1. Normal cardiothoracic imaging landmarks, PA view

2. COMMENTS Key cardiothoracic landmarks include the suprasternal notch just above the junction of the clavicles and subxiphoid region. The bony sternum overlies the spine on the frontal film and is therefore not clearly identified in that projection. The junction of the ribs with the sternum is usually composed of calcified cartilage and are shown as a segmental change as the rib approaches the sternum. Note the small spaces between the ribs at the sternum which is the only allowable soft tissue window for ultrasound imaging of the heart. The nipples are soft tissue and sometimes appear on chest x-rays as suspicious symmetric nodules in the lower lung fields. Key cardiothoracic landmarks include the suprasternal notch just above the junction of the clavicles and subxiphoid region. The bony sternum overlies the spine on the frontal film and is therefore not clearly identified in that projection. The junction of the ribs with the sternum is usually composed of calcified cartilage and are shown as a segmental change as the rib approaches the sternum. Note the small spaces between the ribs at the sternum which is the only allowable soft tissue window for ultrasound imaging of the heart. The nipples are soft tissue and sometimes appear on chest x-rays as suspicious symmetric nodules in the lower lung fields.

3. Normal cardiothoracic imaging landmarks, lateral view

4. Lateral landmarks on chest radiographs Although it is not uncommon to find the lateral chest film displayed with the body either looking left or right, depending on which side of the patient was closest to the film, it is most sensible to present the lateral the film always in some fixed manner to the viewer so that consistent visual pattern recognition can be achieved. A favored direction is as if the patient were being viewed through the left lateral chest wall, so that the image appears as if the patient is facing the viewer's left. This film orientation provides an assessment of the overall heart size which should show a space anteriorly below the sternum if the right cardiac chambers are not enlarged. The dome of the diaphragm will appear convex upward. Although it is not uncommon to find the lateral chest film displayed with the body either looking left or right, depending on which side of the patient was closest to the film, it is most sensible to present the lateral the film always in some fixed manner to the viewer so that consistent visual pattern recognition can be achieved. A favored direction is as if the patient were being viewed through the left lateral chest wall, so that the image appears as if the patient is facing the viewer's left. This film orientation provides an assessment of the overall heart size which should show a space anteriorly below the sternum if the right cardiac chambers are not enlarged. The dome of the diaphragm will appear convex upward. The dome that can be seen to extend most anteriorly is identified as the right diaphragm. The left diaphragmatic dome merges with undersurface of the heart, a tissue of the same density, and therefore tends to disappear anteriorly. Another marker of the left diaphragm is the gastric air bubble which should most closely approach the boundary of the left diaphragm if the patient has normal cardiac situs. The dome that can be seen to extend most anteriorly is identified as the right diaphragm. The left diaphragmatic dome merges with undersurface of the heart, a tissue of the same density, and therefore tends to disappear anteriorly. Another marker of the left diaphragm is the gastric air bubble which should most closely approach the boundary of the left diaphragm if the patient has normal cardiac situs. The trachea should be readily visible to the carina. Where there are slight amounts of fluid in the fissures or where the fissure is projected along its edge, the right middle lobe and the right lower lobe inter-pulmonary fissures are commonly visible. The thoracic vertebrae tend to be difficult to visualize at the upper levels because of the overlapping shoulders and soft tissues of the upper thorax, but appear as quite transparent in the lower thoracic spine just above the diaphragm. The trachea should be readily visible to the carina. Where there are slight amounts of fluid in the fissures or where the fissure is projected along its edge, the right middle lobe and the right lower lobe inter-pulmonary fissures are commonly visible. The thoracic vertebrae tend to be difficult to visualize at the upper levels because of the overlapping shoulders and soft tissues of the upper thorax, but appear as quite transparent in the lower thoracic spine just above the diaphragm.

5. Gross anatomy of the thorax and mediastinum

6. Cardiothoracic anatomy Note the extensive overlap of soft tissue structures results in a confusing complexity, particularly the pulmonary vasculature. Note the pulmonary artery is defined in blue because it contains deoxygenated blood and the pulmonary venous structures are red since the blood has been perfused and oxygenated in the alveoli. Note the two fissures separating the three lobes of the right lung (right upper, right middle, and right lower lobe) and the single fissure on the left separating the lingula from the left lower lobe. Note the extensive overlap of soft tissue structures results in a confusing complexity, particularly the pulmonary vasculature. Note the pulmonary artery is defined in blue because it contains deoxygenated blood and the pulmonary venous structures are red since the blood has been perfused and oxygenated in the alveoli. Note the two fissures separating the three lobes of the right lung (right upper, right middle, and right lower lobe) and the single fissure on the left separating the lingula from the left lower lobe.

7. Anterior radiographic view of cardiac anatomy

8. Radiographic view of the heart Detailed illustration and radiograph of the central mediastinum anatomy. The illustration demonstrates the complexity of the overlapping vascular structures and emphasizes the difficulty with which separating out individual vessels occur on the radiograph. In the illustration, the pulmonary artery is shown in blue because it contains deoxygenated blood and the pulmonary veins and aortic arch are red since they are oxygenated. In the radiograph, note the aortic knob which arches over the main pulmonary artery and the faint, lesser-dense areas representing the air-containing tubes of the trachea, carina, and main bronchi. The spinous processes and vertebrae are faintly visible through the central density of the heart and the sharp vertical line descending from the aortic knob after the take-off of the left subclavian represents the descending aorta. Detailed illustration and radiograph of the central mediastinum anatomy. The illustration demonstrates the complexity of the overlapping vascular structures and emphasizes the difficulty with which separating out individual vessels occur on the radiograph. In the illustration, the pulmonary artery is shown in blue because it contains deoxygenated blood and the pulmonary veins and aortic arch are red since they are oxygenated. In the radiograph, note the aortic knob which arches over the main pulmonary artery and the faint, lesser-dense areas representing the air-containing tubes of the trachea, carina, and main bronchi. The spinous processes and vertebrae are faintly visible through the central density of the heart and the sharp vertical line descending from the aortic knob after the take-off of the left subclavian represents the descending aorta. Graphic superimposition of the heart and great vessels shows the position of the significant segments and boundaries of the various chambers. Within the cardiac silhouette most non-calcified soft tissue structures such as the valves are not apparent since they merge with the similar radiographic density of the blood pool. Only where there is calcification (such as the mitral annulus or aortic valve) will a structure be specifically identified within the cardiac silhouette. The pulmonary arteries tend to be more vertically oriented whereas the pulmonary venous structures are more horizontal as they drain into the left atrium. Note the lateral width of the heart from the right atrial border to the left ventricular apex is generally less than one half the width of the whole thorax. Graphic superimposition of the heart and great vessels shows the position of the significant segments and boundaries of the various chambers. Within the cardiac silhouette most non-calcified soft tissue structures such as the valves are not apparent since they merge with the similar radiographic density of the blood pool. Only where there is calcification (such as the mitral annulus or aortic valve) will a structure be specifically identified within the cardiac silhouette. The pulmonary arteries tend to be more vertically oriented whereas the pulmonary venous structures are more horizontal as they drain into the left atrium. Note the lateral width of the heart from the right atrial border to the left ventricular apex is generally less than one half the width of the whole thorax.

9. Gross anatomy - coronal section of the chest

10. Tomographic views This illustration shows the simplifying advantages of a tomographic (coronal) section through the mid left ventricular level. Two of the three aortic leaflets and the coronary orifice are visible. The two fissures separating the three lobes of the right lung and the single fissure of the left separating the lingula from the left lower lobe are clearly defined and show their crescentic orientation. The slice through the heart shows the thinner right ventricular wall compared to the interventricular septum and lateral myocardium. This illustration shows the simplifying advantages of a tomographic (coronal) section through the mid left ventricular level. Two of the three aortic leaflets and the coronary orifice are visible. The two fissures separating the three lobes of the right lung and the single fissure of the left separating the lingula from the left lower lobe are clearly defined and show their crescentic orientation. The slice through the heart shows the thinner right ventricular wall compared to the interventricular septum and lateral myocardium.

11. Gross anatomy of the heart

12. Anterior view of the heart This illustration compares the tissue of the cardiac and great vessels section with a simplified schematic projection illustrating the position of the various valves and the position and overlapping properties of the right sided structures (denoted in blue because their bloodpool is unoxygenated, or desaturated) with the left ventricle (denoted in pink because its bloodpool is oxygenated, or saturated), the ascending aorta and left atrial appendage. This illustration compares the tissue of the cardiac and great vessels section with a simplified schematic projection illustrating the position of the various valves and the position and overlapping properties of the right sided structures (denoted in blue because their bloodpool is unoxygenated, or desaturated) with the left ventricle (denoted in pink because its bloodpool is oxygenated, or saturated), the ascending aorta and left atrial appendage.

13. Left lateral view This illustration shows the cut-section of the heart from the left lateral view. The chordal structures anchoring the mitral valve to the papillary muscles with the left atrium posteriorly show the continuity of those two left-sided cavities. The right ventricular outflow tract anteriorly and superiorly show the thinner anterior right ventricular wall and the higher position of the pulmonary valve in relation to the aortic valve which is seen more subtly in the shadow of the membranous ventricular septum. The simplified graphic on the right shows the projection of the two-leaflet mitral valve and the three leaflet tricuspid valve and the separate but partly overlapping aortic and pulmonary valves. The aorta, left ventricular cavity, and left atrium are depicted in pink since they represent oxygenated blood whereas the blue defines the superior vena cava, right ventricular outflow tract, and pulmonary artery carrying desaturated, deoxygenated blood.

14. Gross anatomy of the heart, oblique view

15. Gross anatomy of the heart, exterior and venticles

16. Gross anatomy of the heart Note that the right atrium is border-forming along the right lower mediastinum. In the upper mediastinum the superior vena cava makes up the right border and the aortic knob occupies the left. Note the position of the left auricle (atrial appendage) occupying the space below the left vascular hilum which is composed of the proximal pulmonary artery which lies just below the aortic knob. Note that the right atrium is border-forming along the right lower mediastinum. In the upper mediastinum the superior vena cava makes up the right border and the aortic knob occupies the left. Note the position of the left auricle (atrial appendage) occupying the space below the left vascular hilum which is composed of the proximal pulmonary artery which lies just below the aortic knob. In the transparent illustrations, the relative positions of the valves are shown. Note that in the "left-heart" the mitral and aortic valves lie effectively in contact with each other, while on the right the tricuspid and pulmonary vales are separated by an "infundibulum". In the transparent illustrations, the relative positions of the valves are shown. Note that in the "left-heart" the mitral and aortic valves lie effectively in contact with each other, while on the right the tricuspid and pulmonary vales are separated by an "infundibulum". The main components of the coronary arteries almost form two orthogonal hemi-circles as they course along the atrio-ventricular and inter-ventricular grooves from which they send off minor branches. The main components of the coronary arteries almost form two orthogonal hemi-circles as they course along the atrio-ventricular and inter-ventricular grooves from which they send off minor branches.

17. Gross anatomy of the heart, valves and coronary arteries

18. Gross anatomy of the heart Note that the right atrium is border-forming along the right lower mediastinum. In the upper mediastinum the superior vena cava makes up the right border and the aortic knob occupies the left. Note the position of the left auricle (atrial appendage) occupying the space below the left vascular hilum which is composed of the proximal pulmonary artery which lies just below the aortic knob. Note that the right atrium is border-forming along the right lower mediastinum. In the upper mediastinum the superior vena cava makes up the right border and the aortic knob occupies the left. Note the position of the left auricle (atrial appendage) occupying the space below the left vascular hilum which is composed of the proximal pulmonary artery which lies just below the aortic knob. In the transparent illustrations, the relative positions of the valves are shown. Note that in the "left- heart" the mitral and aortic valves lie effectively in contact with each other, while on the right the tricuspid and pulmonary vales are separated by an "infundibulum". In the transparent illustrations, the relative positions of the valves are shown. Note that in the "left- heart" the mitral and aortic valves lie effectively in contact with each other, while on the right the tricuspid and pulmonary vales are separated by an "infundibulum". The main components of the coronary arteries almost form two orthogonal hemi-circles as they course along the atrio-ventricular and inter-ventricular grooves from which they send off minor branches. The main components of the coronary arteries almost form two orthogonal hemi-circles as they course along the atrio-ventricular and inter-ventricular grooves from which they send off minor branches.

19. The membranous septum

20. COMMENTS This figure shows a cut-surface view vertically oriented on the left in a coronal-type projection and a left lateral cut-section on the right. The vertical coronal view illustrates the relative position of the tricuspid and mitral valves compared to the interventricular septum which, in its upper region, is cut in a curved plane demonstrating the thinning of the upper septum called the membranous septum. This is particularly evident in the lateral cut sectional view where the septum thins just below the aortic valve. This figure shows a cut-surface view vertically oriented on the left in a coronal-type projection and a left lateral cut-section on the right. The vertical coronal view illustrates the relative position of the tricuspid and mitral valves compared to the interventricular septum which, in its upper region, is cut in a curved plane demonstrating the thinning of the upper septum called the membranous septum. This is particularly evident in the lateral cut sectional view where the septum thins just below the aortic valve.

21. Gross structure of the myocardium

22. COMMENTS This figure illustrates a segmental cut through the lateral left ventricular myocardium. Most of the course of the major coronary arteries lie in the epicardium on the surface of the heart, with the vessel often embedded in fat. Here the epicardial coronary artery shown here as an obtuse marginal vessel demonstrates that the main artery lies in an epicardial position surrounded by fat with smaller perforating vessels penetrating through the myocardial wall particularly to supply segments such as the septum. This figure illustrates a segmental cut through the lateral left ventricular myocardium. Most of the course of the major coronary arteries lie in the epicardium on the surface of the heart, with the vessel often embedded in fat. Here the epicardial coronary artery shown here as an obtuse marginal vessel demonstrates that the main artery lies in an epicardial position surrounded by fat with smaller perforating vessels penetrating through the myocardial wall particularly to supply segments such as the septum.

23. Cardiac anatomy - Short axis view

24. Short axis view of heart This illustrates a cut section view through the short axis of the left ventricular cavity in a plane through the body of the papillary muscles. Note the greater trabecular pattern of the right ventricle and the thinner right ventricular free wall myocardium (3 mms.) compared to the left ventricular myocardium (up to 11 mm thick in normal septum or lateral walls). The simplified schematic shows the crescentic shape of the right ventricle in this view compared to the circular left ventricular cavity and the path of the coronary arteries anteriorly in the interventricular groove (left anterior descending artery) and posterior interventricular groove (where lies the posterior descending artery). This illustrates a cut section view through the short axis of the left ventricular cavity in a plane through the body of the papillary muscles. Note the greater trabecular pattern of the right ventricle and the thinner right ventricular free wall myocardium (3 mms.) compared to the left ventricular myocardium (up to 11 mm thick in normal septum or lateral walls). The simplified schematic shows the crescentic shape of the right ventricle in this view compared to the circular left ventricular cavity and the path of the coronary arteries anteriorly in the interventricular groove (left anterior descending artery) and posterior interventricular groove (where lies the posterior descending artery).

25. Cardiac anatomy - Anterior view

26. Anterior view of the heart This illustration compares the tissue of the cardiac and great vessels section with a simplified schematic projection illustrating the position of the various valves and the position and overlapping properties of the right sided structures (denoted in blue because their bloodpool is unoxygenated, or desaturated) with the left ventricle (denoted in pink because its bloodpool is oxygenated, or saturated), the ascending aorta and left atrial appendage. This illustration compares the tissue of the cardiac and great vessels section with a simplified schematic projection illustrating the position of the various valves and the position and overlapping properties of the right sided structures (denoted in blue because their bloodpool is unoxygenated, or desaturated) with the left ventricle (denoted in pink because its bloodpool is oxygenated, or saturated), the ascending aorta and left atrial appendage.

27. Cardiac anatomy - Left anterior oblique view

28. Cardiac anatomy - Left lateral view

29. Left lateral view This illustration shows the cut-section of the heart from the left lateral view. The chordal structures anchoring the mitral valve to the papillary muscles with the left atrium posteriorly show the continuity of those two left-sided cavities. The right ventricular outflow tract anteriorly and superiorly show the thinner anterior right ventricular wall and the higher position of the pulmonary valve in relation to the aortic valve which is seen more subtly in the shadow of the membranous ventricular septum. The simplified graphic on the right shows the projection of the two-leaflet mitral valve and the three leaflet tricuspid valve and the separate but partly overlapping aortic and pulmonary valves. The aorta, left ventricular cavity, and left atrium are depicted in pink since they represent oxygenated blood whereas the blue defines the superior vena cava, right ventricular outflow tract, and pulmonary artery carrying desaturated, deoxygenated blood. This illustration shows the cut-section of the heart from the left lateral view. The chordal structures anchoring the mitral valve to the papillary muscles with the left atrium posteriorly show the continuity of those two left-sided cavities. The right ventricular outflow tract anteriorly and superiorly show the thinner anterior right ventricular wall and the higher position of the pulmonary valve in relation to the aortic valve which is seen more subtly in the shadow of the membranous ventricular septum. The simplified graphic on the right shows the projection of the two-leaflet mitral valve and the three leaflet tricuspid valve and the separate but partly overlapping aortic and pulmonary valves. The aorta, left ventricular cavity, and left atrium are depicted in pink since they represent oxygenated blood whereas the blue defines the superior vena cava, right ventricular outflow tract, and pulmonary artery carrying desaturated, deoxygenated blood.

30. Short axis sections and matching SPECT nuclear imaging views

35. COMMENTS This illustrates a cut section view through the short axis of the left ventricular cavity in a plane through the body of the papillary muscles. Note the greater trabecular pattern of the right ventricle and the thinner right ventricular free wall myocardium (3 mms.) compared to the left ventricular myocardium (up to 11 mm thick in normal septum or lateral walls). This illustrates a cut section view through the short axis of the left ventricular cavity in a plane through the body of the papillary muscles. Note the greater trabecular pattern of the right ventricle and the thinner right ventricular free wall myocardium (3 mms.) compared to the left ventricular myocardium (up to 11 mm thick in normal septum or lateral walls).

36. Normal anatomy of the myocardium - Anterior view