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A multi-scale variational neural network for accelerating motion-compensated whole-heart 3D coronary MR angiography. Magn Reson Imaging 2020; 70:155-167. [DOI: 10.1016/j.mri.2020.04.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/03/2020] [Accepted: 04/12/2020] [Indexed: 11/22/2022]
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Ginami G, Lòpez K, Mukherjee RK, Neji R, Munoz C, Roujol S, Mountney P, Razavi R, Botnar RM, Prieto C. Non-contrast enhanced simultaneous 3D whole-heart bright-blood pulmonary veins visualization and black-blood quantification of atrial wall thickness. Magn Reson Med 2019; 81:1066-1079. [PMID: 30230609 PMCID: PMC6492092 DOI: 10.1002/mrm.27472] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 07/06/2018] [Accepted: 07/07/2018] [Indexed: 12/21/2022]
Abstract
PURPOSE Pre-interventional assessment of atrial wall thickness (AWT) and of subject-specific variations in the anatomy of the pulmonary veins may affect the success rate of RF ablation procedures for the treatment of atrial fibrillation (AF). This study introduces a novel non-contrast enhanced 3D whole-heart sequence providing simultaneous information on the cardiac anatomy-including both the arterial and the venous system-(bright-blood volume) and AWT (black-blood volume). METHODS The proposed MT-prepared bright-blood and black-blood phase sensitive inversion recovery (PSIR) BOOST framework acquires 2 differently weighted bright-blood volumes in an interleaved fashion. The 2 data sets are then combined in a PSIR-like reconstruction to obtain a complementary black-blood volume for atrial wall visualization. Image-based navigation and non-rigid respiratory motion correction are exploited for 100% scan efficiency and predictable acquisition time. The proposed approach was evaluated in 11 healthy subjects and 4 patients with AF scheduled for RF ablation. RESULTS Improved depiction of the cardiac venous system was obtained in comparison to a T2 -prepared BOOST implementation, and quantified AWT was shown to be in good agreement with previously reported measurements obtained in healthy subjects (right atrium AWT: 2.54 ± 0.87 mm, left atrium AWT: 2.51 ± 0.61 mm). Feasibility for MT-prepared BOOST acquisitions in patients with AF was demonstrated. CONCLUSION The proposed motion-corrected MT-prepared BOOST sequence provides simultaneous non-contrast pulmonary vein depiction as well as black-blood visualization of atrial walls. The proposed sequence has a large spectrum of potential clinical applications and further validation in patients is warranted.
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Affiliation(s)
- Giulia Ginami
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
| | - Karina Lòpez
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
| | - Rahul K. Mukherjee
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
| | - Radhouene Neji
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
- MR Research Collaborations, Siemens Healthcare LimitedFrimleyUnited Kingdom
| | - Camila Munoz
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
| | - Sébastien Roujol
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
| | - Peter Mountney
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
- Medical Imaging TechnologiesSiemens HealthineersPrincetonNew Jersey
| | - Reza Razavi
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
| | - René M. Botnar
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
- Escuela de IngenieríaPontificia Universidad Católica de ChileSantiagoChile
| | - Claudia Prieto
- School of Biomedical Engineering and Imaging SciencesKing’s College LondonLondonUnited Kingdom
- Escuela de IngenieríaPontificia Universidad Católica de ChileSantiagoChile
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Bustin A, Ginami G, Cruz G, Correia T, Ismail TF, Rashid I, Neji R, Botnar RM, Prieto C. Five-minute whole-heart coronary MRA with sub-millimeter isotropic resolution, 100% respiratory scan efficiency, and 3D-PROST reconstruction. Magn Reson Med 2018; 81:102-115. [PMID: 30058252 PMCID: PMC6617822 DOI: 10.1002/mrm.27354] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/23/2018] [Accepted: 04/19/2018] [Indexed: 01/08/2023]
Abstract
Purpose To enable whole‐heart 3D coronary magnetic resonance angiography (CMRA) with isotropic sub‐millimeter resolution in a clinically feasible scan time by combining respiratory motion correction with highly accelerated variable density sampling in concert with a novel 3D patch‐based undersampled reconstruction (3D‐PROST). Methods An undersampled variable density spiral‐like Cartesian trajectory was combined with 2D image‐based navigators to achieve 100% respiratory efficiency and predictable scan time. 3D‐PROST reconstruction integrates structural information from 3D patch neighborhoods through sparse representation, thereby exploiting the redundancy of the 3D anatomy of the coronary arteries in an efficient low‐rank formulation. The proposed framework was evaluated in a static resolution phantom and in 10 healthy subjects with isotropic resolutions of 1.2 mm3 and 0.9 mm3 and undersampling factors of ×5 and ×9. 3D‐PROST was compared against fully sampled (1.2 mm3 only), conventional parallel imaging, and compressed sensing reconstructions. Results Phantom and in vivo (1.2 mm3) reconstructions were in excellent agreement with the reference fully sampled image. In vivo average acquisition times (min:s) were 7:57 ± 1:18 (×5) and 4:35 ± 0:44 (×9) for 0.9 mm3 resolution. Sub‐millimeter 3D‐PROST resulted in excellent depiction of the left and right coronary arteries including small branch vessels, leading to further improvements in vessel sharpness and visible vessel length in comparison with conventional reconstruction techniques. Image quality rated by 2 experts demonstrated that 3D‐PROST provides good image quality and is robust even at high acceleration factors. Conclusion The proposed approach enables free‐breathing whole‐heart 3D CMRA with isotropic sub‐millimeter resolution in <5 min and achieves improved coronary artery visualization in a short and predictable scan time.
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Affiliation(s)
- Aurélien Bustin
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Giulia Ginami
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Gastão Cruz
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Teresa Correia
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Tevfik F Ismail
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Imran Rashid
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Radhouene Neji
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.,MR Research Collaborations, Siemens Healthcare Limited, Frimley, United Kingdom
| | - René M Botnar
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.,Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Claudia Prieto
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.,Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile
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Ginami G, Neji R, Rashid I, Chiribiri A, Ismail TF, Botnar RM, Prieto C. 3D whole-heart phase sensitive inversion recovery CMR for simultaneous black-blood late gadolinium enhancement and bright-blood coronary CMR angiography. J Cardiovasc Magn Reson 2017; 19:94. [PMID: 29178893 PMCID: PMC5702978 DOI: 10.1186/s12968-017-0405-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 11/06/2017] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Phase sensitive inversion recovery (PSIR) applied to late gadolinium enhancement (LGE) imaging is widely used in clinical practice. However, conventional 2D PSIR LGE sequences provide sub-optimal contrast between scar tissue and blood pool, rendering the detection of subendocardial infarcts and scar segmentation challenging. Furthermore, the acquisition of a low flip angle reference image doubles the acquisition time without providing any additional diagnostic information. The purpose of this study was to develop and test a novel 3D whole-heart PSIR-like framework, named BOOST, enabling simultaneous black-blood LGE assessment and bright-blood visualization of cardiac anatomy. METHODS The proposed approach alternates the acquisition of a 3D volume preceded by a T2-prepared Inversion Recovery (T2Prep-IR) module (magnitude image) with the acquisition of a T2-prepared 3D volume (reference image). The two volumes (T2Prep-IR BOOST and bright-blood T2Prep BOOST) are combined in a PSIR-like reconstruction to obtain a complementary 3D black-blood volume for LGE assessment (PSIR BOOST). The black-blood PSIR BOOST and the bright-blood T2Prep BOOST datasets were compared to conventional clinical sequences for scar detection and coronary CMR angiography (CMRA) in 18 patients with a spectrum of cardiovascular disease (CVD). RESULTS Datasets from 12 patients were quantitatively analysed. The black-blood PSIR BOOST dataset provided statistically improved contrast to noise ratio (CNR) between blood and scar when compared to a clinical 2D PSIR sequence (15.8 ± 3.3 and 4.1 ± 5.6, respectively). Overall agreement in LGE depiction was found between 3D black-blood PSIR BOOST and clinical 2D PSIR acquisitions, with 11/12 PSIR BOOST datasets considered diagnostic. The bright-blood T2Prep BOOST dataset provided high quality depiction of the proximal coronary segments, with improvement of visual score when compared to a clinical CMRA sequence. Acquisition time of BOOST (~10 min), providing information on both LGE uptake and heart anatomy, was comparable to that of a clinical single CMRA sequence. CONCLUSIONS The feasibility of BOOST for simultaneous black-blood LGE assessment and bright-blood coronary angiography was successfully tested in patients with cardiovascular disease. The framework enables free-breathing multi-contrast whole-heart acquisitions with 100% scan efficiency and predictable scan time. Complementary information on 3D LGE and heart anatomy are obtained reducing examination time.
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Affiliation(s)
- Giulia Ginami
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital (Lambeth Wing), Westminster Bridge Rd, London, SE1 7EH UK
| | - Radhouene Neji
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital (Lambeth Wing), Westminster Bridge Rd, London, SE1 7EH UK
- MR Research Collaborations, Siemens Healthcare Limited, Sir William Siemens Square Frimley, Camberley, GU16 8QD UK
| | - Imran Rashid
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital (Lambeth Wing), Westminster Bridge Rd, London, SE1 7EH UK
| | - Amedeo Chiribiri
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital (Lambeth Wing), Westminster Bridge Rd, London, SE1 7EH UK
| | - Tevfik F. Ismail
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital (Lambeth Wing), Westminster Bridge Rd, London, SE1 7EH UK
| | - René M. Botnar
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital (Lambeth Wing), Westminster Bridge Rd, London, SE1 7EH UK
- Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Vicuna Mackenna, 4860 Santiago, Chile
| | - Claudia Prieto
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas’ Hospital (Lambeth Wing), Westminster Bridge Rd, London, SE1 7EH UK
- Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Vicuna Mackenna, 4860 Santiago, Chile
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Ginami G, Neji R, Phinikaridou A, Whitaker J, Botnar RM, Prieto C. Simultaneous bright- and black-blood whole-heart MRI for noncontrast enhanced coronary lumen and thrombus visualization. Magn Reson Med 2017; 79:1460-1472. [PMID: 28722267 PMCID: PMC5811778 DOI: 10.1002/mrm.26815] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/07/2017] [Accepted: 06/08/2017] [Indexed: 12/18/2022]
Abstract
PURPOSE To develop a 3D whole-heart Bright-blood and black-blOOd phase SensiTive (BOOST) inversion recovery sequence for simultaneous noncontrast enhanced coronary lumen and thrombus/hemorrhage visualization. METHODS The proposed sequence alternates the acquisition of two bright-blood datasets preceded by different preparatory pulses to obtain variations in blood/myocardium contrast, which then are combined in a phase-sensitive inversion recovery (PSIR)-like reconstruction to obtain a third, coregistered, black-blood dataset. The bright-blood datasets are used for both visualization of the coronary lumen and motion estimation, whereas the complementary black-blood dataset potentially allows for thrombus/hemorrhage visualization. Furthermore, integration with 2D image-based navigation enables 100% scan efficiency and predictable scan times. The proposed sequence was compared to conventional coronary MR angiography (CMRA) and PSIR sequences in a standardized phantom and in healthy subjects. Feasibility for thrombus depiction was tested ex vivo. RESULTS With BOOST, the coronary lumen is visualized with significantly higher (P < 0.05) contrast-to-noise ratio and vessel sharpness when compared to conventional CMRA. Furthermore, BOOST showed effective blood signal suppression as well as feasibility for thrombus visualization ex vivo. CONCLUSION A new PSIR sequence for noncontrast enhanced simultaneous coronary lumen and thrombus/hemorrhage detection was developed. The sequence provided improved coronary lumen depiction and showed potential for thrombus visualization. Magn Reson Med 79:1460-1472, 2018. © 2017 International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Giulia Ginami
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Radhouene Neji
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom.,MR Research Collaborations, Siemens Healthcare Limited, Frimley, United Kingdom
| | - Alkystis Phinikaridou
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - John Whitaker
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - René M Botnar
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom.,Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Claudia Prieto
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom.,Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile
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Henningsson M, Hussain T, Vieira MS, Greil GF, Smink J, Ensbergen GV, Beck G, Botnar RM. Whole-heart coronary MR angiography using image-based navigation for the detection of coronary anomalies in adult patients with congenital heart disease. J Magn Reson Imaging 2015; 43:947-55. [PMID: 26451972 DOI: 10.1002/jmri.25058] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/15/2015] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The purpose of this study was to evaluate a recently developed two-dimensional (2D) image-based navigation approach (iNAVG+C ) combined with respiratory bellows gating for CMRA in patients with congenital heart disease. METHODS Nine healthy volunteers (mean age 32 ± 6 years [standard deviation]) and 29 patients (28 ± 9 years) were scanned on a 1.5 Tesla clinical scanner using iNAV(G+C) motion compensated T2prepared CMRA, and the conventional 1D NAV approach. Scan time was recorded for each CMRA scan. An image quality score was given to each coronary artery from (0, uninterpretable; to 4, excellent image quality). Additionally, vessel sharpness of each coronary artery was measured. RESULTS Average scan time was significantly shorter (P < 0.01) using the proposed iNAVC+G approach (7:57 ± 1:34) compared with 1D NAV (9:15 ± 3:02). Improved visual scores of the right coronary artery (iNAV(G+C) : 4,3,4 (median, 25th percentile, 75th percentile) versus 1D NAV: 3,3,4; P < 0.001) and left anterior descending artery (iNAV(G+C) : 3,3,4 versus 1D NAV: 3,2,3; P < 0.001) were obtained using iNAV(G+C) compared with 1D NAV as well as an increased vessel sharpness of the right coronary artery (iNAV(G+C) : 65.3% ± 6.6% (mean ± standard deviation) versus 1D NAV: 60.2% ± 11.4%; P < 0.05) and left anterior descending artery (iNAV(G+C) : 63.2% ± 6.7% versus 1D NAV: 58.3% ± 9.5%; P < 0.05). CONCLUSION Image-based navigation in combination with respiratory bellows gating allows for more robust suppression of respiratory motion artifacts for whole-heart CMRA compared with conventional 1D NAV as images can be acquired in a shorter time and with improved image quality.
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Affiliation(s)
- Markus Henningsson
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Tarique Hussain
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Miguel S Vieira
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | - Gerald F Greil
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
| | | | | | | | - Rene M Botnar
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom
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Tseng CL, Sussman MS, Atenafu EG, Letourneau D, Ma L, Soliman H, Thibault I, Cho BCJ, Simeonov A, Yu E, Fehlings MG, Sahgal A. Magnetic resonance imaging assessment of spinal cord and cauda equina motion in supine patients with spinal metastases planned for spine stereotactic body radiation therapy. Int J Radiat Oncol Biol Phys 2015; 91:995-1002. [PMID: 25832691 DOI: 10.1016/j.ijrobp.2014.12.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Revised: 12/14/2014] [Accepted: 12/17/2014] [Indexed: 10/23/2022]
Abstract
PURPOSE To assess motion of the spinal cord and cauda equina, which are critical neural tissues (CNT), which is important when evaluating the planning organ-at-risk margin required for stereotactic body radiation therapy. METHODS AND MATERIALS We analyzed CNT motion in 65 patients with spinal metastases (11 cervical, 39 thoracic, and 24 lumbar spinal segments) in the supine position using dynamic axial and sagittal magnetic resonance imaging (dMRI, 3T Verio, Siemens) over a 137-second interval. Motion was segregated according to physiologic cardiorespiratory oscillatory motion (characterized by the average root mean square deviation) and random bulk shifts associated with gross patient motion (characterized by the range). Displacement was evaluated in the anteroposterior (AP), lateral (LR), and superior-inferior (SI) directions by use of a correlation coefficient template matching algorithm, with quantification of random motion measure error over 3 separate trials. Statistical significance was defined according to P<.05. RESULTS In the AP, LR, and SI directions, significant oscillatory motion was observed in 39.2%, 35.1%, and 10.8% of spinal segments, respectively, and significant bulk motions in all cases. The median oscillatory CNT motions in the AP, LR, and SI directions were 0.16 mm, 0.17 mm, and 0.44 mm, respectively, and the maximal statistically significant oscillatory motions were 0.39 mm, 0.41 mm, and 0.77 mm, respectively. The median bulk displacements in the AP, LR, and SI directions were 0.51 mm, 0.59 mm, and 0.66 mm, and the maximal statistically significant displacements were 2.21 mm, 2.87 mm, and 3.90 mm, respectively. In the AP, LR, and SI directions, bulk displacements were greater than 1.5 mm in 5.4%, 9.0%, and 14.9% of spinal segments, respectively. No significant differences in axial motion were observed according to cord level or cauda equina. CONCLUSIONS Oscillatory CNT motion was observed to be relatively minor. Our results support the importance of controlling bulk patient motion and the practice of applying a planning organ-at-risk margin.
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Affiliation(s)
- Chia-Lin Tseng
- Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada
| | - Marshall S Sussman
- Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Eshetu G Atenafu
- Department of Biostatistics, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Daniel Letourneau
- Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lijun Ma
- Department of Radiation Oncology, University of California San Francisco, San Francisco, California
| | - Hany Soliman
- Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
| | - Isabelle Thibault
- Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
| | - B C John Cho
- Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada
| | - Anna Simeonov
- Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada
| | - Eugene Yu
- Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Michael G Fehlings
- Department of Neurosurgery and Spine Program, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Arjun Sahgal
- Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario, Canada.
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Elboher E, Werman M. Asymmetric correlation: a noise robust similarity measure for template matching. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2013; 22:3062-3073. [PMID: 23591492 DOI: 10.1109/tip.2013.2257811] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present an efficient and noise robust template matching method based on asymmetric correlation (ASC). The ASC similarity function is invariant to affine illumination changes and robust to extreme noise. It correlates the given non-normalized template with a normalized version of each image window in the frequency domain. We show that this asymmetric normalization is more robust to noise than other cross correlation variants, such as the correlation coefficient. Direct computation of ASC is very slow, as a DFT needs to be calculated for each image window independently. To make the template matching efficient, we develop a much faster algorithm, which carries out a prediction step in linear time and then computes DFTs for only a few promising candidate windows. We extend the proposed template matching scheme to deal with partial occlusion and spatially varying light change. Experimental results demonstrate the robustness of the proposed ASC similarity measure compared to state-of-the-art template matching methods.
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Affiliation(s)
- Elhanan Elboher
- School of Computer Science, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Henningsson M, Smink J, Razavi R, Botnar RM. Prospective respiratory motion correction for coronary MR angiography using a 2D image navigator. Magn Reson Med 2012; 69:486-94. [PMID: 22529009 DOI: 10.1002/mrm.24280] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 02/13/2012] [Accepted: 03/12/2012] [Indexed: 11/10/2022]
Affiliation(s)
- Markus Henningsson
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom.
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Henningsson M, Koken P, Stehning C, Razavi R, Prieto C, Botnar RM. Whole-heart coronary MR angiography with 2D self-navigated image reconstruction. Magn Reson Med 2011; 67:437-45. [PMID: 21656563 DOI: 10.1002/mrm.23027] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 05/05/2011] [Indexed: 12/29/2022]
Abstract
Several self-navigation techniques have been proposed to improve respiratory motion compensation in coronary MR angiography. In this work, we implemented a 2D self-navigation method by using the startup profiles of a whole-heart balanced Steady-state free precession sequence, which are primarily used to catalyze the magnetization towards the steady-state. To create 2D self-navigation images (2DSN), we added phase encoding gradients to the startup profiles. With this approach we calculated foot-head and left-right motion and performed retrospective translational motion correction. The 2DSN images were reconstructed from 10 startup profiles acquired at the beginning of each shot. Nine healthy subjects were scanned, and the proposed method was compared to a 1D self-navigation (1DSN) method with foot-head correction only. Foot-head correction was also performed with the diaphragmatic 1D pencil beam navigator (1Dnav) using a tracking factor of 0.6. 2DSN shows improved motion correction compared to 1DSN and 1Dnav for all coronary arteries and all subjects for the investigated diaphragmatic gating window of 10 mm. The visualized vessel length of the right coronary artery could be significantly improved with a multiple targeted 2D self-navigation approach, compared to 2DSN method.
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Affiliation(s)
- Markus Henningsson
- Division of Imaging Sciences & Biomedical Engineering, King's College London, London, United Kingdom.
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Blood Oxygen Level-Dependent Magnetic Resonance Imaging of the Human Liver. J Comput Assist Tomogr 2010; 34:523-31. [DOI: 10.1097/rct.0b013e3181d5d503] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Yoshida K, Takahashi H, Saijo M, Ueguchi T, Tanaka H, Fujita N, Murase K. Phase-contrast MR studies of CSF flow rate in the cerebral aqueduct and cervical subarachnoid space with correlation-based segmentation. Magn Reson Med Sci 2010; 8:91-100. [PMID: 19783872 DOI: 10.2463/mrms.8.91] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Accurate measurement of cerebrospinal fluid (CSF) flow rate elucidates pathophysiological changes in the intracranial environment and is thus clinically useful. We investigated the feasibility of correlation coefficient (CC) analysis for extracting CSF lumens in the cerebral aqueduct and cervical subarachnoid space (SAS) to quantify CSF flow rate and net flow from data acquired by phase-contrast magnetic resonance imaging (PC-MRI). METHODS First, in phantom studies on pulsatile flow using a 1.5-tesla MR imaging system, we investigated the accuracy of CC analysis and used a statistical approach to determine an optimal threshold value for extracting the CSF lumens (CC(min)). Second, we performed phantom studies on constant flow with various flow rates to estimate the accuracy of low flow measurement by PC-MRI. Finally, in 6 healthy male volunteers aged 24 +/- 2 years, we estimated the CSF lumen areas, net flows, and peak flow rates in the cerebral aqueduct and cervical SAS using CC analysis with the optimal CC(min) value determined in phantom studies. Three observers analyzed results to compare reproducibility of CC analysis with that of manual segmentation. RESULTS The optimal CC(min) value for CC analysis was 0.41 for a matrix measuring 256 x 256. The CSF lumen area extracted by CC analysis was 6.15 +/- 2.52 mm(2), and the net flow in the cerebral aqueduct was 0.74 +/- 0.38 mL/min; in the cervical SAS, lumen area was 135.60 +/- 17.94 mm(2) and net flow, 12.55 +/- 12.67 mL/min. The reproducibility of CSF lumen extraction was better by CC analysis than manual segmentation. CONCLUSION CC analysis offers a quick and reproducible method for segmenting CSF lumens and calculating CSF flow rate.
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Affiliation(s)
- Keita Yoshida
- Department of Medical Physics and Engineering, Division of Medical Technology and Science, Course of Health Science, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
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Macgowan CK, Liu GKC, van Amerom JFP, Sussman MS, Wright GA. Self-gated Fourier velocity encoding. Magn Reson Imaging 2009; 28:95-102. [PMID: 19553052 DOI: 10.1016/j.mri.2009.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 04/01/2009] [Accepted: 05/11/2009] [Indexed: 11/26/2022]
Abstract
Self-gating is investigated to improve the velocity resolution of real-time Fourier velocity encoding measurements in the absence of a reliable electrocardiogram waveform (e.g., fetal magnetic resonance or severe arrhythmia). Real-time flow data are acquired using interleaved k-space trajectories which share a common path near the origin of k-space. These common data provide a rapid self-gating signal that can be used to combine the interleaved data. The combined interleaves cover a greater area of k-space than a single real-time acquisition, thereby providing higher velocity resolution for a given aliasing velocity and temporal resolution. For example, this approach provided velocity spectra with a temporal resolution of 19 ms and velocity resolution of 22 cm/s over an 818 cm/s field-of-view. The method was validated experimentally using a computer-controlled pulsatile flow apparatus and applied in vivo to measure aortic-valve flow in a healthy volunteer.
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Affiliation(s)
- Christopher K Macgowan
- Department of Medical Biophysics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
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Automated measurement and classification of pulmonary blood-flow velocity patterns using phase-contrast MRI and correlation analysis. Magn Reson Imaging 2009; 27:38-47. [DOI: 10.1016/j.mri.2008.05.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 05/03/2008] [Accepted: 05/16/2008] [Indexed: 11/22/2022]
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15
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Kumarasamy SK, Wang Y, Viswanathan V, Kraut RS. Multivariate profiling of neurodegeneration-associated changes in a subcellular compartment of neurons via image processing. BioData Min 2008; 1:10. [PMID: 19014586 PMCID: PMC2639580 DOI: 10.1186/1756-0381-1-10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 11/14/2008] [Indexed: 11/21/2022] Open
Abstract
Background Dysfunction in the endolysosome, a late endosomal to lysosomal degradative intracellular compartment, is an early hallmark of some neurodegenerative diseases, in particular Alzheimer's disease. However, the subtle morphological changes in compartments of affected neurons are difficult to quantify quickly and reliably, making this phenotype inaccessible as either an early diagnostic marker, or as a read-out for drug screening. Methods We present a method for automatic detection of fluorescently labeled endolysosomes in degenerative neurons in situ. The Drosophila blue cheese (bchs) mutant was taken as a genetic neurodegenerative model for direct in situ visualization and quantification of endolysosomal compartments in affected neurons. Endolysosomal compartments were first detected automatically from 2-D image sections using a combination of point-wise multi-scale correlation and normalized correlation operations. This detection algorithm performed well at recognizing fluorescent endolysosomes, unlike conventional convolution methods, which are confounded by variable intensity levels and background noise. Morphological feature differences between endolysosomes from wild type vs. degenerative neurons were then quantified by multivariate profiling and support vector machine (SVM) classification based on compartment density, size and contrast distribution. Finally, we ranked these distributions according to their profiling accuracy, based on the backward elimination method. Results This analysis revealed a statistically significant difference between the neurodegenerative phenotype and the wild type up to a 99.9% confidence interval. Differences between the wild type and phenotypes resulting from overexpression of the Bchs protein are detectable by contrast variations, whereas both size and contrast variations distinguish the wild type from either of the loss of function alleles bchs1 or bchs58. In contrast, the density measurement differentiates all three bchs phenotypes (loss of function as well as overexpression) from the wild type. Conclusion Our model demonstrates that neurodegeneration-associated endolysosomal defects can be detected, analyzed, and classified rapidly and accurately as a diagnostic imaging-based screening tool.
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Affiliation(s)
- Saravana K Kumarasamy
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, the Nanos, #04-01, 138669, Singapore
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16
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Prakash V, Stainsby JA, Satkunasingham J, Craig T, Catton C, Chan P, Dawson L, Hensel J, Jaffray D, Milosevic M, Nichol A, Sussman MS, Lockwood G, Ménard C. Validation of Supervised Automated Algorithm for Fast Quantitative Evaluation of Organ Motion on Magnetic Resonance Imaging. Int J Radiat Oncol Biol Phys 2008; 71:1253-60. [DOI: 10.1016/j.ijrobp.2007.11.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2007] [Revised: 11/12/2007] [Accepted: 11/12/2007] [Indexed: 10/22/2022]
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17
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Alves N, Chau T. Vision-based segmentation of continuous mechanomyographic grasping sequences. IEEE Trans Biomed Eng 2008; 55:765-73. [PMID: 18270015 DOI: 10.1109/tbme.2007.902223] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In detecting motor related activity from mechanomyographic (MMG) recordings, the acquisition of long, continuous streams of MMG signals is typically preferred over the painstaking collection of individual, isolated contractions. However, a major challenge with continuous collection is the subsequent separation of the MMG data stream into segments representing individual contractions. This paper proposes a method for segmenting continuously recorded MMG data streams using computer vision while providing a highly reduced set of key images for rapid human expert verification. Transverse plane video recordings of functional grasp sequences were synchronized with the acquisition of MMG signals from the forearm. An automatic, vision-based algorithm exploiting skin color detection, motion estimation, and template matching provided segmentation cues for MMG signals arising from multiple grips. The automatic segmentation method tolerated extraneous hand movements, differentiated among multiple grips and estimated grip transition times. Our implementation segmented two grips with an average accuracy of 97.8 -/+ 4%, and up to seven grips with an accuracy of 73 -/+ 20%. The automatically extracted contraction initiation and termination times were within 173 -/+ 133 ms of the times obtained via manual segmentation. It is suggested that the proposed method would be particularly conducive to the assembly of large collections of signals for training MMG-driven prostheses.
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Affiliation(s)
- Natasha Alves
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada.
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18
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Noseworthy MD, Haider MA, Sussman MS, Wright GA. Free-breathing Motion Compensation Using Template Matching. J Comput Assist Tomogr 2007; 31:193-7. [PMID: 17414752 DOI: 10.1097/01.rct.0000235069.50055.30] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Modeling tracer kinetics from dynamic magnetic resonance imaging (dMRI) to understand microvascular characteristics typically requires acquisitions longer than 1 breath-hold. This has limited the application of dMRI in assessment of the upper abdomen. Here we present a template-based motion correction strategy for dMRI of liver metastases based on the correlation coefficient (CC), originally developed for tracking coronary arteries. This postprocessing method allows patient free breathing during sagittal dMRI acquisition and allows a more precise parametric mapping using tracer kinetic models. In a study of 6 subjects, a 64 x 64 template was accurately tracked retrospectively with mean CC = 0.72 +/- 0.07. Mean superior-inferior displacement tracked was 1.82 +/- 1.20 pixels, whereas mean anterior-posterior displacement was 7.72 +/- 4.58 pixels. Application of the CC method significantly improved the global fit (chi2) of a tracer kinetic model throughout tumor regions. Therefore, use of the CC postprocessing method for dMRI scans can improve the precision of dMRI tracer kinetic models.
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Al-Kwifi O, Stainsby J, Foltz WD, Sussman MS, Huang Y, Wright GA. Characterizing coronary motion and its effect on MR coronary angiography—Initial experience. J Magn Reson Imaging 2006; 24:842-50. [PMID: 16929527 DOI: 10.1002/jmri.20697] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To characterize coronary artery motion as a prescan procedure to select the optimum scan setting that will produce high-resolution images. MATERIALS AND METHODS A 2D real-time scan was used to image the major coronary arteries during breath-holding and free-breathing conditions. With the use of the 2D images, motion displacement of each artery was measured along three axes. Motion data obtained from a computer simulation were used to estimate point-spread functions (PSFs) associated with different high-resolution spiral acquisition strategies, including real-time, cardiac-gated, and respiratory-gated acquisitions. The simulation output determined the optimum acquisition and scan parameters that would produce the highest-spatial-resolution images of the coronary arteries. The effects of heart rate (HR), extended breath-holding, and number of slices per heart cycle were also investigated. RESULTS Substantial variations in coronary motion occur among individuals, which directly influences the optimum parameters for a high-resolution scan. Lower HRs and longer breath-holds yield substantially increased spatial resolution. The maximum number of slices per heart cycle can also be determined to minimize slice-to-slice distortion. CONCLUSION The results suggest that to obtain high-resolution coronary images, one should perform a prescan coronary-motion characterization for each individual so that the scan parameters can be optimized before data acquisition.
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Affiliation(s)
- Osama Al-Kwifi
- Imaging Research Program, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada.
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20
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Ryu M, Kim JD, Min BG, Kim J, Kim YY. Probe classification of on-off type DNA microarray images with a nonlinear matching measure. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:014027. [PMID: 16526904 DOI: 10.1117/1.2168166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We propose a nonlinear matching measure, called counting measure, as a signal detection measure that is defined as the number of on pixels in the spot area. It is applied to classify probes for an on-off type DNA microarray, where each probe spot is classified as hybridized or not. The counting measure also incorporates the maximum response search method, where the expected signal is obtained by taking the maximum among the measured responses of the various positions and sizes of the spot template. The counting measure was compared to existing signal detection measures such as the normalized covariance and the median for 2390 patient samples tested on the human papillomavirus (HPV) DNA chip. The counting measure performed the best regardless of whether or not the maximum response search method was used. The experimental results showed that the counting measure combined with the positional search was the most preferable.
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Affiliation(s)
- Munho Ryu
- Chonbuk National University, Division of Bionics and Bioinformatics, 664-14 1 Ga, Duckjin-Dong, Duckjin-Gu, Jeonju, Jeonbuk 561-756, South Korea.
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21
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Larson AC, Kellman P, Arai A, Hirsch GA, McVeigh E, Li D, Simonetti OP. Preliminary investigation of respiratory self-gating for free-breathing segmented cine MRI. Magn Reson Med 2005; 53:159-68. [PMID: 15690515 PMCID: PMC1939886 DOI: 10.1002/mrm.20331] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Segmented cine MRI generally requires breath-holding, which can be problematic for many patients. Navigator echo techniques, particularly successful for free-breathing coronary MRA, are incompatible with the acquisition strategies and SSFP pulse sequences commonly used for cine MRI. The purpose of this work is to introduce a new self-gating technique deriving respiratory gating information directly from the raw imaging data acquired for segmented cine MRI. The respiratory self-gating technique uses interleaved radial k-space sampling to provide low-resolution images in real time during the free-breathing acquisition that are compared to target expiration images. Only the raw data-producing images with high correlation to the target images are included in the final high-resolution reconstruction. The self-gating technique produced cine series with no significant differences in quantitative image sharpness to series produced using comparable breath-held techniques. Because of the difficulties associated with breath-holding, the respiratory self-gating technique represents an important practical advance for cardiac MRI. , Inc.
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Affiliation(s)
- Andrew C Larson
- Department of Biomedical Engineering, NorthWestern University, Chicago, IL 60611, USA.
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22
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Robert N, Komljenovic PT, Grant R, Sussman MS, Rowlands JA. A lesion stabilization method for coronary angiography. Phys Med Biol 2005; 50:1295-312. [PMID: 15798323 DOI: 10.1088/0031-9155/50/6/017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A method to make a coronary artery segment of interest appear stationary when viewing a sequence of angiographic images is proposed. The purpose of this method is to facilitate the assessment of lesions caused by coronary artery disease by improving detectability. A description of the stabilization algorithm based on template matching is given. Stabilization was performed on 41 clinical coronary angiograms exhibiting various stenoses and was successful in 39/41 cases. A quantitative analysis of stabilization errors was performed by introducing simulated moving vessels of decreasing contrast into sequences of clinical images.
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Affiliation(s)
- Normand Robert
- Sunnybrook and Women's Health Science Centre, University of Toronto, Room S632, 2075 Bayview Avenue, Toronto M4N 3M5, Canada.
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Stainsby JA, Sussman MS, Flexman ML, Wright GA. Real-time magnetic resonance with physiologic monitoring for improved scan localization. Magn Reson Med 2005; 53:954-9. [PMID: 15799048 DOI: 10.1002/mrm.20413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Imaging of the coronary arteries at diagnostic resolutions is made difficult due to cardiac and respiratory motion during data acquisition. Cardiac gating and respiratory gating or breath holding are effective ways to reduce the effects of motion. The optimal cardiac and respiratory timings vary widely across individuals. This work presents a real-time magnetic resonance imaging approach with physiologic monitoring that can be used to predict the optimal timings on a subject-by-subject basis during a brief real-time prescan. The feasibility of this approach at determining the optimal cardiac trigger delay and respiratory phase is demonstrated.
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Affiliation(s)
- Jeffrey A Stainsby
- Sunnybrook & Women's College Health Sciences Centre, Toronto, Ontario, Canada.
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Sussman MS, Robert N, Wright GA. Adaptive averaging for improved SNR in real-time coronary artery MRI. IEEE TRANSACTIONS ON MEDICAL IMAGING 2004; 23:1034-1045. [PMID: 15338736 DOI: 10.1109/tmi.2004.828677] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A technique has been developed for combining a series of low signal-to-noise ratio (SNR) real-time magnetic resonance (MR) images to produce composite images with high SNR and minimal artifact in the presence of motion. The main challenge is identifying a set of real-time images with sufficiently small systematic differences to avoid introducing significant artifact into the composite image. To accomplish this task, one must: 1) identify images identical within the limits of noise; 2) detect systematic errors within such images with sufficient sensitivity. These steps are achieved by evaluating the correlation coefficient (CC) between regions in prospective images and a template containing the anatomy of interest. Images identical within noise are selected by comparing the measured CC values to the theoretical distribution expected due to noise. Sensitivity for systematic error depends on the SNR of the CC (=SNR(CCmax)), which in turn depends on the noise, and the template size and structure. By varying the template size, SNR(CCmax) may be altered. Experiments on phantoms and coronary artery images demonstrate that the SNR(CCmax) necessary to avoid introducing significant artifact varies with the target composite SNR. The future potential of this technique is demonstrated on high-resolution (approximately 0.9 mm), reduced field-of-view real-time coronary images.
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Affiliation(s)
- Marshall S Sussman
- Department of Medical Biophysics, Sunnybrook Health Science Centre, University of Toronto, Toronto, ON M5G 2N2, Canada.
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25
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Al-Kwifi O, Kim JK, Stainsby J, Huang Y, Sussman MS, Farb RI, Wright GA. Pulsatile motion effects on 3D magnetic resonance angiography: Implications for evaluating carotid artery stenoses. Magn Reson Med 2004; 52:605-11. [PMID: 15334581 DOI: 10.1002/mrm.20185] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In-plane carotid artery motion during a 3D MR angiography (MRA) scan can significantly degrade the resulting image resolution. This study characterizes the effect of cardiac pulsatility on 3D contrast-enhanced (CE) MRA with elliptical centric acquisitions using a point-spread function (PSF) analysis. Internal carotid artery (ICA) motion was collected from volunteers and patients using both MR and ultrasound (US) scans. After measuring the carotid artery motion displacement, a simulation was performed which calculated the blurring effects for three different protocols: nongated and two different cardiac gating schemes. The motion sensitivity of each protocol was evaluated for different spatial resolutions. The selection of optimal imaging parameters for a given scan time was investigated. The final results showed that cardiac-gated acquisitions only over a limited region of k-space high spatial frequencies are more time-efficient than cardiac gating for the entire k-space, as it allows for higher resolutions to be achieved and for capturing the arterial phase with low spatial frequencies. Selecting the optimal gating parameters depends directly on the motion characteristics of each individual. Our initial clinical experience is presented, and the need for a real-time tool that characterizes motion behavior for each individual as a prescan protocol is discussed.
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Affiliation(s)
- Osama Al-Kwifi
- Medical Imaging Research, Sunnybrook and Women's College Health Science Centre, Toronto, Ontario, Canada.
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26
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Foltz WD, Al-Kwifi O, Sussman MS, Stainsby JA, Wright GA. Optimized spiral imaging for measurement of myocardial T2 relaxation. Magn Reson Med 2003; 49:1089-97. [PMID: 12768587 DOI: 10.1002/mrm.10467] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microcirculation oxygen levels and blood volumes should be reflected in measurements of myocardial T(2) relaxation. This work describes the optimization of a spiral imaging strategy for robust myocardial T(2) measurement to minimize the standard deviation of T(2) measurement (sigmaT(2)). Theoretical and experimental studies of blurring at muscle/blood interfaces enabled the derivation of parameter sets which reduce sigma T(2) to the level of 5%. T(2) relaxation mapping within healthy volunteers provided estimation of residual sigmaT(2) within the optimized technique. The standard deviation in T(2) measurement across regions of interest (ROIs) in different locations is about 9%. The standard deviation in T(2) measurement in an ROI across different time points is about 5%.
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Affiliation(s)
- Warren D Foltz
- Department of Medical Biophysics, University of Toronto, Canada.
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27
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Sussman MS, Wright GA. Factors affecting the correlation coefficient template matching algorithm with application to real-time 2-D coronary artery MR imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2003; 22:206-216. [PMID: 12715997 DOI: 10.1109/tmi.2002.808363] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper characterizes factors affecting the accuracy of the correlation coefficient (CC) template matching algorithm, as applied to motion tracking from two-dimensional real-time coronary artery magnetic resonance images. The performance of this algorithm is analyzed in the presence of both random and systematic error. In the presence of random error, it is shown that a necessary and sufficient condition for accurate motion tracking is a large CC difference-to-noise ratio (CCDNR). The CCDNR itself is in turn affected by five factors: image and template size, image and template structure, and the magnitude of the noise. Techniques are introduced for manipulating some of these factors in order to increase the CCDNR for greater motion tracking accuracy. In the presence of superimposed systematic error it is shown that, while large CCDNR is necessary, it alone is not sufficient to ensure accurate motion tracking. Techniques are developed for improving motion tracking accuracy that minimize the effects of systematic error, while maintaining an adequate CCDNR level. The ability of these techniques to improve motion tracking accuracy is demonstrated both in phantoms and in coronary artery images.
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Affiliation(s)
- Marshall S Sussman
- Department of Medical Biophysics, Room. S612, Imaging Research Program, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, North York, ON M4N 3M5, Canada.
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