CT CHEST ANATOMY

USC/SOM

Department of Radiology

Kirk Peterson, MDClass of 2004

The following slide set is a collection of CT axial (transverse) 5mm slices from the lower neck to the upper abdomen. Soft

tissue window settings were selected to provide the best views of the mediastinal anatomy. Every few slides, outlines with a legend have been provided to label anatomical structures of interest. Radiologist frequently page up and down on digital

images to “follow” structures from their origin to their termination. Try this with this slide set. Use the labeled slides to help orient yourself while you page up and down to try and identify various anatomical structures. It will be best to view

these slides in the movie mode.Images are viewed as looking from the feet

right left

Right and left Subclavian arteries

We are at the level of T2-T3 around the lung apices. Trachea. Esophagus.Rt.Brachiocephalic Vein Left subclavian artery, if you follow this branch up two slides, you can see the artery head left as it prepares to pass under the clavicle. If you

follow it down for six slides, you can see the artery becomes part of the aortic arch. The left subclavian is usually the last branch off the aortic arch. Can you recall the three branches off the aortic arch ? Left common carotid, in typical arches, this is the second branch off the aortic arch. Brachiocephalic artery, the first branch off the aortic arch. It will divide into

the right common carotid and right subclavian arteries. If you scroll up two slides, you can see the subclavian branch heading toward the right. Right lung apex with air density, you can see the left lung apex is also visualized.

We are at the level of T3. Note the air densities of the lungs, esophagus and trachea (none of which are labeled on this slide.) This bright structure is the left subclavian vein joining the internal jugular vein to form the brachiocephalic vein. The reason for its brightness is that contrast was administered intravenously in the left arm and the left subclavian vein is bringing contrast toward the heart before it has had a chance to mix with nonopacified blood. The brightness surrounding the vessel is due to artifact. Brachiocephalic artery. Scroll down four slides to see that this is the first branch off the aortic arch. Left common carotid. Scroll down four slides to see that this is the second branch off the aortic arch. Left subclavian

artery. Scroll down four slides to see that this is the third branch off the aortic arch. Sternal head of the right clavicle.

Note fat density mass deep to scapula. This is a benign lipoma as an incidental finding.The lesion has the typical density of fat [less than soft tissue and bone but greater than lung

We are at the level of the superior portion of the aortic arch. that gave rise to the aforementioned vessels. Here we see the Left Brachiocephalic Vein crossing midline and

Joining the Right Brachiocephalic Vein. Once their union is complete, this single vein is known as the Superior Vena Cava (SVC). Note head of first rib articulating with manubrium. These small high densities in

the mostly air dense lungs are pulmonary vessels filled with IV contrast

At the most caudal portion of the aortic arch, we can distinguish the ascending portion ofThe aorta (anterior portion of your screen) from the descending aorta located along the left margin of the vertebral body.

This is the contrast opacified Superior Vena Cava preparing to enter the Right Atrium.

Internal Mammary Artery and vein.The vein is the larger medial structure

Just distal to the bifurcation of the trachea. The ascending and descending aorta are noted (ascending is superior on your screen.) Here you can appreciate the right and left primary bronchi. This is our first view of the pulmonary artery. Remember this artery begins as the truncus arteriosis

or the right ventricle and will divide into the right and left pulmonary arteries to deliver deoxygenated blood to the lungs. The left pulmonary artery and trunk are visualized in this image. Superior Vena Cava on the right and the smaller blue outline on the left is a left pulmonary vein.

We are at the superior portion of the left atrium. Ascending and descending aorta. Here we have the main pulmonary veins returning from the lungs and preparing to enter the left atrium. Follow up and down to confirm that these are veins versus arteries. Right and left Pulmonary Arteries. Look closely, you can see how the pulmonary arteries tend to run with the air density (black) bronchi. The pulmonary trunk is outlined again at the

superior portion of your screen. The right atrium is beginning to be visualized. You can still appreciate the SVC in the inferior portion of the yellow outline. The superior portion of the outline is most likely the right atrial appendage (auricle). This is the Left Atrium. The superior portion

of the outline is most likely the left atrial appendage (auricle)

A neat little anatomical find, here you can see the left coronary artery branchingoff the aorta

Note bifurcation of Lt main coronary a. into Lt.Ant. Descending and circumflex arteries

We are at the mid portion of the left atrium. If you look closely, you can actually distinguish the individual leaflets of the aortic semilunar valve. Left Atrium, you can trace the pulmonary veins as they enter the left atrium. Left Ventricle. Right Atrium with a narrowing and entry to the right

ventricle (the right ventricle is the most superior portion of the yellow outline.) These two structures will become more distinct in more caudal images. Pulmonary Veins. Pulmonary Arteries. Esophagus. Azygous Vein.

Level of the mid portion of the Left Ventricle. You still see the thoracic aorta located along the left margin of the thoracic vertebral body. The left ventricle has become quite distinct at this level. You can appreciate the thick ventricle wall with the

contrast filled cavity in this image. Left Atrium. Our first glimpse of the Inferior Vena Cava (IVC), page down to confirm this. The IVC brings deoxygenated blood from the lower extremities to the inferior aspect of the right atrium while the SVC

brings deoxygenated blood from the head and upper extremities to superior portion of the right atrium. Esophagus.

Arrows indicate pericardium with low density epicardial and pericardial fat outlining the pericardium

Level of the inferior margin of the heart and superior portion of the right lobe of the liver. Thoracic Aorta. Left Ventricle. Right Ventricle. Inferior Vena Cava. Right Lobe of the Liver. Esophagus