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Li X, Huang Y, Malagi A, Yang CC, Yoosefian G, Huang LT, Tang E, Gao C, Han F, Bi X, Ku MC, Yang HJ, Han H. Reliable Off-Resonance Correction in High-Field Cardiac MRI Using Autonomous Cardiac B 0 Segmentation with Dual-Modality Deep Neural Networks. Bioengineering (Basel) 2024; 11:210. [PMID: 38534485 DOI: 10.3390/bioengineering11030210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/09/2024] [Accepted: 02/18/2024] [Indexed: 03/28/2024] Open
Abstract
B0 field inhomogeneity is a long-lasting issue for Cardiac MRI (CMR) in high-field (3T and above) scanners. The inhomogeneous B0 fields can lead to corrupted image quality, prolonged scan time, and false diagnosis. B0 shimming is the most straightforward way to improve the B0 homogeneity. However, today's standard cardiac shimming protocol requires manual selection of a shim volume, which often falsely includes regions with large B0 deviation (e.g., liver, fat, and chest wall). The flawed shim field compromises the reliability of high-field CMR protocols, which significantly reduces the scan efficiency and hinders its wider clinical adoption. This study aims to develop a dual-channel deep learning model that can reliably contour the cardiac region for B0 shim without human interaction and under variable imaging protocols. By utilizing both the magnitude and phase information, the model achieved a high segmentation accuracy in the B0 field maps compared to the conventional single-channel methods (Dice score: 2D-mag = 0.866, 3D-mag = 0.907, and 3D-mag-phase = 0.938, all p < 0.05). Furthermore, it shows better generalizability against the common variations in MRI imaging parameters and enables significantly improved B0 shim compared to the standard method (SD(B0Shim): Proposed = 15 ± 11% vs. Standard = 6 ± 12%, p < 0.05). The proposed autonomous model can boost the reliability of cardiac shimming at 3T and serve as the foundation for more reliable and efficient high-field CMR imaging in clinical routines.
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Affiliation(s)
- Xinqi Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Yuheng Huang
- Krannert Cardiovascular Research Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Bioengineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Archana Malagi
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Chia-Chi Yang
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Ghazal Yoosefian
- Krannert Cardiovascular Research Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Li-Ting Huang
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Eric Tang
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Chang Gao
- MR R&D Collaborations, Siemens Medical Solutions Inc., Los Angeles, CA 90048, USA
| | - Fei Han
- MR R&D Collaborations, Siemens Medical Solutions Inc., Los Angeles, CA 90048, USA
| | - Xiaoming Bi
- MR R&D Collaborations, Siemens Medical Solutions Inc., Los Angeles, CA 90048, USA
| | - Min-Chi Ku
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Hsin-Jung Yang
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Hui Han
- Department of Radiology, Weill Medical College of Cornell University, New York, NY 10065, USA
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Coletti C, Fotaki A, Tourais J, Zhao Y, van de Steeg-Henzen C, Akçakaya M, Tao Q, Prieto C, Weingärtner S. Robust cardiac T 1 ρ $$ {\mathrm{T}}_{1_{\boldsymbol{\rho}}} $$ mapping at 3T using adiabatic spin-lock preparations. Magn Reson Med 2023; 90:1363-1379. [PMID: 37246420 PMCID: PMC10984724 DOI: 10.1002/mrm.29713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 04/26/2023] [Accepted: 05/04/2023] [Indexed: 05/30/2023]
Abstract
PURPOSE The aim of this study is to develop and optimize an adiabaticT 1 ρ $$ {\mathrm{T}}_{1\uprho} $$ (T 1 ρ , adiab $$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$ ) mapping method for robust quantification of spin-lock (SL) relaxation in the myocardium at 3T. METHODS Adiabatic SL (aSL) preparations were optimized for resilience againstB 0 $$ {\mathrm{B}}_0 $$ andB 1 + $$ {\mathrm{B}}_1^{+} $$ inhomogeneities using Bloch simulations. OptimizedB 0 $$ {\mathrm{B}}_0 $$ -aSL, Bal-aSL andB 1 $$ {\mathrm{B}}_1 $$ -aSL modules, each compensating for different inhomogeneities, were first validated in phantom and human calf. MyocardialT 1 ρ $$ {\mathrm{T}}_{1\uprho} $$ mapping was performed using a single breath-hold cardiac-triggered bSSFP-based sequence. Then, optimizedT 1 ρ , adiab $$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$ preparations were compared to each other and to conventional SL-preparedT 1 ρ $$ {\mathrm{T}}_{1\uprho} $$ maps (RefSL) in phantoms to assess repeatability, and in 13 healthy subjects to investigate image quality, precision, reproducibility and intersubject variability. Finally, aSL and RefSL sequences were tested on six patients with known or suspected cardiovascular disease and compared with LGE,T 1 $$ {\mathrm{T}}_1 $$ , and ECV mapping. RESULTS The highestT 1 ρ , adiab $$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$ preparation efficiency was obtained in simulations for modules comprising 2 HS pulses of 30 ms each. In vivoT 1 ρ , adiab $$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$ maps yielded significantly higher quality than RefSL maps. Average myocardialT 1 ρ , adiab $$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$ values were 183.28± $$ \pm $$ 25.53 ms, compared with 38.21± $$ \pm $$ 14.37 ms RefSL-preparedT 1 ρ $$ {\mathrm{T}}_{1\uprho} $$ .T 1 ρ , adiab $$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$ maps showed a significant improvement in precision (avg. 14.47± $$ \pm $$ 3.71% aSL, 37.61± $$ \pm $$ 19.42% RefSL, p < 0.01) and reproducibility (avg. 4.64± $$ \pm $$ 2.18% aSL, 47.39± $$ \pm $$ 12.06% RefSL, p < 0.0001), with decreased inter-subject variability (avg. 8.76± $$ \pm $$ 3.65% aSL, 51.90± $$ \pm $$ 15.27% RefSL, p < 0.0001). Among aSL preparations,B 0 $$ {\mathrm{B}}_0 $$ -aSL achieved the better inter-subject variability. In patients,B 1 $$ {\mathrm{B}}_1 $$ -aSL preparations showed the best artifact resilience among the adiabatic preparations.T 1 ρ , adiab $$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$ times show focal alteration colocalized with areas of hyper-enhancement in the LGE images. CONCLUSION Adiabatic preparations enable robust in vivo quantification of myocardial SL relaxation times at 3T.
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Affiliation(s)
- Chiara Coletti
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Anastasia Fotaki
- Department of Biomedical Engineering, King’s College London, London, United Kingdom
| | - Joao Tourais
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Yidong Zhao
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | | | - Mehmet Akçakaya
- Department of Electrical and Computer Engineering and Center for Magnetic Resonance Research, University of Minnesota, Minnesota, USA
| | - Qian Tao
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
| | - Claudia Prieto
- Department of Biomedical Engineering, King’s College London, London, United Kingdom
- School of Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile
- Milleniun Institute for Intelligent Healthcare Engineering, Santiago, Chile
| | - Sebastian Weingärtner
- Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands
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Loh M, Führes T, Stuprich C, Uder M, Saake M, Laun FB. Influence of saturation effects on biexponential liver intravoxel incoherent motion. Magn Reson Med 2023; 90:270-279. [PMID: 36861449 DOI: 10.1002/mrm.29622] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 01/20/2023] [Accepted: 02/07/2023] [Indexed: 03/03/2023]
Abstract
PURPOSE Studies on intravoxel incoherent motion (IVIM) imaging in the liver have been carried out with different acquisition protocols. The number of acquired slices and the distances between slices can influence IVIM measurements due to saturation effects, but these effects have often been disregarded. This study investigated differences in biexponential IVIM parameters between two slice settings. METHODS Fifteen healthy volunteers (21-30 years) were examined at a field strength of 3 T. Diffusion-weighted images of the abdomen were acquired with 16 b values (0-800 s/mm2 ), with four slices for the few slices setting and 24-27 slices for the many slices setting. Regions of interest were manually drawn in the liver. The data were fitted with a monoexponential signal curve and a biexponential IVIM curve, and biexponential IVIM parameters were determined. The dependence on the slice setting was assessed with Student's t test for paired samples (normally distributed IVIM parameters) and the Wilcoxon signed-rank test (non-normally distributed parameters). RESULTS None of the parameters were significantly different between the settings. For few slices and many slices, respectively, the mean values (SDs) for D $$ D $$ were 1.21 μm 2 / ms $$ 1.21{\upmu \mathrm{m}}^2/\mathrm{ms} $$ ( 0.19 μm 2 / ms $$ 0.19\kern0.3em {\upmu \mathrm{m}}^2/\mathrm{ms} $$ ) and 1.20 μm 2 / ms $$ 1.20{\upmu \mathrm{m}}^2/\mathrm{ms} $$ ( 0.11 μm 2 / ms $$ 0.11\kern0.3em {\upmu \mathrm{m}}^2/\mathrm{ms} $$ ); for f $$ f $$ they were 29.7% (6.2%) and 27.7% (3.6%); and for D * $$ {D}^{\ast } $$ they were 8.76 ⋅ 10 - 2 mm 2 / s $$ 8.76\cdot {10}^{-2}{\mathrm{mm}}^2/\mathrm{s} $$ ( 4.54 ⋅ 10 - 2 mm 2 / s $$ 4.54\cdot {10}^{-2}\kern0.3em {\mathrm{mm}}^2/\mathrm{s} $$ ) and 8.71 ⋅ 10 - 2 mm 2 / s $$ 8.71\cdot {10}^{-2}{\mathrm{mm}}^2/\mathrm{s} $$ ( 4.06 ⋅ 10 - 2 mm 2 / s $$ 4.06\cdot {10}^{-2}\kern0.3em {\mathrm{mm}}^2/\mathrm{s} $$ ). CONCLUSION Biexponential IVIM parameters in the liver are comparable among IVIM studies that use different slice settings, with mostly negligible saturation effects. However, this may not hold for studies that use much shorter TR.
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Affiliation(s)
- Martin Loh
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Tobit Führes
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christoph Stuprich
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Michael Uder
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Marc Saake
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Frederik Bernd Laun
- Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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Elagha A, Othman Y, Darweesh R, Awadein G, Hashad A. Characterization of the interatrial septum by high-field cardiac MRI: a comparison with multi-slice computed tomography. Egypt Heart J 2020; 72:81. [PMID: 33180202 PMCID: PMC7661592 DOI: 10.1186/s43044-020-00109-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/14/2020] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Assessment of the interatrial septum (IAS) has become an attractive area of interest for a variety of important interventional procedures. Newer imaging modalities like multi-slice computed tomography (MSCT) and cardiac MRI (CMR) can provide higher resolution and wider field of view than echocardiography. Moreover, high-field (3-Tesla) CMR can even enhance spatial and temporal resolution.
The characteristics of the interatrial septum were retrospectively studied in 371 consecutive subjects (201 men, 31–73 years old) in whom MSCT was performed primarily for non-invasive evaluation of the coronary arteries. All subjects underwent both MSCT and MRI scans within 0–30 day’s interval. A 3D volume covering the whole heart was acquired across the heart with and without contrast enhancement. Also, patients underwent cardiac MSCT examinations using 64-row MSCT scanners.
Results
The mean scan time of MSCT was 10.4 ± 2.8 s and 9.7 ± 2.9 min for CMR. The mean length of IAS by CMR and CT was 39.65 ± 4.6 mm and 39.28 ± 4.7 mm, respectively. The mean maximal thickness of IAS by CMR and CT was 3.1 ± 0.97 mm and 3.15 ± 0.95 mm, respectively. The mean thickness of fossa ovalis by CMR and CT was 1.04 ± 0.36 mm and 1.04 ± 0.44 mm, respectively. The mean length of fossa ovalis by CMR and CT was 12.8 ± 3.7 mm and 12.8 ± 3.5 mm, respectively. Finally, the mean angle of IAS by CMR and CT was identical (155 ± 9.2°). Measurements of various morphological features of IAS showed no statistically significant difference between CMR and CT, with an excellent correlation and close relationship regarding IAS length, maximal IAS thickness, fossa ovalis thickness, fossa ovalis length, and IAS angle (r = 0.98, 0.98, 0.95, 0.96, and 0.92, respectively).
Conclusion
Whole-heart 3D acquisition at 3-T MRI using a free-breathing technique provides a valuable non-invasive imaging tool for excellent assessment of the interatrial septum—as compared to MSCT—that may have significant clinical implication for diagnostic purposes and therapeutic interventional procedures, as it may facilitate planning, improve outcome, and shorten its duration.
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Zaric O, Juras V, Szomolanyi P, Schreiner M, Raudner M, Giraudo C, Trattnig S. Frontiers of Sodium MRI Revisited: From Cartilage to Brain Imaging. J Magn Reson Imaging 2020; 54:58-75. [PMID: 32851736 PMCID: PMC8246730 DOI: 10.1002/jmri.27326] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/20/2020] [Accepted: 05/20/2020] [Indexed: 12/19/2022] Open
Abstract
Sodium magnetic resonance imaging (23 Na-MRI) is a highly promising imaging modality that offers the possibility to noninvasively quantify sodium content in the tissue, one of the most relevant parameters for biochemical investigations. Despite its great potential, due to the intrinsically low signal-to-noise ratio (SNR) of sodium imaging generated by low in vivo sodium concentrations, low gyromagnetic ratio, and substantially shorter relaxation times than for proton (1 H) imaging, 23 Na-MRI is extremely challenging. In this article, we aim to provide a comprehensive overview of the literature that has been published in the last 10-15 years and which has demonstrated different technical designs for a range of 23 Na-MRI methods applicable for disease diagnoses and treatment efficacy evaluations. Currently, a wider use of 3.0T and 7.0T systems provide imaging with the expected increase in SNR and, consequently, an increased image resolution and a reduced scanning time. A great interest in translational research has enlarged the field of sodium MRI applications to almost all parts of the body: articular cartilage tendons, spine, heart, breast, muscle, kidney, and brain, etc., and several pathological conditions, such as tumors, neurological and degenerative diseases, and others. The quantitative parameter, tissue sodium concentration, which reflects changes in intracellular sodium concentration, extracellular sodium concentration, and intra-/extracellular volume fractions is becoming acknowledged as a reliable biomarker. Although the great potential of this technique is evident, there must be steady technical development for 23 Na-MRI to become a standard imaging tool. The future role of sodium imaging is not to be considered as an alternative to 1 H MRI, but to provide early, diagnostically valuable information about altered metabolism or tissue function associated with disease genesis and progression. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 1.
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Affiliation(s)
- Olgica Zaric
- Institute for Clinical Molecular MRI in the Musculoskeletal System, Karl Landsteiner Society, Vienna, Austria
| | - Vladimir Juras
- High-Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.,Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Pavol Szomolanyi
- High-Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Markus Schreiner
- Deartment of Orthopaedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria
| | - Marcus Raudner
- High-Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Chiara Giraudo
- Radiology Institute, Department of Medicine, DIMED Padova University Via Giustiniani 2, Padova, Italy
| | - Siegfried Trattnig
- Institute for Clinical Molecular MRI in the Musculoskeletal System, Karl Landsteiner Society, Vienna, Austria.,High-Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Clinical Molecular MRI, Christian Doppler Forschungsgesellschaft, Vienna, Austria
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Hock M, Terekhov M, Stefanescu MR, Lohr D, Herz S, Reiter T, Ankenbrand M, Kosmala A, Gassenmaier T, Juchem C, Schreiber LM. B 0 shimming of the human heart at 7T. Magn Reson Med 2020; 85:182-196. [PMID: 32700791 DOI: 10.1002/mrm.28423] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 01/31/2023]
Abstract
PURPOSE Inhomogeneities of the static magnetic B0 field are a major limiting factor in cardiac MRI at ultrahigh field (≥ 7T), as they result in signal loss and image distortions. Different magnetic susceptibilities of the myocardium and surrounding tissue in combination with cardiac motion lead to strong spatio-temporal B0 -field inhomogeneities, and their homogenization (B0 shimming) is a prerequisite. Limitations of state-of-the-art shimming are described, regional B0 variations are measured, and a methodology for spherical harmonics shimming of the B0 field within the human myocardium is proposed. METHODS The spatial B0 -field distribution in the heart was analyzed as well as temporal B0 -field variations in the myocardium over the cardiac cycle. Different shim region-of-interest selections were compared, and hardware limitations of spherical harmonics B0 shimming were evaluated by calibration-based B0 -field modeling. The role of third-order spherical harmonics terms was analyzed as well as potential benefits from cardiac phase-specific shimming. RESULTS The strongest B0 -field inhomogeneities were observed in localized spots within the left-ventricular and right-ventricular myocardium and varied between systolic and diastolic cardiac phases. An anatomy-driven shim region-of-interest selection allowed for improved B0 -field homogeneity compared with a standard shim region-of-interest cuboid. Third-order spherical harmonics terms were demonstrated to be beneficial for shimming of these myocardial B0 -field inhomogeneities. Initial results from the in vivo implementation of a potential shim strategy were obtained. Simulated cardiac phase-specific shimming was performed, and a shim term-by-term analysis revealed periodic variations of required currents. CONCLUSION Challenges in state-of-the-art B0 shimming of the human heart at 7 T were described. Cardiac phase-specific shimming strategies were found to be superior to vendor-supplied shimming.
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Affiliation(s)
- Michael Hock
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maxim Terekhov
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Maria Roxana Stefanescu
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - David Lohr
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Stefan Herz
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Diagnostic and Interventional Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Theresa Reiter
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Internal Medicine I, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Markus Ankenbrand
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
| | - Aleksander Kosmala
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Diagnostic and Interventional Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Tobias Gassenmaier
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany.,Department of Diagnostic and Interventional Radiology, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Christoph Juchem
- Department of Biomedical Engineering, Columbia University, New York, New York, USA.,Department of Radiology, Columbia University, New York, New York, USA
| | - Laura Maria Schreiber
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, Wuerzburg, Germany
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Xiong Y, Zhang Z, He L, Ma Y, Han H, Zhao X, Guo H. Intracranial simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) MRA: Analyzation, optimization, and extension for dynamic MRA. Magn Reson Med 2019; 82:1646-1659. [DOI: 10.1002/mrm.27855] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 05/20/2019] [Accepted: 05/20/2019] [Indexed: 01/15/2023]
Affiliation(s)
- Yuhui Xiong
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine Tsinghua University Beijing People's Republic of China
| | - Zhe Zhang
- China National Clinical Research Center for Neurological Diseases Beijing Tiantan Hospital, Capital Medical University Beijing People's Republic of China
| | - Le He
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine Tsinghua University Beijing People's Republic of China
| | - Yu Ma
- Tsinghua University Yuquan Hospital Beijing People's Republic of China
| | - Hualu Han
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine Tsinghua University Beijing People's Republic of China
| | - Xihai Zhao
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine Tsinghua University Beijing People's Republic of China
| | - Hua Guo
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine Tsinghua University Beijing People's Republic of China
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Gómez PA, Molina-Romero M, Buonincontri G, Menzel MI, Menze BH. Designing contrasts for rapid, simultaneous parameter quantification and flow visualization with quantitative transient-state imaging. Sci Rep 2019; 9:8468. [PMID: 31186480 PMCID: PMC6560213 DOI: 10.1038/s41598-019-44832-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 05/22/2019] [Indexed: 02/01/2023] Open
Abstract
Magnetic resonance imaging (MRI) has evolved into an outstandingly versatile diagnostic modality, as it has the ability to non-invasively produce detailed information on a tissue's structure and function. Complementary data is normally obtained in separate measurements, either as contrast-weighted images, which are fast and simple to acquire, or as quantitative parametric maps, which offer an absolute quantification of underlying biophysical effects, such as relaxation times or flow. Here, we demonstrate how to acquire and reconstruct data in a transient-state with a dual purpose: 1 - to generate contrast-weighted images that can be adjusted to emphasise clinically relevant image biomarkers; exemplified with signal modulation according to flow to obtain angiography information, and 2 - to simultaneously infer multiple quantitative parameters with a single, highly accelerated acquisition. This is achieved by introducing three novel elements: a model that accounts for flowing blood, a method for sequence design using smooth flip angle excitation patterns that incorporates both parameter encoding and signal contrast, and the reconstruction of temporally resolved contrast-weighted images. From these images we simultaneously obtain angiography projections and multiple quantitative maps. By doing so, we increase the amount of clinically relevant data without adding measurement time, creating new dimensions for biomarker exploration and adding value to MR examinations for patients and clinicians alike.
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9
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Bliesener Y, Zhong X, Guo Y, Boss M, Bosca R, Laue H, Chung C, Sung K, Nayak KS. Radiofrequency transmit calibration: A multi-center evaluation of vendor-provided radiofrequency transmit mapping methods. Med Phys 2019; 46:2629-2637. [PMID: 30924940 DOI: 10.1002/mp.13518] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 02/21/2019] [Accepted: 03/18/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To determine the accuracy and test-retest repeatability of fast radiofrequency (RF) transmit measurement approaches used in Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI). Spatial variation in the transmitted RF field introduces bias and increased variance in quantitative DCE-MRI metrics including tracer kinetic parameter maps. If unaccounted for, these errors can dominate all other sources of bias and variance. The amount and pattern of variation depend on scanner-specific hardware and software. METHODS Human tissue mimicking torso and brain phantoms were constructed. RF transmit maps were measured and compared across eight different commercial scanners, from three major vendors, and three clinical sites. Vendor-recommended rapid methods for RF mapping were compared to a slower reference method. Imaging was repeated at all sites after 2 months. Ranges and magnitude of RF inhomogeneity were compared scanner-wise at two time points. Limits of Agreement of vendor-recommended methods and double-angle reference method were assessed. RESULTS At 3 T, B1 + inhomogeneity spans across 35% in the head and 120% in the torso. Fast vendor provided methods are within 30% agreement with the reference double angle method for both the head and the torso phantom. CONCLUSIONS If unaccounted for, B1 + inhomogeneity can severely impact tracer-kinetic parameter estimation. Depending on the scanner, fast vendor provided B1 + mapping sequences allow unbiased and reproducible measurements of B1 + inhomogeneity to correct for this source of bias.
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Affiliation(s)
- Yannick Bliesener
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Xinran Zhong
- Department of Radiological Sciences & Physics and Biology in Medicine IDP, University of California Los Angeles, Los Angeles, CA, USA
| | - Yi Guo
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Michael Boss
- Applied Physics Division, National Institute of Standards and Technology, Boulder, CO, USA
| | - Ryan Bosca
- Imaging Physics, Sanford Health, Fargo, ND, USA
| | - Hendrik Laue
- Institute for Medical Image Computing, Fraunhofer MEVIS, Bremen, Germany
| | - Caroline Chung
- Radiation Oncology and Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Kyunghyun Sung
- Department of Radiological Sciences & Physics and Biology in Medicine IDP, University of California Los Angeles, Los Angeles, CA, USA
| | - Krishna S Nayak
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
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Kiriki M, Jomoto W, Ikeda T, Kotoura N. [Imaging Parameter Optimization of 3D Phase Contrast-MRA to Reduce Susceptibility-artifact and Radiofrequency-shielding around the Intracranial Stent]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2019; 74:1293-1301. [PMID: 30464097 DOI: 10.6009/jjrt.2018_jsrt_74.11.1293] [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] [Indexed: 11/11/2022]
Abstract
The purpose of this study was to evaluate the degree of signal attenuation generated around the stent by the susceptibility artifacts and radiofrequency (RF) shielding in phase contrast-magnetic resonance angiography (PCA) images and construct optimal PCA imaging parameters for intracranial stent lumen images. The two types of PCA images of stents (Neuroform, Enterpraise II) placed in the vascular flow phantom were imaged with different the flip angle (FA) and echo time (TE). Each original image of the vascular flow phantom was reconstructed into a coronal multiplanar reconstruction (MPR) image and a profile curve along the long axis of the stent was calculated. The reduction of in-stent signal was assessed by relative in-stent signal (RIS) calculated by comparing intra-stent signal intensity to the reference tube in the original images. When the TE was 2.3 ms, the profile curve was the highest signal intensity. However, RIS had not changed by the extension of TE. When the FA was high, the RIS showed a high value, but when it exceeded 25 degrees, the signal attenuated in the distal part of the slab.The susceptibility artifacts and RF shielding generated around the stent can be reduced by the shortest TbE (2.3 ms) and 20 degrees of FA in the PCA imaging.
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Affiliation(s)
- Masato Kiriki
- Department of Radiological Technology, Hyogo College of Medicine College Hospital
| | - Wataru Jomoto
- Department of Radiological Technology, Hyogo College of Medicine College Hospital
| | - Takashi Ikeda
- Department of Radiological Technology, Hyogo College of Medicine College Hospital
| | - Noriko Kotoura
- Department of Radiological Technology, Hyogo College of Medicine College Hospital
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11
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Zhang B, Sodickson DK, Cloos MA. A high-impedance detector-array glove for magnetic resonance imaging of the hand. Nat Biomed Eng 2018; 2:570-577. [PMID: 30854251 PMCID: PMC6405230 DOI: 10.1038/s41551-018-0233-y] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Densely packed resonant structures used for magnetic resonance imaging (MRI), such as nuclear magnetic resonance phased-array detectors, suffer from resonant inductive coupling, which restricts coil design to fixed geometries, imposes performance limitations, and narrows the scope of MRI experiments to motionless subjects. Here, we report the design of high-impedance detectors, and the fabrication and performance of a wearable detector array for MRI of the hand, that cloak themselves from electrodynamic interactions with neighboring elements. We experimentally verified that the detectors do not suffer from signal-to-noise degradation mechanisms typically observed with the use of traditional low-impedance elements. The detectors are adaptive and can accommodate movement, providing access to the imaging of soft-tissue biomechanics with unprecedented flexibility. The design of the wearable detector glove exemplifies the potential of high-impedance detectors in enabling a wide range of applications that are not well suited to traditional coil designs.
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Affiliation(s)
- Bei Zhang
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, USA. .,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, NY, USA.
| | - Daniel K Sodickson
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, USA.,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, NY, USA.,Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA.,Tech4Health, NYU Langone Health, New York, NY, USA
| | - Martijn A Cloos
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, USA. .,Center for Advanced Imaging Innovation and Research, New York University School of Medicine, New York, NY, USA. .,Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA. .,Tech4Health, NYU Langone Health, New York, NY, USA.
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12
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Beqiri A, Price AN, Padormo F, Hajnal JV, Malik SJ. Extended RF shimming: Sequence-level parallel transmission optimization applied to steady-state free precession MRI of the heart. NMR IN BIOMEDICINE 2017; 30:e3701. [PMID: 28195684 PMCID: PMC5484304 DOI: 10.1002/nbm.3701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 12/23/2016] [Accepted: 12/30/2016] [Indexed: 05/12/2023]
Abstract
Cardiac magnetic resonance imaging (MRI) at high field presents challenges because of the high specific absorption rate and significant transmit field (B1+ ) inhomogeneities. Parallel transmission MRI offers the ability to correct for both issues at the level of individual radiofrequency (RF) pulses, but must operate within strict hardware and safety constraints. The constraints are themselves affected by sequence parameters, such as the RF pulse duration and TR, meaning that an overall optimal operating point exists for a given sequence. This work seeks to obtain optimal performance by performing a 'sequence-level' optimization in which pulse sequence parameters are included as part of an RF shimming calculation. The method is applied to balanced steady-state free precession cardiac MRI with the objective of minimizing TR, hence reducing the imaging duration. Results are demonstrated using an eight-channel parallel transmit system operating at 3 T, with an in vivo study carried out on seven male subjects of varying body mass index (BMI). Compared with single-channel operation, a mean-squared-error shimming approach leads to reduced imaging durations of 32 ± 3% with simultaneous improvement in flip angle homogeneity of 32 ± 8% within the myocardium.
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Affiliation(s)
- Arian Beqiri
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
| | - Anthony N. Price
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
- Centre for the Developing BrainKing's College LondonLondonUK
| | - Francesco Padormo
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
| | - Joseph V. Hajnal
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
- Centre for the Developing BrainKing's College LondonLondonUK
| | - Shaihan J. Malik
- Division of Imaging Sciences and Biomedical EngineeringKing's College LondonLondonUK
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13
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Wittlinger T, Martinovic I, Moritz A, Romanzetti S. Evaluation of the Spatial Resolution with 1.5–4 Tesla in a Stenosis Model. Asian Cardiovasc Thorac Ann 2016; 14:387-93. [PMID: 17005885 DOI: 10.1177/021849230601400508] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Since it was first described in the early 1990s, magnetic resonance coronary angiography has evolved into a promising noninvasive modality for imaging the coronary arteries. The aim of this study was to evaluate the detection accuracy and spatial resolution of vascular stenosis in contrast-enhanced 3-dimensional magnetic resonance angiography on a flow phantom. The examinations were performed with 1.5, 3, and 4 T whole-body imaging systems. For imaging at 4 T, we used a gradient-echo-multi-slice sequence. The system was flushed with gadopentetate dimeglumine contrast medium at flow rates of 40 and 60 mL·min−1. The accurate detection of in vitro stenoses was possible in segments of 0.4 mm in diameter at 4 T. The best results were obtained at a flow velocity of 40 mL·min−1 and a contrast medium concentration of 0.2 mmol·L−1. Contrast-enhanced high-field 3-dimensional magnetic resonance imaging provided a highly accurate evaluation of the degree of stenosis in this model. Exact evaluation of vessel diameters < 0.4 mm was not possible, even with 4 T. In vivo studies are necessary to overcome the current limitations in the visualization of small distal vessel segments.
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Affiliation(s)
- Thomas Wittlinger
- , Department of Thoracic and Cardiovascular Surgery, University Hospital, Theodor-Stern-Kai 7, Frankfurt 60590, Germany.
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14
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Chen S, Ning J, Zhao X, Wang J, Zhou Z, Yuan C, Chen H. Fast simultaneous noncontrast angiography and intraplaque hemorrhage (fSNAP) sequence for carotid artery imaging. Magn Reson Med 2016; 77:753-758. [PMID: 26786908 DOI: 10.1002/mrm.26111] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/23/2015] [Accepted: 12/09/2015] [Indexed: 11/10/2022]
Abstract
PURPOSE To propose a fast simultaneous noncontrast angiography and intraplaque hemorrhage (fSNAP) sequence for carotid artery imaging. METHODS The proposed fSNAP sequence uses a low-resolution reference acquisition for phase-sensitive reconstruction to speed up the scan, and an inversion recovery acquisition with arbitrary k-space filling order to generate similar contrast to conventional SNAP. Four healthy volunteers and eight patients were recruited to test the performance of fSNAP in vivo. The lumen area quantification, muscle-blood CNR, IPH-blood CNR, lumen SNR, and standard deviation and intraplaque hemorrhage (IPH) detection accuracy were compared between fSNAP and SNAP. RESULTS By using a low-resolution reference acquisition with 1/4 matrix size of the full-resolution reference scan, the scan time of fSNAP was 37.5% less than that of SNAP. A high agreement of lumen area measurement (ICC = 0.97, 95% CI: 0.96-0.99) and IPH detection (Kappa = 1) were found between fSNAP and SNAP. Also, no significant difference was found for muscle-blood CNR (P = 0.25), IPH-blood CNR (P = 0.35), lumen SNR (P = 0.60), and standard deviation (P = 0.46) between the two techniques. CONCLUSION The feasibility of fSNAP was validated. fSNAP can improve the imaging efficiency with similar performance to SNAP on carotid artery imaging. Magn Reson Med 77:753-758, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Shuo Chen
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Jia Ning
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Xihai Zhao
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Jinnan Wang
- Clinical Sites Research Program, Philips Research North America, Briarcliff Manor, New York, USA
| | - Zechen Zhou
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Chun Yuan
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China.,Department of Radiology, University of Washington, Seattle, Washington, USA
| | - Huijun Chen
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
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15
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Richardson OC, Bane O, Scott MLJ, Tanner SF, Waterton JC, Sourbron SP, Carroll TJ, Buckley DL. Gadofosveset-based biomarker of tissue albumin concentration: Technical validation in vitro and feasibility in vivo. Magn Reson Med 2015; 73:244-53. [PMID: 24515975 PMCID: PMC4296221 DOI: 10.1002/mrm.25128] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/19/2013] [Indexed: 11/07/2022]
Abstract
PURPOSE There is currently no adequate method of mapping physiologic and pathophysiologic tissue albumin concentrations in human subjects. The objective of this study was to devise and evaluate a biomarker of regional albumin concentration using gadofosveset-enhanced MRI. THEORY AND METHODS A binding and relaxation model was devised and evaluated in vitro in solutions of albumin at 3.0 Tesla (T) and 4.7T. The method was evaluated in the heart in seven volunteers at 3.0T. RESULTS MRI-derived estimates of albumin concentration were in good agreement with true values over the range 0.1-1.0 mM (Pearson correlation coefficients of 0.85 and 0.88 for 3.0T and 4.7T, respectively). The mean calculated albumin concentration in the myocardium for the volunteers was 0.02 mM (range, 0.01-0.03 mM). CONCLUSION Accurate estimates of albumin concentration in vitro suggest this may be a viable noninvasive alternative to existing techniques. In the myocardium the MRI-derived estimates of albumin concentration indicate the practical feasibility of the technique but were below expected values. Gadofosveset-enhanced MR relaxometry has potential in providing biomarkers of regional albumin concentration; further evaluation is required before it can be used reliably in vivo.
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Affiliation(s)
- Owen C Richardson
- Division of Medical Physics, University of LeedsLeeds, United Kingdom
| | - Octavia Bane
- Departments of Biomedical Engineering and Radiology, Northwestern UniversityChicago, Illinois, USA
| | - Marietta LJ Scott
- Personalized Healthcare and Biomarkers, AstraZenecaMacclesfield, Cheshire, United Kingdom
| | - Steven F Tanner
- Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS TrustLeeds, United Kingdom.
| | - John C Waterton
- Personalized Healthcare and Biomarkers, AstraZenecaMacclesfield, Cheshire, United Kingdom
| | - Steven P Sourbron
- Division of Medical Physics, University of LeedsLeeds, United Kingdom
| | - Timothy J Carroll
- Departments of Biomedical Engineering and Radiology, Northwestern UniversityChicago, Illinois, USA
| | - David L Buckley
- Division of Medical Physics, University of LeedsLeeds, United Kingdom
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16
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Rasper M, Gramer BM, Settles M, Laugwitz KL, Ibrahim T, Rummeny EJ, Huber A. Dual-source RF transmission in cardiac SSFP imaging at 3 T: systematic spatial evaluation of image quality improvement compared to conventional RF transmission. Clin Imaging 2014; 39:231-6. [PMID: 25481220 DOI: 10.1016/j.clinimag.2014.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 10/21/2014] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
Abstract
The purpose of this investigation was to systematically evaluate the spatial distribution of image quality improvement with dual-source radiofrequency (RF) transmission in cardiac steady-state free precession sequences at 3.0 T. Imaging with and without dual-source RF transmission was performed in 30 patients. Contrast-to-noise ratio for the left ventricular myocardium was significantly higher using dual-source RF transmission, but improvement was not uniformly distributed. The posterior myocardium showed significantly less contrast-to-noise ratio gain than all other cardiac regions. Signal-to-noise ratio increase was higher in the right than in the left ventricle. Subjective image quality was significantly enhanced by parallel RF transmission.
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Affiliation(s)
- Michael Rasper
- Institute of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Bettina M Gramer
- Institute of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Marcus Settles
- Institute of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Karl-Ludwig Laugwitz
- Department of Cardiology, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Tareq Ibrahim
- Department of Cardiology, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Ernst J Rummeny
- Institute of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
| | - Armin Huber
- Institute of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 Munich, Germany.
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17
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Krieger SN, Gauthier CJ, Ivanov D, Huber L, Roggenhofer E, Sehm B, Turner R, Egan GF. Regional reproducibility of calibrated BOLD functional MRI: Implications for the study of cognition and plasticity. Neuroimage 2014; 101:8-20. [DOI: 10.1016/j.neuroimage.2014.06.072] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/24/2014] [Accepted: 06/28/2014] [Indexed: 02/02/2023] Open
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18
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Improving perfusion quantification in arterial spin labeling for delayed arrival times by using optimized acquisition schemes. Z Med Phys 2014; 25:221-9. [PMID: 25125192 DOI: 10.1016/j.zemedi.2014.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/10/2014] [Accepted: 07/10/2014] [Indexed: 12/20/2022]
Abstract
OBJECTIVE The improvement in Arterial Spin Labeling (ASL) perfusion quantification, especially for delayed bolus arrival times (BAT), with an acquisition redistribution scheme mitigating the T1 decay of the label in multi-TI ASL measurements is investigated. A multi inflow time (TI) 3D-GRASE sequence is presented which adapts the distribution of acquisitions accordingly, by keeping the scan time constant. MATERIAL AND METHODS The MR sequence increases the number of averages at long TIs and decreases their number at short TIs and thus compensating the T1 decay of the label. The improvement of perfusion quantification is evaluated in simulations as well as in-vivo in healthy volunteers and patients with prolonged BATs due to age or steno-occlusive disease. RESULTS The improvement in perfusion quantification depends on BAT. At healthy BATs the differences are small, but become larger for longer BATs typically found in certain diseases. The relative error of perfusion is improved up to 30% at BATs>1500ms in comparison to the standard acquisition scheme. CONCLUSION This adapted acquisition scheme improves the perfusion measurement in comparison to standard multi-TI ASL implementations. It provides relevant benefit in clinical conditions that cause prolonged BATs and is therefore of high clinical relevance for neuroimaging of steno-occlusive diseases.
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19
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Fan Z, Yu W, Xie Y, Dong L, Yang L, Wang Z, Conte AH, Bi X, An J, Zhang T, Laub G, Shah PK, Zhang Z, Li D. Multi-contrast atherosclerosis characterization (MATCH) of carotid plaque with a single 5-min scan: technical development and clinical feasibility. J Cardiovasc Magn Reson 2014; 16:53. [PMID: 25184808 PMCID: PMC4222690 DOI: 10.1186/s12968-014-0053-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 07/08/2014] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Multi-contrast weighted imaging is a commonly used cardiovascular magnetic resonance (CMR) protocol for characterization of carotid plaque composition. However, this approach is limited in several aspects including low slice resolution, long scan time, image mis-registration, and complex image interpretation. In this work, a 3D CMR technique, named Multi-contrast Atherosclerosis Characterization (MATCH), was developed to mitigate the above limitations. METHODS MATCH employs a 3D spoiled segmented fast low angle shot readout to acquire data with three different contrast weightings in an interleaved fashion. The inherently co-registered image sets, hyper T1-weighting, gray blood, and T2-weighting, are used to detect intra-plaque hemorrhage (IPH), calcification (CA), lipid-rich necrotic core (LRNC), and loose-matrix (LM). The MATCH sequence was optimized by computer simulations and testing on four healthy volunteers and then evaluated in a pilot study of six patients with carotid plaque, using the conventional multi-contrast protocol as a reference. RESULTS On MATCH images, the major plaque components were easy to identify. Spatial co-registration between the three image sets with MATCH was particularly helpful for the reviewer to discern co-existent components in an image and appreciate their spatial relation. Based on Cohen's kappa tests, moderate to excellent agreement in the image-based or artery-based component detection between the two protocols was obtained for LRNC, IPH, CA, and LM, respectively. Compared with the conventional multi-contrast protocol, the MATCH protocol yield significantly higher signal contrast ratio for IPH (3.1±1.3 vs. 0.4±0.3, p<0.001) and CA (1.6±1.5 vs. 0.7±0.6, p=0.012) with respect to the vessel wall. CONCLUSIONS To the best of our knowledge, the proposed MATCH sequence is the first 3D CMR technique that acquires spatially co-registered multi-contrast image sets in a single scan for characterization of carotid plaque composition. Our pilot clinical study suggests that the MATCH-based protocol may outperform the conventional multi-contrast protocol in several respects. With further technical improvements and large-scale clinical validation, MATCH has the potential to become a CMR method for assessing the risk of plaque disruption in a clinical workup.
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Affiliation(s)
- Zhaoyang Fan
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Wei Yu
- Department of Radiology, Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yibin Xie
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Li Dong
- Department of Radiology, Anzhen Hospital, Capital Medical University, Beijing, China
| | - Lixin Yang
- Department of Radiology, Anzhen Hospital, Capital Medical University, Beijing, China
| | - Zhanhong Wang
- Department of Radiology, Anzhen Hospital, Capital Medical University, Beijing, China
| | | | - Xiaoming Bi
- MR R&D, Siemens Healthcare, Los Angeles, CA, USA
| | - Jing An
- MR Collaborations NE Asia, Siemens Healthcare, Beijing, China
| | - Tianjing Zhang
- MR Collaborations NE Asia, Siemens Healthcare, Beijing, China
| | - Gerhard Laub
- MR R&D, Siemens Healthcare, Los Angeles, CA, USA
| | - Prediman Krishan Shah
- Oppenheimer Atherosclerosis Research Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Atherosclerosis Prevention and Management Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Zhaoqi Zhang
- Department of Radiology, Anzhen Hospital, Capital Medical University, Beijing, China
| | - Debiao Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Bioengineering, University of California, Los Angeles, CA, USA
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Wu T, Wang J, Song Y, Deng X, Li A, Wei J, He L, Zhao X, Li R, Zhou Z, Wu W, Huang J, Jiao S, Yuan C, Chen H. Homologous HOmologous Black-Bright-blood and flexible Interleaved imaging sequence (HOBBI) for dynamic contrast-enhanced MRI of the vessel wall. Magn Reson Med 2014; 73:1754-63. [PMID: 24805922 DOI: 10.1002/mrm.25287] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 03/27/2014] [Accepted: 04/16/2014] [Indexed: 12/17/2022]
Abstract
PURPOSE To present a HOmologous Black-Bright-blood and flexible Interleaved imaging (HOBBI) sequence for dynamic contrast-enhanced magnetic resonance imaging (MRI) of the vessel wall. THEORY AND METHODS A HOBBI sequence is proposed to acquire high-spatial-resolution black-blood and high-temporal-resolution bright-blood dynamic contrast-enhanced images in an interleaved fashion. Black-blood imaging allows for thin vessel wall evaluation, whereas bright-blood imaging obtains the arterial input function accurately. A simulation was performed to assess the accuracy of the pharmacokinetic parameters [transfer constant (K(trans) ) and fractional plasma volume (vp )] generated from HOBBI. In vivo evaluation was also used to validate HOBBI in an animal model of aortic atherosclerosis. RESULTS In the simulation test, the estimated K(trans) and vp measured by HOBBI were more accurate than those from black-blood dynamic contrast-enhanced-MRI. In the animal model testing, K(trans) and vp also demonstrated good interscan reproducibility (K(trans) : ICC = 0.77, vp : ICC = 0.72, respectively). Additionally, K(trans) showed a significant increase from 1 month (0.026 ± 0.013 min(-1) ) to 2 months (0.069 ± 0.018 min(-1) ) in animal model plaque progression after balloon injury. CONCLUSION The proposed HOBBI sequence was demonstrated to be feasible and accurate in estimating the pharmacokinetic parameters of the atherosclerotic vessel wall, and has potential to become an early screening tool for atherosclerosis disease.
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Affiliation(s)
- Tingting Wu
- Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
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21
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Soleimanifard S, Stuber M, Hays AG, Weiss RG, Schär M. Robust volume-targeted balanced steady-state free-precession coronary magnetic resonance angiography in a breathhold at 3.0 Tesla: a reproducibility study. J Cardiovasc Magn Reson 2014; 16:27. [PMID: 24758168 PMCID: PMC4006454 DOI: 10.1186/1532-429x-16-27] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 03/28/2014] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Transient balanced steady-state free-precession (bSSFP) has shown substantial promise for noninvasive assessment of coronary arteries but its utilization at 3.0 T and above has been hampered by susceptibility to field inhomogeneities that degrade image quality. The purpose of this work was to refine, implement, and test a robust, practical single-breathhold bSSFP coronary MRA sequence at 3.0 T and to test the reproducibility of the technique. METHODS A 3D, volume-targeted, high-resolution bSSFP sequence was implemented. Localized image-based shimming was performed to minimize inhomogeneities of both the static magnetic field and the radio frequency excitation field. Fifteen healthy volunteers and three patients with coronary artery disease underwent examination with the bSSFP sequence (scan time = 20.5 ± 2.0 seconds), and acquisitions were repeated in nine subjects. The images were quantitatively analyzed using a semi-automated software tool, and the repeatability and reproducibility of measurements were determined using regression analysis and intra-class correlation coefficient (ICC), in a blinded manner. RESULTS The 3D bSSFP sequence provided uniform, high-quality depiction of coronary arteries (n = 20). The average visible vessel length of 100.5 ± 6.3 mm and sharpness of 55 ± 2% compared favorably with earlier reported navigator-gated bSSFP and gradient echo sequences at 3.0 T. Length measurements demonstrated a highly statistically significant degree of inter-observer (r = 0.994, ICC = 0.993), intra-observer (r = 0.894, ICC = 0.896), and inter-scan concordance (r = 0.980, ICC = 0.974). Furthermore, ICC values demonstrated excellent intra-observer, inter-observer, and inter-scan agreement for vessel diameter measurements (ICC = 0.987, 0.976, and 0.961, respectively), and vessel sharpness values (ICC = 0.989, 0.938, and 0.904, respectively). CONCLUSIONS The 3D bSSFP acquisition, using a state-of-the-art MR scanner equipped with recently available technologies such as multi-transmit, 32-channel cardiac coil, and localized B0 and B1+ shimming, allows accelerated and reproducible multi-segment assessment of the major coronary arteries at 3.0 T in a single breathhold. This rapid sequence may be especially useful for functional imaging of the coronaries where the acquisition time is limited by the stress duration and in cases where low navigator-gating efficiency prohibits acquisition of a free breathing scan in a reasonable time period.
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Affiliation(s)
- Sahar Soleimanifard
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Matthias Stuber
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
- Department of Radiology, Centre Hospitalier Universitaire Vaudois, Center for Biomedical Imaging (CIBM) and University of Lausanne, Lausanne, Switzerland
- Russell H. Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, Johns Hopkins University, Baltimore, MD, USA
| | - Allison G Hays
- Russell H. Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, Johns Hopkins University, Baltimore, MD, USA
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| | - Robert G Weiss
- Russell H. Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, Johns Hopkins University, Baltimore, MD, USA
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, MD, USA
| | - Michael Schär
- Russell H. Morgan Department of Radiology and Radiological Science, Division of Magnetic Resonance Research, Johns Hopkins University, Baltimore, MD, USA
- Philips Healthcare, Cleveland, OH, USA
- Barrow Neurological Institute, Keller Center for Imaging Innovation, 350 W. Thomas Rd, Phoenix, AZ 85013, USA
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Zaman A, Higgins DM, Motwani M, Kidambi A, Kouwenhoven M, Kozerke S, Greenwood JP, Plein S. Robust myocardial T2and T2* mapping at 3T using image-based shimming. J Magn Reson Imaging 2014; 41:1013-20. [DOI: 10.1002/jmri.24636] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 03/06/2014] [Indexed: 11/06/2022] Open
Affiliation(s)
- Arshad Zaman
- Multidisciplinary Cardiovascular Research Centre; Division of Cardiovascular and Diabetes Research; Leeds Institute of Genetics; Health & Therapeutics; University of Leeds; Leeds UK
| | | | - Manish Motwani
- Multidisciplinary Cardiovascular Research Centre; Division of Cardiovascular and Diabetes Research; Leeds Institute of Genetics; Health & Therapeutics; University of Leeds; Leeds UK
| | - Ananth Kidambi
- Multidisciplinary Cardiovascular Research Centre; Division of Cardiovascular and Diabetes Research; Leeds Institute of Genetics; Health & Therapeutics; University of Leeds; Leeds UK
| | | | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich; Switzerland
| | - John P. Greenwood
- Multidisciplinary Cardiovascular Research Centre; Division of Cardiovascular and Diabetes Research; Leeds Institute of Genetics; Health & Therapeutics; University of Leeds; Leeds UK
| | - Sven Plein
- Multidisciplinary Cardiovascular Research Centre; Division of Cardiovascular and Diabetes Research; Leeds Institute of Genetics; Health & Therapeutics; University of Leeds; Leeds UK
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Chow K, Flewitt JA, Green JD, Pagano JJ, Friedrich MG, Thompson RB. Saturation recovery single-shot acquisition (SASHA) for myocardial T
1
mapping. Magn Reson Med 2013; 71:2082-95. [DOI: 10.1002/mrm.24878] [Citation(s) in RCA: 263] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 06/18/2013] [Accepted: 06/18/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Kelvin Chow
- Department of Biomedical Engineering; Faculty of Medicine and Dentistry; University of Alberta; Edmonton Canada
| | - Jacqueline A. Flewitt
- Stephenson Cardiovascular Centre; Libin Cardiovascular Institute of Alberta, University of Calgary; Calgary Canada
- Marvin Carsley CMR Centre; Montreal Heart Institute, Université de Montréal; Montreal Canada
| | | | - Joseph J. Pagano
- Department of Biomedical Engineering; Faculty of Medicine and Dentistry; University of Alberta; Edmonton Canada
| | - Matthias G. Friedrich
- Stephenson Cardiovascular Centre; Libin Cardiovascular Institute of Alberta, University of Calgary; Calgary Canada
- Marvin Carsley CMR Centre; Montreal Heart Institute, Université de Montréal; Montreal Canada
| | - Richard B. Thompson
- Department of Biomedical Engineering; Faculty of Medicine and Dentistry; University of Alberta; Edmonton Canada
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24
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Yuan J, Chow SKK, Zhang Q, Yeung DKW, Ahuja AT, King AD. The use of dynamic tracer concentration in veins for quantitative DCE-MRI kinetic analysis in head and neck. PLoS One 2013; 8:e59885. [PMID: 23527281 PMCID: PMC3603985 DOI: 10.1371/journal.pone.0059885] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 02/18/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Head and neck Magnetic Resonance (MR) Images are vulnerable to the arterial blood in-flow effect. To compensate for this effect and enhance accuracy and reproducibility, dynamic tracer concentration in veins was proposed and investigated for quantitative dynamic contrast-enhanced (DCE) MRI analysis in head and neck. METHODOLOGY 21 patients with head and neck tumors underwent DCE-MRI at 3T. An automated method was developed for blood vessel selection and separation. Dynamic concentration-time-curves (CTCs) in arteries and veins were used for the Tofts model parameter estimations. The estimation differences by using CTCs in arteries and veins were compared. Artery and vein voxels were accurately separated by the automated method. Remarkable inter-slice tracer concentration differences were found in arteries while the inter-slice concentration differences in veins were moderate. Tofts model fitting by using the CTCs in arteries and veins produced significantly different parameter estimations. The individual artery CTCs resulted in large (>50% generally) inter-slice parameter estimation variations. Better inter-slice consistency was achieved by using the vein CTCs. CONCLUSIONS The use of vein CTCs helps to compensate for arterial in-flow effect and reduce kinetic parameter estimation error and inconsistency for head and neck DCE-MRI.
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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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25
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Clique H, Cheng HLM, Marie PY, Felblinger J, Beaumont M. 3D myocardial T
1
mapping at 3T using variable flip angle method: Pilot study. Magn Reson Med 2013; 71:823-9. [DOI: 10.1002/mrm.24688] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Hélène Clique
- Université de Lorraine; IADI; UMR S 947 Nancy France
- INSERM; IADI; U947 Nancy France
| | - Hai-Ling Margaret Cheng
- The Hospital for Sick Children; Research Institute; Toronto Ontario Canada
- University of Toronto; Medical Biophysics; Toronto Ontario Canada
| | - Pierre-Yves Marie
- Université de Lorraine; RCV; UMR S 961 Nancy France
- INSERM; RCV; U1116 Nancy France
- CHU Nancy; Department of Nuclear Medicine; Nancy France
| | - Jacques Felblinger
- Université de Lorraine; IADI; UMR S 947 Nancy France
- CHU Nancy; CIC-IT; Nancy France
- INSERM; CIC-IT, CIT801; Nancy France
| | - Marine Beaumont
- INSERM; IADI; U947 Nancy France
- CHU Nancy; CIC-IT; Nancy France
- INSERM; CIC-IT, CIT801; Nancy France
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26
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Wang J, Börnert P, Zhao H, Hippe DS, Zhao X, Balu N, Ferguson MS, Hatsukami TS, Xu J, Yuan C, Kerwin WS. Simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) imaging for carotid atherosclerotic disease evaluation. Magn Reson Med 2013; 69:337-45. [PMID: 22442116 PMCID: PMC3418400 DOI: 10.1002/mrm.24254] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Revised: 02/20/2012] [Accepted: 02/23/2012] [Indexed: 12/24/2022]
Abstract
A simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) MR imaging technique is proposed to detect both luminal stenosis and hemorrhage in atherosclerosis patients in a single scan. Thirteen patients with diagnosed carotid atherosclerotic plaque were admitted after informed consent. All scans were performed on a 3T MR imaging system with SNAP, 2D time-of-flight and magnetization-prepared 3D rapid acquisition gradient echo sequences. The SNAP sequence utilized a phase sensitive acquisition, and was designed to provide positive signals corresponding to intraplaque hemorrhage and negative signals corresponding to lumen. SNAP images were compared to time-of-flight images to evaluate lumen size measurements using linear mixed models and the intraclass correlation coefficient. Intraplaque hemorrhage identification accuracy was evaluated by comparing to magnetization-prepared 3D rapid acquisition gradient echo images using Cohen's Kappa. Diagnostic quality SNAP images were generated from all subjects. Quantitatively, the lumen size measurements by SNAP were strongly correlated (intraclass correlation coefficient = 0.96, P < 0.001) with those measured by time-of-flight. For intraplaque hemorrhage detection, strong agreement (κ = 0.82, P < 0.001) was also identified between SNAP and magnetization-prepared 3D rapid acquisition gradient echo images. In conclusion, a SNAP imaging technique was proposed and shows great promise for imaging both lumen size and carotid intraplaque hemorrhage with a single scan.
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Affiliation(s)
- Jinnan Wang
- Clinical Sites Research Program, Philips Research North America, Briarcliff Manor, New York, USA.
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27
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Gregori J, Schuff N, Kern R, Günther M. T2-based arterial spin labeling measurements of blood to tissue water transfer in human brain. J Magn Reson Imaging 2013; 37:332-42. [PMID: 23019041 PMCID: PMC3554863 DOI: 10.1002/jmri.23822] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 08/14/2012] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To investigate blood to tissue water transfer in human brain, in vivo and spatially resolved using a T2-based arterial spin labeling (ASL) method with 3D readout. MATERIALS AND METHODS A T2-ASL method is introduced to measure the water transfer processes between arterial blood and brain tissue based on a 3D-GRASE (gradient and spin echo) pulsed ASL sequence with multiecho readout. An analytical mathematical model is derived based on the General Kinetic Model, including blood and tissue compartment, T1 and T2 relaxation, and a blood-to-tissue transfer term. Data were collected from healthy volunteers on a 3 T system. The mean transfer time parameter T(bl → ex) (blood to extravascular compartment transfer time) was derived voxelwise by nonlinear least-squares fitting. RESULTS Whole-brain maps of T(bl → ex) show stable results in cortical regions, yielding different values depending on the brain region. The mean value across subjects and regions of interest (ROIs) in gray matter was 440 ± 30 msec. CONCLUSION A novel method to derive whole-brain maps of blood to tissue water transfer dynamics is demonstrated. It is promising for the investigation of underlying physiological mechanisms and development of diagnostic applications in cerebrovascular diseases.
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Affiliation(s)
- Johannes Gregori
- Institute for Medical Image Computing MEVIS, Fraunhofer MEVIS, Bremen, Germany.
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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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29
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Kim KN, Jeong H, Heo P, Kim YB, Cho ZH. Improving RF field strength and uniformity in a local region by controlling individual transmitting RF phase in a 7T tranceive array coil. Biomed Eng Lett 2012. [DOI: 10.1007/s13534-012-0075-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Constantinides C, Angeli S. Elimination of mutual inductance in NMR phased arrays: the paddle design revisited. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 222:59-67. [PMID: 22820010 DOI: 10.1016/j.jmr.2012.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 06/09/2012] [Accepted: 06/11/2012] [Indexed: 06/01/2023]
Abstract
This study proposes a method to empirically minimize mutual inductance, using passive end-ring circular paddles, with neighboring coil loops placed in a non-overlapped configuration. The proposed concepts are validated through B(1)-field simulations for resonant coils at f(o)=300.5 MHz, having various sizes (3-10 cm), and for paddles with sizes ranging from 16 to 30 mm, and bench tests on constructed 4×4cm(2) two- (1×2) and four-coil loop (2×2) planar arrays. Simulation results yield total mean percentage B(1)-field differences of only 7.03% between the two non-overlapping coil array configurations (paddles vs. no-paddles). Pair-wise comparisons of elicited mean B(1)-field differences from the use of different circular and rectangular paddle sizes, yield values <5.3%. Theoretical calculation of the normalized mutual coupling coefficient in the non-overlapped coil configuration reduces to almost zero with optimally sized-paddles having a radius of approximately 28% the coil's largest dimension. In the absence of paddles, differences in the split of resonance peaks of 9.9 MHz were observed for the two coils in the 1×2 array, which vanished with paddle placement. Single coil responses (unloaded/loaded) without paddles, and responses from array coils with use of optimally-sized paddles yielded quality factor ratios that ranged between 1.1-1.86 and 1.0-1.5, respectively. Phantom and mouse loaded reflection coefficients S(11)/S(22) were -16.7/-16.2dB and -28.2/-16.1 dB, for the two array loops, respectively. Under unloaded conditions and in the absence of paddles, split resonances were observed for the 1×2 array, yielding transmission coefficients of -5.5 to -8.1 dB, reversing to single resonance responses upon paddle placements, with transmission coefficients of -14.4 to -15.6 dB.
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Affiliation(s)
- Christakis Constantinides
- Department of Mechanical and Manufacturing Engineering, School of Engineering, University of Cyprus, Cyprus.
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Young VE, Patterson AJ, Tunnicliffe EM, Sadat U, Graves MJ, Tang TY, Priest AN, Kirkpatrick PJ, Gillard JH. Signal-to-noise ratio increase in carotid atheroma MRI: a comparison of 1.5 and 3 T. Br J Radiol 2012; 85:937-44. [PMID: 22294703 DOI: 10.1259/bjr/70496948] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVES This study reports quantitative comparisons of signal-to-noise ratio (SNR) at 1.5 and 3 T from images of carotid atheroma obtained using a multicontrast, cardiac-gated, blood-suppressed fast spin echo protocol. METHODS 18 subjects, with carotid atherosclerosis (>30% stenosis) confirmed on ultrasound, were imaged on both 1.5 and 3 T systems using phased-array coils with matched hardware specifications. T(1) weighted (T(1)W), T(2) weighted (T(2)W) and proton density-weighted (PDW) images were acquired with identical scan times. Multiple slices were prescribed to encompass both the carotid bifurcation and the plaque. Image quality was quantified using the SNR and contrast-to-noise ratio (CNR). A phantom experiment was also performed to validate the SNR method and confirm the size of the improvement in SNR. Comparisons of the SNR values from the vessel wall with muscle and plaque/lumen CNR measurements were performed at a patient level. To account for the multiple comparisons a Bonferroni correction was applied. RESULTS One subject was excluded from the protocol owing to image quality and protocol failure. The mean improvement in SNR in plaque was 1.9, 2.1 and 2.1 in T(1)W, T(2)W and PDW images, respectively. All plaque SNR improvements were statistically significant at the p<0.05 level. The phantom experiment reported an improvement in SNR of 2.4 for PDW images. CONCLUSIONS Significant gains in SNR can be obtained for carotid atheroma imaging at 3 T compared with 1.5 T. There was also a trend towards increased CNR. However, this was not significant after the application of the Bonferroni correction.
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Affiliation(s)
- V E Young
- Department of Radiology, Addenbrookes Hospital, Cambridge, UK.
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SHIMADA K, NAGASAKA T, SHIDAHARA M, MACHIDA Y, TAMURA H. In vivo Measurement of Longitudinal Relaxation Time of Human Blood by Inversion-recovery Fast Gradient-echo MR Imaging at 3T. Magn Reson Med Sci 2012; 11:265-71. [DOI: 10.2463/mrms.11.265] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Lee JJ, Liu S, Nacif MS, Ugander M, Han J, Kawel N, Sibley CT, Kellman P, Arai AE, Bluemke DA. Myocardial T1 and extracellular volume fraction mapping at 3 tesla. J Cardiovasc Magn Reson 2011; 13:75. [PMID: 22123333 PMCID: PMC3269374 DOI: 10.1186/1532-429x-13-75] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 11/28/2011] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND To compare 11 heartbeat (HB) and 17 HB modified lock locker inversion recovery (MOLLI) pulse sequence at 3T and to establish preliminary reference values for myocardial T1 and the extracellular volume fraction (ECV). METHODS Both phantoms and normal volunteers were scanned at 3T using 11 HB and 17 HB MOLLI sequence with the following parameters: spatial resolution = 1.75 × 1.75 × 10 mm on a 256 × 180 matrix, TI initial = 110 ms, TI increment = 80 ms, flip angle = 35°, TR/TE = 1.9/1.0 ms. All volunteers were administered Gadolinium-DTPA (Magnevist, 0.15 mmol/kg), and multiple post-contrast MOLLI scans were performed at the same pre-contrast position from 3.5-23.5 minutes after a bolus contrast injection. Late gadolinium enhancement (LGE) images were also acquired 12-30 minutes after the gadolinium bolus. RESULTS T1 values of 11 HB and 17 HB MOLLI displayed good agreement in both phantom and volunteers. The average pre-contrast myocardial and blood T1 was 1315 ± 39 ms and 2020 ± 129 ms, respectively. ECV was stable between 8.5 to 23.5 minutes post contrast with an average of 26.7 ± 1.0%. CONCLUSION The 11 HB MOLLI is a faster method for high-resolution myocardial T1 mapping at 3T. ECV fractions are stable over a wide time range after contrast administration.
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Affiliation(s)
- Jason J Lee
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD, USA
| | - Songtao Liu
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD, USA
- Molecular Biomedical Imaging Laboratory, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD, USA
| | - Marcelo S Nacif
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD, USA
| | - Martin Ugander
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Jing Han
- U.S. Food and Drug Administration, Rockville, MD, USA
| | - Nadine Kawel
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD, USA
| | - Christopher T Sibley
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD, USA
- Molecular Biomedical Imaging Laboratory, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD, USA
| | - Peter Kellman
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Andrew E Arai
- Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - David A Bluemke
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD, USA
- Molecular Biomedical Imaging Laboratory, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD, USA
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Yuan J, Chow SKK, King AD, Yeung DKW. Heuristic linear mapping of physiological parameters in dynamic contrast-enhanced MRI without T₁ measurement and contrast agent concentration. J Magn Reson Imaging 2011; 35:916-25. [PMID: 22095582 DOI: 10.1002/jmri.22885] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Accepted: 10/11/2011] [Indexed: 12/20/2022] Open
Abstract
PURPOSE To present a novel heuristic linear mapping method to individually estimate physiological parameters for Tofts model without T(1) measurement and contrast agent concentration. MATERIALS AND METHODS A linear relationship was used for k(ep) mapping through a heuristic time intensity curve (TIC) shape factor (TSF). K(trans) maps were subsequently estimated using k(ep) maps and another approximate linear model derived from the Tofts model. Twenty-seven patients with head-and-neck squamous cell carcinoma received dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Physiological parameters maps were obtained using this heuristic linear mapping method and compared to the maps obtained by the normal nonlinear least-square fitting with T(1) measurement. RESULTS High linearity (R(2) >0.95) between k(ep) and TSF was found in all patients for k(ep) <5/min. This linearity is robust for TSF timepoint selection. The k(ep) maps generated by this linear fitting were highly consistent with those by the normal nonlinear approach (P > 0.05). The K(trans) maps were consistent with the normally derived maps in pattern distribution but the absolute value might be scaled due to the assumption of the reference K(trans) value. CONCLUSION This novel method generates reliable and consistent physiological parameter maps with significantly lower computation complexity than the multiparameter nonlinear fitting. The DCE-MRI scan time can be greatly shortened without T(1) mapping.
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Affiliation(s)
- Jing Yuan
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong, China.
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Smith TB, Nayak KS. Reduced field of view MRI with rapid, B1-robust outer volume suppression. Magn Reson Med 2011; 67:1316-23. [PMID: 22083545 DOI: 10.1002/mrm.23116] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 06/15/2011] [Accepted: 07/05/2011] [Indexed: 11/08/2022]
Abstract
MRI scans are inefficient when the size of the anatomy under investigation is small relative to the subject's full extent. The field of view must be expanded, and acquisition times accordingly prolonged. Shorter scans are feasible with reduced field of view imaging (rFOV) using outer volume suppression (OVS), a magnetization preparation sequence that attenuates signal outside a region of interest (ROI). This work presents a new OVS sequence with a cylindrical ROI, short duration, and improved tolerance for B(1)+ inhomogeneity. The sequence consists of a nonselective adiabatic tipdown pulse, which provides B(1)+-robust signal suppression, and a fast 2D spiral cylindrical tipback pulse. Analysis of the Bloch equations with transverse initial magnetization reveals a conjugate symmetric constraint for tipback pulses with small flip angles. This property is exploited to achieve two-shot performance from the single-shot tipback pulse. The OVS sequence is validated in phantoms and in vivo with multislice spiral imaging at 3 T. The relative signal-to-noise ratio efficiency of the proposed sequence was 98% in a phantom and 75-90% in vivo. The effectiveness is demonstrated with cardiovascular rFOV imaging, which exhibits improved resolution and reduced artifacts compared to conventional, full field of view imaging.
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Affiliation(s)
- Travis B Smith
- Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089-2564, USA.
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Use of 2D sensitivity encoding for slow-infusion contrast-enhanced isotropic 3-T whole-heart coronary MR angiography. AJR Am J Roentgenol 2011; 197:374-82. [PMID: 21785083 DOI: 10.2214/ajr.10.5724] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The purpose of this study was to improve the blood-pool signal-to-noise ratio (SNR) and blood-myocardium contrast-to-noise ratio (CNR) of slow-infusion 3-T whole-heart coronary MR angiography (MRA). SUBJECTS AND METHODS In 2D sensitivity encoding (SENSE), the number of acquired k-space lines is reduced, allowing less radiofrequency excitation per cardiac cycle and a longer TR. The former can be exploited for signal enhancement with a higher radiofrequency excitation angle, and the latter leads to noise reduction due to lower data-sampling bandwidth. Both effects contribute to SNR gain in coronary MRA when spatial and temporal resolution and acquisition time remain identical. Numeric simulation was performed to select the optimal 2D SENSE pulse sequence parameters and predict the SNR gain. Eleven patients underwent conventional unenhanced and the proposed 2D SENSE contrast-enhanced coronary MRA acquisition. Blood-pool SNR, blood-myocardium CNR, visible vessel length, vessel sharpness, and number of side branches were evaluated. RESULTS Consistent with the numeric simulation, using 2D SENSE in contrast-enhanced coronary MRA resulted in significant improvement in aortic blood-pool SNR (unenhanced vs contrast-enhanced, 37.5 ± 14.7 vs 121.3 ± 44.0; p < 0.05) and CNR (14.4 ± 6.9 vs 101.5 ± 40.8; p < 0.05) in the patient sample. A longer length of left anterior descending coronary artery was visualized, but vessel sharpness, coronary artery coverage, and image quality score were not improved with the proposed approach. CONCLUSION In combination with contrast administration, 2D SENSE was found effective in improving SNR and CNR in 3-T whole-heart coronary MRA. Further investigation of cardiac motion compensation is necessary to exploit the SNR and CNR advantages and to achieve submillimeter spatial resolution.
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Constantinides C, Angeli S, Gkagkarellis S, Cofer G. INTERCOMPARISON OF PERFORMANCE OF RF COIL GEOMETRIES FOR HIGH FIELD MOUSE CARDIAC MRI. CONCEPTS IN MAGNETIC RESONANCE. PART A, BRIDGING EDUCATION AND RESEARCH 2011. [PMID: 23204945 PMCID: PMC3508705 DOI: 10.1002/cmr.a.20225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Multi-turn spiral surface coils are constructed in flat and cylindrical arrangements and used for high field (7.1 T) mouse cardiac MRI. Their electrical and imaging performances, based on experimental measurements, simulations, and MRI experiments in free space, and under phantom, and animal loading conditions, are compared with a commercially available birdcage coil. Results show that the four-turn cylindrical spiral coil exhibits improved relative SNR (rSNR) performance to the flat coil counterpart, and compares fairly well with a commercially available birdcage coil. Phantom experiments indicate a 50% improvement in the SNR for penetration depths ≤ 6.1 mm from the coil surface compared to the birdcage coil, and an increased penetration depth at the half-maximum field response of 8 mm in the 4-spiral cylindrical coil case, in contrast to 2.9 mm in the flat 4-turn spiral case. Quantitative comparison of the performance of the two spiral coil geometries in anterior, lateral, inferior, and septal regions of the murine heart yield maximum mean percentage rSNR increases of the order of 27-167% in vivo post-mortem (cylindrical compared to flat coil). The commercially available birdcage outperforms the cylindrical spiral coil in rSNR by a factor of 3-5 times. The comprehensive approach and methodology adopted to accurately design, simulate, implement, and test radiofrequency coils of any geometry and type, under any loading conditions, can be generalized for any application of high field mouse cardiac MRI.
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Affiliation(s)
| | - S. Angeli
- Department of Mechanical and Manufacturing Engineering, School of Engineering, University of Cyprus
| | - S. Gkagkarellis
- Department of Mechanical and Manufacturing Engineering, School of Engineering, University of Cyprus
| | - G. Cofer
- Center for In Vivo Microscopy at Duke University Medical Center, Durham, NC, USA
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Hays AG, Schär M, Kelle S. Clinical applications for cardiovascular magnetic resonance imaging at 3 tesla. Curr Cardiol Rev 2011; 5:237-42. [PMID: 20676283 PMCID: PMC2822147 DOI: 10.2174/157340309788970351] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 03/18/2009] [Accepted: 03/19/2009] [Indexed: 12/03/2022] Open
Abstract
Cardiovascular magnetic resonance (CMR) imaging has evolved rapidly and is now accepted as a powerful diagnostic tool with significant clinical and research applications. Clinical 3 Tesla (3 T) scanners are increasingly available and offer improved diagnostic capabilities compared to 1.5 T scanners for perfusion, viability, and coronary imaging. Although technical challenges remain for cardiac imaging at higher field strengths such as balanced steady state free precession (bSSFP) cine imaging, the majority of cardiac applications are feasible at 3 T with comparable or superior image quality to that of 1.5 T. This review will focus on the benefits and limitations of 3 T CMR for common clinical applications and examine areas in development for potential clinical use.
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Affiliation(s)
- Allison G Hays
- Department of Medicine, Division of Cardiology, Johns Hopkins University, Baltimore, Maryland, USA
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Breton E, Kim D, Chung S, Axel L. Quantitative contrast-enhanced first-pass cardiac perfusion MRI at 3 tesla with accurate arterial input function and myocardial wall enhancement. J Magn Reson Imaging 2011; 34:676-84. [PMID: 21761467 DOI: 10.1002/jmri.22647] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 04/08/2011] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To develop, and validate in vivo, a robust quantitative first-pass perfusion cardiovascular MR (CMR) method with accurate arterial input function (AIF) and myocardial wall enhancement. MATERIALS AND METHODS A saturation-recovery (SR) pulse sequence was modified to sequentially acquire multiple slices after a single nonselective saturation pulse at 3 Tesla. In each heartbeat, an AIF image is acquired in the aortic root with a short time delay (TD) (50 ms), followed by the acquisition of myocardial images with longer TD values (∼150-400 ms). Longitudinal relaxation rates (R(1) = 1/T(1)) were calculated using an ideal saturation recovery equation based on the Bloch equation, and corresponding gadolinium contrast concentrations were calculated assuming fast water exchange condition. The proposed method was validated against a reference multi-point SR method by comparing their respective R(1) measurements in the blood and left ventricular myocardium, before and at multiple time-points following contrast injections, in 7 volunteers. RESULTS R(1) measurements with the proposed method and reference multi-point method were strongly correlated (r > 0.88, P < 10(-5)) and in good agreement (mean difference ±1.96 standard deviation 0.131 ± 0.317/0.018 ± 0.140 s(-1) for blood/myocardium, respectively). CONCLUSION The proposed quantitative first-pass perfusion CMR method measured accurate R(1) values for quantification of AIF and myocardial wall contrast agent concentrations in 3 cardiac short-axis slices, in a total acquisition time of 523 ms per heartbeat.
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Affiliation(s)
- Elodie Breton
- New York University Langone Medical Center, New York, NY 10016, USA
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Rial B, Robson MD, Neubauer S, Schneider JE. Rapid quantification of myocardial lipid content in humans using single breath-hold 1H MRS at 3 Tesla. Magn Reson Med 2011; 66:619-24. [PMID: 21721038 PMCID: PMC3427889 DOI: 10.1002/mrm.23011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 04/25/2011] [Accepted: 04/28/2011] [Indexed: 01/03/2023]
Abstract
A rapid, proton magnetic resonance spectroscopy method to evaluate human myocardial lipid levels in a single breath-hold at 3 T using a commercial whole-body system is presented. During a 10 s breath-hold, water unsuppressed and suppressed spectra were acquired by two phased array coils using a short-echo time spectroscopic stimulated echo (STEAM) sequence electrocardiogram-triggered to mid-diastole. Lipid-to-water ratios were obtained in the septum of 15 healthy volunteers, (0.46 ± 0.19)%. These results agreed well with ratios obtained from averaged spectra acquired in seven multiple breath-holds, (0.45 ± 0.20)%, providing increased signal-to-noise ratio but requiring longer acquisition times. Excellent correlation was found between the two methods (r = 0.94, P < 0.05). Reproducibility of 1H MRS for measuring myocardial lipid levels in a short breath-hold was acceptable in five repeated measurements within the same subject (coefficient of variation = 19%). Thus, single breath-hold proton spectroscopy allows reliable and quick quantification of myocardial lipids at 3 T. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.
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Affiliation(s)
- Belen Rial
- Department of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom
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Brandts A, Westenberg JJM, Versluis MJ, Kroft LJM, Smith NB, Webb AG, de Roos A. Quantitative assessment of left ventricular function in humans at 7 T. Magn Reson Med 2011; 64:1471-7. [PMID: 20593368 DOI: 10.1002/mrm.22529] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The purpose of this study was to determine the ability of 7 T cardiac magnetic resonance imaging (MRI) to quantitatively assess left ventricular volumes, mass, and function from cine short-axis series and left ventricular diastolic filling from velocity-encoded MRI in 10 healthy volunteers. As comparative "gold standard," the corresponding measures obtained at 1.5 T were taken. Left ventricular volumes, function, and mass were obtained by manual image segmentation. Trans-mitral flow graphs were obtained from 2D one-directional through-plane velocity-encoded MRI planned at the mitral valve in end-systole. Imaging at 7 T MRI was successful in 80% of the examinations. Assessment of left ventricular volumes, function, and mass at 7 T showed good agreement with 1.5 T (no significant differences between variables describing volumes, function, and mass with intraclass correlation coefficients ranging from 0.77 to 0.96). Trans-mitral stroke volume and the ratio between early and atrial peak filling rate showed strong agreement at both field strengths (no significant differences between stroke volumes and filling ratios with intraclass correlation coefficients 0.92 for stroke volumes and 0.77 for peak filling ratios). In conclusion, this study shows that assessing left ventricular volumes, function, and flow is feasible at 7 T MRI and that standardized MRI protocols provide similar quantitative results when compared with 1.5 T MRI.
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Affiliation(s)
- Anne Brandts
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
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Wang J, Ferguson MS, Balu N, Yuan C, Hatsukami TS, Börnert P. Improved carotid intraplaque hemorrhage imaging using a slab-selective phase-sensitive inversion-recovery (SPI) sequence. Magn Reson Med 2011; 64:1332-40. [PMID: 20597120 DOI: 10.1002/mrm.22539] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Intraplaque hemorrhage in atherosclerotic plaques has been associated with accelerated plaque growth as well as exacerbation of clinical symptoms. The identification of intraplaque hemorrhage using magnetic resonance imaging primarily relies on the detection of methemoglobin on T(1) weighted images. Current techniques are limited by insufficient intraplaque hemorrhage-wall contrast and poor blood suppression. In this study, a slab-selective phase-sensitive inversion-recovery (SPI) technique is proposed by combining a phase-sensitive reconstruction with a T(1) weighted sequence specifically designed to achieve improved intraplaque hemorrhage imaging. The SPI sequence was optimized and then used on ex vivo plaque specimens for histology based validation and intraplaque hemorrhage-wall contrast-to-noise ratio comparison with magnetization-prepared 3D rapid acquisition gradient echo MP-RAGE. SPI and MP-RAGE were also tested on a group of atherosclerosis patients to compare in vivo intraplaque hemorrhage-wall contrast-to-noise ratio and blood suppression effectiveness. On ex vivo specimens SPI had better intraplaque hemorrhage identification accuracy and a significantly higher intraplaque hemorrhage-wall contrast-to-noise ratio (P = 0.01) than MP-RAGE. Similar results were found in the in vivo test: Slab-selective phase-sensitive inversion-recovery provided a significantly improved intraplaque hemorrhage-wall contrast-to-noise ratio (P < 0.01) and blood suppression efficiency (P < 0.01). In conclusion, SPI is a novel technique optimized for intraplaque hemorrhage detection and validated against histology. It has demonstrated its capability for improved in vivo intraplaque hemorrhage identification and blood suppression in atherosclerosis patients.
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Affiliation(s)
- Jinnan Wang
- Clinical Sites Research Program, Philips Research North America, Briarcliff Manor, Seattle, WA 98109, USA.
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Zhu DC, Vu AT, Ota H, DeMarco JK. An optimized 3D spoiled gradient recalled echo pulse sequence for hemorrhage assessment using inversion recovery and multiple echoes (3D SHINE) for carotid plaque imaging. Magn Reson Med 2011; 64:1341-51. [PMID: 20574968 DOI: 10.1002/mrm.22517] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Intraplaque hemorrhage into the carotid atherosclerotic plaque has been shown to create instability and progression. We have developed an optimized 3D Spoiled Gradient recalled echo pulse sequence for Hemorrhage assessment using INversion recovery and multiple Echoes (3D SHINE) for carotid plaque imaging. The sequence was developed by incorporating multiecho acquisition to its clinically validated optimized single-echo counterpart 3D inversion recovery prepared fast spoiled gradient recalled sequence. With similar scan time (4 min), 3D spoiled gradient recalled echo pulse sequence for hemorrhage assessment using inversion recovery and multiple echoes maintained comparable high-resolution volumetric coverage, black-blood effect, contrast, signal-to-noise and contrast-to-noise ratios, and similar sensitivity and specificity in detecting whether intraplaque hemorrhage was present on an artery. The multiple echoes acquired with 3D SHINE allowed the estimation of intraplaque hemorrhage T*(2) and then the subsequent characterization of intraplaque hemorrhage (T*(2) for type I < 14 msec, and for type II > 14 msec). The type I intraplaque hemorrhage size estimated by 3D SHINE was significantly and positively correlated with the size estimated manually by an expert reviewer using the histology-validated multicontrast MRI technique (r = 0.836 ± 0.080, p < 0.001). With only one fast sequence, 3D SHINE can detect and characterize intraplaque hemorrhage that has previously required a multicontrast approach using a combination of black-blood T(1)-weighted, black-blood T(2)-weighted, and time-of-flight imaging techniques.
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Affiliation(s)
- David C Zhu
- Department of Radiology, Michigan State University, East Lansing, Michigan 48824, USA.
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Song R, Loeffler RB, Hillenbrand CM. Improved renal perfusion measurement with a dual navigator-gated Q2TIPS fair technique. Magn Reson Med 2011; 64:1352-9. [PMID: 20593428 DOI: 10.1002/mrm.22532] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A dual navigator-gated, flow-sensitive alternating inversion recovery (FAIR) true fast imaging with steady precession (True-FISP) sequence has been developed for accurate quantification of renal perfusion. FAIR methods typically overestimate renal perfusion when respiratory motion causes the inversion slice to move away from the imaging slice, which then incorporates unlabeled spins from static tissue. To overcome this issue, the dual navigator scheme was introduced to track inversion and imaging slices, and thus to ensure the same position for both slices. Accuracy was further improved by a well-defined bolus length, which was achieved by a modification version of Q2TIPS (quantitative imaging of perfusion using a single subtraction, second version with interleaved thin-slice TI(1) periodic saturation): a series of saturation pulses was applied to both sides of the imaging slice at a certain time after the inversion. The dual navigator-gated technique was tested in eight volunteers. The measured renal cortex perfusion rates were between 191 and 378 mL/100 g/min in the renal cortex with a mean of 376 mL/100 g/min. The proposed technique may prove most beneficial for noncontrast-based renal perfusion quantification in young children and patients who may have difficulty holding their breath for prolonged periods or are sedated/anesthetized.
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Affiliation(s)
- Ruitian Song
- Department of Radiological Sciences, Division of Translational Imaging Research, St. Jude Children's Research Hospital, Memphis, Tennessee 38105-3678, USA
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Wu WC, Jain V, Li C, Giannetta M, Hurt H, Wehrli FW, Wang DJJ. In vivo venous blood T1 measurement using inversion recovery true-FISP in children and adults. Magn Reson Med 2011; 64:1140-7. [PMID: 20564586 DOI: 10.1002/mrm.22484] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A time-efficient method is described for in vivo venous blood T(1) measurement using multiphase inversion-recovery-prepared balanced steady-state free precession imaging. Computer simulations and validation experiments using a flow phantom were carried out to demonstrate the accuracy of the proposed method for measuring blood T(1) by taking advantage of the continuous inflow of fresh blood with longitudinal magnetization undisturbed by previous radiofrequency pulses. In vivo measurement of venous blood T(1) in the sagittal sinus was carried out in 26 healthy children and adults aged 7-39 years. The measured venous blood T(1) values decreased with age as a whole (P = 0.006) and were higher in females than males (P = 0.013), matching the expected developmental changes and gender differences in human hematocrit level. The estimated mean blood T(1) values were highly correlated with normal hematocrit levels across age and gender groups (Spearman's r = 0.93, P = 0.008). The longitudinal repeatability of this technique was 4.0% as measured by the within-subject coefficient of variation. The proposed multiphase inversion recovery-prepared balanced steady-state free precession imaging method is a feasible technique for fast (< 1 min) and reliable in vivo venous blood T(1) measurement and may serve as an index of hematocrit level in individual subjects.
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Affiliation(s)
- Wen-Chau Wu
- Graduate Institute of Oncology, National Taiwan University, Taipei 100, Taiwan, Republic of China
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Chung S, Kim D, Breton E, Axel L. Rapid B1+ mapping using a preconditioning RF pulse with TurboFLASH readout. Magn Reson Med 2011; 64:439-46. [PMID: 20665788 DOI: 10.1002/mrm.22423] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In MRI, the transmit radiofrequency field (B(1)(+)) inhomogeneity can lead to signal intensity variations and quantitative measurement errors. By independently mapping the local B(1)(+) variation, the radiofrequency-related signal variations can be corrected for. In this study, we present a new fast B(1)(+) mapping method using a slice-selective preconditioning radiofrequency pulse. Immediately after applying a slice-selective preconditioning pulse, a turbo fast low-angle-shot imaging sequence with centric k-space reordering is performed to capture the residual longitudinal magnetization left behind by the slice-selective preconditioning pulse due to B(1)(+) variation. Compared to the reference double-angle method, this method is considerably faster. Specifically, the total scan time for the double-angle method is equal to the product of 2 (number of images), the number of phase-encoding lines, and approximately 5T(1), whereas the slice-selective preconditioning method takes approximately 5T(1). This method was validated in vitro and in vivo with a 3-T whole-body MRI system. The combined brain and pelvis B(1)(+) measurements showed excellent agreement and strong correlation with those by the double-angle method (mean difference = 0.025; upper and lower 95% limits of agreement were -0.07 and 0.12; R = 0.93; P < 0.001). This fast B(1)(+) mapping method can be used for a variety of applications, including body imaging where fast imaging is desirable.
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Affiliation(s)
- Sohae Chung
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, New York, New York, USA
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Dong L, Wang J, Yarnykh VL, Underhill HR, Neradilek MB, Polissar N, Hatsukami TS, Yuan C. Efficient flow suppressed MRI improves interscan reproducibility of carotid atherosclerosis plaque burden measurements. J Magn Reson Imaging 2010; 32:452-8. [PMID: 20677277 DOI: 10.1002/jmri.22274] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To determine if better flow suppression can meaningfully improve the reproducibility of measurements associated with carotid atherosclerotic disease, particularly for lumen and wall areas. MATERIALS AND METHODS Eighteen subjects with carotid artery stenosis identified by duplex ultrasound (11 with 16%-49% stenosis; 7 with 50%-79% stenosis) underwent two carotid magnetic resonance imaging (MRI) examinations on a 3T scanner with a 4-channel phased array coil. High-resolution intermediate-weighted TSE (TR/TE = 4000/8.5 msec, 0.55 mm in-plane resolution, 2 mm slice thickness, 16 slices, 3-minute scan time) with two different flow-suppression techniques (multislice double inversion recovery [mDIR] and motion-sensitized driven-equilibrium [MSDE]) were obtained separately. For each subject, bilateral arteries were reviewed. One radiologist blinded to timepoints, flow suppression techniques, and clinical information measured the arterial lumen area, wall area, and total vessel wall area. RESULTS Compared to mDIR, the MSDE technique had a smaller interscan standard deviation (SD) in lumen (SD: 3.6 vs. 5.2 mm(2), P = 0.02), wall area measurements (SD: 4.5 vs. 6.4 mm(2), P = 0.02), and a trend towards smaller SD in total vessel area measurement (SD: 4.4 vs. 4.9 mm(2), P = 0.07). CONCLUSION The results from this study demonstrate that vessel wall imaging could quantify atherosclerotic plaque measurements more reliably with an improved blood suppression technique. This relationship between flow-suppression efficiency and reproducibility of plaque measurements is important, as more reliable area measurements will be useful in clinical diagnosis and in serial MRI studies that monitor carotid atherosclerotic lesion progression and regression.
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Affiliation(s)
- Li Dong
- Department of Radiology, University of Washington, Seattle, Washington 98109, USA
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Lee HL, Shankaranarayanan A, Pohost GM, Nayak KS. Improved 3-Tesla cardiac cine imaging using wideband. Magn Reson Med 2010; 63:1716-22. [PMID: 20512877 DOI: 10.1002/mrm.22384] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cine balanced steady-state free precession (SSFP) is the most widely used sequence for assessing cardiac ventricular function at 1.5 T because it provides high signal-to-noise ratio efficiency and strong contrast between myocardium and blood. At 3 T, the use of SSFP is limited by susceptibility-induced off-resonance, resulting in either banding artifacts or the need to use a short-sequence pulse repetition time that limits the readout duration and hence the achievable spatial resolution. In this work, we apply wideband SSFP, a variant of SSFP that uses two alternating pulse repetition times to establish a steady state with wider band spacing in its frequency response and overcome the key limitations of SSFP. Prospectively gated cine two-dimensional imaging with wideband SSFP is evaluated in healthy volunteers and compared to conventional balanced SSFP, using quantitative metrics and qualitative interpretation by experienced clinicians. We demonstrate that by trading off temporal resolution and signal-to-noise ratio efficiency, wideband SSFP mitigates banding artifacts and enables imaging with approximately 30% higher spatial resolution compared to conventional SSFP with the same effective band spacing.
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Affiliation(s)
- Hsu-Lei Lee
- Magnetic Resonance Engineering Laboratory, Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, California, USA.
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49
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Breton E, McGorty K, Wiggins GC, Axel L, Kim D. Image-guided radio-frequency gain calibration for high-field MRI. NMR IN BIOMEDICINE 2010; 23:368-374. [PMID: 20014333 PMCID: PMC2988285 DOI: 10.1002/nbm.1471] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 09/02/2009] [Accepted: 09/27/2009] [Indexed: 05/28/2023]
Abstract
High-field (≥ 3T) MRI provides a means to increase the signal-to-noise ratio, due to its higher tissue magnetization compared with 1.5T. However, both the static magnetic field (B(0)) and the transmit radio-frequency (RF) field (B 1+) inhomogeneities are comparatively higher at higher field strengths than those at 1.5T. These challenging factors at high-field strengths make it more difficult to accurately calibrate the transmit RF gain using standard RF calibration procedures. An image-based RF calibration procedure was therefore developed, in order to accurately calibrate the transmit RF gain within a specific region-of-interest (ROI). Using a turbo fast low-angle shot (TurboFLASH) pulse sequence with centric k-space reordering, a series of 'saturation-no-recovery' images was acquired by varying the flip angle of the preconditioning pulse. In the resulting images, the signal null occurs in regions where the flip angle of the preconditioning pulse is 90°. For a given ROI, the mean signal can be plotted as a function of the nominal flip angle, and the resulting curve can be used to quantitatively identify the signal null. This image-guided RF calibration procedure was evaluated through phantom and volunteer imaging experiments at 3T and 7T. The image-guided RF calibration results in vitro were consistent with standard B(0) and B 1+ maps. The standard automated RF calibration procedure produced approximately 20% and 15-30% relative error in the transmit RF gain in the left kidney at 3T and brain at 7T, respectively. For initial application, a T(2) mapping pulse sequence was applied at 7T. The T(2) measurements in the thalamus at 7T were 60.6 ms and 48.2 ms using the standard and image-guided RF calibration procedures, respectively. This rapid, image-guided RF calibration procedure can be used to optimally calibrate the flip angle for a given ROI and thus minimize measurement errors for quantitative MRI and MR spectroscopy.
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Affiliation(s)
- Elodie Breton
- Department of Radiology, Center for Biomedical Imaging, New York University School of Medicine, NY, USA
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50
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Schär M, Vonken EJ, Stuber M. Simultaneous B(0)- and B(1)+-map acquisition for fast localized shim, frequency, and RF power determination in the heart at 3 T. Magn Reson Med 2010; 63:419-26. [PMID: 20099330 DOI: 10.1002/mrm.22234] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
High-field (>or=3 T) cardiac MRI is challenged by inhomogeneities of both the static magnetic field (B(0)) and the transmit radiofrequency field (B(1)+). The inhomogeneous B fields not only demand improved shimming methods but also impede the correct determination of the zero-order terms, i.e., the local resonance frequency f(0) and the radiofrequency power to generate the intended local B(1)+ field. In this work, dual echo time B(0)-map and dual flip angle B(1)+-map acquisition methods are combined to acquire multislice B(0)- and B(1)+-maps simultaneously covering the entire heart in a single breath hold of 18 heartbeats. A previously proposed excitation pulse shape dependent slice profile correction is tested and applied to reduce systematic errors of the multislice B(1)+-map. Localized higher-order shim correction values including the zero-order terms for frequency f(0) and radiofrequency power can be determined based on the acquired B(0)- and B(1)+-maps. This method has been tested in 7 healthy adult human subjects at 3 T and improved the B(0) field homogeneity (standard deviation) from 60 Hz to 35 Hz and the average B(1)+ field from 77% to 100% of the desired B(1)+ field when compared to more commonly used preparation methods.
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Affiliation(s)
- Michael Schär
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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