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Schmidt M, Crnac J, Dederichs B, Theissen P, Schicha H, Sechtem U. Magnetic resonance imaging in valvular heart disease. INTERNATIONAL JOURNAL OF CARDIAC IMAGING 1997; 13:219-31. [PMID: 9220284 DOI: 10.1023/a:1005732803228] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Magnetic resonance techniques can be employed to depict valvular abnormalities but are especially helpful in quantifying regurgitant or stenotic lesions which cannot be quantitatively assessed by other noninvasive techniques. Gradient echo techniques and phase velocity mapping are the most important magnetic resonance pulse sequences employed for these purposes. Valvular regurgitation can be quantitated by measuring the area of signal void on conventional gradient-echo images, by calculating stroke volume differences from k-space segmented gradient echo images, by measuring the proximal convergence zone from velocity encoded images or by comparing stroke volumes of the ventricles from velocity measurements. In contrast to this variety of possibilities in regurgitant lesions, stenotic lesions can only be quantitated by using velocity mapping techniques. Magnetic resonance spectroscopy can be used to assess myocardial metabolism in chronic valvular lesions. However, this tool needs further development and more clinical data before its use can be recommended to assess the necessity and optimal timing of surgical intervention.
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Affiliation(s)
- M Schmidt
- Klinik und Poliklinik für Nuklearmedizin, Universität zu Köln, Germany
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52
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Chatzimavroudis GP, Walker PG, Oshinski JN, Franch RH, Pettigrew RI, Yoganathan AP. Slice location dependence of aortic regurgitation measurements with MR phase velocity mapping. Magn Reson Med 1997; 37:545-51. [PMID: 9094076 DOI: 10.1002/mrm.1910370412] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Although several methods have been used clinically to assess aortic regurgitation (AR), there is no "gold standard" for regurgitant volume measurement. Magnetic resonance phase velocity mapping (PVM) can be used for noninvasive blood flow measurements. To evaluate the accuracy of PVM in quantifying AR with a single imaging slice in the ascending aorta, in vitro experiments were performed by using a compliant aortic model. Attention was focused on determining the slice location that provided the best results. The most accurate measurements were taken between the aortic valve annulus and the coronary ostia where the measured (Y) and actual (X) flow rate had close agreement (Y = 0.954 x + 0.126, r2 = 0.995, standard deviation of error = 0.139 L/min). Beyond the coronary ostia, coronary flow and aortic compliance negatively affected the accuracy of the measurements. In vivo measurements taken on patients with AR showed the same tendency with the in vitro results. In making decisions regarding patient treatment, diagnostic accuracy is very important. The results from this study suggest that higher accuracy is achieved by placing the slice between the aortic valve and the coronary ostia and that this is the region where attention should be focused for further clinical investigation.
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Affiliation(s)
- G P Chatzimavroudis
- Cardiovascular Fluid Mechanics Laboratory, School of Chemical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0100, USA
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53
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Diebold B, Delouche A, Delouche P, Guglielmi JP, Dumee P, Herment A. In vitro flow mapping of regurgitant jets. Systematic description of free jet with laser Doppler velocimetry. Circulation 1996; 94:158-69. [PMID: 8674174 DOI: 10.1161/01.cir.94.2.158] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Color Doppler and magnetic resonance imaging give pictures of abnormal jets within which the respective contribution of fluid mechanics and image artifacts are difficult to establish because of current technical limitations of these modalities. We conducted the present study to provide numerical descriptions of the velocity fields within regurgitant free jets. METHODS AND RESULTS Laser Doppler measurements were collected in rigid models with pulsatile flow conditions, giving several series of two-dimensional flow images. The data were studied with the use of two-dimensional or M-mode flow images as well as regular plots. Numerical descriptions validated in steady flow conditions were tested at the various times of the cycle. In these free jets, the momentum was conserved throughout the cycle. The transverse velocity profiles were approximately similar. A central laminar core was found at peak ejection and during the deceleration. Its length (l = 4.08 d-0.036 mm, r = .99) and its diameter (d) were proportional to the orifice diameter. At peak ejection, the velocity decay was hyperbolic, and the transverse velocity profiles were clearly gaussian. The different relations that were tested could be combined in a single formula describing the velocity field: V(x,y,t peak) = V(O,O,t peak).4.(d/x).10(-45(y/x)2) (r = .92). CONCLUSIONS These in vitro measurements demonstrated the presence of a central laminar core and similar transverse velocity profiles in free turbulent jets. This allowed us to validate a series of numerical relations that can be combined to describe the velocity fields at peak ejection. On the other hand, further studies are needed to describe the various singularities often encountered in pathology.
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Affiliation(s)
- B Diebold
- Department of Cardiology, Hôpital Broussais, Paris, France.
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Peshock RM, Wfflett DL, Sayad DE, Hundley WG, Chwialkowski MC, Clarke GD, Parkey RW. QUANTITATIVE MR IMAGING OF THE HEART. Magn Reson Imaging Clin N Am 1996. [DOI: 10.1016/s1064-9689(21)00182-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
MRI has developed very rapidly and now provides anatomic and functional information in cases of valvular heart disease. MRI has several important attributes that make it advantageous for the evaluation of valvular heart disease. First, the natural contrast between flowing blood and surrounding cardiovascular structures provides sharp delineation of endocardial and epicardial borders without the need for contrast media. This feature in combination with the essential three-dimensional nature of this imaging technique allows precise quantification of cardiac volumes, function, and mass without the use of any assumed formulas or geometric models. Second, blood flow-sensitive GRE techniques are able to identify areas of turbulent flow caused by stenotic or regurgitant valves. With this technique regurgitant jets can be visualized and semiquantitative grading can be performed as with color Doppler. Third, recently developed velocity-encoded techniques permit measurements of blood flow velocities across stenotic native and prosthetic heart valves and retrograde flow caused by regurgitation. Moreover, the close interstudy reproducibility of measurements of cardiac dimensions and valvular regurgitation suggests a role in assessing the effect of therapeutic interventions.
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Affiliation(s)
- S Globits
- Department of Radiology, University of California, San Francisco
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58
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Steffens JC, Bourne MW, Sakuma H, O'Sullivan M, Higgins CB. Quantification of collateral blood flow in coarctation of the aorta by velocity encoded cine magnetic resonance imaging. Circulation 1994; 90:937-43. [PMID: 8044965 DOI: 10.1161/01.cir.90.2.937] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Knowledge about the volume of collateral flow provides insight into the severity of coarctation of the aorta and may be critical in planning the operative approach. There is currently no method for the quantification of collateral flow in coarctation of the aorta. In this study, we applied velocity encoded cine magnetic resonance imaging (VENC-MR) to establish the flow pattern and volume of collateral flow in the descending thoracic aorta in normal subjects and patients with coarctation, introducing a new possibility to quantify the severity of the coarctation by determining the amount of collateral flow. METHODS AND RESULTS VENC-MR was used to measure flow in the proximal and distal descending thoracic aorta in 10 normal subjects. In 23 patients with coarctation, flow was measured near the coarctation site and above the diaphragm. Patients were divided into a group with moderate to severe coarctation and a group with mild coarctation on the basis of clinical gradient between upper and lower extremities and the estimation of the gradient across the coarctation by Doppler echocardiography. The gradient across the coarctation and the degree of anatomic narrowing were also assessed by MR imaging. In normal volunteers, VENC-MR showed a 7 +/- 6% decrease in total flow, from proximal to distal aorta. The interobserver reproducibility was 3.9% to 4.9% (mean, 4.4%). In patients with moderate to severe coarctation, VENC-MR demonstrated an 83 +/- 50% increase in total flow from proximal to distal aorta, yielding a significant change compared with normal subjects (P < .01). Patients with mild coarctation showed a normal flow pattern and no significant change in total flow. There was a significant relation between the amount of flow increase in the distal aorta and the reduction in luminal diameter at the coarctation site (r = .94) as well as the clinical gradient (r = .84). CONCLUSIONS This study shows the normal flow pattern in the descending thoracic aorta and its reversal in coarctation due to collateral flow. Thus, VENC-MR can measure collateral flow in coarctation and serves as a unique method for providing this important measurement of the severity of coarctation of the aorta.
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Affiliation(s)
- J C Steffens
- Department of Radiology, University of California, San Francisco 94143-0628
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59
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VALVULAR HEART DISEASE. Radiol Clin North Am 1994. [DOI: 10.1016/s0033-8389(22)00392-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Fujita N, Chazouilleres AF, Hartiala JJ, O'Sullivan M, Heidenreich P, Kaplan JD, Sakuma H, Foster E, Caputo GR, Higgins CB. Quantification of mitral regurgitation by velocity-encoded cine nuclear magnetic resonance imaging. J Am Coll Cardiol 1994; 23:951-8. [PMID: 8106701 DOI: 10.1016/0735-1097(94)90642-4] [Citation(s) in RCA: 168] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVES The feasibility of velocity-encoded cine nuclear magnetic resonance (NMR) imaging to measure regurgitant volume and regurgitant fraction in patients with mitral regurgitation was evaluated. BACKGROUND Velocity-encoded cine NMR imaging has been reported to provide accurate measurement of the volume of blood flow in the ascending aorta and through the mitral annulus. Therefore, we hypothesized that the difference between mitral inflow and aortic systolic flow provides the regurgitant volume in the setting of mitral regurgitation. METHODS Using velocity-encoded cine NMR imaging at a magnet field strength of 1.5 T and color Doppler echocardiography, 19 patients with isolated mitral regurgitation and 10 normal subjects were studied. Velocity-encoded cine NMR images were acquired in the short-axis plane of the ascending aorta and from the short-axis plane of the left ventricle at the level of the mitral annulus. Two independent observers measured the ascending aortic flow volume and left ventricular inflow volume to calculate the regurgitant volume as the difference between left ventricular inflow volume and aortic flow volume, and the regurgitant fraction was calculated. Using accepted criteria of color flow Doppler imaging and spectral analysis, the severity of mitral regurgitation was qualitatively graded as mild, moderate or severe and compared with regurgitant volume and regurgitant fraction, as determined by velocity-encoded cine NMR imaging. RESULTS In normal subjects the regurgitant volume was -6 +/- 345 ml/min (mean +/- SD). In patients with mild, moderate and severe mitral regurgitation, the regurgitant volume was 156 +/- 203, 1,384 +/- 437 and 4,763 +/- 2,449 ml/min, respectively. In normal subjects the regurgitant fraction was 0.7 +/- 6.1%. In patients with mild, moderate and severe mitral regurgitation, the regurgitant fraction was 3.1 +/- 3.4%, 24.5 +/- 8.9% and 48.6 +/- 7.6%, respectively. The regurgitant fraction correlated well with the echocardiographic severity of mitral regurgitation (r = 0.87). Interobserver reproducibilities for regurgitant volume and regurgitant fraction were excellent (r = 0.99, SEE = 238 ml; r = 0.98, SEE = 4.1%, respectively). CONCLUSIONS These findings suggest that velocity-encoded NMR imaging can be used to estimate regurgitant volume and regurgitant fraction in patients with mitral regurgitation and can discriminate patients with moderate or severe mitral regurgitation from normal subjects and patients with mild regurgitation. It may be useful for monitoring the effect of therapy intended to reduce the severity of mitral regurgitation.
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Affiliation(s)
- N Fujita
- Department of Radiology, University of California, San Francisco 94143-0628
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Mohiaddin RH, Longmore DB. Functional aspects of cardiovascular nuclear magnetic resonance imaging. Techniques and application. Circulation 1993; 88:264-81. [PMID: 8319341 DOI: 10.1161/01.cir.88.1.264] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- R H Mohiaddin
- Royal Brompton National Heart and Lung Hospital, Magnetic Resonance Unit, London, UK
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Kappetein PA, Guit GL, Bogers AJ, Weeda HW, Zwinderman KH, Schönberger JP, Huysmans HA. Noninvasive long-term follow-up after coarctation repair. Ann Thorac Surg 1993; 55:1153-9. [PMID: 8494425 DOI: 10.1016/0003-4975(93)90024-c] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Thirty patients operated on for aortic coarctation while less than 3 years of age underwent magnetic resonance imaging, digital subtraction angiography, and bicycle exercise testing 14 to 33 years (mean, 22 years) after operation. Diameters of the aorta at the site of the anastomosis, of the distal arch, and of the aorta at the level of the diaphragm were measured in the images. Blood pressures were obtained from the right arm and leg before and after exercise. Patients were divided into three groups according to blood pressure data: group I, resting gradient less than 30 mm Hg and exercise gradient less than 50 mm Hg; group II, resting gradient less than 30 mm Hg and exercise gradient greater than 50 mm Hg; and group III, resting gradient 30 mm Hg or greater. A control group underwent the same test. The frequency of hypertensive patients was greater in groups II (58%) and III (100%) than in group I (20%). The anastomosis/descending aorta ratio seen in digital subtraction angiograms was smaller in group II and III patients. Exercise blood pressure gradient correlated significantly (r = -0.48; p = 0.009) with anastomosis/descending aorta ratio in digital subtraction angiograms but not in magnetic resonance images. Twenty of 30 patients (67%) had a significant anatomic narrowing at the site of the anastomosis. Blood pressure data correlated with diameters measured in digital subtraction angiograms but not with diameters measured in magnetic resonance images.
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Affiliation(s)
- P A Kappetein
- Department of Thoracic Surgery, University Hospital Leiden, The Netherlands
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63
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Ohnishi S, Fukui S, Kusuoka H, Kitabatake A, Inoue M, Kamada T. Assessment of valvular regurgitation using cine magnetic resonance imaging coupled with phase compensation technique: comparison with Doppler color flow mapping. Angiology 1992; 43:913-24. [PMID: 1443765 DOI: 10.1177/000331979204301106] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
To elucidate whether or not a newly developed technique in cinematic-displayed (cine) magnetic resonance imaging (MRI) can improve the semiquantitative evaluation of valvular regurgitant flow, 20 patients with valvular lesions were studied. Three pulse sequences of cine MRI, ie, standard, short echo time (TE), and rephasing scans, were compared with reference obtained by Doppler color flow mapping. Short TE technique and rephasing scan technique improved image quality remarkably as compared with standard technique. Each of the three cine MRI techniques showed good correlation with the Doppler method (p < 0.001). However, short TE and rephasing scan techniques gave a faithful estimation of the extent as compared with the Doppler method, whereas standard technique overestimated the regurgitation. Thus, cine magnetic resonance imaging with phase compensation technique can be utilized for the semiquantitative assessment of valvular regurgitation in a manner similar to that of Doppler color flow mapping.
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Affiliation(s)
- S Ohnishi
- Division of Cardiology, Oriono-Izumi Hospital, Osaka, Japan
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Casolo GC, Zampa V, Rega L, Berti L, Filice M, Picchione N, Poggesi L. Evaluation of mitral stenosis by cine magnetic resonance imaging. Am Heart J 1992; 123:1252-60. [PMID: 1575142 DOI: 10.1016/0002-8703(92)91030-5] [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: 12/27/2022]
Abstract
To evaluate the ability of cine magnetic resonance imaging (cine MRI) in the assessment of mitral stenosis (MS), we studied 20 patients (14 women and 6 men, mean age 60.6 +/- 8.5 years) with rheumatic mitral valve stenosis by using an 0.5 T magnet. Cine MRI showed several signs of MS. Mitral leaflet thickening, reduced diastolic opening, and abnormal valve motion toward the left ventricular outflow tract were all common features. MS was also characterized by an abnormal diastolic transmitral signal from blood. Both left atrial and left ventricular dimensions were similar to those obtained at two-dimensional echocardiography (2-DE) (r = 0.89 and r = 0.86, respectively; p less than 0.001). A significant relationship was also found between the maximum mitral leaflet separation measured by cine MRI in diastole and the mitral valve area as calculated using the pressure half-time method and continuous wave Doppler (r = 0.81; p less than 0.001). These data indicate the improved ability of MRI to detect and assess MS and also suggest that this technique may contribute to the noninvasive assessment of MS.
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Affiliation(s)
- G C Casolo
- Clinica Medica 1, University of Florence, Italy
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65
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Nishimura F. Oblique cine MRI for the evaluation of aortic regurgitation: comparison with cineangiography. Clin Cardiol 1992; 15:73-8. [PMID: 1737408 DOI: 10.1002/clc.4960150204] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The results of oblique cine magnetic resonance imaging (MRI) through a long axis slice of the left ventricle in 40 patients was compared with cineangiography in order to determine the usefulness of cine MR imaging for the evaluation of aortic regurgitation (AR). A diastolic dark low-intensity flow signal extending from the aortic valve into the left ventricle was seen in all 30 patients with AR, and in none of the 10 patients without AR. The length and area of the low-intensity signal due to the regurgitant flow were planimetered, and the ratio to the length and area of the left ventricle was calculated. The best correlation with angiography was with the ratio of the area of the low-intensity signal (ALIS) to the area of the left ventricle (ALV); it correctly classified the degree of regurgitation in 28 of the 30 patients (93.3%). The ALIS/ALV ratio was under 25% in all 11 patients with angiographic mild AR, 26-50% in 10 of the 11 patients with moderate AR, and over 51% in 7 of the 8 patients with severe AR. Thus the results point to a high degree of correlation between long axis oblique cine MRI and cineangiography in the identification of AR and in providing a semiquantitative estimation of its severity.
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Affiliation(s)
- F Nishimura
- Department of Cardiology, Kameda General Hospital, Kamogawa, Japan
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Reimold SC, Ganz P, Bittl JA, Thomas JD, Thoreau D, Plappert TJ, Lee RT. Effective aortic regurgitant orifice area: description of a method based on the conservation of mass. J Am Coll Cardiol 1991; 18:761-8. [PMID: 1869740 DOI: 10.1016/0735-1097(91)90800-o] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of conservation of mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is less than 4.8 cm in diameter. Twenty-three patients undergoing cardiac catheterization were studied; 20 of these patients had aortic regurgitation. Retrograde supravalvular diastolic velocity was determined from a Doppler catheter positioned above the aortic valve. The effective regurgitant orifice area was calculated with use of the Doppler catheter-derived regurgitant volume and mean transvalvular diastolic velocity as determined by either catheterization or continuous wave Doppler echocardiography. The catheterization-derived regurgitant orifice area increased with the angiographic grade of as follows: 1+ (0.04 to 0.10 cm2), 2+ (0.15 to 0.49 cm2), 3+ (0.29 to 1.11 cm2) and 4+ (1.24 to 1.33 cm2). By combining Doppler catheter, echocardiographic and cardiac catheterization techniques, the effective aortic regurgitant orifice area may be estimated; this hydrodynamic area correlates with grading by supravalvular aortography. Calculation of this area provides a quantitative alternative to aortography for estimating the severity of aortic regurgitation but should be used with caution in patients with a markedly dilated aorta.
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Affiliation(s)
- S C Reimold
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts
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69
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Globits S, Mayr H, Frank H, Neuhold A, Glogar D. Quantification of regurgitant lesions by MRI. INTERNATIONAL JOURNAL OF CARDIAC IMAGING 1990; 6:109-16. [PMID: 2097304 DOI: 10.1007/bf02398894] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We examined 46 patients with angiographically documented regurgitant lesions (26 patients with mitral regurgitation, 20 patients with aortic regurgitation) using an 0.5 Tesla magnet. In each patient a multislice-multiphase spinecho sequence in sagittal-coronal double angulated plane was performed to assess left and right ventricular volumes, ejection fraction and regurgitant fraction. Additionally a blood flow sensitive gradient echo technique was done to visualize direction and extension of the regurgitant jet. MRI data were compared with quantitative and qualitative assessment of regurgitation by angiography and echocardiography. Using the gradient echo technique MRI could demonstrate the regurgitant jet in all patients. A linear correlation for volume parameters by MRI and angio was found with best correlation for the left ventricular stroke volume (r = 0.82, p less than 0.0001). Furthermore MRI regurgitant fraction correlated with angiographically determined regurgitant fraction in patients with aortic regurgitation (r = 0.91, p less than 0.0001) and mitral regurgitation (r = 0.67, p less than 0.001), respectively. Semiquantitative assessment of regurgitation by gradient echo technique showed an agreement with angiographic grading by Sellers in 70% of mitral and 75% of aortic regurgitation, respectively. The comparison of MRI and color Doppler sonography showed only moderate correlation of r = 0.72 (p less than 0.01).
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Affiliation(s)
- S Globits
- Cardiology Department, University of Vienna, Austria
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