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From the RSNA Refresher Courses¹

Cardiac MR Imaging: A Guide for the Beginner

¹ From the Department of Radiology, Beth Israel Medical Center, First Ave and 16th St, New York, NY 10003. Presented as a refresher course at the 1998 RSNA scientific assembly. Received July 28, 1998; revision requested August 26 and received September 25; accepted September 25. Address reprint requests to the author.

View larger version (11K): [in a new window]   Figures 1, 2.  (1) ECG gating. (a) From an engineering point of view, the R waves should be precisely spaced and unambiguously greater in voltage than any other ECG signal. (b) In the clinical setting, differentiation of R waves from background noise may be less precise. (c) R waves are identified by comparing the voltage of a signal with a known ("threshold") voltage. Thus, an R-wave triggering signal is a signal greater than the threshold. (2) Pseudo-R-R intervals. If the T-wave voltage exceeds the threshold voltage, then the T waves are interpreted by the imager as R waves. The assumed R-R intervals (arrows) are unequal; the result is temporally irregular phase-encoding steps and subsequently incoherent images.

View larger version (21K): [in a new window]   Figures 1, 2.  (1) ECG gating. (a) From an engineering point of view, the R waves should be precisely spaced and unambiguously greater in voltage than any other ECG signal. (b) In the clinical setting, differentiation of R waves from background noise may be less precise. (c) R waves are identified by comparing the voltage of a signal with a known ("threshold") voltage. Thus, an R-wave triggering signal is a signal greater than the threshold. (2) Pseudo-R-R intervals. If the T-wave voltage exceeds the threshold voltage, then the T waves are interpreted by the imager as R waves. The assumed R-R intervals (arrows) are unequal; the result is temporally irregular phase-encoding steps and subsequently incoherent images.

View larger version (25K): [in a new window]   Figures 1, 2.  (1) ECG gating. (a) From an engineering point of view, the R waves should be precisely spaced and unambiguously greater in voltage than any other ECG signal. (b) In the clinical setting, differentiation of R waves from background noise may be less precise. (c) R waves are identified by comparing the voltage of a signal with a known ("threshold") voltage. Thus, an R-wave triggering signal is a signal greater than the threshold. (2) Pseudo-R-R intervals. If the T-wave voltage exceeds the threshold voltage, then the T waves are interpreted by the imager as R waves. The assumed R-R intervals (arrows) are unequal; the result is temporally irregular phase-encoding steps and subsequently incoherent images.

View larger version (35K): [in a new window]   Figures 1, 2.  (1) ECG gating. (a) From an engineering point of view, the R waves should be precisely spaced and unambiguously greater in voltage than any other ECG signal. (b) In the clinical setting, differentiation of R waves from background noise may be less precise. (c) R waves are identified by comparing the voltage of a signal with a known ("threshold") voltage. Thus, an R-wave triggering signal is a signal greater than the threshold. (2) Pseudo-R-R intervals. If the T-wave voltage exceeds the threshold voltage, then the T waves are interpreted by the imager as R waves. The assumed R-R intervals (arrows) are unequal; the result is temporally irregular phase-encoding steps and subsequently incoherent images.

View larger version (114K): [in a new window]   Figure 3a.  Comparison of spin-echo acquisition with gradient reversal acquisition. (a) Midsystolic spin-echo MR image (short-axis section obtained 138 msec after the R wave) shows a difference in signal intensity between the left (L) and right (R) ventricular myocardium and the epicardial fat (arrows). (b) Gradient reversal MR image obtained in the same location at the same phase of the cardiac cycle shows that the difference in signal intensity between the cavitary blood and the ventricular myocardium and between the myocardium and fat is markedly decreased.

View larger version (131K): [in a new window]   Figure 3b.  Comparison of spin-echo acquisition with gradient reversal acquisition. (a) Midsystolic spin-echo MR image (short-axis section obtained 138 msec after the R wave) shows a difference in signal intensity between the left (L) and right (R) ventricular myocardium and the epicardial fat (arrows). (b) Gradient reversal MR image obtained in the same location at the same phase of the cardiac cycle shows that the difference in signal intensity between the cavitary blood and the ventricular myocardium and between the myocardium and fat is markedly decreased.

View larger version (98K): [in a new window]   Figure 4.  Image defect caused by an aortic valvular prosthesis in a 38-year-old man treated for congenital aortic regurgitation. Horizontal long-axis gradient reversal MR image shows a huge signal void in the center of the heart (V). The signal void causes the size of the prosthesis to be exaggerated but otherwise does not prevent interpretation of the image.

View larger version (148K): [in a new window]   Figure 5a.  Use of a torso coil to increase signal. (a) Horizontal short-axis spin-echo MR image (two signals acquired) of a 68-year-old man with an infiltrating sarcoma (S) of the posterior wall of the left ventricle (LV) shows a clear difference in signal intensity between the epicardial fat and the free-wall myocardium of the right ventricle (arrowheads). The left main coronary artery is seen in cross section (arrow). Note the increased signal intensity of the anterior chest wall compared with that of the posterior chest wall. (b) Spin-echo MR image (same section as in a, four signals acquired) of a 50-year-old man evaluated for tricuspid regurgitation shows interventricular septal trabeculae in the right ventricle (arrows). However, the diagnostic quality of both images is nearly equal.

View larger version (168K): [in a new window]   Figure 5b.  Use of a torso coil to increase signal. (a) Horizontal short-axis spin-echo MR image (two signals acquired) of a 68-year-old man with an infiltrating sarcoma (S) of the posterior wall of the left ventricle (LV) shows a clear difference in signal intensity between the epicardial fat and the free-wall myocardium of the right ventricle (arrowheads). The left main coronary artery is seen in cross section (arrow). Note the increased signal intensity of the anterior chest wall compared with that of the posterior chest wall. (b) Spin-echo MR image (same section as in a, four signals acquired) of a 50-year-old man evaluated for tricuspid regurgitation shows interventricular septal trabeculae in the right ventricle (arrows). However, the diagnostic quality of both images is nearly equal.

View larger version (79K): [in a new window]   Figure 6.  Placement of ECG leads. Leads should be placed within a 10-cm radius over the precordium. Wires should pass over the shoulder parallel to the long axis (B field) of the magnet.

View larger version (150K): [in a new window]   Figure 7a.  Scout images. (a) Coronal gradient reversal MR image (one signal acquired) shows the aortic root (Ao), left ventricle (LV), main pulmonary artery (PA), and right atrium (RA). (b) Coronal gradient reversal MR image (one signal acquired) obtained 3 cm posterior to a shows the distal aortic arch (AA), left atrium (LA), posterior left ventricle (LV), and right pulmonary artery (RP).

View larger version (153K): [in a new window]   Figure 7b.  Scout images. (a) Coronal gradient reversal MR image (one signal acquired) shows the aortic root (Ao), left ventricle (LV), main pulmonary artery (PA), and right atrium (RA). (b) Coronal gradient reversal MR image (one signal acquired) obtained 3 cm posterior to a shows the distal aortic arch (AA), left atrium (LA), posterior left ventricle (LV), and right pulmonary artery (RP).

View larger version (133K): [in a new window]   Figure 8a.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (131K): [in a new window]   Figure 8b.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (124K): [in a new window]   Figure 8c.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (119K): [in a new window]   Figure 8d.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (130K): [in a new window]   Figure 8e.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (137K): [in a new window]   Figure 8f.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (136K): [in a new window]   Figure 8g.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (139K): [in a new window]   Figure 8h.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (158K): [in a new window]   Figure 8i.  Series of axial spin-echo MR images with each image obtained 1 cm caudad to the previous one. (a) The ascending aorta (Aa), main pulmonary artery (MP), and superior vena cava (S) are outlined by mediastinal fat. The transverse portion of the right pulmonary artery (RP) is behind the aorta and superior vena cava and anterior to the right bronchus (RB). The left upper lobe pulmonary vein (arrow) is anterior to the left bronchus (LB). The descending aorta (Ad) lies to the left of the spine. (b) The left upper lobe pulmonary vein (open arrow) is seen entering the left atrium. Posterior to the ascending aorta (Aa), medial to the superior vena cava (S), and anterior to the right pulmonary artery (RP) is the signal void of the superior pericardial recess (solid arrow). (c) The signal void of the anterior aspect of the pericardial space (straight solid arrow) is seen between the ascending aorta (Aa) and proximal main pulmonary artery (MP). The right upper lobe pulmonary vein (open arrow) enters the left atrium (LA) posterior to the superior vena cava (S). The left lower lobe pulmonary vein (arrowheads) passes anterior to the descending aorta (Ad) before entering the left atrium. The left atrial appendage (curved arrow) forms the left border of the heart. (d) The left lower lobe pulmonary vein (Ll) is seen entering the left atrium (LA). The three sinuses of the pulmonary artery may be identified (1, 2, and 3). (e) Just caudad to the pulmonary valve, the right ventricular outflow tract (RVO) is seen. The posterior left aortic sinus (PLS) is situated between the left atrium (LA) and right ventricular outflow tract. The trabeculated right atrial appendage (arrows) lies anterior to the root of the ascending aorta. (f) The entrance of the superior vena cava (S) into the right atrium and the ostium of the right atrial appendage (RAA) are seen. The commissures of the aortic valve define the anterior, posterior right, and posterior left aortic sinuses (AS, PRS, and PLS, respectively). The right lower lobe pulmonary vein (open arrow) enters the left atrium (LA). Note the fatty infiltration of the sinus venosus portion of the interatrial septum (solid arrows). (g) The signal void of the descending portion of the right coronary artery (arrow) is seen within the fat of the anterior atrioventricular ring. The posterior right aortic sinus (PRS) is interposed between the right atrium (RA) and left atrium (LA). The anterior mitral leaflet (arrowhead) is continuous with the aortic annulus. (h) The tricuspid valve (small white arrows) separates the right atrium (RA) from the right ventricle (RV). The muscular interventricular septum (black arrow) is shared by the right ventricle and left ventricle (LV). The atrioventricular septum (large white arrow) separates the left ventricle from the right atrium. The mitral valve separates the left atrium (LA) from the left ventricle. (i) The inferior vena cava (IVC) is seen entering the right atrium (RA). The coronary sinus (C) enters the right atrium medial to the increased-signal-intensity fat of the posterior atrioventricular ring (arrow).

View larger version (151K): [in a new window]   Figure 9a.  Constructing the left ventricular axes. (a) Axial spin-echo MR image shows a line (1) drawn between the middle of the mitral valve and the left ventricular apex. This line defines the plane containing the true long axis of the left ventricle. (b) Right anterior oblique sagittal MR image containing the mitral valve and left ventricular apex shows a line (2) drawn between the middle of the mitral valve and the left ventricular apex. This line defines the long axis of the left ventricle. Images obtained normal to this line are along the cardiac short axis. (c) Cardiac short-axis MR image shows the left ventricle (LV) as a round structure. The normal right ventricle seems to be an appendage of the left ventricle.

View larger version (166K): [in a new window]   Figure 9b.  Constructing the left ventricular axes. (a) Axial spin-echo MR image shows a line (1) drawn between the middle of the mitral valve and the left ventricular apex. This line defines the plane containing the true long axis of the left ventricle. (b) Right anterior oblique sagittal MR image containing the mitral valve and left ventricular apex shows a line (2) drawn between the middle of the mitral valve and the left ventricular apex. This line defines the long axis of the left ventricle. Images obtained normal to this line are along the cardiac short axis. (c) Cardiac short-axis MR image shows the left ventricle (LV) as a round structure. The normal right ventricle seems to be an appendage of the left ventricle.

View larger version (150K): [in a new window]   Figure 9c.  Constructing the left ventricular axes. (a) Axial spin-echo MR image shows a line (1) drawn between the middle of the mitral valve and the left ventricular apex. This line defines the plane containing the true long axis of the left ventricle. (b) Right anterior oblique sagittal MR image containing the mitral valve and left ventricular apex shows a line (2) drawn between the middle of the mitral valve and the left ventricular apex. This line defines the long axis of the left ventricle. Images obtained normal to this line are along the cardiac short axis. (c) Cardiac short-axis MR image shows the left ventricle (LV) as a round structure. The normal right ventricle seems to be an appendage of the left ventricle.

View larger version (159K): [in a new window]   Figure 10a.  Short-axis section. (a) End-diastolic gradient reversal MR image shows a sharp border between the high-signal-intensity moving blood of the left ventricular cavity and the intermediate-signal-intensity myocardium. However, it is difficult to differentiate the right ventricular cavity from free-wall myocardium. (b) End-systolic gradient reversal MR image shows the papillary muscles of the posterior wall of the left ventricle more clearly (arrows). Left ventricular cavity size has decreased, and myocardial thickness has increased.

View larger version (162K): [in a new window]   Figure 10b.  Short-axis section. (a) End-diastolic gradient reversal MR image shows a sharp border between the high-signal-intensity moving blood of the left ventricular cavity and the intermediate-signal-intensity myocardium. However, it is difficult to differentiate the right ventricular cavity from free-wall myocardium. (b) End-systolic gradient reversal MR image shows the papillary muscles of the posterior wall of the left ventricle more clearly (arrows). Left ventricular cavity size has decreased, and myocardial thickness has increased.

View larger version (152K): [in a new window]   Figure 11.  Four-chamber section. Spin-echo MR image shows the aortic sinuses (1, 2, and 3) in the center of the heart. Within the fat of the anterior atrioventricular ring lies the right coronary artery (solid arrow) and tricuspid valve. The trabeculated right ventricular (RV) free-wall myocardium is demonstrated. The anteroposterior relationships between the left atrial appendage (LAA) and left upper lobe pulmonary vein (open arrow) as well as the left bronchus (LB) and descending left pulmonary artery (LP) are well demonstrated.

View larger version (127K): [in a new window]   Figure 12a.  The right ventricle in orthogonal sections. (a) Axial spin-echo MR image at the level of the dome of the right diaphragm (D) shows the cavity of the right ventricle (RV) appearing to drape around the left ventricle (LV). The moderator band (arrow) is found on the right ventricular side of the interventricular septum and connects the free wall with the septum. (b) Coronal spin-echo MR image shows the cavity of the right ventricle extending from the fat of the anterior atrioventricular ring, which contains the signal void of the right coronary artery (arrow), to the fat of the anterior interventricular groove. The right atrial appendage (RA) is seen in cross section. (c) Sagittal spin-echo MR image of a patient with pulmonary hypertension and right ventricular hypertrophy clearly shows the hypertrophied right ventricular myocardial trabeculae (T) and supraventricular crest (C). Note the straightening of the interventricular septum.

View larger version (133K): [in a new window]   Figure 12b.  The right ventricle in orthogonal sections. (a) Axial spin-echo MR image at the level of the dome of the right diaphragm (D) shows the cavity of the right ventricle (RV) appearing to drape around the left ventricle (LV). The moderator band (arrow) is found on the right ventricular side of the interventricular septum and connects the free wall with the septum. (b) Coronal spin-echo MR image shows the cavity of the right ventricle extending from the fat of the anterior atrioventricular ring, which contains the signal void of the right coronary artery (arrow), to the fat of the anterior interventricular groove. The right atrial appendage (RA) is seen in cross section. (c) Sagittal spin-echo MR image of a patient with pulmonary hypertension and right ventricular hypertrophy clearly shows the hypertrophied right ventricular myocardial trabeculae (T) and supraventricular crest (C). Note the straightening of the interventricular septum.

View larger version (135K): [in a new window]   Figure 12c.  The right ventricle in orthogonal sections. (a) Axial spin-echo MR image at the level of the dome of the right diaphragm (D) shows the cavity of the right ventricle (RV) appearing to drape around the left ventricle (LV). The moderator band (arrow) is found on the right ventricular side of the interventricular septum and connects the free wall with the septum. (b) Coronal spin-echo MR image shows the cavity of the right ventricle extending from the fat of the anterior atrioventricular ring, which contains the signal void of the right coronary artery (arrow), to the fat of the anterior interventricular groove. The right atrial appendage (RA) is seen in cross section. (c) Sagittal spin-echo MR image of a patient with pulmonary hypertension and right ventricular hypertrophy clearly shows the hypertrophied right ventricular myocardial trabeculae (T) and supraventricular crest (C). Note the straightening of the interventricular septum.

View larger version (136K): [in a new window]   Figure 13a.  Type I aortic dissection. (a) Axial spin-echo MR image through the transverse right pulmonary artery (RP) shows a dilated ascending aorta (Aa), which contains the high-signal-intensity intimal flap of the dissection (arrows). The descending aorta (Ad) is seen as a homogeneous signal void without a flap. (b) Off-coronal gradient reversal MR image through the aortic valve in another patient shows the dilated ascending aorta (Aa), left ventricle (LV), main pulmonary artery (PA), and right atrium (RA). A calcification of the aortic valve (large arrow) appears as a signal void in the aortic anulus. A jet of accelerating flow leaves the stenotic aortic valve and is deflected off the flap of an ascending aortic dissection into the true lumen of the mid-ascending aorta (small arrows). The false lumen (F) is separated from the true lumen.

View larger version (178K): [in a new window]   Figure 13b.  Type I aortic dissection. (a) Axial spin-echo MR image through the transverse right pulmonary artery (RP) shows a dilated ascending aorta (Aa), which contains the high-signal-intensity intimal flap of the dissection (arrows). The descending aorta (Ad) is seen as a homogeneous signal void without a flap. (b) Off-coronal gradient reversal MR image through the aortic valve in another patient shows the dilated ascending aorta (Aa), left ventricle (LV), main pulmonary artery (PA), and right atrium (RA). A calcification of the aortic valve (large arrow) appears as a signal void in the aortic anulus. A jet of accelerating flow leaves the stenotic aortic valve and is deflected off the flap of an ascending aortic dissection into the true lumen of the mid-ascending aorta (small arrows). The false lumen (F) is separated from the true lumen.

View larger version (176K): [in a new window]   Figure 14a.  Pericardial disease. (a) Short-axis gradient reversal MR image obtained at end diastole in a 52-year-old man with congestive heart failure shows the right ventricular (RV) and left ventricular (LV) myocardium surrounded by a high-signal-intensity pericardial effusion (arrowheads). (b) Coronal spin-echo MR image of a 59-year-old woman with uremic pericarditis shows the attachment of the pericardium over the main pulmonary artery (PA) and ascending aorta (Aa). Note the thickened pericardium (arrowheads) as well as the increased-signal-intensity fibrinous exudate within the pericardial space (arrows).

View larger version (167K): [in a new window]   Figure 14b.  Pericardial disease. (a) Short-axis gradient reversal MR image obtained at end diastole in a 52-year-old man with congestive heart failure shows the right ventricular (RV) and left ventricular (LV) myocardium surrounded by a high-signal-intensity pericardial effusion (arrowheads). (b) Coronal spin-echo MR image of a 59-year-old woman with uremic pericarditis shows the attachment of the pericardium over the main pulmonary artery (PA) and ascending aorta (Aa). Note the thickened pericardium (arrowheads) as well as the increased-signal-intensity fibrinous exudate within the pericardial space (arrows).

View larger version (164K): [in a new window]   Figure 15.  Ectopic fat in a 65-year-old man with shortness of breath. Axial spin-echo MR image shows a high-signal-intensity mass (M) immediately posterior to the left atrium (LA). The mass, which had been diagnosed as a mural left atrial tumor at echocardiography, is revealed to be mesenteric fat associated with a hiatal hernia. In addition, note the thickened left ventricular myocardium of hypertrophic obstructive cardiomyopathy (arrow) and especially the anteriorly displaced anterior mitral leaflet (arrowheads), which results in left ventricular outflow obstruction. Secondary signs of mitral regurgitation include left atrial enlargement and bilateral pleural effusions.

View larger version (110K): [in a new window]   Figure 16a.  Sustained ventricular tachycardia resulting from arrhythmogenic right ventricular dysplasia. (a) Axial spin-echo MR image of a 34-year-old man shows a thin veneer of epicardial fat that extends from the anterior atrioventricular ring (short large arrow) and then stops. The right ventricular free-wall myocardium (small arrows) from this point to the moderator band (long large arrow) is less than 2 mm thick. (b) Axial gradient reversal MR image of a 40-year-old woman with palpitations shows that a portion of the right ventricular (RV) free-wall myocardium fails to thicken (arrow). As a result, the right ventricular cavity appears to extend to the anterior chest wall.

View larger version (93K): [in a new window]   Figure 16b.  Sustained ventricular tachycardia resulting from arrhythmogenic right ventricular dysplasia. (a) Axial spin-echo MR image of a 34-year-old man shows a thin veneer of epicardial fat that extends from the anterior atrioventricular ring (short large arrow) and then stops. The right ventricular free-wall myocardium (small arrows) from this point to the moderator band (long large arrow) is less than 2 mm thick. (b) Axial gradient reversal MR image of a 40-year-old woman with palpitations shows that a portion of the right ventricular (RV) free-wall myocardium fails to thicken (arrow). As a result, the right ventricular cavity appears to extend to the anterior chest wall.

View larger version (122K): [in a new window]   Figure 17a.  Intracardiac shunts. (a) Axial spin-echo MR image of a 26-year-old man with a sinus venosus atrial septal defect shows that the superior portion of the interatrial septum is incomplete (arrow). There is dilatation of the right ventricular outflow tract (RVO) and a normal-size left atrium (LA). (b) Axial spin-echo MR image of a 4-month-old boy with a large ventricular septal defect and a primum atrial septal defect shows a discontinuity in the interventricular septum (arrows) and a break in the posterior medial interatrial septum (arrowhead). Note the increased myocardial thickness and cavity size of the right ventricle (RV) and the dilatation of the left ventricle (LV).

View larger version (144K): [in a new window]   Figure 17b.  Intracardiac shunts. (a) Axial spin-echo MR image of a 26-year-old man with a sinus venosus atrial septal defect shows that the superior portion of the interatrial septum is incomplete (arrow). There is dilatation of the right ventricular outflow tract (RVO) and a normal-size left atrium (LA). (b) Axial spin-echo MR image of a 4-month-old boy with a large ventricular septal defect and a primum atrial septal defect shows a discontinuity in the interventricular septum (arrows) and a break in the posterior medial interatrial septum (arrowhead). Note the increased myocardial thickness and cavity size of the right ventricle (RV) and the dilatation of the left ventricle (LV).