1
|
Piccini D, Bonanno G, Ginami G, Littmann A, Zenge MO, Stuber M. Is there an optimal respiratory reference position for self-navigated whole-heart coronary MR angiography? J Magn Reson Imaging 2015; 43:426-33. [PMID: 26174582 DOI: 10.1002/jmri.24992] [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: 02/18/2015] [Accepted: 06/18/2015] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To test the direct influence of the reference respiratory position on image quality for self-navigated whole-heart coronary MRI. METHODS Self-navigated whole-heart coronary MRI was performed in 11 healthy adult subjects. Respiratory motion was compensated for by using three different respiratory reference positions of the heart: end-inspiratory, end-expiratory, and the mean of the entire respiratory excursion. All datasets were reconstructed without motion compensation for comparison. Image quality was assessed in all reconstructions using signal-to-noise ratio (SNR) and contrst-to-noise ratio (CNR) measurements, as well as percentage vessel sharpness and visible length of the coronary arteries. RESULTS While SNR and CNR remained close to constant in all reconstructions, a clear and significant improvement in vessel sharpness was identified in all motion corrected datasets with respect to their uncorrected counterpart (e.g., percentage sharpness of the proximal right coronary artery (RCA): 61.6 ± 8.2% for end-inspiration, 64.1 ± 10.7% for end-expiration, and 63.3 ± 7.0% for the mean respiratory position versus 55.0 ± 10.4 for the uncorrected datasets; P < 0.05). Among all motion corrected reconstructions, the use of an end-expiratory reference position most consistently provided the highest image quality. In particular, some of the improvements in vessel sharpness and length measured for end-expiration were statistically significant with respect to the reconstructions performed at end-inspiration (e.g., percentage sharpness of the proximal left anterior descending coronary: 58.2 ± 7.4% versus 55.8 ± 8.4%; P < 0.05; and visible length of the RCA: 125.7 ± 25.9 mm versus 114.4 ± 27.4 mm; P < 0.05). CONCLUSION The use of end-expiration as a reference position for respiratory motion correction in free-breathing self-navigated whole heart coronary MRA significantly improves image quality. J
Collapse
Affiliation(s)
- Davide Piccini
- Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland.,Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.,Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Gabriele Bonanno
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.,Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Giulia Ginami
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.,Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | | | | | - Matthias Stuber
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.,Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| |
Collapse
|
2
|
Cardiovascular Magnetic Resonance Imaging for the Biomedical Engineer. Cardiovasc Eng Technol 2011. [DOI: 10.1007/s13239-011-0066-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
3
|
Heinrichs U, Utting JF, Frauenrath T, Hezel F, Krombach GA, Hodenius MA, Kozerke S, Niendorf T. MyocardialT2*mapping free of distortion using susceptibility-weighted fast spin-echo imaging: A feasibility study at 1.5 T and 3.0 T. Magn Reson Med 2009; 62:822-8. [DOI: 10.1002/mrm.22054] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
4
|
Abstract
Modern rapid magnetic resonance (MR) imaging techniques have led to widespread use of the modality in cardiac imaging. Despite this progress, many MR studies suffer from image degradation due to involuntary motion during the acquisition. This review describes the type and extent of the motion of the heart due to the cardiac and respiratory cycles, which create image artifacts. Methods of eliminating or reducing the problems caused by the cardiac cycle are discussed, including electrocardiogram gating, subject-specific acquisition windows, and section tracking. Similarly, for respiratory motion of the heart, techniques such as breath holding, respiratory gating, section tracking, phase-encoding ordering, subject-specific translational models, and a range of new techniques are considered.
Collapse
Affiliation(s)
- Andrew D Scott
- Cardiovascular Magnetic Resonance Unit, the Royal Brompton Hospital, London, England.
| | | | | |
Collapse
|
5
|
Dewan M, Hager GD, Lorenz CH. Image-based coronary tracking and beat-to-beat motion compensation: Feasibility for improving coronary MR angiography. Magn Reson Med 2008; 60:604-15. [DOI: 10.1002/mrm.21663] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
6
|
Goldfarb JW, Shinnar M. Free-breathing delayed hyperenhanced imaging of the myocardium: a clinical application of real-time navigator echo imaging. J Magn Reson Imaging 2006; 24:66-71. [PMID: 16736492 DOI: 10.1002/jmri.20609] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To compare a free-breathing (FB) acquisition with the current standard of breath-holding (BH) in a clinical setting using identical two-dimensional MR pulse sequences for imaging of myocardial delayed hyperenhancement. MATERIALS AND METHODS Two-dimensional gadolinium-enhanced images were acquired using FB and BH techniques in 18 subjects to evaluate delayed enhancement of myocardial infarction. The FB acquisition used a navigator echo to monitor the position of the right hemidiaphragm for respiratory gating and correction. Visual analysis using a 16-segment model, quantitative signal difference to noise ratios, and percent left ventricle (LV) viability measurements for the two acquisition types were statistically compared. RESULTS An excellent agreement between two-dimensional BH and two-dimensional FB acquisitions was found. In one patient, a nontransmural infarct was seen only in the FB images. There were no statistically significant differences in the number of infarcted segments or the measured signal difference to noise ratios (SDNR) between the two methods. Linear regression and Bland Altman analysis of the percentage LV viable myocardium yielded a good fit and narrow limits of agreement. CONCLUSION An FB navigator echo acquisition can be effectively used in the setting of myocardial delay hyperenhanced imaging. Image quality is similar or superior to that of BH imaging.
Collapse
Affiliation(s)
- James W Goldfarb
- Robert Wood Johnson University Hospital, New Brunswick, New Jersey, USA.
| | | |
Collapse
|
7
|
Muthupillai R, Smink J, Hong S, Ravindran R, Lee VV, Flamm SD. SENSE or k-MAG to Accelerate Free Breathing Navigator-Guided Coronary MR Angiography. AJR Am J Roentgenol 2006; 186:1669-75. [PMID: 16714657 DOI: 10.2214/ajr.05.1012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE The purpose of this study was to assess the relative merits of reducing the scanning time of navigator-guided (NAV) coronary MR angiography by including, both independently and in combination, two time-saving strategies: k-space weighted motion-adapted gating (k-MAG) and sensitivity encoding (SENSE, factor = 2). SUBJECTS AND METHODS Coronary arteries of 21 healthy subjects were imaged with four NAV MR angiography sequences: conventional NAV sequence, NAV with the addition of SENSE, NAV with the addition of k-MAG, and NAV with a combination of SENSE and k-MAG. All imaging parameters including the magnetization preparation schemes, prescribed spatial resolution, and acquisition duration per R-R interval were identical for all techniques. The total scanning time, navigator efficiency, visible length of the coronary artery, and subjective image quality were used as metrics for evaluating the performance of the techniques. RESULTS The results show that the addition of k-MAG to NAV coronary MR angiography (with or without SENSE) improved scan efficiency and decreased scanning time by an average of 17% without compromising the length of coronary artery visible or the image quality. The addition of SENSE to the NAV technique (with or without k-MAG) reduces the scanning time by an average of 50%. CONCLUSION While the average image quality of coronary arteries was unaffected by the addition of k-MAG to navigator techniques, there was a slight reduction in image quality scores for the navigator sequence with SENSE. Identification of the proximal coronary arteries was not hampered by the addition of k-MAG, SENSE, or both to the NAV coronary MR angiography sequence.
Collapse
Affiliation(s)
- Raja Muthupillai
- Department of Radiology, St. Luke's Episcopal Hospital and Texas Heart Institute and Baylor College of Medicine, 6720 Bertner Ave., MC 2-256, Houston, TX 77030, USA.
| | | | | | | | | | | |
Collapse
|
8
|
Niendorf T, Sodickson DK. Parallel imaging in cardiovascular MRI: methods and applications. NMR IN BIOMEDICINE 2006; 19:325-41. [PMID: 16705633 DOI: 10.1002/nbm.1051] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Cardiovascular MR imaging (CVMR) has become a valuable modality for the non-invasive detection and characterization of cardiovascular diseases. CVMR requires high imaging speed and efficiency, which is fundamentally limited in conventional cardiovascular MRI studies. With the introduction of parallel imaging, alternative means for increasing acquisition speed beyond these limits have become available. In parallel imaging some image data are acquired simultaneously, using RF detector coil sensitivities to encode simultaneous spatial information that complements the information gleaned from sequential application of magnetic field gradients. The resulting improvements in imaging speed can be used in various ways, including shortening long examinations, improving spatial resolution and/or anatomic coverage, improving temporal resolution, enhancing image quality, overcoming physiological constraints, detecting and correcting for physiologic motion, and streamlining work flow. Examples of each of these strategies will be provided in this review. First, basic principles and key concepts of parallel MR are described. Second, practical considerations such as coil array design, coil sensitivity calibrations, customized pulse sequences and tailored imaging parameters are outlined. Next, cardiovascular applications of parallel MR are reviewed, ranging from cardiac anatomical and functional assessment to myocardial perfusion and viability to MR angiography of the coronary arteries and the large vessels. Finally, current trends and future directions in parallel CVMR are considered.
Collapse
Affiliation(s)
- Thoralf Niendorf
- Department of Diagnostic Radiology, University Hospital, RWTH Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany
| | | |
Collapse
|
9
|
Danias PG, Roussakis A, Ioannidis JPA. Diagnostic performance of coronary magnetic resonance angiography as compared against conventional X-ray angiography: a meta-analysis. J Am Coll Cardiol 2005; 44:1867-76. [PMID: 15519021 DOI: 10.1016/j.jacc.2004.07.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2003] [Revised: 07/26/2004] [Accepted: 07/29/2004] [Indexed: 11/22/2022]
Abstract
OBJECTIVES This study was designed to define the current role of coronary magnetic resonance angiography (CMRA) for the diagnosis of coronary artery disease (CAD). BACKGROUND Coronary magnetic resonance angiography has been proposed as a promising noninvasive method for diagnosis of CAD, but individual studies evaluating its clinical value have been of limited sample size. METHODS We identified all studies (MEDLINE and EMBASE) that evaluated CAD by both CMRA and conventional angiography in >/=10 subjects during the period 1991 to January 2004. We recorded true and false positive and true and false negative CMRA assessments for detection of CAD using X-ray angiography as the reference standard. Analysis was done at segment, vessel, and subject level. RESULTS We analyzed 39 studies (41 separate comparisons). Across 25 studies (27 comparisons) with data on 4,620 segments (993 subjects), sensitivity and specificity for detection of CAD were 73% and 86%, respectively. Vessel-level analyses (16 studies, 2,041 vessels) showed sensitivity 75% and specificity 85%. Subject-level analyses (13 studies, 607 subjects) showed sensitivity 88% and specificity 56%. At the segment level, sensitivity was 69% to 79% for all but the left circumflex (61%) coronary artery; specificity was 82% to 91%. There was considerable between-study heterogeneity, but weighted summary receiver-operating characteristic curves agreed with these estimates. There were no major differences between subgroups based on technical or population characteristics, year of publication, reported blinding, or sample size. CONCLUSIONS In evaluable segments of the native coronary arteries, CMRA has moderately high sensitivity for detecting significant proximal stenoses and may have value for exclusion of significant multivessel CAD in selected subjects considered for diagnostic catheterization.
Collapse
|
10
|
Niendorf T, Saranathan M, Lingamneni A, Pedrosa I, Spencer M, Cline H, Foo TKF, Rofsky NM. Short breath-hold, volumetric coronary MR angiography employing steady-state free precession in conjunction with parallel imaging. Magn Reson Med 2005; 53:885-94. [PMID: 15799036 DOI: 10.1002/mrm.20446] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An ECG-gated, 3D steady-state free precession (SSFP) technique in conjunction with sensitivity encoding (SENSE)-based parallel imaging was implemented for short breath-hold, volumetric coronary MR angiograpy (CMRA). Two parallel imaging acquisition strategies (employing 1 R-R and 2 R-R intervals, respectively) were developed to achieve 1) very short breath-hold times (12 s for a heart rate of 60 bpm), and 2) small acquisition windows to minimize sensitivity to physiologic motion. Both strategies were examined in CMRA applications over a range of heart rates. A four-point scale blinded reading (with 4 indicating the most desirable features) revealed substantial image quality improvements for the accelerated data as compared to the nonaccelerated approach. The 1 R-R interval scheme yielded an image score of 3.39 +/- 0.60, and was found to be particularly suitable for low heart rates (P = 0.0008). The 2 R-R interval strategy yielded an image score of 3.35 +/- 0.64, and was more appropriate for higher heart rates (P = 0.03). The results demonstrate that 3D SSFP combined with parallel imaging is a versatile method for short breath-hold CMRA while maintaining high spatial resolution. This strategy permits imaging of the major coronary artery distributions in two to three breath-holds using targeted slabs, and offers the potential for single breath-hold, large-volume CMRA.
Collapse
Affiliation(s)
- Thoralf Niendorf
- Applied Science Laboratory, GE Healthcare, Boston, Massachusetts, USA
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Abstract
Coronary magnetic resonance angiography (coronary MRA) continues to advance rapidly from both a technical and clinical perspective. Coronary MRA has benefited directly from improvements in spatial resolution, contrast definition, and advances in motion correction, which have furthered its routine use in evaluating coronary artery bypass grafts and anomalous coronary arteries. Work in refining the techniques for more accurate identification of coronary artery disease (CAD) continues, with advances in navigator-gated and breath-hold motion correction techniques, novel k-space strategies (e.g., spiral and radial k-space filling), development and application of intravascular contrast agents, and imaging at higher field strengths. Ultimately, these developments may lead to the routine application of coronary MRA as a screening tool for CAD. This article reviews the development of coronary MRA, discusses the requirements and tools necessary for optimal visualization of the coronary arteries, and describes the application of coronary MRA to acquired and congenital CAD.
Collapse
Affiliation(s)
- Scott D Flamm
- Department of Radiology, St. Luke's Episcopal Hospital and Texas Heart Institute, Houston, Texas 77030, USA.
| | | |
Collapse
|
12
|
Budoff MJ, Achenbach S, Duerinckx A. Clinical utility of computed tomography and magnetic resonance techniques for noninvasive coronary angiography. J Am Coll Cardiol 2003; 42:1867-78. [PMID: 14662244 DOI: 10.1016/j.jacc.2003.07.018] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The purpose of this study was to provide a comprehensive review of the literature relating to electron beam angiography (EBA), magnetic resonance angiography, and spiral computed tomography, currently the three most promising noninvasive methods to visualize obstructions in the coronary tree. BACKGROUND Given the high costs and invasiveness of coronary angiography, there is increased interest in noninvasive coronary angiography, which has made great strides to become a clinically useful tool to augment conventional coronary angiography (CCA). METHODS MEDLINE searches were performed to include all articles related to noninvasive angiography utilizing either magnetic resonance imaging (MRI), multi-row detector spiral computed tomography (MDCT), and electron beam tomography (EBT). Weighted analysis was performed to define the published sensitivity and specificity for each technique. RESULTS Electron beam angiography (EBA) provides an overall sensitivity of 87% and specificity of 91% for the detection of obstructive coronary artery disease (CAD). Four-level MDCT data demonstrated an overall sensitivity of 59% and specificity of 89%, with higher accuracy in two recent studies of 16-level detector devices. Magnetic resonance angiography demonstrated sensitivity for detection of obstructive CAD of 77% and specificity of 71%. CONCLUSIONS Noninvasive coronary angiography is a rapidly developing technique and currently not an alternative to CCA in all cases. All three methods are currently used clinically in certain centers with appropriate expertise. Selective use should prove both cost-effective and provide a safer, less-invasive method for patients to determine the need for medical versus revascularization therapy.
Collapse
Affiliation(s)
- Matthew J Budoff
- Division of Cardiology, Saint John's Cardiovascular Research Center, Harbor-UCLA Medical Center Research and Education Institute, Torrance, California 90502, USA.
| | | | | |
Collapse
|
13
|
Kolmogorov VN, Watts R, Prince MR, Zabih R, Wang Y. Simultaneous multiple volume (SMV) acquisition algorithm for real-time navigator gating. Magn Reson Imaging 2003; 21:969-75. [PMID: 14684198 DOI: 10.1016/s0730-725x(03)00203-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Navigator gating techniques can effectively reduce motion effects in MRI by accepting data only when the object is in a small range of positions at the cost of significantly prolonging scan time. A simultaneous multiple volume (SMV) algorithm is reported here that can substantially increase the scan efficiency while maintaining the effectiveness of motion suppression. This is achieved by acquiring different image volumes at different motion states. Initial experiments demonstrate that SMV can significantly increase the scan efficiency of navigator MRI.
Collapse
|
14
|
Nagel E. In response to the article by Thomas Wittlinger and co-workers: Magnetic resonance imaging of coronary artery occlusions in the navigator technique. Int J Cardiovasc Imaging 2002; 18:1-3. [PMID: 12135117 DOI: 10.1023/a:1014395606192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
15
|
Du YP, McVeigh ER, Bluemke DA, Silber HA, Foo TK. A comparison of prospective and retrospective respiratory navigator gating in 3D MR coronary angiography. Int J Cardiovasc Imaging 2001; 17:287-94; discussion 295-6. [PMID: 11599868 PMCID: PMC2396324 DOI: 10.1023/a:1011675130904] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A comparison between the prospective and retrospective respiratory navigator gating in MR coronary angiography was performed with eight normal subjects. A three-dimensional (3D) ECG-gated fast gradient echo pulse sequence was used for image data acquisition. The results show that the MR coronary angiography obtained using retrospective gating retains a considerable amount of motion artifacts. In this study, the images acquired using prospective navigator gating demonstrated significantly reduced motion artifacts (p = 0.009), improved vessel visibility (p = 0.021) with reduced imaging time (p = 0.013) compared to the images obtained using retrospective navigator gating.
Collapse
Affiliation(s)
- Y P Du
- Applied Science Lab, GE-Medical Systems, Milwaukee, Wisconsin, USA.
| | | | | | | | | |
Collapse
|
16
|
Foo TK, Saranathan M, Hardy CJ, Ho VB. Coronary artery magnetic resonance imaging: a patient-tailored approach. Top Magn Reson Imaging 2000; 11:406-16. [PMID: 11153707 DOI: 10.1097/00002142-200012000-00009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
Coronary artery magnetic resonance imaging strategies have tended to focus on the use of a single method performed during either breath-holding or free-breathing for all patients. However, significant variations exist among patients in terms of breath-holding ability and respiratory regularity that make the use of a single technique alone not universally successful. Therefore, it is prudent to make available a number of magnetic resonance imaging methods such that an appropriate respiratory motion reduction strategy can be tailored to suit the patient's respiratory pattern and characteristics. A tailored approach that can draw on different image acquisition techniques for coronary artery imaging is presented. A decision tree is proposed to triage patients into imaging regimes with the greatest probability of success, according to the patient's ability to breath-hold or exhibit steady respiration. Methods include volume free-breathing acquisitions using navigator echoes for respiratory monitoring in the 8- to 10-min scan time range, two-dimensional spiral navigators (2- to 3-min scan time), breath-held multislice and vessel-tracking spirals (16- to 20-second scan time), and real-time imaging approaches incorporating adaptive signal averaging. The development of multiple acquisition strategies substantially improves the opportunities to generate high-quality, diagnostic images of the coronary arteries.
Collapse
Affiliation(s)
- T K Foo
- Applied Science Laboratory, GE Medical Systems, Milwaukee, Wisconsin, USA
| | | | | | | |
Collapse
|
17
|
Affiliation(s)
- P G Danias
- Charles A. Dana Research Institute and the Harvard-Thorndike Laboratory, Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
| | | | | | | |
Collapse
|
18
|
Langerak SE, Kunz P, de Roos A, Vliegen HW, van Der Wall EE. Evaluation of coronary artery bypass grafts by magnetic resonance imaging. J Magn Reson Imaging 1999; 10:434-41. [PMID: 10508306 DOI: 10.1002/(sici)1522-2586(199909)10:3<434::aid-jmri27>3.0.co;2-g] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Magnetic resonance (MR) angiography and flow mapping have the potential to become a major noninvasive diagnostic tool for the assessment of coronary artery bypass graft morphology and function. Several MR sequences, such as conventional non-respiratory compensated methods, and phase contrast cine flow sequences have been reported for the evaluation of bypass graft patency. However the visualization of different graft segments and the detection of graft stenosis remains difficult. Recent advances in MR coronary angiography and flow mapping are volume coronary angiongraphy with targeted scans, navigator gated angiography, contrast-enhanced angiography, and breath-hold or navigator gated flow sequences. Future approaches, such as navigator gated fast MR techniques resulting in high-resolution angiography in combination with breath-hold MR flow mapping with high temporal resolution, might allow a comprehensive evaluation of bypass graft stenosis and function. This review article will address the major issues concerning the MR evaluation of bypass grafts.
Collapse
Affiliation(s)
- S E Langerak
- Department of Cardiology (C5-P), Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | | | | | | | | |
Collapse
|