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Mahon C, Mohiaddin RH. The emerging applications of cardiovascular magnetic resonance imaging in transcatheter aortic valve implantation. Clin Radiol 2019; 76:73.e21-73.e37. [PMID: 31879023 DOI: 10.1016/j.crad.2019.11.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/13/2019] [Indexed: 12/22/2022]
Abstract
Transcatheter aortic valve implantation (TAVI) is an alternative to surgical aortic valve replacement in selected patients with severe symptomatic aortic stenosis (AS) and high surgical risk. The planning and follow-up of TAVI requires an array of imaging techniques, each has advantages and limitations. Echocardiography and multidetector computer tomography (MDCT) have established applications in patient selection and procedure guidance, but are limited in some patients. TAVI applications of cardiovascular magnetic resonance imaging (CMRI) are emerging. CMRI can provide the structural and functional imaging details required for TAVI procedure in away comparable or superior to that obtained by echocardiography and MDCT combined. In this review, we look at the continuously evolving role of CMRI as a complimentary or an alternative to more established imaging techniques and address the advantages and disadvantages of CMRI in this setting. We discuss the role of CMRI in selecting anatomically suitable patients for the TAVI procedure and in the post-TAVI follow-up with particular emphasis on its applications for assessing AS severity and haemodynamic impact, vascular imaging for TAVI access route, quantification of paravalvular leaks and LV remodelling in the post TAVI setting as well as providing imaging biomarkers tool for AS risk-stratification.
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Affiliation(s)
- C Mahon
- Royal Brompton and Harefield NHS Foundation Trust, London, UK
| | - R H Mohiaddin
- Royal Brompton and Harefield NHS Foundation Trust, London, UK; National Heart and Lung Institute, Imperial College London, London, UK.
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2
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Lutz A, Bornstedt A, Manzke R, Etyngier P, Nienhaus GU, Rottbauer W, Rasche V. Acceleration of tissue phase mapping with sensitivity encoding at 3T. J Cardiovasc Magn Reson 2011; 13:59. [PMID: 21992267 PMCID: PMC3217863 DOI: 10.1186/1532-429x-13-59] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 10/12/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The objective of this study was to investigate the impact of sensitivity encoding on the quantitative assessment of cardiac motion in black blood cine tissue phase mapping (TPM) sequences. Up to now whole volume coverage of the heart is still limited by the long acquisition times. Therefore, a significant increase in imaging speed without deterioration of quantitative motion information is indispensable. METHODS 20 volunteers were enrolled in this study. Each volunteer underwent myocardial short-axis TPM scans with different SENSE acceleration factors. The influence of SENSE acceleration on the measured motion curves was investigated. RESULTS It is demonstrated that all TPM sequences with SENSE acceleration have only minimum influence on the motion curves. Even with a SENSE factor of four, the decrease in the amplitude of the motion curve was less than 3%. No significant difference was observed for the global correlation coefficient and deviation between the motion curves obtained by the reproducibility and the SENSE accelerated measurements. CONCLUSIONS It is feasible to accelerate myocardial TPM measurements with SENSE factors up to 4 without losing substantial information of the motion pattern.
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Affiliation(s)
- Anja Lutz
- Department of Internal Medicine II, University Hospital of Ulm, Ulm Germany
| | - Axel Bornstedt
- Department of Internal Medicine II, University Hospital of Ulm, Ulm Germany
| | - Robert Manzke
- Philips Research North America, Briarcliff Manor, USA
| | | | | | - Wolfgang Rottbauer
- Department of Internal Medicine II, University Hospital of Ulm, Ulm Germany
| | - Volker Rasche
- Department of Internal Medicine II, University Hospital of Ulm, Ulm Germany
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3
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Siemionow M, Arslan E. Ischemia/reperfusion injury: a review in relation to free tissue transfers. Microsurgery 2005; 24:468-75. [PMID: 15378577 DOI: 10.1002/micr.20060] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Events during ischemia/reperfusion (I/R) injury include: neutrophil-mediated endothelial cytotoxicity and activation, generation of free radicals, triggering of cytokines and chemokines, and activation of adhesion molecules and complement system. This article briefly reviews events occurring during tissue ischemia and reperfusion in relation to free tissue transfers. The consequences of tissue damage at the microcirculatory level are presented. Preventive measures of I/R injury are outlined.
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Affiliation(s)
- Maria Siemionow
- Department of Plastic Surgery, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
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4
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Markle BM, Cross RR. Cross-sectional imaging in congenital anomalies of the heart and great vessels: magnetic resonance imaging and computed tomography. Semin Roentgenol 2004; 39:234-62. [PMID: 15143688 DOI: 10.1053/j.ro.2003.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Bruce M Markle
- Departments of Diagnostic Imaging and Radiology, Department of Pediatric Cardiology, Children's National Medical Center, 111 Michigan Ave., NW, Washington, DC 20010, USA
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5
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Wang ZJ, Reddy GP, Gotway MB, Yeh BM, Higgins CB. Cardiovascular shunts: MR imaging evaluation. Radiographics 2003; 23 Spec No:S181-94. [PMID: 14557511 DOI: 10.1148/rg.23si035503] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Magnetic resonance (MR) imaging has become an important tool for the accurate and noninvasive assessment of congenital heart disease. Because more precise delineation of anatomy and evaluation of function can be obtained with MR imaging than with either echocardiography or angiography, MR imaging is frequently used to evaluate cardiovascular shunt lesions. It is essential that imaging specialists be able to recognize the MR imaging features of various kinds of shunts, including supracristal ventricular septal defect, atrioventricular septal defect, and partial anomalous pulmonary venous connection. MR imaging is particularly useful for evaluating shunt severity, which can be expressed quantitatively as the ratio of pulmonary flow to systemic flow. This ratio can be estimated accurately with the use of either volumetric cine MR imaging or velocity-encoded cine MR imaging.
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Affiliation(s)
- Zhen J Wang
- Department of Radiology, Box 0628, University of California, 505 Parnassus Ave, San Francisco, CA 94143-0628, USA
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6
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Reddy GP, Higgins CB. Magnetic resonance imaging of congenital heart disease: evaluation of morphology and function. Semin Roentgenol 2003; 38:342-51. [PMID: 14621376 DOI: 10.1016/s0037-198x(03)00055-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Gautham P Reddy
- Department of Radiology, Suite M396, 505 Parnassus Avenue, Box 0628, University of California, San Francisco, San Francisco, CA 94143-0628, USA
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7
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Spuentrup E, Schroeder J, Mahnken AH, Schaeffter T, Botnar RM, Kühl HP, Hanrath P, Günther RW, Buecker A. Quantitative assessment of left ventricular function with interactive real-time spiral and radial MR imaging. Radiology 2003; 227:870-6. [PMID: 12773686 DOI: 10.1148/radiol.2273020303] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An interactive real-time spiral gradient-echo and an interactive real-time radial steady-state free precession sequence were investigated for the quantitative assessment of left ventricular function. Data were acquired in 18 patients without electrocardiographic triggering and breath holding. With the interactive real-time spiral gradient-echo sequence, significant underestimation of endocardial and epicardial volumes was demonstrated; with the interactive real-time radial steady-state free precession sequence, excellent agreement was shown with standard cardiac-triggered segmented k-space breath-hold steady-state free precession MR imaging. Interactive real-time radial steady-state free precession imaging allows accurate quantitative assessment of left ventricular volumes.
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Affiliation(s)
- Elmar Spuentrup
- Department of Diagnostic Radiology, University Hospital, Technical University of Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany.
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8
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Masood S, Gao J, Yang GZ. Virtual tagging: numerical considerations and phantom validation. IEEE TRANSACTIONS ON MEDICAL IMAGING 2002; 21:1123-1131. [PMID: 12564880 DOI: 10.1109/tmi.2002.804429] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper presents a virtual tagging framework for measuring, as well as visualising, myocardial deformation using magnetic resonance (MR) velocity imaging. Tagging grids are allocated artificially according to the deformation gradient with varying shapes and densities. The control points are then deformed such that the difference between the induced deformation velocity and that of actually measured MR data is minimum. A full three-dimensional implementation of the technique combined with the mass conservation constraint is provided. Numerical considerations of applying the proposed framework and different optimization strategies have been investigated with both simulated and phantom experiments. The accuracy of the technique in terms of following material deformation is compared with that of conventional tagging technique.
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Affiliation(s)
- Sharmeen Masood
- Royal Society/Wolfson Foundation Medical Image Computing Laboratory, Imperial College of Science, Technology and Medicine, University of London, SW7 2BZ London, UK
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9
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Varaprasathan GA, Araoz PA, Higgins CB, Reddy GP. Quantification of flow dynamics in congenital heart disease: applications of velocity-encoded cine MR imaging. Radiographics 2002; 22:895-905; discussion 905-6. [PMID: 12110719 DOI: 10.1148/radiographics.22.4.g02jl10895] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Velocity-encoded cine (VEC) magnetic resonance (MR) imaging is a valuable technique for quantitative assessment of flow dynamics in congenital heart disease (CHD). VEC MR imaging has a variety of clinical applications, including the measurement of collateral flow and pressure gradients in coarctation of the aorta, differentiation of blood flow in the left and right pulmonary arteries, quantification of shunts, and evaluation of valvular regurgitation and stenosis. After surgical repair of CHD, VEC MR imaging can be used to monitor conduit blood flow, stenosis, and flow dynamics. There are some pitfalls that can occur in VEC MR imaging. These include potential underestimation of velocity and flow, aliasing, inadequate depiction of very small vessels, and possible errors in pressure gradient measurements. Nevertheless, VEC MR imaging is a valuable tool for preoperative planning and postoperative monitoring in patients with CHD.
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Affiliation(s)
- Gita A Varaprasathan
- Department of Radiology, Box 0628, University of California, San Francisco, 505 Parnassus Ave, Suite L325, 94143-0628, USA
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10
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Abstract
BACKGROUND Human hemodynamics occurs in very short periods of time. To quantify blood flow under these circumstances, a fast-scan imaging technique is required. Echo-planar imaging can be a good candidate because it is able to acquire images in <50-100 msec. An imaging scheme with these properties can produce real-time images as well as overcome motion artifacts such as blurring and ghosting, which alter image quality. Additionally, echo-planar imaging does not require a calibration protocol to perform flow experiments in the human cardiovascular system. Consequently, echo-planar imaging appears to be the best imaging tool available to quantify blood flow in the vena cava. From a clinical point of view, echo-planar imaging has become a widespread commodity to produce magnetic resonance images in real-time. METHODS Flow-encoded half Fourier echo-planar imaging is proposed to determine blood flow in the arteries. This flow sequence was used to investigate vena cava blood flow in healthy volunteers and compared with other diagnostic imaging modalities. RESULTS Two-dimensional flow maps were obtained by using the two components (sine and cosine images) resulting from the flow-encoded echo-planar imaging sequence. Velocity profiles of vena cava of two healthy volunteers were calculated from the previous bidimensional blood flow maps. CONCLUSIONS We proved that real-time flow imaging of the cardiovascular system can be achieved with flow-encoded echo-planar imaging and a partial Fourier method. It is possible to quantify blood flow in the superior vena cava in humans. We believe that this imaging tool might offer relevant anatomic and physiologic information of the vena cava as well as of the cardiovascular system.
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Affiliation(s)
- Alfredo O Rodríguez
- Departamento de Ingeniería Eléctrica, Universidad Autónoma de México (UAM) Iztapalapa, San Rafael Atlixco 186, 09340 México City, D.F., México.
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11
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Petersen SE, Voigtländer T, Kreitner KF, Kalden P, Wittlinger T, Scharhag J, Horstick G, Becker D, Hommel G, Thelen M, Meyer J. Quantification of shunt volumes in congenital heart diseases using a breath-hold MR phase contrast technique--comparison with oximetry. Int J Cardiovasc Imaging 2002; 18:53-60. [PMID: 12135123 DOI: 10.1023/a:1014394626363] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AIMS Comparison of breath-hold MR phase contrast technique in the estimation of cardiac shunt volumes with the invasive oximetric technique. METHODS AND RESULTS Seventeen patients with various cardiac shunts (10 ASD, 3 VSD, 1 PDA, 3 PFO) and five healthy volunteers were investigated using a 1.5 Tesla system. The mean flow velocity, the mean volume flow and the transverse area in the ascending aorta and the left and right pulmonary artery were measured using the MR phase contrast breath-hold technique (through plane, FLASH 2D-sequence, TR/TE 11/5 ms, phase length 106 ms, VENC 250 cm/s). The ratio of mean flow in the pulmonary (Qp: sum of mean flows in the left and right pulmonary arteries) and the systemic circulation (Qs: mean flow in the ascending aorta) was calculated and compared with invasively measured Qp:Qs ratios. Oximetry was performed within 24 h of the MR investigation. The non-invasive shunt measurement in the 17 patients showed a mean Qp:Qs ratio of 2.00 +/- 0.86. Comparing the MR data with the invasively measured Qp:Qs showed a correlation coefficient of r = 0.91 (p < 0.001). CONCLUSION Cardiac shunt volumes can be measured reliably using a shorter acquisition time with breath-hold MR phase contrast technique.
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Affiliation(s)
- Steffen E Petersen
- 2nd Medical Clinic, Johannes Gutenberg University Hospital Mainz, Germany.
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12
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Schaeffter T, Weiss S, Eggers H, Rasche V. Projection reconstruction balanced fast field echo for interactive real-time cardiac imaging. Magn Reson Med 2001; 46:1238-41. [PMID: 11746592 DOI: 10.1002/mrm.1322] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A balanced fast field echo (FFE) sequence (also referred to as true fast imaging with steady precession (true FISP)), based on projection reconstruction (PR) is evaluated in combination with real-time reconstruction and interactive scanning capabilities for cardiac function studies. Cardiac image sequences obtained with the balanced PR-FFE method are compared with images obtained with a spin-warp (2D Fourier transform (2DFT)) technique. In particular, the representation of motion artifacts in both techniques is investigated. Balanced PR-FFE provides a similar contrast to spin-warp-related techniques, but is less sensitive to motion artifacts. The use of angular undersampling within balanced PR-FFE is examined as a means to increase temporal resolution while causing only minor artifacts. Furthermore, a modification of the profile order allows the reconstruction of PR images at different spatial and temporal resolution levels from the same data. This study shows that balanced PR-FFE is a robust tool for cardiac function studies.
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Affiliation(s)
- T Schaeffter
- Philips Research Laboratories, Hamburg, Germany.
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13
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Masood S, Yang GZ, Pennell DJ, Firmin DN. Investigating intrinsic myocardial mechanics: the role of MR tagging, velocity phase mapping, and diffusion imaging. J Magn Reson Imaging 2000; 12:873-83. [PMID: 11105025 DOI: 10.1002/1522-2586(200012)12:6<873::aid-jmri10>3.0.co;2-j] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Assessment of myocardial mechanics is an integral part of understanding and predicting heart disease. This review covers the two most common magnetic resonance (MR) methods used to measure myocardial motion: myocardial tagging and myocardial velocity mapping. Myocardial tagging has been well established in clinical research, despite its time-consuming postprocessing procedure. Myocardial velocity mapping uses the phase shifts of the spins to encode the velocity into the MR signal. This means that once the myocardial contours have been segmented, the data can be automatically processed to obtain quantitative measurements. Diffusion MR also has found applications in cardiac imaging, with preliminary results of myocardial fiber architecture being obtained recently. These three different MR techniques have provided valuable insights into the assessment of intrinsic cardiac mechanics. J. Magn. Reson. Imaging 2000;12:873-883.
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Affiliation(s)
- S Masood
- Department of Computing, Imperial College, London, U.K
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14
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Setser RM, Fischer SE, Lorenz CH. Quantification of left ventricular function with magnetic resonance images acquired in real time. J Magn Reson Imaging 2000; 12:430-8. [PMID: 10992310 DOI: 10.1002/1522-2586(200009)12:3<430::aid-jmri8>3.0.co;2-v] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The application of real-time magnetic resonance imaging (MRI) techniques to cardiac imaging is particularly attractive because current MR examinations of left ventricular (LV) function can be prohibitively long and are dependent on electrocardiographic triggering. We conducted a study of the minimum spatial and temporal resolution requirements necessary for real-time ventricular function MR imaging to quantify LV volumes accurately, both at resting conditions and during cardiac stress tests. In addition, we implemented a real-time segmented echoplanar imaging pulse sequence and used it to quantify LV volume in 10 healthy volunteers. We compared these results with those obtained using conventional gradient-echo cine imaging and found good agreement throughout the cardiac cycle (mean difference -0.8 +/- 10.6 ml). In conclusion, real-time cardiac MR imaging can be used to quantify LV volumes accurately throughout the cardiac cycle, over the physiologic range of heart rates, thereby decreasing the time required for a complete functional cardiac examination. J. Magn. Reson. Imaging 2000;12:430-438.
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Affiliation(s)
- R M Setser
- Cardiovascular Division, Barnes-Jewish Hospital at Washington University Medical Center, St. Louis, Missouri 63110, USA
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15
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Abstract
As outlined in this article, the strength of MR imaging is that it can provide flow, function, and in some cases metabolic data in a single examination, independent of patient body habitus. Future prospects for real-time imaging and in vivo mapping of fiber orientation promise further advances in our understanding of the structure-function relationship in diastole. Many of the MR imaging methods that have been developed for cardiovascular imaging are now mature and available on state-of-the-art scanners. Although MR imaging can provide detailed characterization of diastolic function, there is a paucity of clinical results which could lead to use guidelines. When more clinicians have access and become familiar with MR imaging, and the type of information that it can provide, clinical trials will be needed to establish the role of MR imaging for evaluation of diastolic function. In the meantime, MR imaging remains an excellent research tool for this application and will help yield further insights into the pathophysiology of diastolic dysfunction.
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Affiliation(s)
- C H Lorenz
- Department of Medicine, Barnes-Jewish Hospital, Washington University Medical Center, St. Louis, Missouri, USA.
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Lladó (coordinador) GP, Costa FC, Beiras AC, Domínguez JF, Romo AI, Jiménez Borreguero LJ, Gálvez y Rafaela Soler Fernández CP. Guías de práctica clínica de la Sociedad Española de Cardiología en resonancia magnética. Rev Esp Cardiol 2000. [DOI: 10.1016/s0300-8932(00)75125-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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van der Wall EE, Bax J. Current clinical relevance of cardiovascular magnetic resonance and its relationship to nuclear cardiology. J Nucl Cardiol 1999; 6:462-9. [PMID: 10461614 DOI: 10.1016/s1071-3581(99)90013-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Migliavacca F, Kilner PJ, Pennati G, Dubini G, Pietrabissa R, Fumero R, de Leval MR. Computational fluid dynamic and magnetic resonance analyses of flow distribution between the lungs after total cavopulmonary connection. IEEE Trans Biomed Eng 1999; 46:393-9. [PMID: 10217877 DOI: 10.1109/10.752936] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Total cavopulmonary connection is a surgical procedure adopted to treat complex congenital malformations of the right heart. It consists basically in a connection of both venae cavae directly to the right pulmonary artery. In this paper a three-dimensional model of this connection is presented, which is based on in vivo measurements performed by means of magnetic resonance. The model was developed by means of computational fluid dynamics techniques, namely the finite element method. The aim of this study was to verify the capability of such a model to predict the distribution of the blood flow into the pulmonary arteries, by comparison with in vivo velocity measurements. Different simulations were performed on a single clinical case to test the sensitivity of the model to different boundary conditions, in terms of inlet velocity profiles as well as outlet pressure levels. Results showed that the flow distribution between the lungs is slightly affected by the shape of inlet velocity profiles, whereas it is influenced by different pressure levels to a greater extent.
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Affiliation(s)
- F Migliavacca
- Dipartimento di Bioingegneria, Politecnico di Milano, Italy
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Bogren HG, Buonocore MH. Complex flow patterns in the great vessels: a review. INTERNATIONAL JOURNAL OF CARDIAC IMAGING 1999; 15:105-13. [PMID: 10453409 DOI: 10.1023/a:1006281923372] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The article reviews the applications of magnetic resonance velocity mapping based on phase shifts in the protons to quantify blood flow velocity and blood flow volume. The method can be used to study normal physiology of blood flow in the aorta and its major branches, including forward and backward flow, to measure the aortic valve function in aortic valvular disease, stenosis and regurgitation, as well as pulmonary artery flow velocities in pulmonic insufficiency and regurgitation. Superior vena cava flows, pulmonary vein flows, left-to-right shunts, atrial and ventricular pulmonary conduit flows can also be measured. Two- and three-directional velocity mapping is reviewed and can be used to study three- or four-D flows in the aorta and the major arteries in great detail.
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Affiliation(s)
- H G Bogren
- Department of Radiology, UC Davis Medical Center, Sacramento, USA
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20
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Wise RG, Huang CL, Gresham GA, Al-Shafei AI, Carpenter TA, Hall LD. Magnetic resonance imaging analysis of left ventricular function in normal and spontaneously hypertensive rats. J Physiol 1998; 513 ( Pt 3):873-87. [PMID: 9824724 PMCID: PMC2231313 DOI: 10.1111/j.1469-7793.1998.873ba.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/1998] [Accepted: 09/09/1998] [Indexed: 11/30/2022] Open
Abstract
1. We have used magnetic resonance imaging (MRI) to examine acute morphological changes in the left ventricle throughout the cardiac cycle in normal Wistar Kyoto rats (WKY) and also to follow the development of chronic changes in spontaneously hypertensive rats (SHR). This involved the development of MRI and quantitative analysis techniques for characterizing contractile changes during the cardiac cycle. 2. Images of the cardiac anatomy in two age groups (8 and 12 weeks old) of young anaesthetized adult normal WKY and SHR were acquired in planes both parallel and perpendicular to the principal cardiac axis. 3. Complete coverage of the heart by imaging planes was achieved with high time resolution (13 ms), with typically 12 time frames in the cardiac cycle, using a short echo time (5 ms) multislice gradient-echo imaging sequence. Imaging was synchronized to the R wave of the electrocardiogram. 4. The image slices could be reconstructed into complete geometrically and temporally coherent three-dimensional data sets. Left ventricular (LV) volumes were thus reconstructed throughout the cardiac cycle by combining transverse cardiac image sections. This volume analysis revealed structural and functional differences between the normal WKY and SHR in both age groups of 8 and 12 weeks. Measurements from the cardiac images were additionally validated against histological measurements. 5. The SHR showed a raised LV end-systolic volume and a correspondingly poorer ejection fraction as well as LV hypertrophy when compared with the controls. Left ventricular function in the SHR appeared stable between the two age groups. 6. We developed a simple geometrical model of the left ventricle based on a single longitudinal image section and successfully used this to describe some functional parameters of the left ventricle in the WKY and SHR. This geometrical model has the potential to greatly reduce the imaging time needed to study the beating heart in future serial investigations of cardiac physiology in rats. 7. Our experimental and analytical methods together form a powerful set of quantitative techniques which combine both imaging and functional analysis and will be applicable for future studies of chronic physiological changes in animal disease models.
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Affiliation(s)
- R G Wise
- Herchel Smith Laboratory for Medicinal Chemistry, University of Cambridge, School for Clinical Medicine, Robinson Way, Cambridge CB2 2PZ, UK
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21
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Hokken RB, de Bruin HG, Taams MA, Bogers AJ, van Herwerden LA, Roelandt JR, Bos E, Oudkerk M. Gradient echo MRI for measurement of the pulmonary autograft diameter after transplantation to the aortic root: validation and comparison with ultrasound. J Magn Reson Imaging 1998; 8:1015-21. [PMID: 9786137 DOI: 10.1002/jmri.1880080504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The purpose of this study was to s the value of MRI for measurement of pulmonary autograft diameters after transplantation to the aortic root in adults. Thirty-eight adults underwent this operation. MRI and transesophageal echocardiography (TEE) were performed in 30 and 27 patients, respectively, after a mean follow-up period of 2.8 years. For internal validation of MRI, measurements at the diastolic short and long axes of the sinus level were used. Pulmonary autograft diameters were measured and compared with MRI and TEE at five different levels: the subannular region (1), annulus (2), sinus (3), sinotubular junction (4), and the distal part of the autograft (5). The correlation coefficient (r2) between long- and short-axis measurements for corresponding sinuses was .97. Diameters obtained with MRI were 1 to 3 mm larger than those obtained with TEE (P < .05), except for the annulus at systole (P > .3). Cine gradient echo MRI is an appropriate technique to evaluate pulmonary autograft diameters during follow-up. Concordance with TEE was good, apart from a systematic difference of approximately 2 mm.
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Affiliation(s)
- R B Hokken
- Department of Cardiopulmonary Surgery, University Hospital Sophia/Dijkzigt/Dr. Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
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BENSON LEEN, OVAERT CAROLINE, NYKANEN DAVID, FREEDOM ROBERTM. Nonsurgical Management of Coarctation of the Aorta. J Interv Cardiol 1998. [DOI: 10.1111/j.1540-8183.1998.tb00137.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Abstract
Cine MRI and VEC MRI can be used to quantitate the physiology of the heart and great vessels in patients with CHD. This information can be a valuable adjunct to anatomical imaging for preoperative planning as well as postoperative monitoring. Some important clinical applications of quantitative cardiovascular functional MRI include measurement of ventricular masses, stroke volumes, and ejection fractions; estimation of shunts and valvular regurgitation; assessment of collateral blood flow and pressure gradients in aortic coarctation; and postsurgical evaluation of conduit blood flow and pressure gradients.
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Affiliation(s)
- G P Reddy
- Department of Radiology, University of California, San Francisco 94143-0628, USA
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Abstract
Several magnetic resonance imaging methods for measuring blood flow have greatly enhanced the capability of magnetic resonance imaging as a physiologic tool in cardiology. This article concentrates on phase-related techniques. Magnetic resonance velocity mapping is a flexible, robust, and accurate method of obtaining functional information in the cardiovascular system. It has the potential to contribute significantly to clinical decision making, and it should be a routine part of cardiovascular imaging whenever information on flow is required.
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Affiliation(s)
- R H Mohiaddin
- Magnetic Resonance Unit, Royal Brompton Hospital, Imperial College of Science, Technology and Medicine, National Heart and Lung Institute, London, United Kingdom
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25
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Bogren HG, Mohiaddin RH, Kilner PJ, Jimenez-Borreguero LJ, Yang GZ, Firmin DN. Blood flow patterns in the thoracic aorta studied with three-directional MR velocity mapping: the effects of age and coronary artery disease. J Magn Reson Imaging 1997; 7:784-93. [PMID: 9307902 DOI: 10.1002/jmri.1880070504] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The objective was to investigate how the blood flows in the thoracic aorta, with special emphasis on flow reversal and flow into the coronary arteries. Three-directional MR velocity mapping was used to map multidirectional flow velocities in the aorta in 14 normal subjects and 14 patients with coronary artery disease. Dynamic flow vector maps and through-plane velocity maps were used. The flow reversed in all subjects in the upper ascending aorta and usually also in the distal aortic arch. Retrograde flow became antegrade again at various levels in the ascending aorta and in the coronary sinuses. Seven flow characteristics were investigated that, lumped together, were significantly different (P = .0005) in normal subjects compared with patients and in normal subjects 70 years of age and older compared with those younger than 70 years of age.
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Affiliation(s)
- H G Bogren
- Magnetic Resonance Unit, Royal Brompton Hospital, London, United Kingdom.
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27
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Urchuk SN, Fremes SE, Plewes DB. In vivo validation of MR pulse pressure measurement in an aortic flow model: preliminary results. Magn Reson Med 1997; 38:215-23. [PMID: 9256100 DOI: 10.1002/mrm.1910380209] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
MR imaging experiments were conducted to investigate the feasibility of estimating vascular pulse pressure waveforms from measurements of blood flow rates and vessel cross-sectional area. Blood flow waveforms were measured in the aorta's of three 25-30-kg pigs at multiple imaging sections using phase-contrast velocity imaging. Estimates of pulse pressure were derived from these data by evaluating a model characterizing the relationship between pressure, flow, and the cross-sectional area of a vessel segment. Comparisons between the MR-derived estimates of pressure and those obtained from a micromanometer pressure catheter indicate that accurate measurements (mean error +/- SD = 8.2 +/- 3.4, n = 6) can be obtained using conventional velocity imaging techniques. Optimization of the method will require the application of rapid imaging techniques and the development of strategies for obtaining a more localized measurement. With these improvements, our results suggest that MR-based measurement of pulse pressure and related elastic parameters is feasible.
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Affiliation(s)
- S N Urchuk
- Department of Medical Biophysics, Sunnybrook Health Science Centre, University of Toronto, Ontario, Canada
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28
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Mohiaddin RH, Gatehouse PD, Henien M, Firmin DN. Cine MR Fourier velocimetry of blood flow through cardiac valves: comparison with Doppler echocardiography. J Magn Reson Imaging 1997; 7:657-63. [PMID: 9243384 DOI: 10.1002/jmri.1880070408] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Noninvasive measurement of blood flow velocity through the cardiac valves has important clinical applications. A wide variety of MR methods are available for flow measurement. The aim of this study was to investigate the ability of cine MR Fourier velocimetry to measure flow through healthy cardiac valves and to compare MR and Doppler peak velocity measurements. Ten healthy volunteers (age mean +/- SD, 24 +/- 4 years) without history of valvular disease were studied. Four of the subjects were females. In each subject, aortic, pulmonary, mitral, and tricuspid valves were evaluated with MR and Doppler imaging. A whole-body mobile MR machine was used, operating at .5-T with actively shielded magnetic field gradient coils on all three axes capable of 20 mT/m at a slew rate of 60 mT/ m/msec. The heart rate during MR and Doppler studies was not significantly different. The mean difference between the two studies was 2 beats/min, with a 95% confidence interval of -22 beats/min, +25 beats/ min. Peak systolic flow velocity in the aortic and pulmonary valves and peak diastolic flow velocity in the mitral and tricuspid valves measured with MRI and Doppler echocardiography correlated well. The mean difference between the two measurements (MR-Doppler) was 63 mm/sec, with a 95% confidence interval of -180 mm/sec, +310 mm/sec. The agreement between two observers interpreting the same MR velocity maps was close. The mean difference between their two measurements was 23 mm/sec, with a 95% confidence interval of -20 mm/sec, +60 mm/sec. There was no significant difference between MR and Doppler imaging or between the two MR observers. MR Fourier velocimetry has the necessary ease, reliability, and speed to measure blood flow through the cardiac valves, although measurement of late diastolic flow in the atrioventricular valves is limited. Measurement of peak blood velocity through the cardiac valves by this method showed satisfactory agreement with Doppler, but its clinical application for assessing diseased cardiac valves must be established.
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Affiliation(s)
- R H Mohiaddin
- Magnetic Resonance Unit, Royal Brompton Hospital, London, United Kingdom.
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29
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Warner OJ, Ohri SK, Pennell DJ, Smith PL. Magnetic resonance coronary artery imaging for redo coronary operations. Ann Thorac Surg 1996; 62:1513-6. [PMID: 8893597 DOI: 10.1016/0003-4975(96)00777-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Imaging the native coronary vessels using contrast angiography can be difficult in the context of redo coronary operations when native disease is severe. When previous vein grafts undergo aneurysmal dilatation, imaging of the native vessel is restricted by the inability to infuse a sufficient volume of contrast medium through the graft and into the native vessel. We present a case of a patient whose redo coronary artery bypass graft operation was planned on the basis of magnetic resonance imaging of his native coronary arteries and vein graft after unsuccessful coronary angiography.
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Affiliation(s)
- O J Warner
- Department of Surgery, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom
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30
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Posma JL, van der Wall EE, Blanksma PK, van der Wall E, Lie KI. New diagnostic options in hypertrophic cardiomyopathy. Am Heart J 1996; 132:1031-41. [PMID: 8892780 DOI: 10.1016/s0002-8703(96)90018-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The pathophysiologic features and clinical manifestations of HCM have been elucidated by the introduction of several new diagnostic options. Knowledge of the molecular defects of HCM has advanced rapidly, and genetic screening studies have reemphasized the value of the standard electrocardiogram as an initial screening tool. Analysis of heart rate variability, late potentials, and QT dispersion were not found to be reliable prognostic markers in HCM. However, measurement of dispersion of conduction is probably a sensitive technique in identifying a high risk for sudden cardiac death. Significant developments include transthoracic and transesophageal echocardiography and their role in studying the mitral valve, early detection of left ventricular chamber dilatation, analysis of coronary flow, and intraoperative echocardiography. Finally, advances in the application of magnetic resonance imaging and positron-emission tomography are underway.
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Affiliation(s)
- J L Posma
- Department of Cardiology, Thoraxcenter, University Hospital Groningen, The Netherlands
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31
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Rebergen SA, van der Wall EE, Helbing WA, de Roos A, van Voorthuisen AE. Quantification of pulmonary and systemic blood flow by magnetic resonance velocity mapping in the assessment of atrial-level shunts. INTERNATIONAL JOURNAL OF CARDIAC IMAGING 1996; 12:143-52. [PMID: 8915715 DOI: 10.1007/bf01806217] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The objective of this study was to asses the feasibility and accuracy of magnetic resonance (MR) velocity mapping to calculate pulmonary-to-systemic flow ratio (Qp:Qs) in patients with a suspected or diagnosed atrial-level shunt. During a one-year period, all patients referred to our department for further evaluation of an atrial-level shunt underwent the same imaging protocol. Multiphase-multisection gradient-echo MR image sets of the heart were acquired to measure left and right ventricular stroke volumes for validation. Ascending aorta and main pulmonary artery volume flow were measured with MR velocity mapping. Qp:Qs ratios were calculated from both stroke volume data and flow data. Twelve patients, including 6 children, were studied. Six patients had an established diagnosis of atrial septal defect, and the other 6 patients were suspected to have an atrial-level shunt. Measurements of left and right ventricular stroke corresponded closely with those of aortic (r = 0.98) and pulmonary flow (r = 0.99) respectively, and Qp:Qs flow ratios agreed with stroke volume ratios (r = 0.92). In 5 patients with a suspected shunt, the diagnosis could be rejected. Shunts were demonstrated in the other 7 patients. M(r) velocity mapping offers an accurate method to measure aortic and pulmonary artery volume flow that can be useful in the evaluation of atrial-level shunts, in order to establish a definite diagnosis and/or to quantify the Qp:Qs ratio.
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Affiliation(s)
- S A Rebergen
- Department Diagnostic Radiology and Nuclear Medicine, Leiden University Hospital, The Netherlands
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32
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Yang GZ, Burger P, Kilner PJ, Karwatowski SP, Firmin DN. Dynamic range extension of cine velocity measurements using motion-registered spatiotemporal phase unwrapping. J Magn Reson Imaging 1996; 6:495-502. [PMID: 8724416 DOI: 10.1002/jmri.1880060313] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A motion-registered spatiotemporal phase-unwrapping method for extending the dynamic range of cine magnetic resonance phase velocity measurements is presented. The interframe cardiac movement is estimated from the magnitude image derived from the velocity encoded raw data, which ensures that the phase signal is unwrapped in the temporal direction with reference to pixels belonging to the same anatomic flow region. An extra step of spatial phase correction is then used to further eliminate any residual errors. The combination of spatial and temporal information for phase unwrapping provides a robust way of extending the dynamic range of cine velocity data in the presence of large phase aliasing errors.
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Affiliation(s)
- G Z Yang
- Magnetic Resonance Unit, Royal Brompton Hospital, London, United Kingdom
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33
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Hofman MB, de Cock CC, van der Linden JC, van Rossum AC, Visser FC, Sprenger M, Westerhof N. Transesophageal cardiac pacing during magnetic resonance imaging: feasibility and safety considerations. Magn Reson Med 1996; 35:413-22. [PMID: 8699954 DOI: 10.1002/mrm.1910350320] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The feasibility and safety of transesophageal cardiac pacing during clinical MRI at 1.5 Tesla is considered. An MRI compatible pace catheter was developed. In vitro testing showed a normal performance of the pulse generator, image artifacts that extended less than 11 mm from the catheter, and a less than 5% increase in noise. Cardiac stimulation induced by MRI was not observed and, theoretically, is not expected. Potentially, tissue around the catheter tip may become heated. This heating (delta tau) was monitored. Eight dogs were exposed to MRI during pacing. For low RF radiation exposure, a time-averaged squared B1 field below 0.08 p tau 2 (SAR < 0.03 W/kg), delta tau was below 1 degree C. For high RF radiation exposure, but at normal RF radiation specific absorption rate (0.4 W/kg) delta tau was 5 degrees C. Thus, transesophageal atrial pacing during MRI at low RF exposure seems to be possible to perform cardiac stress studies or to correct unstable heart rates.
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Affiliation(s)
- M B Hofman
- Department of Clinical Physics and Engineering, ICaR-VU, Free University, Amsterdam, The Netherlands
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34
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Szolar DH, Sakuma H, Higgins CB. Cardiovascular applications of magnetic resonance flow and velocity measurements. J Magn Reson Imaging 1996; 6:78-89. [PMID: 8851410 DOI: 10.1002/jmri.1880060117] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
With recent developments of MR techniques for blood flow measurements, qualitative and quantitative information on both flow volume and flow velocity in the major vessels can be obtained. MR flow quantitation uses the phase, rather than the amplitude of the MR signal, to reconstruct the images. Previous validation studies have demonstrated the accuracy of the phase shift techniques for measuring flow velocities. This technique is now being applied successfully in the cardiovascular system to quantify global and regional ventricular function, valvular heart disease, pulmonary artery disease, thoracic aortic disease, congenital heart disease, and ischemic heart disease.
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Affiliation(s)
- D H Szolar
- Department of Radiology, University of California, San Francisco 94143-0628, USA
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35
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36
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Fujimoto S, Mohiaddin RH, Parker KH, Gibson DG. Magnetic resonance velocity mapping of normal human transmitral velocity profiles. Heart Vessels 1995; 10:236-40. [PMID: 8903998 DOI: 10.1007/bf01744902] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We used magnetic resonance imaging (MRI) velocity mapping to assess the velocity profile of early diastolic mitral inflow in 11 normal subjects. Velocity maps of left ventricular inflow were obtained in the horizontal long axis of the left ventricle at the time of peak early diastolic filling. Velocity profile curves across the mitral inflow were obtained at 1-cm intervals from the mitral ring to 4 cm into the cavity. The jet width was 3.06 +/- 0.64 cm at the mitral ring level, increasing to 3.6 +/- 0.61 cm at 4 cm. The peak/mean velocity was 1.2 +/- 0.07 at the mitral ring and increased to around 1.4 at 3-4 cm from the mitral ring. The point at which the peak velocity was recorded at each level was skewed towards the septal side by 10%-13% of jet width from the center at the mitral ring and 2-4 cm from the ring. However, at a depth of 1 cm, corresponding to the mitral tip level, the peak velocity was at the center of the jet. The ratio of vertical and horizontal dimensions of the jet cross section was 1.11 +/- 0.05. Thus, the mitral inflow velocity profile is relatively flat at the mitral ring and tip level; the inflow jet cross section is effectively circular.
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Affiliation(s)
- S Fujimoto
- Cardiac Department, Royal Brompton Hospital, London, UK
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37
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Mohiaddin RH. Flow patterns in the dilated ischemic left ventricle studied by MR imaging with velocity vector mapping. J Magn Reson Imaging 1995; 5:493-8. [PMID: 8574031 DOI: 10.1002/jmri.1880050503] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Magnetic resonance velocity vector mapping was used to study flow patterns in dilated and healthy left ventricles. Eleven patients (age mean +/- SD, 57 +/- 12 years) with dilated left ventricle resulting from coronary artery disease and 10 healthy volunteers (age 50 +/- 9) were studied. Cine gradient echo images were acquired in the left ventricle vertical and horizontal long axes. Vertical and horizontal velocity components in the horizontal long axis plane of the left ventricle were encoded simultaneously. Maps of velocity components were then processed into multiple computer generated streaks whose orientation and length corresponded to velocity vectors. The following parameters (mean +/- SD) differed significantly between the two groups: The heart rate (patients 70 +/- 11 beat/min. controls 57 +/- 8, P < .001), end-diastolic volume (patients 264 +/- 83 ml, controls 143 +/- 25 ml, P < .001), ejection fraction (patients 31% +/- 7, controls 61% +/- 5, P < .001), diameter of the inflow stream (patients 1.7 +/- 0.6 cm, controls 3.2 +/- 0.3 cm, P < .001). In normal subjects the predominant direction of diastolic flow through the mitral valve was toward the apex, with short-lived vortices curling back behind each mitral leaflet. The vortex beneath the anterior leaflet tended to be larger and more dominant. In patients with dilated left ventricle, the inflow was directed toward the free wall, giving rise to a well developed circular flow pattern turning back toward the septum and outflow tract and persisting through diastole. Magnetic resonance velocity vector mapping is an excellent method for studying left ventricular flow patterns.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R H Mohiaddin
- Magnetic Resonance Unit, Royal Brompton Hospital National Heart and Lung Institute, London, United Kingdom
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38
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Pennell DJ, Firmin DN, Burger P, Yang GZ, Manzara CC, Ell PJ, Swanton RH, Walker JM, Underwood SR, Longmore DB. Assessment of magnetic resonance velocity mapping of global ventricular function during dobutamine infusion in coronary artery disease. BRITISH HEART JOURNAL 1995; 74:163-70. [PMID: 7546996 PMCID: PMC483993 DOI: 10.1136/hrt.74.2.163] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND Magnetic resonance imaging (MRI) is a versatile technique for examination of the cardiovascular system but only recently has assessment of myocardial ischaemia in coronary artery disease (CAD) become possible, for example by demonstrating abnormalities of regional ventricular contraction during stress. Global ventricular function during stress was assessed by MRI of aortic flow, which has not been previously attempted. DESIGN Variables measured by MRI reflecting the effect of ischaemia on global ventricular function during dobutamine stress were correlated with thallium-201 myocardial perfusion tomography. PATIENTS 10 normal controls and 25 patients with CAD. SETTING Tertiary cardiac referral centre. METHODS Novel MRI sequences and analysis systems were used to measure the following variables during staged dobutamine infusion to 20 micrograms/kg/min: stroke volume, cardiac output, cardiac power output, peak flow, peak flow acceleration, aortic back flow, and flow wave velocity. Heart rate, blood pressure, double product, and maximum tolerated dobutamine dose were also measured. Multiple regression analysis was used to compare changes during stress with 201TI tomography. RESULTS All parameters except for stroke volume and diastolic blood pressure increased in the controls. In the patients with CAD a significant relation was shown between the extent of reversible ischaemia and the change in peak flow acceleration (P < 0.00001), peak flow (P = 0.002), cardiac power output (P = 0.036), maximum dobutamine dose (P = 0.039), and systolic blood pressure (P = 0.04). Peak flow acceleration accounted for 58.4% of the variation in reversible ischaemia, and after allowing for this, only cardiac power output remained independently predictive adding a further 4.2% to the model (adjusted r2 = 0.626). A decrease in peak flow acceleration with an increase in dobutamine infusion indicated moderate or severe ischaemia (chi 2 = 10.2, P = 0.017). CONCLUSION MRI may be used to assess variables of aortic flow during stress, which includes acceleration with high temporal resolution. Peak flow acceleration was the most sensitive indicator of the effect of ischaemia on global ventricular function.
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Affiliation(s)
- D J Pennell
- Magnetic Resonance Unit, Royal Brompton Hospital, London
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39
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de Roos A, Doornbos J, van der Wall EE, van Voorthuisen AE. Magnetic resonance of the heart and great vessels. Nat Med 1995; 1:711-3. [PMID: 7585158 DOI: 10.1038/nm0795-711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- A de Roos
- Department of Diagnostic Radiology, University Hospital Leiden, The Netherlands
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40
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Kupari M, Hekali P, Poutanen VP. Cross sectional profiles of systolic flow velocities in left ventricular outflow tract of normal subjects. Heart 1995; 74:34-9. [PMID: 7662450 PMCID: PMC483943 DOI: 10.1136/hrt.74.1.34] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND The idea that blood passes through the left ventricular outflow tract with a flat velocity profile has recently been questioned. OBJECTIVE To construct flow velocity profiles by magnetic resonance imaging over the whole cross sectional subaortic flow area in normal subjects. SUBJECTS Nine people without heart disease aged 25 to 56. DESIGN Cardiac gated cine magnetic resonance images were produced with a 1.0 T magnet perpendicular to the longitudinal axis of the left ventricular outflow tract 0.5 to 1.0 cm below the aortic annulus in mid-systole. Velocity was encoded every 30-40 ms throughout systole in the direction of flow perpendicular to the image plane. MAIN OUTCOME MEASURES Systolic velocity-time curves reconstructed in nine different regions (area of each circle 0.2 cm2) of the subaortic flow area. The systolic peak velocity and the mean flow rate were taken as indices of regional flow. RESULTS The spatial inhomogeneity of the peak velocity, calculated as the percentage ratio of the range of the regional measurements to their mean, averaged 18.2% (5.0%), and the inhomogeneity of the mean flow rate was 19.2% (3.5%). There were significant trends (P < 0.05) across the regional measurements towards highest peak velocities and mean systolic flow rate in the anteromedial sector of the subaortic flow area. The peak systolic velocity in the centre of the flow area averaged 98 (8) cm/s while the coincident spatial average was 94 (5) cm (P = 0.013). CONCLUSIONS The distribution of systolic velocities across the left ventricular outflow tract is skewed towards fastest flow in the anteromedial sector of the flow area. The peak velocities measured in the centre of the flow area slightly overestimate the coincident spatial average velocities.
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Affiliation(s)
- M Kupari
- Division of Cardiology, (First Department of Medicine), Helsinki University Central Hospital, Finland
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41
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Hofman MB, Visser FC, van Rossum AC, Vink QM, Sprenger M, Westerhof N. In vivo validation of magnetic resonance blood volume flow measurements with limited spatial resolution in small vessels. Magn Reson Med 1995; 33:778-84. [PMID: 7651113 DOI: 10.1002/mrm.1910330606] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The accuracy of magnetic resonance phase contrast volume flow measurements in small blood vessels is expected to be smaller than in large vessels, because of partial volume effects at the vessel boundary. Accuracy was validated in the dog femoral artery, diameter 3.5 +/- 0.7 mm, using an ultrasonic transit-time flowmeter (TT). The number of pixels per vessel diameter (ND) ranged from 1.6 to 4.8. The vessel cross-section was determined using a threshold in the magnitude image. Between the two methods the correlation coefficient was 0.95 (range 10-200 ml/min). The proportional difference (PD), (QTT-QMR)/1/2(QTT+QMR), was 0.8%, showing no systematic difference between the methods. The PDs standard deviation was 27%, and 19% for flow rates above 30 ml/min. Only a significant decrease of the PDs variance was found at the highest ND values, suggesting other sources of error than partial volume effects. It is concluded that with an ND value of about 3, accurate blood volume flow rates can be determined.
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Affiliation(s)
- M B Hofman
- Department of Physiology, Free University, Amsterdam, The Netherlands
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42
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Stein JH, Broderick L, Neumann A, Snell RJ, Hanashiro PK, Caralis DG. A unique left-to-right shunt characterized by multimodality cardiac imaging. Chest 1995; 107:1162-4. [PMID: 7705131 DOI: 10.1378/chest.107.4.1162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We describe the first reported patient with a persistent left superior vena cava that communicates directly with the left atrium as an isolated congenital defect. She developed mitral stenosis and physiologic conditions that favored left-to-right shunting--a modified Lutembacher's syndrome. Noninvasive cardiac imaging completely elucidated her cardiac anatomy and physiology.
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Affiliation(s)
- J H Stein
- Department of Medicine, Rush Medical College, Chicago, IL, USA
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43
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Mohiaddin RH, Gatehouse PD, Firmin DN. Exercise-related changes in aortic flow measured with spiral echo-planar MR velocity mapping. J Magn Reson Imaging 1995; 5:159-63. [PMID: 7766976 DOI: 10.1002/jmri.1880050209] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Spiral echo-planar magnetic resonance (MR) velocity mapping was used to measure exercise-related changes in flow in the descending thoracic aorta in 10 healthy volunteers. Flow was measured at rest and immediately after dynamic exercise, with a 0.5-T imager with a surface receiving coil and electrocardiographic triggering. Supine exercise was performed with a home-built pedaling apparatus. Spiral velocity mapping was performed in a transverse plane through the descending thoracic aorta with the subject at rest. The subject was then asked to perform maximum exercise, stop, and hold his breath during a four-heartbeat acquisition time. Eight cine frames with a temporal resolution of 50 msec were acquired through systole. Each image was acquired in 40 msec during spiral acquisition of k-space data, starting at the center, 6 msec after the excitation pulse. Reproducibility of the technique was established by repeating the flow measurement in four consecutive heartbeats. At rest, the heart rate (mean +/- standard deviation), mean aortic flow, peak aortic flow, and time to peak flow were 68 beats per minute +/- 6, 41 milliliters per beat +/- 8, 107 mL/sec +/- 20, and 175 msec +/- 25, respectively. After exercise, the heart rate and mean and peak aortic flow were significantly increased (P < .001), measuring 101 beats per minute +/- 12, 57 milliliters per beat +/- 11, and 158 mL/sec +/- 29, respectively, while the time to peak flow (115 msec +/- 32) was significantly reduced (P < .001). The four sets of values obtained for the first four consecutive heartbeats measured at rest were similar, as were those obtained for the first four heartbeats after exercise.
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Affiliation(s)
- R H Mohiaddin
- Magnetic Resonance Unit, Royal Brompton Hospital, London, England
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44
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Mohiaddin RH, Underwood R, Romeira L, Anagnostopoulos C, Karwatowski SP, Laney R, Somerville J. Comparison between cine magnetic resonance velocity mapping and first-pass radionuclide angiocardiography for quantitating intracardiac shunts. Am J Cardiol 1995; 75:529-32. [PMID: 7864007 DOI: 10.1016/s0002-9149(99)80600-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- R H Mohiaddin
- Royal Brompton Hospital, National Heart and Lung Institute, London, United Kingdom
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45
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de Roos A. Standard MRI. Int J Cardiovasc Imaging 1995. [DOI: 10.1007/bf01142214] [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: 11/27/2022]
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Skinner MP, Yuan C, Mitsumori L, Hayes CE, Raines EW, Nelson JA, Ross R. Serial magnetic resonance imaging of experimental atherosclerosis detects lesion fine structure, progression and complications in vivo. Nat Med 1995; 1:69-73. [PMID: 7584956 DOI: 10.1038/nm0195-69] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A major problem in the study of lesions of atherosclerosis is the difficulty of imaging noninvasively the lesions and following their progression in vivo. To address this problem, we have developed advanced magnetic resonance techniques to noninvasively and serially image advanced lesions of atherosclerosis in the rabbit abdominal aorta. Both lumen and wall were imaged with high resolution. Progression of disease, resulting in increase in lesion mass, decrease in arterial lumen, or stenosis, and intralesion complications, can be detected. Images acquired in vivo correlate with the fine structure of the lesions of atherosclerosis, including the fibrous cap, necrotic core, and lesion fissures, as verified by gross examination, dissection microscopy, and histology. The ability to noninvasively identify the features of atherosclerotic plaques, has significant implications for determining risks and benefits associated with different therapeutic approaches.
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Affiliation(s)
- M P Skinner
- Department of Pathology, University of Washington, Seattle 98195, USA
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Underwood SR. Abnormal exercise electrocardiogram in an asymptomatic person. Int J Cardiol 1994; 44:97-9. [PMID: 8021058 DOI: 10.1016/0167-5273(94)90073-6] [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: 01/28/2023]
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Mohiaddin RH, Kilner PJ, Rees S, Longmore DB. Magnetic resonance volume flow and jet velocity mapping in aortic coarctation. J Am Coll Cardiol 1993; 22:1515-21. [PMID: 8227813 DOI: 10.1016/0735-1097(93)90565-i] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVES Nuclear magnetic resonance (MRI) velocity mapping was used to characterize flow waveforms and to measure volume flow in the ascending and descending thoracic aorta in patients with aortic coarctation and in healthy volunteers. We present the method and discuss the relation between these measurements and aortic narrowing assessed by MRI. Finally, we compare coarctation jet velocity measured by MRI velocity mapping with that obtained from continuous wave Doppler echocardiography. BACKGROUND The development of a noninvasive imaging method for morphologic visualization of aortic coarctation and for measurement of its impact on blood flow is highly desirable in the preoperative and postoperative management of patients. METHODS Magnetic resonance imaging phase-shift velocity mapping was used to measure ascending and descending aortic volume flow in 39 patients with aortic coarctation and in 12 healthy volunteers. Magnetic resonance imaging was also used for anatomic and peak jet velocity measurements. The latter were compared with those available from continuous wave Doppler study in 40% of the patients. RESULTS Whereas ascending aortic volume flow measurement did not show significant differences between the patient and healthy control groups, volume flow curves in the descending aorta did show significant differences between the two groups. Peak volume flow (mean +/- SD) was 10.6 +/- 5.3 liters/min in patients and 19.6 +/- 4.7 liters/min in control subjects (p < 0.001). Time-averaged flow was 2.5 +/- 0.9 liters/min in patients and 3.9 +/- 1.1 liters/min in control subjects (p < 0.05). The descending/ascending aorta flow ratio was 0.47 +/- 0.19 in patients and 0.64 +/- 0.08 in control subjects (p < 0.05). These variables correlate well with the degree of aortic narrowing. Peak coarctation jet velocity measured by MRI velocity mapping is comparable to that obtained from continuous wave Doppler study (r = 0.95). CONCLUSIONS We established normal ranges for volume flow in the descending aorta and demonstrated abnormalities in patients with aortic coarctation. These abnormalities are likely to be related to resistance to flow imposed by the coarctation and could represent an additional index for monitoring patients before and after intervention.
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Affiliation(s)
- R H Mohiaddin
- Royal Brompton National Heart and Lung Hospital, National Heart and Lung Institute, London, England, United Kingdom
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