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Krahn PRP, Singh SM, Ramanan V, Biswas L, Yak N, Anderson KJT, Barry J, Pop M, Wright GA. Cardiovascular magnetic resonance guided ablation and intra-procedural visualization of evolving radiofrequency lesions in the left ventricle. J Cardiovasc Magn Reson 2018; 20:20. [PMID: 29544514 PMCID: PMC5856306 DOI: 10.1186/s12968-018-0437-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 02/15/2018] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Radiofrequency (RF) ablation has become a mainstay of treatment for ventricular tachycardia, yet adequate lesion formation remains challenging. This study aims to comprehensively describe the composition and evolution of acute left ventricular (LV) lesions using native-contrast cardiovascular magnetic resonance (CMR) during CMR-guided ablation procedures. METHODS RF ablation was performed using an actively-tracked CMR-enabled catheter guided into the LV of 12 healthy swine to create 14 RF ablation lesions. T2 maps were acquired immediately post-ablation to visualize myocardial edema at the ablation sites and T1-weighted inversion recovery prepared balanced steady-state free precession (IR-SSFP) imaging was used to visualize the lesions. These sequences were repeated concurrently to assess the physiological response following ablation for up to approximately 3 h. Multi-contrast late enhancement (MCLE) imaging was performed to confirm the final pattern of ablation, which was then validated using gross pathology and histology. RESULTS Edema at the ablation site was detected in T2 maps acquired as early as 3 min post-ablation. Acute T2-derived edematous regions consistently encompassed the T1-derived lesions, and expanded significantly throughout the 3-h period post-ablation to 1.7 ± 0.2 times their baseline volumes (mean ± SE, estimated using a linear mixed model determined from n = 13 lesions). T1-derived lesions remained approximately stable in volume throughout the same time frame, decreasing to 0.9 ± 0.1 times the baseline volume (mean ± SE, estimated using a linear mixed model, n = 9 lesions). CONCLUSIONS Combining native T1- and T2-based imaging showed that distinctive regions of ablation injury are reflected by these contrast mechanisms, and these regions evolve separately throughout the time period of an intervention. An integrated description of the T1-derived lesion and T2-derived edema provides a detailed picture of acute lesion composition that would be most clinically useful during an ablation case.
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Affiliation(s)
- Philippa R. P. Krahn
- Department of Medical Biophysics, University of Toronto, Toronto, ON Canada
- Sunnybrook Research Institute, Toronto, ON Canada
| | - Sheldon M. Singh
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, ON Canada
- Division of Cardiology, Schulich Heart Centre, Sunnybrook Health Sciences Centre, Toronto, ON Canada
- Faculty of Medicine, University of Toronto, Toronto, ON Canada
| | | | | | - Nicolas Yak
- Sunnybrook Research Institute, Toronto, ON Canada
| | | | | | - Mihaela Pop
- Department of Medical Biophysics, University of Toronto, Toronto, ON Canada
- Sunnybrook Research Institute, Toronto, ON Canada
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, ON Canada
| | - Graham A. Wright
- Department of Medical Biophysics, University of Toronto, Toronto, ON Canada
- Sunnybrook Research Institute, Toronto, ON Canada
- Schulich Heart Research Program, Sunnybrook Research Institute, Toronto, ON Canada
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Zhang L, Lai P, Pop M, Wright GA. Accelerated multicontrast volumetric imaging with isotropic resolution for improved peri-infarct characterization using parallel imaging, low-rank and spatially varying edge-preserving sparse modeling. Magn Reson Med 2017; 79:3018-3031. [PMID: 29030882 DOI: 10.1002/mrm.26970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 09/21/2017] [Accepted: 09/22/2017] [Indexed: 01/27/2023]
Abstract
PURPOSE To achieve consistent effectiveness in reconstruction of fine image features for cases of varying contrast-to-noise ratio (CNR) to facilitate translating accelerated multicontrast volumetric imaging with isotropic resolution toward clinical utility in peri-infarct characterization. THEORY AND METHODS A low-rank and spatially varying edge-preserving constrained compressed sensing parallel imaging reconstruction method (CP-LASER) is developed to effectively preserve contrast of small-scale structures for highly accelerated multicontrast volumetric imaging in CNR-limited scenarios. CP-LASER synergistically integrates parallel imaging, low-rank and spatially varying edge-preserving sparse modeling to achieve high signal-to-noise-ratio efficiency by leveraging prior knowledge about signal properties including coil sensitivity weighting, spatiotemporally correlated signal relaxation, and spatially varying sparsity. RESULTS In the preclinical study using highly accelerated multicontrast volumetric imaging with an isotropic 1.5-mm resolution, CP-LASER demonstrated robust multicontrast reconstruction of peri-infarct characteristics with excellent correspondence with histopathology. CP-LASER provides better delineation of the peri-infarct border zone with improved sharpness than alternative methods in a clinical demonstration on 1.5T with an isotropic 2.2-mm resolution achieved in a single breath-hold. CONCLUSION Accelerated multicontrast volumetric imaging with isotropic resolution using CP-LASER has demonstrated the potential to improve peri-infarct characterization in a clinical setting. Magn Reson Med 79:3018-3031, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Li Zhang
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Schulich Heart Research Program and Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Peng Lai
- Global Applied Science Laboratory, GE Healthcare, Menlo Park, California, USA
| | - Mihaela Pop
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Schulich Heart Research Program and Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Graham A Wright
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Schulich Heart Research Program and Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
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Huang TY, Tseng YS, Chuang TC. Automatic calibration of trigger delay time for cardiac MRI. NMR IN BIOMEDICINE 2014; 27:417-424. [PMID: 24478224 DOI: 10.1002/nbm.3076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 12/18/2013] [Accepted: 12/24/2013] [Indexed: 06/03/2023]
Abstract
This study aimed to automatically identify the cardiac rest period using a rapid free-breathing (FB) calibration scanning procedure, and to determine the optimal trigger delay for cardiac imaging. A standard deviation (SD) method was used to rapidly identify cardiac quiescent phases employing multiphase cine cardiac images. The accuracy of this method was investigated using 46 datasets acquired from 22 healthy volunteers. The possibility of using a low-resolution FB method to rapidly acquire cine images was also evaluated. The reproducibility and accuracy of the trigger delay obtained using the rapid calibration scanning process were assessed before its application to a real-time feedback system. The real-time trigger delay calibration system was then used to perform T1 -weighted, short-axis imaging at the end of the cardiac systolic period. Linear regression analysis of the trigger times obtained using the SD method and a reference method indicated that the SD algorithm accurately identified the cardiac rest period (linear regression: slope = 0.94-1, R(2) = 0.68-0.84). Group analysis showed that the number of pixels in the left ventricular blood pool in images acquired at the end-systolic time calculated in real time was significantly lower than in those acquired 50 ms in advance or later (p < 0.01, paired t-test). The low-resolution FB imaging method was reproducible for the calibration scanning of an image in a vertical long-axis slice position (average SD of trigger times, 16-39 ms). Combined with rapid FB calibration scanning, the real-time feedback system accurately adjusted the trigger delay for T1 -weighted short-axis imaging. The real-time feedback method is rapid and reliable for trigger time calibration, and could facilitate cardiac imaging during routine examination.
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Affiliation(s)
- Teng-Yi Huang
- Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
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Kadbi M, Kotys M, Alshaher M, Fischer S, Amini AA. An improved real-time cine Late Gadolinium Enhancement (LGE) imaging method at 3T. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:531-4. [PMID: 22254365 DOI: 10.1109/iembs.2011.6090097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A real-time Late Gadolinium Enhancement (LGE) MRI technique (free breathing and non-gated) is presented for detection of myocardial scars. Conventional LGE imaging methods currently in use are applied in conjunction with breath-hold and, thus, are difficult to use in patients with cardiac disease and may lead to motion artifacts. Additionally, conventional techniques involve ECG gating, which is problematic in patients with arrhythmias requiring multiple breath holds and use of arrhythmia rejection techniques. Finally, conventional LGE techniques require accurate estimates for the inversion time in order to null the normal myocardium, revealing the location of the scar with high contrast. Real-time LGE imaging obviates these difficulties and can, in principle, acquire cine images to assess wall motion over several heart phases as part of the same scan. To date, the main limitation of real-time LGE imaging has been long acquisition window and low temporal resolution. These limitations lead to temporal blurring of wall motion and possible overestimation of infarct size. The goal of this study was to increase the temporal resolution of real-time, cine LGE imaging, providing the possibility for better visualization of the wall motion and more accurate assessment of myocardial viability.
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Affiliation(s)
- Mo Kadbi
- Medical Imaging Lab, Electrical and Computer Engineering Department, University of Louisville, Louisville, KY, United States.
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Cardiac imaging: Part 1, MR pulse sequences, imaging planes, and basic anatomy. AJR Am J Roentgenol 2011; 197:808-15. [PMID: 21940567 DOI: 10.2214/ajr.10.7231] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE MRI is a well-established modality for evaluating congenital and acquired cardiac diseases. This article reviews the latest pulse sequences used for cardiac MRI. In addition, the standard cardiac imaging planes and corresponding anatomy are described and illustrated. CONCLUSION Familiarity with the basic pulse sequences, imaging planes, and anatomy pertaining to cardiac MRI is essential to formulate optimal protocols and interpretations.
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Ferrari VA, Witschey WR, Zhou R. Cardiac Magnetic Resonance Assessment of Myocardial Fibrosis. Circ Cardiovasc Imaging 2011; 4:604-6. [DOI: 10.1161/circimaging.111.969204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Victor A. Ferrari
- From the Cardiovascular Magnetic Resonance Program, Penn Cardiovascular Institute, and the Noninvasive Imaging Laboratory, Hospital of the University of Pennsylvania, University of Pennsylvania Medical Center, Philadelphia, PA (V.A.F.); Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, PA (W.R.T.W.); and Molecular Imaging Laboratories, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia,
| | - Walter R.T. Witschey
- From the Cardiovascular Magnetic Resonance Program, Penn Cardiovascular Institute, and the Noninvasive Imaging Laboratory, Hospital of the University of Pennsylvania, University of Pennsylvania Medical Center, Philadelphia, PA (V.A.F.); Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, PA (W.R.T.W.); and Molecular Imaging Laboratories, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia,
| | - Rong Zhou
- From the Cardiovascular Magnetic Resonance Program, Penn Cardiovascular Institute, and the Noninvasive Imaging Laboratory, Hospital of the University of Pennsylvania, University of Pennsylvania Medical Center, Philadelphia, PA (V.A.F.); Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, PA (W.R.T.W.); and Molecular Imaging Laboratories, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia,
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Connelly KA, Detsky JS, Graham JJ, Paul G, Vijayaragavan R, Dick AJ, Wright GA. Multicontrast late gadolinium enhancement imaging enables viability and wall motion assessment in a single acquisition with reduced scan times. J Magn Reson Imaging 2009; 30:771-7. [DOI: 10.1002/jmri.21907] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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