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Hamilton-Craig C, Stäeb D, Al Najjar A, O’Brien K, Crawford W, Fletcher S, Barth M, Galloway G. 7-Tesla Functional Cardiovascular MR Using Vectorcardiographic Triggering-Overcoming the Magnetohydrodynamic Effect. ACTA ACUST UNITED AC 2021; 7:323-332. [PMID: 34449723 PMCID: PMC8396263 DOI: 10.3390/tomography7030029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/14/2021] [Accepted: 06/19/2021] [Indexed: 11/16/2022]
Abstract
Objective: Ultra-high-field B0 ≥ 7 tesla (7T) cardiovascular magnetic resonance (CMR) offers increased resolution. However, electrocardiogram (ECG) gating is impacted by the magneto-hydrodynamic effect distorting the ECG trace. We explored the technical feasibility of a 7T magnetic resonance scanner using an ECG trigger learning algorithm to quantitatively assess cardiac volumes and vascular flow. Methods: 7T scans were performed on 10 healthy volunteers on a whole-body research MRI MR scanner (Siemens Healthineers, Erlangen, Germany) with 8 channel Tx/32 channels Rx cardiac coils (MRI Tools GmbH, Berlin, Germany). Vectorcardiogram ECG was performed using a learning phase outside of the magnetic field, with a trigger algorithm overcoming severe ECG signal distortions. Vectorcardiograms were quantitatively analyzed for false negative and false positive events. Cine CMR was performed after 3rd-order B0 shimming using a high-resolution breath-held ECG-retro-gated segmented spoiled gradient echo, and 2D phase contrast flow imaging. Artefacts were assessed using a semi-quantitative scale. Results: 7T CMR scans were acquired in all patients (100%) using the vectorcardiogram learning method. 3,142 R-waves were quantitatively analyzed, yielding sensitivity of 97.6% and specificity of 98.7%. Mean image quality score was 0.9, sufficient to quantitate both cardiac volumes, ejection fraction, and aortic and pulmonary blood flow. Mean left ventricular ejection fraction was 56.4%, right ventricular ejection fraction was 51.4%. Conclusion: Reliable cardiac ECG triggering is feasible in healthy volunteers at 7T utilizing a state-of-the-art three-lead trigger device despite signal distortion from the magnetohydrodynamic effect. This provides sufficient image quality for quantitative analysis. Other ultra-high-field imaging applications such as human brain functional MRI with physiologic noise correction may benefit from this method of ECG triggering.
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Affiliation(s)
- Christian Hamilton-Craig
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia; (D.S.); (A.A.N.); (W.C.); (S.F.); (M.B.); (G.G.)
- Correspondence:
| | - Daniel Stäeb
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia; (D.S.); (A.A.N.); (W.C.); (S.F.); (M.B.); (G.G.)
- MR Research Collaborations, Siemens Healthineers Pty Ltd., Bayswater, VIC 3153, Australia;
| | - Aiman Al Najjar
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia; (D.S.); (A.A.N.); (W.C.); (S.F.); (M.B.); (G.G.)
| | - Kieran O’Brien
- MR Research Collaborations, Siemens Healthineers Pty Ltd., Bayswater, VIC 3153, Australia;
| | - William Crawford
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia; (D.S.); (A.A.N.); (W.C.); (S.F.); (M.B.); (G.G.)
- Department of Medical Science, University of Oxford, Oxford 01865, UK
- School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, QLD 4000, Australia
| | - Sabine Fletcher
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia; (D.S.); (A.A.N.); (W.C.); (S.F.); (M.B.); (G.G.)
| | - Markus Barth
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia; (D.S.); (A.A.N.); (W.C.); (S.F.); (M.B.); (G.G.)
| | - Graham Galloway
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia; (D.S.); (A.A.N.); (W.C.); (S.F.); (M.B.); (G.G.)
- Imaging Technology, Translational Research Institute, Brisbane, QLD 4000, Australia
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Kofler A, Dewey M, Schaeffter T, Wald C, Kolbitsch C. Spatio-Temporal Deep Learning-Based Undersampling Artefact Reduction for 2D Radial Cine MRI With Limited Training Data. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:703-717. [PMID: 31403407 DOI: 10.1109/tmi.2019.2930318] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work we reduce undersampling artefacts in two-dimensional (2D) golden-angle radial cine cardiac MRI by applying a modified version of the U-net. The network is trained on 2D spatio-temporal slices which are previously extracted from the image sequences. We compare our approach to two 2D and a 3D deep learning-based post processing methods, three iterative reconstruction methods and two recently proposed methods for dynamic cardiac MRI based on 2D and 3D cascaded networks. Our method outperforms the 2D spatially trained U-net and the 2D spatio-temporal U-net. Compared to the 3D spatio-temporal U-net, our method delivers comparable results, but requiring shorter training times and less training data. Compared to the compressed sensing-based methods kt-FOCUSS and a total variation regularized reconstruction approach, our method improves image quality with respect to all reported metrics. Further, it achieves competitive results when compared to the iterative reconstruction method based on adaptive regularization with dictionary learning and total variation and when compared to the methods based on cascaded networks, while only requiring a small fraction of the computational and training time. A persistent homology analysis demonstrates that the data manifold of the spatio-temporal domain has a lower complexity than the one of the spatial domain and therefore, the learning of a projection-like mapping is facilitated. Even when trained on only one single subject without data-augmentation, our approach yields results which are similar to the ones obtained on a large training dataset. This makes the method particularly suitable for training a network on limited training data. Finally, in contrast to the spatial 2D U-net, our proposed method is shown to be naturally robust with respect to image rotation in image space and almost achieves rotation-equivariance where neither data-augmentation nor a particular network design are required.
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Bonanno G, Hays AG, Weiss RG, Schär M. Self-gated golden angle spiral cine MRI for coronary endothelial function assessment. Magn Reson Med 2018; 80:560-570. [PMID: 29282752 PMCID: PMC5910207 DOI: 10.1002/mrm.27060] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 12/01/2017] [Accepted: 12/05/2017] [Indexed: 01/28/2023]
Abstract
PURPOSE Depressed coronary endothelial function (CEF) is a marker for atherosclerotic disease, an independent predictor of cardiovascular events, and can be quantified non-invasively with ECG-triggered spiral cine MRI combined with isometric handgrip exercise (IHE). However, MRI-CEF measures can be hindered by faulty ECG-triggering, leading to prolonged breath-holds and degraded image quality. Here, a self-gated golden angle spiral method (SG-GA) is proposed to eliminate the need for ECG during cine MRI. METHODS SG-GA was tested against retrospectively ECG-gated golden angle spiral MRI (ECG-GA) and gold-standard ECG-triggered spiral cine MRI (ECG-STD) in 10 healthy volunteers. CEF data were obtained from cross-sectional images of the proximal right and left coronary arteries in a 3T scanner. Self-gating heart rates were compared to those from simultaneous ECG-gating. Coronary vessel sharpness and cross-sectional area (CSA) change with IHE were compared among the 3 methods. RESULTS Self-gating precision, accuracy, and correlation-coefficient were 7.7 ± 0.5 ms, 9.1 ± 0.7 ms, and 0.93 ± 0.01, respectively (mean ± standard error). Vessel sharpness by SG-GA was equal or higher than ECG-STD (rest: 63.0 ± 1.7% vs. 61.3 ± 1.3%; exercise: 62.6 ± 1.3% vs. 56.7 ± 1.6%, P < 0.05). CSA changes were in agreement among the 3 methods (ECG-STD = 8.7 ± 4.0%, ECG-GA = 9.6 ± 3.1%, SG-GA = 9.1 ± 3.5%, P = not significant). CONCLUSION CEF measures can be obtained with the proposed self-gated high-quality cine MRI method even when ECG is faulty or not available. Magn Reson Med 80:560-570, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Gabriele Bonanno
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD
- Division of MR Research, Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD
| | - Allison G. Hays
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD
| | - Robert G. Weiss
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD
- Division of MR Research, Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD
| | - Michael Schär
- Division of MR Research, Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD
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Coristine AJ, Chaptinel J, Ginami G, Bonanno G, Coppo S, van Heeswijk RB, Piccini D, Stuber M. Improved respiratory self-navigation for 3D radial acquisitions through the use of a pencil-beam 2D-T 2 -prep for free-breathing, whole-heart coronary MRA. Magn Reson Med 2018; 79:1293-1303. [PMID: 28568961 PMCID: PMC5931377 DOI: 10.1002/mrm.26764] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 05/01/2017] [Accepted: 05/03/2017] [Indexed: 12/26/2022]
Abstract
PURPOSE In respiratory self-navigation (SN), signal from static structures, such as the chest wall, may complicate motion detection or introduce post-correction artefacts. Suppressing signal from superfluous tissues may therefore improve image quality. We thus test the hypothesis that SN whole-heart coronary magnetic resonance angiography (MRA) will benefit from an outer-volume suppressing 2D-T2 -Prep and present both phantom and in vivo results. METHODS A 2D-T2 -Prep and a conventional T2 -Prep were used prior to a free-breathing 3D-radial SN sequence. Both techniques were compared by imaging a home-built moving cardiac phantom and by performing coronary MRA in nine healthy volunteers. Reconstructions were performed using both a reference-based and a reference-independent approach to motion tracking, along with several coil combinations. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared, along with vessel sharpness (VS). RESULTS In phantoms, using the 2D-T2 -Prep increased SNR by 16% to 53% and mean VS by 8%; improved motion tracking precision was also achieved. In volunteers, SNR increased by an average of 29% to 33% in the blood pool and by 15% to 25% in the myocardium, depending on the choice of reconstruction coils and algorithm, and VS increased by 34%. CONCLUSION A 2D-T2 -Prep significantly improves image quality in both phantoms and volunteers when performing SN coronary MRA. Magn Reson Med 79:1293-1303, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- A. J. Coristine
- Department of BioMedical Engineering, Case Western Reserve University (CWRU), Cleveland, Ohio, USA
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
| | - J. Chaptinel
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
| | - G. Ginami
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
| | - G. Bonanno
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
| | - S. Coppo
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
| | - R. B. van Heeswijk
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
| | - D. Piccini
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
- Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland
| | - M. Stuber
- Department of Radiology, University Hospital (CHUV) / University of Lausanne (UNIL), Lausanne, VD, Switzerland
- CardioVascular Magnetic Resonance (CVMR) research centre, Centre for BioMedical Imaging (CIBM), Lausanne, VD, Switzerland
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Küstner T, Schwartz M, Martirosian P, Gatidis S, Seith F, Gilliam C, Blu T, Fayad H, Visvikis D, Schick F, Yang B, Schmidt H, Schwenzer NF. MR-based respiratory and cardiac motion correction for PET imaging. Med Image Anal 2017; 42:129-144. [PMID: 28800546 DOI: 10.1016/j.media.2017.08.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 07/18/2017] [Accepted: 08/01/2017] [Indexed: 01/22/2023]
Abstract
PURPOSE To develop a motion correction for Positron-Emission-Tomography (PET) using simultaneously acquired magnetic-resonance (MR) images within 90 s. METHODS A 90 s MR acquisition allows the generation of a cardiac and respiratory motion model of the body trunk. Thereafter, further diagnostic MR sequences can be recorded during the PET examination without any limitation. To provide full PET scan time coverage, a sensor fusion approach maps external motion signals (respiratory belt, ECG-derived respiration signal) to a complete surrogate signal on which the retrospective data binning is performed. A joint Compressed Sensing reconstruction and motion estimation of the subsampled data provides motion-resolved MR images (respiratory + cardiac). A 1-POINT DIXON method is applied to these MR images to derive a motion-resolved attenuation map. The motion model and the attenuation map are fed to the Customizable and Advanced Software for Tomographic Reconstruction (CASToR) PET reconstruction system in which the motion correction is incorporated. All reconstruction steps are performed online on the scanner via Gadgetron to provide a clinically feasible setup for improved general applicability. The method was evaluated on 36 patients with suspected liver or lung metastasis in terms of lesion quantification (SUVmax, SNR, contrast), delineation (FWHM, slope steepness) and diagnostic confidence level (3-point Likert-scale). RESULTS A motion correction could be conducted for all patients, however, only in 30 patients moving lesions could be observed. For the examined 134 malignant lesions, an average improvement in lesion quantification of 22%, delineation of 64% and diagnostic confidence level of 23% was achieved. CONCLUSION The proposed method provides a clinically feasible setup for respiratory and cardiac motion correction of PET data by simultaneous short-term MRI. The acquisition sequence and all reconstruction steps are publicly available to foster multi-center studies and various motion correction scenarios.
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Affiliation(s)
- Thomas Küstner
- Institute of Signal Processing and System Theory, University of Stuttgart, Stuttgart, Germany; Department of Radiology, University of Tübingen, Tübingen, Germany.
| | - Martin Schwartz
- Institute of Signal Processing and System Theory, University of Stuttgart, Stuttgart, Germany; Section on Experimental Radiology, University of Tübingen, Germany
| | | | - Sergios Gatidis
- Department of Radiology, University of Tübingen, Tübingen, Germany
| | - Ferdinand Seith
- Department of Radiology, University of Tübingen, Tübingen, Germany
| | - Christopher Gilliam
- Department of Electronic Engineering, Chinese University of Hong Kong, Hong Kong
| | - Thierry Blu
- Department of Electronic Engineering, Chinese University of Hong Kong, Hong Kong
| | - Hadi Fayad
- INSERM U1101, LaTIM, University of Bretagne, Brest, France
| | | | - F Schick
- Section on Experimental Radiology, University of Tübingen, Germany
| | - B Yang
- Institute of Signal Processing and System Theory, University of Stuttgart, Stuttgart, Germany
| | - H Schmidt
- Department of Radiology, University of Tübingen, Tübingen, Germany
| | - N F Schwenzer
- Department of Radiology, University of Tübingen, Tübingen, Germany
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Abstract
BACKGROUND To develop a prospective cardiac motion self-gating method that provides robust and accurate cardiac triggers in real time. METHODS The proposed self-gating method consists of an "imaging mode" that acquires the k-space segments and a "self-gating mode" that captures the cardiac motion by repeatedly sampling the k-space centerline. A training based principal component analysis algorithm is utilized to process the self-gating data where the projection onto the first principal component was used as the self-gating signal. Retrospective studies using a sequence with self-gating mode only was performed on 8 healthy subjects to validate the accuracy and reliability of the self-gating triggers. Prospective studies using both ECG-gated and self-gated cardiac CINE sequences were conducted on 6 healthy subjects to compare the image quality. RESULTS Using the ECG as the reference, the proposed method was able to detect self-gating triggers within ±10 ms accuracy on all 8 subjects in the retrospective study. The prospectively self-gated CINE sequence successfully detected 100% of the cardiac triggers and provided excellent CINE image quality without using ECG signals. CONCLUSIONS The proposed cardiac self-gating method is a robust and accurate alternative to conventional ECG-based gating method for a number of cardiac MRI applications.
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Affiliation(s)
- Fei Han
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Stanislas Rapacchi
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Peng Hu
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Biomedical Physics Inter-Departmental Graduate Program, University of California, Los Angeles, CA, USA
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Yerly J, Ginami G, Nordio G, Coristine AJ, Coppo S, Monney P, Stuber M. Coronary endothelial function assessment using self-gated cardiac cine MRI andk-tsparse SENSE. Magn Reson Med 2015; 76:1443-1454. [DOI: 10.1002/mrm.26050] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/30/2015] [Accepted: 10/23/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Jérôme Yerly
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Giulia Ginami
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Giovanna Nordio
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Andrew J. Coristine
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Simone Coppo
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Pierre Monney
- Cardiac MR Center, Service of Cardiology; University Hospital of Lausanne; Lausanne Switzerland
| | - Matthias Stuber
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
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8
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Han F, Zhou Z, Rapacchi S, Nguyen KL, Finn JP, Hu P. Segmented golden ratio radial reordering with variable temporal resolution for dynamic cardiac MRI. Magn Reson Med 2015; 76:94-103. [PMID: 26243442 DOI: 10.1002/mrm.25861] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/29/2015] [Accepted: 07/06/2015] [Indexed: 12/26/2022]
Abstract
PURPOSE Golden ratio (GR) radial reordering allows for retrospective choice of temporal resolution by providing a near-uniform k-space sampling within any reconstruction window. However, when applying GR to electrocardiogram (ECG)-gated cardiac imaging, the k-space coverage may not be as uniform because a single reconstruction window is broken into several temporally isolated ones. The goal of this study was to investigate the image artifacts caused by applying GR to ECG-gated cardiac imaging and to propose a segmented GR method to address this issue. METHODS Computer simulation and phantom experiments were used to evaluate the image artifacts resulting from three k-space sampling patterns (ie, uniform radial, conventional GR, and segmented GR). Two- and three-dimensional cardiac cine images were acquired in seven healthy subjects. Imaging artifacts due to k-space sampling nonuniformity were graded on a 5-point scale by an experienced cardiac imaging reader. RESULTS Segmented GR provides more uniform k-space sampling that is independent of heart-rate variation than conventional GR. Cardiac cine images using segmented GR have significantly higher and more reliable image quality than conventional GR. CONCLUSION Segmented GR successfully addresses the nonuniform sampling that occurs with combining conventional GR with ECG gating. This technique can potentially be applied to any ECG-gated cardiac imaging application to allow for retrospective selection of a reconstruction window. Magn Reson Med 76:94-103, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Fei Han
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Ziwu Zhou
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Stanislas Rapacchi
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Kim-Lien Nguyen
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Division of Cardiology, VA Greater Los Angeles Healthcare System and David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - J Paul Finn
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Peng Hu
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Biomedical Physics Inter-Departmental Graduate Program, University of California, Los Angeles, California, USA
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Krämer M, Herrmann KH, Biermann J, Freiburger S, Schwarzer M, Reichenbach JR. Self-gated cardiac Cine MRI of the rat on a clinical 3 T MRI system. NMR IN BIOMEDICINE 2015; 28:162-167. [PMID: 25417764 DOI: 10.1002/nbm.3234] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 10/09/2014] [Accepted: 10/11/2014] [Indexed: 06/04/2023]
Abstract
The ability to perform small animal functional cardiac imaging on clinical MRI scanners may be of particular value in cases in which the availability of a dedicated high field animal MRI scanner is limited. Here, we propose radial MR cardiac imaging in the rat on a whole-body clinical 3 T scanner in combination with interspersed projection navigators for self-gating without any additional external triggering requirements for electrocardiogram (ECG) and respiration. Single navigator readouts were interspersed using the same TR and a high navigator frequency of 54 Hz into a radial golden-angle acquisition. The extracted navigator function was thresholded to exclude data for reconstruction from inhalation phases during the breathing cycle, enabling free breathing acquisition. To minimize flow artifacts in the dynamic cine images a center-out half echo radial acquisition scheme with ramp sampling was used. Navigator functions were derived from the corresponding projection navigator data from which both respiration and cardiac cycles were extracted. Self-gated cine acquisition resulted in high-quality cardiac images which were free of major artifacts with spatial resolution of up to 0.21 × 0.21 × 1.00 mm(3) and a contrast-to-noise ratio (CNR) of 21 ± 3 between the myocardium and left ventricle. Self-gated golden ratio based radial acquisition successfully acquired cine images of the rat heart on a clinical MRI system without the need for dedicated animal ECG equipment.
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Affiliation(s)
- Martin Krämer
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, D-07743, Jena, Germany
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Sharif B, Dharmakumar R, Arsanjani R, Thomson L, Merz CNB, Berman DS, Li D. Non-ECG-gated myocardial perfusion MRI using continuous magnetization-driven radial sampling. Magn Reson Med 2014; 72:1620-8. [PMID: 24443160 PMCID: PMC4102672 DOI: 10.1002/mrm.25074] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 10/31/2013] [Accepted: 11/17/2013] [Indexed: 01/18/2023]
Abstract
PURPOSE Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preliminary study is to evaluate whether, in the simple case of single-slice two-dimensional imaging, adequate myocardial contrast can be obtained for accurate visualization of hypoperfused territories in the setting of myocardial ischemia. METHODS A T1-weighted pulse sequence with continuous golden-angle radial sampling was developed for non-ECG-gated FPP imaging. A sliding-window scheme with no temporal acceleration was used to reconstruct 8 frames/s. Canines were imaged at 3T with and without coronary stenosis using the proposed scheme and a conventional magnetization-prepared ECG-gated FPP method. RESULTS Our studies showed that the proposed non-ECG-gated method is capable of generating high-resolution (1.7 × 1.7 × 6 mm(3) ) artifact-free FPP images of a single slice at high heart rates (92 ± 21 beats/min), while matching the performance of conventional FPP imaging in terms of hypoperfused-to-normal myocardial contrast-to-noise ratio (proposed: 5.18 ± 0.70, conventional: 4.88 ± 0.43). Furthermore, the detected perfusion defect areas were consistent with the conventional FPP images. CONCLUSION Non-ECG-gated FPP imaging using optimized continuous golden-angle radial acquisition achieves desirable image quality (i.e., adequate myocardial contrast, high spatial resolution, and minimal artifacts) in the setting of ischemia.
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Affiliation(s)
- Behzad Sharif
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Rohan Dharmakumar
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Reza Arsanjani
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Louise Thomson
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Barbra Streisand Women’s Heart Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - C. Noel Bairey Merz
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Barbra Streisand Women’s Heart Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Daniel S. Berman
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Debiao Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
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Usman M, Atkinson D, Kolbitsch C, Schaeffter T, Prieto C. Manifold learning based ECG-free free-breathing cardiac CINE MRI. J Magn Reson Imaging 2014; 41:1521-7. [DOI: 10.1002/jmri.24731] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 08/05/2014] [Indexed: 11/09/2022] Open
Affiliation(s)
- Muhammad Usman
- King's College London; Division of Imaging Sciences and Biomedical Engineering; British Heart Foundation (BHF) Centre of Excellence, Medical Engineering Centre of Research Excellence; London UK
| | - David Atkinson
- University College London, Centre for Medical Imaging; London UK
| | - Christoph Kolbitsch
- King's College London; Division of Imaging Sciences and Biomedical Engineering; British Heart Foundation (BHF) Centre of Excellence, Medical Engineering Centre of Research Excellence; London UK
| | - Tobias Schaeffter
- King's College London; Division of Imaging Sciences and Biomedical Engineering; British Heart Foundation (BHF) Centre of Excellence, Medical Engineering Centre of Research Excellence; London UK
| | - Claudia Prieto
- King's College London; Division of Imaging Sciences and Biomedical Engineering; British Heart Foundation (BHF) Centre of Excellence, Medical Engineering Centre of Research Excellence; London UK
- Pontificia Universidad Católica de Chile, Escuela de Ingeniería; Santiago Chile
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Ingle RR, Santos JM, Overall WR, McConnell MV, Hu BS, Nishimura DG. Self-gated fat-suppressed cardiac cine MRI. Magn Reson Med 2014; 73:1764-74. [PMID: 24806049 DOI: 10.1002/mrm.25291] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 04/15/2014] [Accepted: 04/23/2014] [Indexed: 11/08/2022]
Abstract
PURPOSE To develop a self-gated alternating repetition time balanced steady-state free precession (ATR-SSFP) pulse sequence for fat-suppressed cardiac cine imaging. METHODS Cardiac gating is computed retrospectively using acquired magnetic resonance self-gating data, enabling cine imaging without the need for electrocardiogram (ECG) gating. Modification of the slice-select rephasing gradients of an ATR-SSFP sequence enables the acquisition of a one-dimensional self-gating readout during the unused short repetition time (TR). Self-gating readouts are acquired during every TR of segmented, breath-held cardiac scans. A template-matching algorithm is designed to compute cardiac trigger points from the self-gating signals, and these trigger points are used for retrospective cine reconstruction. The proposed approach is compared with ECG-gated ATR-SSFP and balanced steady-state free precession in 10 volunteers and five patients. RESULTS The difference of ECG and self-gating trigger times has a variability of 13 ± 11 ms (mean ± SD). Qualitative reviewer scoring and ranking indicate no statistically significant differences (P > 0.05) between self-gated and ECG-gated ATR-SSFP images. Quantitative blood-myocardial border sharpness is not significantly different among self-gated ATR-SSFP ( 0.61±0.15 mm -1), ECG-gated ATR-SSFP ( 0.61±0.15 mm -1), or conventional ECG-gated balanced steady-state free precession cine MRI ( 0.59±0.15 mm -1). CONCLUSION The proposed self-gated ATR-SSFP sequence enables fat-suppressed cardiac cine imaging at 1.5 T without the need for ECG gating and without decreasing the imaging efficiency of ATR-SSFP.
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Affiliation(s)
- R Reeve Ingle
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
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