic lesion segmentation. We found significant differences in perfusion, pH and diffusion lesion volumes (P<0.001, ANOVA). Furthermore, MRAPT MRI depicted graded ischemic acidosis, with the most severe acidosis in the diffusion lesion (-1.05±0.29%/s), moderate acidification within the pH/diffusion mismatch (i.e., metabolic penumbra, -0.67±0.27%/s) and little pH change in the perfusion/pH mismatch (i.e., benign oligemia, -0.04±0.14%/s), providing refined stratification of ischemic tissue injury.
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Affiliation(s)
- Yingkun Guo
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Iris Yuwen Zhou
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Suk-Tak Chan
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Yu Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA; China-America Joint Neuroscience Institute, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Emiri T Mandeville
- Neuroprotection Research Laboratory, Department of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Takahiro Igarashi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Eng H Lo
- Neuroprotection Research Laboratory, Department of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Xunming Ji
- China-America Joint Neuroscience Institute, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA; China-America Joint Neuroscience Institute, Xuanwu Hospital, Capital Medical University, Beijing, China; Neuroprotection Research Laboratory, Department of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
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17
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Automatic cortical surface reconstruction of high-resolution T1 echo planar imaging data. Neuroimage 2016; 134:338-354. [PMID: 27079529 DOI: 10.1016/j.neuroimage.2016.04.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 04/02/2016] [Indexed: 01/01/2023] Open
Abstract
Echo planar imaging (EPI) is the method of choice for the majority of functional magnetic resonance imaging (fMRI), yet EPI is prone to geometric distortions and thus misaligns with conventional anatomical reference data. The poor geometric correspondence between functional and anatomical data can lead to severe misplacements and corruption of detected activation patterns. However, recent advances in imaging technology have provided EPI data with increasing quality and resolution. Here we present a framework for deriving cortical surface reconstructions directly from high-resolution EPI-based reference images that provide anatomical models exactly geometric distortion-matched to the functional data. Anatomical EPI data with 1mm isotropic voxel size were acquired using a fast multiple inversion recovery time EPI sequence (MI-EPI) at 7T, from which quantitative T1 maps were calculated. Using these T1 maps, volumetric data mimicking the tissue contrast of standard anatomical data were synthesized using the Bloch equations, and these T1-weighted data were automatically processed using FreeSurfer. The spatial alignment between T2(⁎)-weighted EPI data and the synthetic T1-weighted anatomical MI-EPI-based images was improved compared to the conventional anatomical reference. In particular, the alignment near the regions vulnerable to distortion due to magnetic susceptibility differences was improved, and sampling of the adjacent tissue classes outside of the cortex was reduced when using cortical surface reconstructions derived directly from the MI-EPI reference. The MI-EPI method therefore produces high-quality anatomical data that can be automatically segmented with standard software, providing cortical surface reconstructions that are geometrically matched to the BOLD fMRI data.
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18
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Khalifa F, Soliman A, El-Baz A, Abou El-Ghar M, El-Diasty T, Gimel'farb G, Ouseph R, Dwyer AC. Models and methods for analyzing DCE-MRI: a review. Med Phys 2015; 41:124301. [PMID: 25471985 DOI: 10.1118/1.4898202] [Citation(s) in RCA: 199] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To present a review of most commonly used techniques to analyze dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), discusses their strengths and weaknesses, and outlines recent clinical applications of findings from these approaches. METHODS DCE-MRI allows for noninvasive quantitative analysis of contrast agent (CA) transient in soft tissues. Thus, it is an important and well-established tool to reveal microvasculature and perfusion in various clinical applications. In the last three decades, a host of nonparametric and parametric models and methods have been developed in order to quantify the CA's perfusion into tissue and estimate perfusion-related parameters (indexes) from signal- or concentration-time curves. These indexes are widely used in various clinical applications for the detection, characterization, and therapy monitoring of different diseases. RESULTS Promising theoretical findings and experimental results for the reviewed models and techniques in a variety of clinical applications suggest that DCE-MRI is a clinically relevant imaging modality, which can be used for early diagnosis of different diseases, such as breast and prostate cancer, renal rejection, and liver tumors. CONCLUSIONS Both nonparametric and parametric approaches for DCE-MRI analysis possess the ability to quantify tissue perfusion.
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Affiliation(s)
- Fahmi Khalifa
- BioImaging Laboratory, Department of Bioengineering, University of Louisville, Louisville, Kentucky 40292 and Electronics and Communication Engineering Department, Mansoura University, Mansoura 35516, Egypt
| | - Ahmed Soliman
- BioImaging Laboratory, Department of Bioengineering, University of Louisville, Louisville, Kentucky 40292
| | - Ayman El-Baz
- BioImaging Laboratory, Department of Bioengineering, University of Louisville, Louisville, Kentucky 40292
| | - Mohamed Abou El-Ghar
- Radiology Department, Urology and Nephrology Center, Mansoura University, Mansoura 35516, Egypt
| | - Tarek El-Diasty
- Radiology Department, Urology and Nephrology Center, Mansoura University, Mansoura 35516, Egypt
| | - Georgy Gimel'farb
- Department of Computer Science, University of Auckland, Auckland 1142, New Zealand
| | - Rosemary Ouseph
- Kidney Transplantation-Kidney Disease Center, University of Louisville, Louisville, Kentucky 40202
| | - Amy C Dwyer
- Kidney Transplantation-Kidney Disease Center, University of Louisville, Louisville, Kentucky 40202
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Gaddikeri S, Gaddikeri RS, Tailor T, Anzai Y. Dynamic Contrast-Enhanced MR Imaging in Head and Neck Cancer: Techniques and Clinical Applications. AJNR Am J Neuroradiol 2015; 37:588-95. [PMID: 26427839 DOI: 10.3174/ajnr.a4458] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In the past decade, dynamic contrast-enhanced MR imaging has had an increasing role in assessing the microvascular characteristics of various tumors, including head and neck cancer. Dynamic contrast-enhanced MR imaging allows noninvasive assessment of permeability and blood flow, both important features of tumor hypoxia, which is a marker for treatment resistance for head and neck cancer. Dynamic contrast-enhanced MR imaging has the potential to identify early locoregional recurrence, differentiate metastatic lymph nodes from normal nodes, and predict tumor response to treatment and treatment monitoring in patients with head and neck cancer. Quantitative analysis is in its early stage and standardization and refinement of technique are essential. In this article, we review the techniques of dynamic contrast-enhanced MR imaging data acquisition, analytic methods, current limitations, and clinical applications in head and neck cancer.
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Affiliation(s)
- S Gaddikeri
- From the Department of Radiology (S.G., T.T., Y.A.), University of Washington Medical Center, Seattle, Washington
| | - R S Gaddikeri
- Department of Neuroradiology (R.S.G.), Rush University, Chicago, Illinois
| | - T Tailor
- From the Department of Radiology (S.G., T.T., Y.A.), University of Washington Medical Center, Seattle, Washington
| | - Y Anzai
- From the Department of Radiology (S.G., T.T., Y.A.), University of Washington Medical Center, Seattle, Washington Department of Radiology (Y.A.), University of Utah Health Care, Salt Lake City, Utah.
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20
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Kontopodis E, Kanli G, Manikis GC, Van Cauter S, Marias K. Assessing Treatment Response Through Generalized Pharmacokinetic Modeling of DCE-MRI Data. Cancer Inform 2015; 14:41-51. [PMID: 26327778 PMCID: PMC4536783 DOI: 10.4137/cin.s19342] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 05/13/2015] [Accepted: 05/18/2015] [Indexed: 01/31/2023] Open
Abstract
Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) enables the quantification of contrast leakage from the vascular tissue by using pharmacokinetic (PK) models. Such quantitative analysis of DCE-MRI data provides physiological parameters that are able to provide information of tumor pathophysiology and therapeutic outcome. Several assumptive PK models have been proposed to characterize microcirculation in the tumoral tissue. In this paper, we present a comparative study between the well-known extended Tofts model (ETM) and the more recent gamma capillary transit time (GCTT) model, with the latter showing initial promising results in the literature. To enhance the GCTT imaging biomarkers, we introduce a novel method for segmenting the tumor area into subregions according to their vascular heterogeneity characteristics. A cohort of 11 patients diagnosed with glioblastoma multiforme with known therapeutic outcome was used to assess the predictive value of both models in terms of correctly classifying responders and nonresponders based on only one DCE-MRI examination. The results indicate that GCTT model's PK parameters perform better than those of ETM, while the segmentation of the tumor regions of interest based on vascular heterogeneity further enhances the discriminatory power of the GCTT model.
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Affiliation(s)
- Eleftherios Kontopodis
- Foundation for Research and Technology – Hellas (FORTH), Institute of Computer Science, Computational BioMedicine Lab, Heraklion, Greece
| | - Georgia Kanli
- Foundation for Research and Technology – Hellas (FORTH), Institute of Computer Science, Computational BioMedicine Lab, Heraklion, Greece
| | - Georgios C Manikis
- Foundation for Research and Technology – Hellas (FORTH), Institute of Computer Science, Computational BioMedicine Lab, Heraklion, Greece
| | - Sofie Van Cauter
- Department of Radiology, University Hospitals Leuven, Leuven, Belgium
| | - Kostas Marias
- Foundation for Research and Technology – Hellas (FORTH), Institute of Computer Science, Computational BioMedicine Lab, Heraklion, Greece
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Hattingen E, Jurcoane A, Nelles M, Müller A, Nöth U, Mädler B, Mürtz P, Deichmann R, Schild HH. Quantitative MR Imaging of Brain Tissue and Brain Pathologies. Clin Neuroradiol 2015. [PMID: 26223371 DOI: 10.1007/s00062-015-0433-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Measurement of basic quantitative magnetic resonance (MR) parameters (e.g., relaxation times T1, T2*, T2 or respective rates R (1/T)) corrected for radiofrequency (RF) coil bias yields different conventional and new tissue contrasts as well as volumes for tissue segmentation. This approach also provides quantitative measures of microstructural and functional tissue changes. We herein demonstrate some prospects of quantitative MR imaging in neurological diagnostics and science.
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Affiliation(s)
- E Hattingen
- Neuroradiologie, Radiologische Klinik des Universitätsklinikums Bonn, Sigmund Freud Strasse 25, 53127, Bonn, Germany.
| | - A Jurcoane
- Neuroradiologie, Radiologische Klinik des Universitätsklinikums Bonn, Sigmund Freud Strasse 25, 53127, Bonn, Germany
| | - M Nelles
- Neuroradiologie, Radiologische Klinik des Universitätsklinikums Bonn, Sigmund Freud Strasse 25, 53127, Bonn, Germany
| | - A Müller
- Neuroradiologie, Radiologische Klinik des Universitätsklinikums Bonn, Sigmund Freud Strasse 25, 53127, Bonn, Germany
| | - U Nöth
- Brain Imaging Center, Universitätsklinikum Frankfurt, Frankfurt/Main, Germany
| | - B Mädler
- Philips Medical Systems, Philips GmbH, Hamburg, Germany
| | - P Mürtz
- Neuroradiologie, Radiologische Klinik des Universitätsklinikums Bonn, Sigmund Freud Strasse 25, 53127, Bonn, Germany
| | - R Deichmann
- Brain Imaging Center, Universitätsklinikum Frankfurt, Frankfurt/Main, Germany
| | - H H Schild
- Radiologische Klinik des Universitätsklinikums Bonn, Sigmund Freud Strasse 25, 53127, Bonn, Germany
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22
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Castets CR, Ribot EJ, Lefrançois W, Trotier AJ, Thiaudière E, Franconi JM, Miraux S. Fast and robust 3D T1 mapping using spiral encoding and steady RF excitation at 7 T: application to cardiac manganese enhanced MRI (MEMRI) in mice. NMR IN BIOMEDICINE 2015; 28:881-889. [PMID: 25989986 DOI: 10.1002/nbm.3327] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/19/2015] [Accepted: 04/16/2015] [Indexed: 06/04/2023]
Abstract
Mapping longitudinal relaxation times in 3D is a promising quantitative and non-invasive imaging tool to assess cardiac remodeling. Few methods are proposed in the literature allowing us to perform 3D T1 mapping. These methods often require long scan times and use a low number of 3D images to calculate T1 . In this project, a fast 3D T1 mapping method using a stack-of-spirals sampling scheme and regular RF pulse excitation at 7 T is presented. This sequence, combined with a newly developed fitting procedure, allowed us to quantify T1 of the whole mouse heart with a high spatial resolution of 208 × 208 × 315 µm(3) in 10-12 min acquisition time. The sensitivity of this method for measuring T1 variations was demonstrated on mouse hearts after several injections of manganese chloride (doses from 25 to 150 µmol kg(-1) ). T1 values were measured in vivo in both pre- and post-contrast experiments. This protocol was also validated on ischemic mice to demonstrate its efficiency to visualize tissue damage induced by a myocardial infarction. This study showed that combining spiral gradient shape and steady RF excitation enabled fast and robust 3D T1 mapping of the entire heart with a high spatial resolution.
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Affiliation(s)
- Charles R Castets
- Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France
| | - Emeline J Ribot
- Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France
| | - William Lefrançois
- Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France
| | - Aurélien J Trotier
- Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France
| | - Eric Thiaudière
- Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France
| | - Jean-Michel Franconi
- Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France
| | - Sylvain Miraux
- Centre de Resonance Magnetique des Systemes Biologiques, UMR 5536 CNRS/Universite de Bordeaux, Bordeaux Cedex, France
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Hagberg GE, Mamedov I, Power A, Beyerlein M, Merkle H, Kiselev VG, Dhingra K, Kubìček V, Angelovski G, Logothetis NK. Diffusion properties of conventional and calcium-sensitive MRI contrast agents in the rat cerebral cortex. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 9:71-82. [PMID: 24470296 DOI: 10.1002/cmmi.1535] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 11/22/2012] [Accepted: 01/15/2013] [Indexed: 01/01/2023]
Abstract
Calcium-sensitive MRI contrast agents can only yield quantitative results if the agent concentration in the tissue is known. The agent concentration could be determined by diffusion modeling, if relevant parameters were available. We have established an MRI-based method capable of determining diffusion properties of conventional and calcium-sensitive agents. Simulations and experiments demonstrate that the method is applicable both for conventional contrast agents with a fixed relaxivity value and for calcium-sensitive contrast agents. The full pharmacokinetic time-course of gadolinium concentration estimates was observed by MRI before, during and after intracerebral administration of the agent, and the effective diffusion coefficient D* was determined by voxel-wise fitting of the solution to the diffusion equation. The method yielded whole brain coverage with a high spatial and temporal sampling. The use of two types of MRI sequences for sampling of the diffusion time courses was investigated: Look-Locker-based quantitative T(1) mapping, and T(1) -weighted MRI. The observation times of the proposed MRI method is long (up to 20 h) and consequently the diffusion distances covered are also long (2-4 mm). Despite this difference, the D* values in vivo were in agreement with previous findings using optical measurement techniques, based on observation times of a few minutes. The effective diffusion coefficient determined for the calcium-sensitive contrast agents may be used to determine local tissue concentrations and to design infusion protocols that maintain the agent concentration at a steady state, thereby enabling quantitative sensing of the local calcium concentration.
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Affiliation(s)
- Gisela E Hagberg
- Department for Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
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24
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Zou X, Brown TR. Relaxation by amplitude modulation: A rapid T
1
measurement method. Magn Reson Med 2014; 71:2155-65. [DOI: 10.1002/mrm.24884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 05/27/2013] [Accepted: 06/21/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Xiaowei Zou
- Department of Biomedical Engineering; Columbia University; New York New York USA
- Medical University of South Carolina; Charleston South Carolina USA
| | - Truman R. Brown
- Medical University of South Carolina; Charleston South Carolina USA
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25
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Yuan J, Chow SKK, Yeung DKW, Ahuja AT, King AD. Quantitative evaluation of dual-flip-angle T1 mapping on DCE-MRI kinetic parameter estimation in head and neck. Quant Imaging Med Surg 2013; 2:245-53. [PMID: 23289084 DOI: 10.3978/j.issn.2223-4292.2012.11.04] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 11/29/2012] [Indexed: 01/17/2023]
Abstract
PURPOSE To quantitatively evaluate the kinetic parameter estimation for head and neck (HN) dynamic contrast-enhanced (DCE) MRI with dual-flip-angle (DFA) T1 mapping. MATERIALS AND METHODS Clinical DCE-MRI datasets of 23 patients with HN tumors were included in this study. T1 maps were generated based on multiple-flip-angle (MFA) method and different DFA combinations. Tofts model parameter maps of k(ep), K(trans) and v(p) based on MFA and DFAs were calculated and compared. Fitted parameter by MFA and DFAs were quantitatively evaluated in primary tumor, salivary gland and muscle. RESULTS T1 mapping deviations by DFAs produced remarkable kinetic parameter estimation deviations in head and neck tissues. In particular, the DFA of [2º, 7º] overestimated, while [7º, 12º] and [7º, 15º] underestimated K(trans) and v(p), significantly (P<0.01). [2º, 15º] achieved the smallest but still statistically significant overestimation for K(trans) and v(p) in primary tumors, 32.1% and 16.2% respectively. k(ep) fitting results by DFAs were relatively close to the MFA reference compared to K(trans) and v(p). CONCLUSIONS T1 deviations induced by DFA could result in significant errors in kinetic parameter estimation, particularly K(trans) and v(p), through Tofts model fitting. MFA method should be more reliable and robust for accurate quantitative pharmacokinetic analysis in head and neck.
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Affiliation(s)
- Jing Yuan
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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26
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Protti A, Sirker A, Shah AM, Botnar R. Late gadolinium enhancement of acute myocardial infarction in mice at 7T: Cine-FLASH versus inversion recovery. J Magn Reson Imaging 2010; 32:878-86. [DOI: 10.1002/jmri.22325] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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27
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The flipped longitudinal polarization sequence. Magn Reson Imaging 2010; 28:957-63. [DOI: 10.1016/j.mri.2010.03.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 03/25/2010] [Accepted: 03/26/2010] [Indexed: 11/23/2022]
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28
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Warntjes MJB, Kihlberg J, Engvall J. Rapid T1 quantification based on 3D phase sensitive inversion recovery. BMC Med Imaging 2010; 10:19. [PMID: 20716333 PMCID: PMC2931447 DOI: 10.1186/1471-2342-10-19] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Accepted: 08/17/2010] [Indexed: 11/10/2022] Open
Abstract
Background In Contrast Enhanced Magnetic Resonance Imaging fibrotic myocardium can be distinguished from healthy tissue using the difference in the longitudinal T1 relaxation after administration of Gadolinium, the so-called Late Gd Enhancement. The purpose of this work was to measure the myocardial absolute T1 post-Gd from a single breath-hold 3D Phase Sensitivity Inversion Recovery sequence (PSIR). Equations were derived to take the acquisition and saturation effects on the magnetization into account. Methods The accuracy of the method was investigated on phantoms and using simulations. The method was applied to a group of patients with suspected myocardial infarction where the absolute difference in relaxation of healthy and fibrotic myocardium was measured at about 15 minutes post-contrast. The evolution of the absolute R1 relaxation rate (1/T1) over time after contrast injection was followed for one patient and compared to T1 mapping using Look-Locker. Based on the T1 maps synthetic LGE images were reconstructed and compared to the conventional LGE images. Results The fitting algorithm is robust against variation in acquisition flip angle, the inversion delay time and cardiac arrhythmia. The observed relaxation rate of the myocardium is 1.2 s-1, increasing to 6 - 7 s-1 after contrast injection and decreasing to 2 - 2.5 s-1 for healthy myocardium and to 3.5 - 4 s-1 for fibrotic myocardium. Synthesized images based on the T1 maps correspond very well to actual LGE images. Conclusions The method provides a robust quantification of post-Gd T1 relaxation for a complete cardiac volume within a single breath-hold.
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Affiliation(s)
- Marcel J B Warntjes
- Center for Medical Imaging Science and Visualization (CMIV), Linköping University, SE58185 Linköping, Sweden.
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29
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Hayashi N, Miyati T, Koda W, Suzuki M, Sanada S, Ohno N, Hamaguchi T, Matsuura Y, Kawahara K, Yamamoto T, Matsui O. [Quantitative evaluation of Gd-EOB-DTPA uptake in phantom study for liver MRI]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2010; 66:502-508. [PMID: 20628218 DOI: 10.6009/jjrt.66.502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Gd-EOB-DTPA is a new liver specific MRI contrast media. In the hepatobiliary phase, contrast media is trapped in normal liver tissue, a normal liver shows high intensity, tumor/liver contrast becomes high, and diagnostic ability improves. In order to indicate the degree of uptake of the contrast media, the enhancement ratio (ER) is calculated. The ER is obtained by calculating (signal intensity (SI) after injection-SI before injection) / SI before injection. However, because there is no linearity between contrast media concentration and SI, ER is not correctly estimated by this method. We discuss a method of measuring ER based on SI and T(1) values using the phantom. We used a column phantom, with an internal diameter of 3 cm, that was filled with Gd-EOB-DTPA diluted solution. Moreover, measurement of the T(1) value by the IR method was also performed. The ER measuring method of this technique consists of the following three components: 1) Measurement of ER based on differences in 1/T(1) values using the variable flip angle (FA) method, 2) Measurement of differences in SI, and 3) Measurement of differences in 1/T(1) values using the IR method. ER values calculated by these three methods were compared. In measurement made using the variable FA method and the IR method, linearity was found between contrast media concentration and ER. On the other hand, linearity was not found between contrast media concentration and SI. For calculation of ER using Gd-EOB-DTPA, a more correct ER is obtained by measuring the T(1) value using the variable FA method.
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Affiliation(s)
- Norio Hayashi
- Department of Radiological Technology, Kanazawa University Hospital
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30
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Qiu M, Paul Maguire R, Arora J, Planeta-Wilson B, Weinzimmer D, Wang J, Wang Y, Kim H, Rajeevan N, Huang Y, Carson RE, Constable RT. Arterial transit time effects in pulsed arterial spin labeling CBF mapping: insight from a PET and MR study in normal human subjects. Magn Reson Med 2010; 63:374-84. [PMID: 19953506 DOI: 10.1002/mrm.22218] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Arterial transit time (ATT), a key parameter required to calculate absolute cerebral blood flow in arterial spin labeling (ASL), is subject to much uncertainty. In this study, ASL ATTs were estimated on a per-voxel basis using data measured by both ASL and positron emission tomography in the same subjects. The mean ATT increased by 260 +/- 20 (standard error of the mean) ms when the imaging slab shifted downwards by 54 mm, and increased from 630 +/- 30 to 1220 +/- 30 ms for the first slice, with an increase of 610 +/- 20 ms over a four-slice slab when the gap between the imaging and labeling slab increased from 20 to 74 mm. When the per-slice ATTs were employed in ASL cerebral blood flow quantification and the in-slice ATT variations ignored, regional cerebral blood flow could be significantly different from the positron emission tomography measures. ATT also decreased with focal activation by the same amount for both visual and motor tasks (approximately 80 ms). These results provide a quantitative relationship between ATT and the ASL imaging geometry and yield an assessment of the assumptions commonly used in ASL imaging. These findings should be considered in the interpretation of, and comparisons between, different ASL-based cerebral blood flow studies. The results also provide spatially specific ATT data that may aid in optimizing the ASL imaging parameters.
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Affiliation(s)
- Maolin Qiu
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520-2048, USA.
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31
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Paldino MJ, Barboriak DP. Fundamentals of quantitative dynamic contrast-enhanced MR imaging. Magn Reson Imaging Clin N Am 2009; 17:277-89. [PMID: 19406359 DOI: 10.1016/j.mric.2009.01.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Quantitative analysis of dynamic contrast-enhanced MR imaging (DCE-MR imaging) has the power to provide information regarding physiologic characteristics of the microvasculature and is, therefore, of great potential value to the practice of oncology. In particular, these techniques could have a significant impact on the development of novel anticancer therapies as a promising biomarker of drug activity. Standardization of DCE-MR imaging acquisition and analysis to provide more reproducible measures of tumor vessel physiology is of crucial importance to realize this potential. The purpose of this article is to review the pathophysiologic basis and technical aspects of DCE-MR imaging techniques.
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Affiliation(s)
- Michael J Paldino
- Division of Neuroradiology, Department of Radiology, Duke University Medical Center, Box 3808, Erwin Road, Durham, NC 27710, USA.
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32
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A fast Look–Locker method for T 1 mapping of the head and neck region. Oral Radiol 2009. [DOI: 10.1007/s11282-009-0005-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Qiu M, Ramani R, Swetye M, Constable RT. Spatial nonuniformity of the resting CBF and BOLD responses to sevoflurane: in vivo study of normal human subjects with magnetic resonance imaging. Hum Brain Mapp 2009; 29:1390-9. [PMID: 17948882 DOI: 10.1002/hbm.20472] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pulsed arterial spin labeling magnetic resonance imaging (MRI) was performed to investigate the local coupling between resting regional cerebral blood flow (rCBF) and BOLD (blood oxygen level dependent) signal changes in 22 normal human subjects during the administration of 0.25 MAC (minimum alveolar concentration) sevoflurane. Two states were compared with subjects at rest: anesthesia and no-anesthesia. Regions of both significantly increased and decreased resting-state rCBF were observed. Increases were limited primarily to subcortical structures and insula, whereas, decreases were observed primarily in neocortical regions. No significant change was found in global CBF (gCBF). By simultaneously measuring rCBF and BOLD, region-specific anesthetic effects on the coupling between rCBF and BOLD were identified. Multiple comparisons of the agent-induced rCBF and BOLD changes demonstrated significant (P < 0.05) spatial variability in rCBF-BOLD coupling. The slope of the linear regression line for AC, where rCBF was increased by sevoflurane, was markedly smaller than the slope for those ROIs where rCBF was decreased by sevoflurane, indicating a bigger change in BOLD per unit change in rCBF in regions where rCBF was increased by sevoflurane. These results suggest that it would be inaccurate to use a global quantitative model to describe coupling across all brain regions and in all anesthesia conditions. The observed spatial nonuniformity of rCBF and BOLD signal changes suggests that any interpretation of BOLD fMRI data in the presence of an anesthetic requires consideration of these insights.
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Affiliation(s)
- Maolin Qiu
- Department of Diagnostic Radiology, Yale University School of Medicine, The Anlyan Center N128, New Haven, Connecticut 06520-8042, USA.
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Page KA, Arora J, Qiu M, Relwani R, Constable RT, Sherwin RS. Small decrements in systemic glucose provoke increases in hypothalamic blood flow prior to the release of counterregulatory hormones. Diabetes 2009; 58:448-52. [PMID: 19017765 PMCID: PMC2628619 DOI: 10.2337/db08-1224] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The hypothalamus is the central brain region responsible for sensing and integrating responses to changes in circulating glucose. The aim of this study was to determine the time sequence relationship between hypothalamic activation and the initiation of the counterregulatory hormonal response to small decrements in systemic glucose. RESEARCH DESIGN AND METHODS Nine nondiabetic volunteers underwent two hyperinsulinemic clamp sessions in which pulsed arterial spin labeling was used to measure regional cerebral blood flow (CBF) at euglycemia ( approximately 95 mg/dl) on one occasion and as glucose levels were declining to a nadir of approximately 50 mg/dl on another occasion. Plasma glucose and counterregulatory hormones were measured during both study sessions. RESULTS CBF to the hypothalamus significantly increased when glucose levels decreased to 77.2 +/- 2 mg/dl compared with the euglycemic control session when glucose levels were 95.7 +/- 3 mg/dl (P = 0.0009). Hypothalamic perfusion was significantly increased before there was a significant elevation in counterregulatory hormones. CONCLUSIONS Our data suggest that the hypothalamus is exquisitely sensitive to small decrements in systemic glucose levels in healthy, nondiabetic subjects and that hypothalamic blood flow, and presumably neuronal activity, precedes the rise in counterregulatory hormones seen during hypoglycemia.
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Affiliation(s)
- Kathleen A Page
- Department of Internal Medicine, Division of Endocrinology, Yale University School of Medicine, New Haven, Connecticut, USA.
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35
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Qiu M, Ramani R, Swetye M, Rajeevan N, Constable RT. Anesthetic effects on regional CBF, BOLD, and the coupling between task-induced changes in CBF and BOLD: an fMRI study in normal human subjects. Magn Reson Med 2009; 60:987-96. [PMID: 18816821 DOI: 10.1002/mrm.21759] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Functional MR imaging was performed in sixteen healthy human subjects measuring both regional cerebral blood flow (CBF) and blood oxygen level dependent (BOLD) signal when visual and auditory stimuli were presented to subjects in the presence or absence of anesthesia. During anesthesia, 0.25 mean alveolar concentration (MAC) sevoflurane was administrated. We found that low-dose sevoflurane decreased the task-induced changes in both BOLD and CBF. Within the visual and auditory regions of interest inspected, both baseline CBF and the task-induced changes in CBF decreased significantly during anesthesia. Low-dose sevoflurane significantly altered the task-induced CBF-BOLD coupling; for a unit change of CBF, a larger change in BOLD was observed in the anesthesia condition than in the anesthesia-free condition. Low-dose sevoflurane was also found to have significant impact on the spatial nonuniformity of the task-induced coupling. The alteration of task-induced CBF-BOLD coupling by low-dose sevoflurane introduces ambiguity to the direct interpretation of functional MRI (fMRI) data based on only one of the indirect measures-CBF or BOLD. Our observations also indicate that the manipulation of the brain with an anesthetic agent complicates the model-based quantitative interpretation of fMRI data, in which the relative task-induced changes in oxidative metabolism are calculated by means of a calibrated model given the relative changes in the indirect vascular measures, usually CBF and BOLD.
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Affiliation(s)
- Maolin Qiu
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520-2048, USA.
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36
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Water proton T 1 measurements in brain tissue at 7, 3, and 1.5T using IR-EPI, IR-TSE, and MPRAGE: results and optimization. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2008; 21:121-30. [PMID: 18259791 DOI: 10.1007/s10334-008-0104-8] [Citation(s) in RCA: 184] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Revised: 12/17/2007] [Accepted: 01/07/2008] [Indexed: 10/22/2022]
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Abstract
Tumor angiogenesis induces the proliferation of immature blood vessels that are both heterogeneous and leaky. These characteristics can be demonstrated by measuring the perfusion parameters with MRI. Perfusion MRI is usually performed with in T1-weighted dynamic imaging after bolus injection of an exogenous contrast agent such as gadolinium chelate. The perfusion parameters are obtained by semi-quantitative or quantitative analysis of the enhancement curves in the tumor and the arterial input. Perfusion can also be assessed without injecting a contrast agent using arterial spin labeling techniques, diffusion MRI, or BOLD (blood oxygen level dependent) MRI. However, these latter methods are limited by a low signal-to-noise ratio and problems with quantification. The main indication for perfusion MRI is the assessment of antiangiogenic and antivascular treatments. New possibilities for demonstrating angiogenic blood vessels are being opened by molecular imaging.
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Affiliation(s)
- L Huwart
- Unité de Radiodiagnostic, Université Catholique de Louvain, Cliniques Universitaires St-Luc, Bruxelles, Belgique
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Nkongchu K, Santyr G. Phase-encoding strategies for optimal spatial resolution and T1 accuracy in 3D Look-Locker imaging. Magn Reson Imaging 2007; 25:1203-14. [PMID: 17524588 DOI: 10.1016/j.mri.2007.02.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Revised: 02/19/2007] [Accepted: 02/20/2007] [Indexed: 11/22/2022]
Abstract
The Look-Locker (LL) imaging method provides an accurate and efficient approach for mapping the spin-lattice relaxation time, T(1). However, the same recovery of signal during LL image acquisition required to estimate T(1) also results in unwanted modulation of k-space. This is particularly problematic with 3D LL imaging as the number of phase-encoding steps during the recovery interval (e.g., 16) increases in an effort to reduce imaging times. This modulation of k-space has the effect of introducing a point spread function (PSF), which can lead to either image blurring (if the earlier tip angles are assigned to the centre of k-space) or edge enhancement (if the earlier tip angles are assigned to the edges of k-space), thus corrupting T(1) estimation, particularly for small objects. In this study, the PSF and its effect on the acquired images for four different interleaved phase-encode schemes (centric-in, centric-out, sequential and hybrid-sequential) are simulated for a range of T(1), tip angle and 3D LL acquisition parameters expected in practice. It is shown by simulation and confirmed experimentally in phantoms that a hybrid sequential phase-encoding scheme reduces image blurring while maintaining T(1) accuracy ( approximately 2%) and precision (2%) over a range of object sizes down to 2 pixels (2 mm).
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Affiliation(s)
- Ken Nkongchu
- Department of Physics, Carleton University, Ottawa, ON, Canada K1S 5B6.
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Marciani L, Wickham MSJ, Bush D, Faulks R, Wright J, Fillery-Travis AJ, Spiller RC, Gowland PA. Magnetic resonance imaging of the behaviour of oil-in-water emulsions in the gastric lumen of man. Br J Nutr 2007; 95:331-9. [PMID: 16469150 DOI: 10.1079/bjn20051628] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Pre-processed foods often contain a high percentage of lipid, present as emulsions stabilised with various surface-active agents. The acidic gastric environment can affect the behaviour of such emulsions, modifying the lipid spatial distribution and, in turn, the rate of gastric emptying and nutrient delivery to the gut. The aim of the present study was to use echo-planar magnetic resonance imaging (EPI) to determine the behaviour of model olive oil emulsions during gastric processing. Six healthy male volunteers were intubated nasogastrically on two separate occasions and fed 500ml 15% (w/w) olive oil-in-water, surfactant-stabilised emulsions designed to have identical droplet size distribution and which were either stable or unstable under gastric acid conditions. EPI was used to assess the oil fraction of the intragastric emulsions, gastric emptying and to visualise the spatial distribution of the oil at 10, 30 and 50min postprandially. The in vivo imaging measurements of the oil volume fraction of the emulsions correlated well (r 0·66, acid-stable; r 0·52, acid-unstable) with that assayed in the gastric aspirates. Compared with the acid-stable emulsion, the acid-unstable emulsion in the gastric lumen rapidly separated into lipid-depleted ‘aqueous’ and lipid layers. Phase separation in the acid-unstable meal allowed the oil-depleted component to empty first and more rapidly than the stable emulsion as determined by the gastric emptying curves. These pilot data suggest that gastric processing and emptying of high-fat foods could be manipulated by careful choice of emulsifier.
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Affiliation(s)
- Luca Marciani
- Wolfson Digestive Diseases Centre, Queen's Medical Centre, University Hospital, Nottingham NG7 2RD, UK
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Canli T, Qiu M, Omura K, Congdon E, Haas BW, Amin Z, Herrmann MJ, Constable RT, Lesch KP. Neural correlates of epigenesis. Proc Natl Acad Sci U S A 2006; 103:16033-8. [PMID: 17032778 PMCID: PMC1592642 DOI: 10.1073/pnas.0601674103] [Citation(s) in RCA: 251] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Indexed: 11/18/2022] Open
Abstract
The effect of life stress on depression is moderated by a repeat length variation in the transcriptional control region of the serotonin transporter gene, which renders carriers of the short variant vulnerable for depression. We investigated the underlying neural mechanisms of these epigenetic processes in individuals with no history of psychopathology by using multimodal magnetic resonance-based imaging (functional, perfusion, and structural), genotyping, and self-reported life stress and rumination. Based on functional MRI and perfusion data, we found support for a model by which life stress interacts with the effect of serotonin transporter genotype on amygdala and hippocampal resting activation, two regions involved in depression and stress. Life stress also differentially affected, as a function of serotonin transporter genotype, functional connectivity of the amygdala and hippocampus with a wide network of other regions, as well as gray matter structural features, and affected individuals' level of rumination. These interactions may constitute a neural mechanism for epigenetic vulnerability toward, or protection against, depression.
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Affiliation(s)
- Turhan Canli
- Department of Psychology Stony Brook University, Stony Brook, NY 11794-2500, USA.
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Wang J, Qiu M, Kim H, Constable RT. T1 measurements incorporating flip angle calibration and correction in vivo. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 182:283-92. [PMID: 16875852 DOI: 10.1016/j.jmr.2006.07.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 06/27/2006] [Accepted: 07/02/2006] [Indexed: 05/11/2023]
Abstract
In this work, we propose a variable FA method that combines in vivo flip angle (FA) calibration and correction with a short TR variable FA approach for a fast and accurate T(1) mapping. The precision T(1)s measured across a uniform milk phantom is estimated to be 2.65% using the conventional (slow) inversion recovery (IR) method and 28.5% for the variable FA method without FA correction, and 2.2% when FA correction is included. These results demonstrate that the sensitivity of the variable FA method to RF nonuniformities can be dramatically reduced when these nonuniformities are directly measured and corrected. The acquisition time for this approach decreases to 10 min from 85 min for the conventional IR method. In addition, we report that the averaged T(1)s measured from five normal subjects are 900 +/- 3 ms, 1337 +/- 8 ms and 2180 +/- 25 ms in white matter (WM), gray matter (GM) and cerebral spinal fluid (CSF) using the variable flip angle method with FA correction at 3 T, respectively. These results are consistent with previously reported values obtained with much longer acquisition times. The method reduces the total scan time for whole brain T(1) mapping, including FA measurement and calibration, to approximately 6 min. The novelty of this method lies in the in vivo calibration and the correction of the FAs, thereby allowing a rapid and accurate T(1) mapping at high field for many applications.
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Affiliation(s)
- Jinghua Wang
- Department of Diagnostic Radiology, Yale University School Medical Center, The Anlyan Center, 330 Cedar Street, P.O. Box 208042, New Haven, CT 06520-8042, USA.
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Hsu JJ, Glover GH. Rapid MRI method for mapping the longitudinal relaxation time. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 181:98-106. [PMID: 16621631 DOI: 10.1016/j.jmr.2006.03.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2005] [Revised: 03/19/2006] [Accepted: 03/21/2006] [Indexed: 05/08/2023]
Abstract
A novel method for mapping the longitudinal relaxation time in a clinically acceptable time is developed based on a recent proposal [J.-J. Hsu, I.J. Lowe, Spin-lattice relaxation and a fast T1-map acquisition method in MRI with transient-state magnetization, J. Magn. Reson. 169 (2004) 270-278] and the speed of the spiral pulse sequence. The method acquires multiple curve-fitting samples with one RF pulse train. It does not require RF pulses of specific flip angles (e.g., 90 degrees or 180 degrees ), nor are the long recovery waiting time and the measurement of the magnetization at thermal equilibrium needed. Given the value of the flip angle, the curve fitting is semi-logarithmic and not computationally intensive. On a heterogeneous phantom, the average percentage difference between measurements of the present method and those of an inversion-recovery method is below 2.7%. In mapping the human brain, the present method, for example, can obtain four curve-fitting samples for five 128 x 128 slices in less than 3.2s and the results are in agreement with other studies in the literature.
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Affiliation(s)
- Jung-Jiin Hsu
- Richard M. Lucas Center for Imaging, Stanford University, 1201 Welch Road MC 5488, Stanford, CA 94305-5488, USA.
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Nkongchu K, Santyr G. An improved 3-D Look--Locker imaging method for T(1) parameter estimation. Magn Reson Imaging 2005; 23:801-7. [PMID: 16214611 DOI: 10.1016/j.mri.2005.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Accepted: 06/16/2005] [Indexed: 10/25/2022]
Abstract
The 3-D Look-Locker (LL) imaging method has been shown to be a highly efficient and accurate method for the volumetric mapping of the spin lattice relaxation time T(1). However, conventional 3-D LL imaging schemes are typically limited to small tip angle RF pulses (<or=5 degrees ) due to the large number of pulses required for adequate phase encoding and sampling of the recovery curve, which would otherwise drive the magnetization to steady state too rapidly, hence, diminishing the signal-to-noise ratio (SNR) available for accurate T(1) estimation. In this work, a more generalized form of the 3-D LL imaging method that incorporates an additional and variable delay time between recovery samples is described, which permits the use of larger tip angles (>5 degrees ), thereby improving the SNR and the accuracy of the method. In phantom studies, a mean T(1) measurement accuracy of less than 2% (0.2-3.1%) using a tip angle of 10 degrees was obtained for a range of T(1) from approximately 300 to 1,700 ms with a measurement time increase of only 15%. This accuracy compares favorably with the conventional 3-D LL method that provided an accuracy between 2.2% and 7.3% using a 5 degrees flip angle.
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Affiliation(s)
- Ken Nkongchu
- Department of Physics, Herzberg Laboratories, Carleton University, Ottawa ON, Canada K1S 5B6.
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Higgins DM, Ridgway JP, Radjenovic A, Sivananthan UM, Smith MA. T1 measurement using a short acquisition period for quantitative cardiac applications. Med Phys 2005; 32:1738-46. [PMID: 16013731 DOI: 10.1118/1.1921668] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Myocardial signal intensity curves for myocardial perfusion studies may be made quantitative by the use of T1 measurements made after the first-pass of contrast agent. A short data acquisition method for T1 mapping is presented in which all data for each T1 map are acquired in a short breath hold, and the slice geometry and timing in the cardiac cycle exactly match that of the dynamic first-pass perfusion sequence. This allows accurate image registration of the T1 map with the first-pass series of images. The T1 method is based on varying the preparation-pulse delay time of a saturation recovery sequence, and in this implementation employs an ECG-triggered, single-shot, spoiled gradient echo technique with SENSE reconstruction. The method allows T1 estimates of three slices to be made in fifteen heartbeats. For a range of samples with T1 values equivalent to those found in the myocardium during the first-pass of contrast agent, T1 estimates were accurate to within 6%, and the variation between slices was 2% or less.
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Affiliation(s)
- David M Higgins
- Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom.
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Klein C, Nekolla SG, Balbach T, Schnackenburg B, Nagel E, Fleck E, Schwaiger M. The influence of myocardial blood flow and volume of distribution on late Gd-DTPA kinetics in ischemic heart failure. J Magn Reson Imaging 2005; 20:588-93. [PMID: 15390232 DOI: 10.1002/jmri.20164] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
PURPOSE To determine the mechanism of enhancement of contrast-enhanced MRI (ceMRI) in chronic ischemic myocardium. While ceMRI can identify scar tissue in chronic ischemic myocardium, the mechanism of enhancement is not completely understood. MATERIALS AND METHODS A total of 11 patients with ischemic heart failure (ejection fraction [EF] 28 +/- 9%) were imaged with ceMRI and positron emission tomography (PET) to measure myocardial blood flow (MBF). Longitudinal relaxation rate (T1) of blood, normal tissue, and scar tissue defined by ceMRI was determined before and two to 50 minutes after contrast (Look Locker technique), and the partition coefficient (lambda) and volume of distribution (VD) were calculated. RESULTS In scar and viable tissue, T1 was significantly different over the whole period after contrast, but not before contrast. However, T1 of scar and blood were similar five to 15 minutes post contrast, making the detection of subendocardial defects difficult. lambda reached an initial steady state in viable tissue, but was delayed (20 minutes) in scar tissue. VD in scar was double that of viable tissue (0.54 +/- 0.01 vs. 0.29 +/- 0.02, respectively) indicating an increased interstitial space. Contrast wash-in kinetics correlated moderately with MBF (r = -0.36), but well with the combination of MBF and VD (r = 0.59). CONCLUSION Late myocardial contrast kinetics depend on both MBF and VD; however the increased VD seems to be the main mechanism for the late enhancement effect.
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Affiliation(s)
- Christoph Klein
- Nuklearmedizinische Klinik und Poliklinik der Technischen Universität München, München, Germany.
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Messroghli DR, Radjenovic A, Kozerke S, Higgins DM, Sivananthan MU, Ridgway JP. Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart. Magn Reson Med 2004; 52:141-6. [PMID: 15236377 DOI: 10.1002/mrm.20110] [Citation(s) in RCA: 980] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A novel pulse sequence scheme is presented that allows the measurement and mapping of myocardial T1 in vivo on a 1.5 Tesla MR system within a single breath-hold. Two major modifications of conventional Look-Locker (LL) imaging are introduced: 1) selective data acquisition, and 2) merging of data from multiple LL experiments into one data set. Each modified LL inversion recovery (MOLLI) study consisted of three successive LL inversion recovery (IR) experiments with different inversion times. We acquired images in late diastole using a single-shot steady-state free-precession (SSFP) technique, combined with sensitivity encoding to achieve a data acquisition window of < 200 ms duration. We calculated T1 using signal intensities from regions of interest and pixel by pixel. T1 accuracy at different heart rates derived from simulated ECG signals was tested in phantoms. T1 estimates showed small systematic error for T1 values from 191 to 1196 ms. In vivo T1 mapping was performed in two healthy volunteers and in one patient with acute myocardial infarction before and after administration of Gd-DTPA. T1 values for myocardium and noncardiac structures were in good agreement with values available from the literature. The region of infarction was clearly visualized. MOLLI provides high-resolution T1 maps of human myocardium in native and post-contrast situations within a single breath-hold.
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Ishimori Y, Kimura H, Matsuda T, Uematsu H, Ishida T, Fukuya Y, Kita A. [Dynamic contrast-enhanced T(1) measuring MRI using variable flip angle SPGR]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2003; 59:1535-41. [PMID: 15001868 DOI: 10.6009/jjrt.kj00000921684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
We modified the multi-phase spoiled gradient recalled echo (SPGR) pulse sequence using the double-echo MR technique for estimation of T(1) during the first pass of contrast agent, and examined its precision. In the first half of the pulse sequence, the flip angle was varied systematically to calculate static T(1) values. It was necessary to choose optimal flip angles to minimize the calculation error of static T(1) values. In the latter half of this sequence, changes in absolute T(1) were calculated using differences in signal intensities before and after the injection of contrast agent. The optimal flip angle was 20 degrees for precise conversion to T(1) values under the short TR (33.3 ms) condition. Double echo MR data were used to minimize the T(2)* effect. The present method appears to be useful for quantitative estimation of dynamic contrast-enhanced MRI.
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Ishimori Y, Kimura H, Uematsu H, Matsuda T, Itoh H. Dynamic T1 estimation of brain tumors using double-echo dynamic MR imaging. J Magn Reson Imaging 2003; 18:113-20. [PMID: 12815646 DOI: 10.1002/jmri.10331] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To assess the clinical utility of a new method for real-time estimation of T1 during the first pass of contrast agent by using this method to examine brain tumors. MATERIALS AND METHODS The multi-phase spoiled gradient-echo pulse sequence using the double-echo magnetic resonance (MR) technique was modified. In the first half of the pulse sequence, the flip angle was varied systematically. Then, static T1 values were calculated using differences in MR signal intensities between different flip angles. In the latter half of this sequence, changes in absolute T1 were calculated using differences in signal intensities before and after injection of contrast agent. The double-echo MR data were used to minimize the T2* effect. Five cases of neurinoma and seven cases of meningioma were examined. Changes in T1 during the first pass of contrast agent were compared between neurinoma and meningioma. RESULTS Changes in absolute T1 were clearly demonstrated on the parametric map. Although the changes in absolute T1 during the first pass of contrast agent did not allow differentiation between the two types of tumors, the mean gradient after the first pass was statistically higher for neurinoma than for meningioma (P < 0.05; meningioma, 0.011 +/- 0.012 second(-1)/second; neurinoma, 0.034 +/- 0.020 second(-1)/second). CONCLUSION The present method appears to be useful for estimation of dynamic T1 changes in brain tumors in clinical settings.
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Zaitsev M, Steinhoff S, Shah NJ. Error reduction and parameter optimization of the TAPIR method for fast T1 mapping. Magn Reson Med 2003; 49:1121-32. [PMID: 12768591 DOI: 10.1002/mrm.10478] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A methodology is presented for the reduction of both systematic and random errors in T(1) determination using TAPIR, a Look-Locker-based fast T(1) mapping technique. The relations between various sequence parameters were carefully investigated in order to develop recipes for choosing optimal sequence parameters. Theoretical predictions for the optimal flip angle were verified experimentally. Inversion pulse imperfections were identified as the main source of systematic errors in T(1) determination with TAPIR. An effective remedy is demonstrated which includes extension of the measurement protocol to include a special sequence for mapping the inversion efficiency itself.
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Affiliation(s)
- M Zaitsev
- Institut für Medizin, Forschungszentrum Jülich GmbH, Germany
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Abstract
A sequence for T(1) relaxation-time mapping which enables high-resolution, multislice imaging in short acquisition times is presented. The sequence is based on the Look-Locker method and employs a magnetization-preparation module prior to data acquisition with a banded k-space data collection scheme. The method was implemented on a standard clinical scanner and the accuracy of the T(1) results was evaluated against spectroscopic measurements. The accuracy of the T(1) maps validated by phantom imaging measurements is <3% for slow-relaxing compartments (T(1) congruent with 2000 ms) and is around 1% for faster-relaxing species (T(1) < or = 1200 ms). Additionally, the inherent multislice, multipoint capability of the method is demonstrated. Multislice, multipoint in vivo results of the human brain obtained using this method are presented. An acquisition time of approximately 8 min was achieved for a T(1) map, which, in principle, can provide whole-brain coverage with 25 slices, a matrix size of 256 x 256, and 12 time points. The speed of the sequence is derived through optimized interleaving of slices and time points, together with the acquisition of multiple echoes, which are used to fill a 3-segment k-space.
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Affiliation(s)
- N J Shah
- Institut für Medizin, Forschungszentrum Jülich, 52425, Germany
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