(Radiographics. 2002;22:S45-S60.)
© RSNA, 2002
Multi–Detector Row and Volume-rendered CT of the Normal and Accessory Flow Pathways of the Thoracic Systemic and Pulmonary Veins1
Leo P. Lawler, MD, FRCR,
Frank M. Corl, MS and
Elliot K. Fishman, MD
1 From the Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, 601 N Caroline St, Baltimore, MD 21287. Presented as an education exhibit at the 2001 RSNA scientific assembly. Received January 18, 2002; revision requested March 5 and received April 3; accepted April 8. E.K.F. is cofounder of HipGraphics, Inc. Address correspondence to E.K.F. (e-mail: efishman@jhmi.edu).
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Abstract
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Multi–detector row computed tomography (CT) and volume rendering can be used as an interpretive aid to present the systemic and pulmonary venous anatomy of the thorax. Both of these venous systems are routinely imaged in clinical practice and are important in interpretation of diagnostic images in health and disease. Multi–detector row CT and three-dimensional volume rendering provide high-quality near-isotropic data (ie, the longitudinal resolution approximates the in-plane resolution). The data sets allow tailored postprocessing to produce images optimized for these vessels, which are often not fully appreciated at planar axial imaging alone. Venous structures of the thorax that can be demonstrated with multi–detector row CT and volume rendering include the jugular veins; the subclavian and brachiocephalic veins; the internal and lateral thoracic veins; the superior and inferior venae cavae; the coronary sinus, the cardiac and pericardiophrenic veins, and vein grafts; the azygos, hemiazygos, and accessory hemiazygos veins; the intercostal veins; the pulmonary veins; and other thoracic veins.
© RSNA, 2002
Index Terms: Computed tomography (CT), multi–detector row, 94.12917 • Computed tomography (CT), volume rendering, 94.12917 • Pulmonary veins, 945.92 • Thorax, anatomy, 94.92 • Thorax, veins, 94.92
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LEARNING OBJECTIVES
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After reading this article and taking the test, the reader will be able to:
- Discuss the applications of multi–detector row CT and volume rendering in imaging of the thoracic systemic veins.
- Describe the anatomy of the thoracic superficial and deep systemic veins and the pulmonary veins.
- Identify normal and pathologic thoracic venous anatomy on volume-rendered CT images.
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Introduction
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Much of the computed tomography (CT) literature has been appropriately focused on the pulmonary and systemic arterial systems of the thorax; these are the source of some of the more common and potentially fatal conditions, which require rapid diagnosis and management. Less attention has been paid to the systemic and pulmonary venous systems, which usually present clinically in a more indolent fashion either as a source of disease or as a source of confusion in image interpretation (1,2). Multi–detector row CT and volume rendering offer an unprecedented opportunity to study in vivo the anatomy of the systemic and pulmonary veins of the thorax. From a series of patients referred to us in routine clinical practice, we have collected a gallery of three-dimensional images that we shall use to describe the veins of the thorax. The anatomy is variable, but there are consistently recognized major vessels and tributaries.
This article describes use of multi–detector row CT and three-dimensional volume rendering for thoracic venous imaging and provides a comprehensive review of systemic and pulmonary venous anatomy by using these techniques as an interpretive aid. Specific topics discussed are the technique; the jugular veins; the subclavian and brachiocephalic veins; the internal and lateral thoracic veins; the superior and inferior venae cavae; the coronary sinus, the cardiac and pericardiophrenic veins, and vein grafts; the azygos, hemiazygos, and accessory hemiazygos veins; the intercostal veins; the pulmonary veins; and other thoracic veins.
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Technique
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There have been isolated reports of the use of multi–detector row CT for evaluation of the thoracic venous system (3–5). Our techniques and images reflect our experience, which is largely with a four–detector row scanner with an adaptive array design (Volume Zoom; Siemens Medical Solutions, Iselin, NJ) and a commercially available volume rendering workstation (3D Virtuoso; Siemens Medical Solutions). Optimal volume-rendered CT angiography requires attention to the three steps of data acquisition, processing, and display. Much of the chest wall and mediastinal systemic venous system is best seen in disease states rather than in health, and we have found that some of the best anatomic in vivo studies have been in patients with obstruction of the superior vena cava (SVC).
Acquisition
There is a wide range of clinical conditions for which thoracic venous studies are required, which include venous thrombosis or obstruction, pulmonary vein assessment for ablation, and arteriovenous malformation. Although preliminary low-dose nonenhanced studies have been recommended before CT angiography to establish z-axis coverage, we rarely find them necessary. Coverage is usually easily estimated from the topogram, and calcified lesions can usually be differentiated from the enhanced venous vasculature. Imaging in a caudal-to-cranial direction is useful for most thoracic veins, since any failure of breath holding will occur toward the thoracic inlet region and contrast artifact in the subclavian vessels is minimized. Z-axis coverage is at least from the thoracic inlet to the celiac axis, and on occasion, visualization of the liver and abdominal vasculature is of value (eg, with interrupted inferior vena cava, partial anomalous venous return, sequestration, or arteriovenous malformation with aortic supply).
In our experience, test bolus injection or bolus densitometry monitoring techniques are not required for consistent vessel enhancement. We use an empiric delay based on presumed circulation time and produce good venous enhancement with standard chest protocols and use of a power injector (eg, 30-second delay for a pulmonary embolism). Delays may be altered on the basis of the distance of the catheter from the venous structures, such as increased delays (on the order of 10 seconds) for lower extremity injections. For patients with decreased cardiac output, the time to peak enhancement will be delayed and 5–10 seconds is added to the contrast material injection. In cases of suspected aberrant anatomy, such as arteriovenous malformation, or those in which there is concern about differentiating between clot and inflow artifact, radiologist monitoring of the case and multiphase imaging may be directed and are easily achieved with multi–detector row CT. This course is decided by means of radiologist review and repeated scanning with an additional 15- to 20-second delay and limited coverage to minimize radiation dose. An 18- to 20-gauge catheter is placed in an antecubital vein in most cases. Smaller catheters, central access, and areas at risk for compartmental syndrome with contrast material extravasation mandate hand injection. For hand injections, the contrast peak is delayed, so the scanning delay is increased by 10–15 seconds depending on the volume of contrast material injected and patient size. We usually use a high iodine concentration (350 mg/mL) of a nonionic contrast agent (Omnipaque 350; Amersham Imaging, Princeton, NJ) at a moderate flow rate (2–3 mL/sec).
The use of multi–detector row CT allows both improved z-axis coverage with smaller collimation and increased z-axis resolution. Near-isotropic collimation (ie, when longitudinal resolution approximates in-plane resolution) is achieved, and the section sensitivity profile is optimized. Short gantry rotation times (500 msec) minimize pulsation artifact. Increased tube loading capacity allows multiphase imaging for congenital or acquired venous anomalies. One must be constantly mindful of radiation dose. Increased pitch with subsecond scanning as well as dose modulation by the machine based on patient geometry and absorption have decreased doses (6). There are also continued efforts to decrease the milliamperage without loss of diagnostic information. For pediatric imaging, multi–detector row CT has nearly eliminated the need for sedation. A sample protocol is provided in the Table.
Postprocessing and Display
By nature, venous structures tend to be tortuous, with variable branching patterns, and three-dimensional viewing is advantageous. Our data are sent to a volume rendering workstation. Interactive real-time clip plane editing of slabs of data with infinite planes and projections will effortlessly isolate the CT data to the vein of interest with the optimal imaging perspective. Unlike maximum intensity projection (MIP) or shaded surface display (SSD), volume rendering is a more computer-intensive process that uses more than just a portion of the data. Whereas MIP and SSD display data based on the maximum attenuation or an assigned threshold, respectively, volume rendering displays all of the attenuations and their spatial relationships and 100% of the data.
The entire Hounsfield spectrum of the vessel and its related structures is represented by a trapezoid histogram, which is a percentage-based classification of the attenuation composition of the voxels based on rays passed through the data set. Even voxels only partially filled with contrast material are represented and weighted accordingly. This graphical representation of the attenuation values can be manipulated through a range of parameters, which include width, center, opacity, brightness, and color. Color is assigned by ascribing it to a range of attenuation values. Depth cues are used, unlike in MIP.
Such postprocessing permits the vessels and their related structures to be shown to best effect. One can formulate a trapezoid for individual tissues to show volume images of bone, vessels, or airways, for example. Volume-rendered images often suffice in isolation, but the conventional two-dimensional data and other techniques such as MIP and cine scrolling can easily provide supplemental images when they are indicated. Small peripheral vessels are often better seen as an assimilation of sections in a volume slab rather than as their individual constituent sections (4,7,8).
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Jugular Veins
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Usually only small portions of the jugular vein are seen during thoracic imaging. The jugular vein drains the brain, face, and neck and enters the dorsal aspect of the brachiocephalic vein. The normal jugular veins are often markedly asymmetric. In cases of occlusion of the jugular vein, its large connection to veins of the upper chest wall can be appreciated (Fig 1).
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Figure 1. Anterior volume-rendered CT image shows collateral vessels of the anterior neck and chest wall that developed in a patient with jugular vein thrombosis (not shown). These collateral vessels drain through the external jugular, left subclavian, transthoracic, and intercostal channels to the left brachiocephalic vein. Arrow = central venous catheter.
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Subclavian and Brachiocephalic Veins
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The subclavian vein arises at the outer edge of the first rib as a continuation of the axillary vein (Fig 2). It joins the jugular vein behind the sternoclavicular joint to form the brachiocephalic (innominate) vein after passing under the clavicle. The left brachiocephalic vein is longer than the right and passes anterior to the ascending aortic arch to enter the SVC, whereas the right travels more vertically inferiorly behind the sternum to enter the SVC (Figs 3, 4).
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Figure 2a. Anterior (a) and inferior (b) volume-rendered CT images show the cephalic (thin solid arrow) and basilic (thick solid arrow) veins entering the axillary vein (open arrow), which continues centrally as the subclavian vein. The contrast material in the veins was assigned a color trapezoid.
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Figure 2b. Anterior (a) and inferior (b) volume-rendered CT images show the cephalic (thin solid arrow) and basilic (thick solid arrow) veins entering the axillary vein (open arrow), which continues centrally as the subclavian vein. The contrast material in the veins was assigned a color trapezoid.
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Figure 3a. (a) Anterior volume-rendered CT image shows the right (long solid arrow) and left (short solid arrow) brachiocephalic veins merging at the SVC (open arrow). (b) Anterior volume-rendered CT image shows the right brachiocephalic vein (solid arrow) joining the SVC (open arrow). (c) Anterior volume-rendered CT image shows the contrast material-enhanced left brachiocephalic vein (arrow) entering the SVC. (d) Anterior volume-rendered CT image shows the left brachiocephalic vein (long arrow) crossing the ascending aorta (short arrow).
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Figure 3b. (a) Anterior volume-rendered CT image shows the right (long solid arrow) and left (short solid arrow) brachiocephalic veins merging at the SVC (open arrow). (b) Anterior volume-rendered CT image shows the right brachiocephalic vein (solid arrow) joining the SVC (open arrow). (c) Anterior volume-rendered CT image shows the contrast material-enhanced left brachiocephalic vein (arrow) entering the SVC. (d) Anterior volume-rendered CT image shows the left brachiocephalic vein (long arrow) crossing the ascending aorta (short arrow).
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Figure 3c. (a) Anterior volume-rendered CT image shows the right (long solid arrow) and left (short solid arrow) brachiocephalic veins merging at the SVC (open arrow). (b) Anterior volume-rendered CT image shows the right brachiocephalic vein (solid arrow) joining the SVC (open arrow). (c) Anterior volume-rendered CT image shows the contrast material-enhanced left brachiocephalic vein (arrow) entering the SVC. (d) Anterior volume-rendered CT image shows the left brachiocephalic vein (long arrow) crossing the ascending aorta (short arrow).
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Figure 3d. (a) Anterior volume-rendered CT image shows the right (long solid arrow) and left (short solid arrow) brachiocephalic veins merging at the SVC (open arrow). (b) Anterior volume-rendered CT image shows the right brachiocephalic vein (solid arrow) joining the SVC (open arrow). (c) Anterior volume-rendered CT image shows the contrast material-enhanced left brachiocephalic vein (arrow) entering the SVC. (d) Anterior volume-rendered CT image shows the left brachiocephalic vein (long arrow) crossing the ascending aorta (short arrow).
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Figure 4a. (a) Anterior volume-rendered CT image obtained with color trapezoids applied to wire components shows a pacemaker in the left subclavian vein that extends through the vein and into the right side of the heart through the left brachiocephalic vein and SVC. The wire tips in the right atrium are seen (arrows). (b) Axial superior volume-rendered CT image shows the left brachiocephalic vein (long solid arrow) crossing the anterior mediastinum to enter the SVC (short solid arrow). Open arrow = aortic arch. Color trapezoids were applied. (c) Left lateral volume-rendered CT image shows the anteroposterior relationship of the left brachiocephalic vein (long arrow) and left subclavian artery (short arrow). (d) Left anterior oblique volume-rendered CT image shows a large unnamed anomalous branch (white arrow) of the left brachiocephalic vein (open arrow); the anomalous branch arises from the lateral aspect of the brachiocephalic vein and rejoins it more medially. Solid black arrow = left subclavian vein.
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Figure 4b. (a) Anterior volume-rendered CT image obtained with color trapezoids applied to wire components shows a pacemaker in the left subclavian vein that extends through the vein and into the right side of the heart through the left brachiocephalic vein and SVC. The wire tips in the right atrium are seen (arrows). (b) Axial superior volume-rendered CT image shows the left brachiocephalic vein (long solid arrow) crossing the anterior mediastinum to enter the SVC (short solid arrow). Open arrow = aortic arch. Color trapezoids were applied. (c) Left lateral volume-rendered CT image shows the anteroposterior relationship of the left brachiocephalic vein (long arrow) and left subclavian artery (short arrow). (d) Left anterior oblique volume-rendered CT image shows a large unnamed anomalous branch (white arrow) of the left brachiocephalic vein (open arrow); the anomalous branch arises from the lateral aspect of the brachiocephalic vein and rejoins it more medially. Solid black arrow = left subclavian vein.
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Figure 4c. (a) Anterior volume-rendered CT image obtained with color trapezoids applied to wire components shows a pacemaker in the left subclavian vein that extends through the vein and into the right side of the heart through the left brachiocephalic vein and SVC. The wire tips in the right atrium are seen (arrows). (b) Axial superior volume-rendered CT image shows the left brachiocephalic vein (long solid arrow) crossing the anterior mediastinum to enter the SVC (short solid arrow). Open arrow = aortic arch. Color trapezoids were applied. (c) Left lateral volume-rendered CT image shows the anteroposterior relationship of the left brachiocephalic vein (long arrow) and left subclavian artery (short arrow). (d) Left anterior oblique volume-rendered CT image shows a large unnamed anomalous branch (white arrow) of the left brachiocephalic vein (open arrow); the anomalous branch arises from the lateral aspect of the brachiocephalic vein and rejoins it more medially. Solid black arrow = left subclavian vein.
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Figure 4d. (a) Anterior volume-rendered CT image obtained with color trapezoids applied to wire components shows a pacemaker in the left subclavian vein that extends through the vein and into the right side of the heart through the left brachiocephalic vein and SVC. The wire tips in the right atrium are seen (arrows). (b) Axial superior volume-rendered CT image shows the left brachiocephalic vein (long solid arrow) crossing the anterior mediastinum to enter the SVC (short solid arrow). Open arrow = aortic arch. Color trapezoids were applied. (c) Left lateral volume-rendered CT image shows the anteroposterior relationship of the left brachiocephalic vein (long arrow) and left subclavian artery (short arrow). (d) Left anterior oblique volume-rendered CT image shows a large unnamed anomalous branch (white arrow) of the left brachiocephalic vein (open arrow); the anomalous branch arises from the lateral aspect of the brachiocephalic vein and rejoins it more medially. Solid black arrow = left subclavian vein.
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Brachiocephalic vein tributaries include the vertebral vein, internal mammary vein, inferior thyroid vein, right first intercostal vein, and pericardiophrenic veins.
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Internal and Lateral Thoracic Veins
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The internal mammary (thoracic) veins drain the anterior intercostal veins and some abdominal veins. They lie medial to the internal mammary artery with a course along the border of the sternum to the brachiocephalic veins and serve as a marker for the internal mammary lymph nodes (Fig 5a, 5b). The insertion of the right is more proximal than that of the left. There are multiple connections between the right and left internal mammary veins behind the sternum. The orifice of the left internal mammary vein is adjacent to the orifice of the left highest intercostal vein in the left brachiocephalic vein. The lateral thoracic vein enters the subclavian vein just lateral to the first rib and lateral to both internal mammary veins and aids drainage of the lateral chest wall (Fig 5c).
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Figure 5a. (a) Anterior volume-rendered CT image shows the internal thoracic veins (long arrows) in a patient with obstruction of the left brachiocephalic vein and SVC. Note the relationship of the pericardiophrenic vein (short arrow). (b) Posterior volume-rendered CT image of the sternum shows the internal thoracic veins (arrows) as they course medial to the costochondral junctions. (c) Anterior volume-rendered CT image shows the lateral thoracic vein (large solid arrow) entering the lateral subclavian vein (open arrow). A central venous catheter (small solid arrow) is seen entering the SVC.
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Figure 5b. (a) Anterior volume-rendered CT image shows the internal thoracic veins (long arrows) in a patient with obstruction of the left brachiocephalic vein and SVC. Note the relationship of the pericardiophrenic vein (short arrow). (b) Posterior volume-rendered CT image of the sternum shows the internal thoracic veins (arrows) as they course medial to the costochondral junctions. (c) Anterior volume-rendered CT image shows the lateral thoracic vein (large solid arrow) entering the lateral subclavian vein (open arrow). A central venous catheter (small solid arrow) is seen entering the SVC.
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Figure 5c. (a) Anterior volume-rendered CT image shows the internal thoracic veins (long arrows) in a patient with obstruction of the left brachiocephalic vein and SVC. Note the relationship of the pericardiophrenic vein (short arrow). (b) Posterior volume-rendered CT image of the sternum shows the internal thoracic veins (arrows) as they course medial to the costochondral junctions. (c) Anterior volume-rendered CT image shows the lateral thoracic vein (large solid arrow) entering the lateral subclavian vein (open arrow). A central venous catheter (small solid arrow) is seen entering the SVC.
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Superior and Inferior Venae Cavae
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The SVC is in contact with the right lung, pleura, trachea, right pulmonary hilum, and aorta. The surface marking of the SVC is at the first right costal cartilage, and its origin is defined at the confluence of the brachiocephalic veins. It passes behind the right sternal margin and enters the pericardium at the second costal cartilage to enterthe right atrium at the level of the third costal car-tilage (Fig 6). The SVC receives the azygos vein just above the right upper lobe bronchus and descends anterior to the right main-stem bronchus, and the left brachiocephalic vein joins it by crossing anterior to the aortic arch.
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Figure 6a. (a) Right anterior oblique volume-rendered CT image shows an enhanced SVC (large solid arrow) coursing behind the ascending aortic arch (small solid arrow) to enter the right atrium (open arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids. Color trapezoids were assigned to the SVC (large arrow), which can be seen curving anterior to the right pulmonary hilum (small arrow). (c) Superior volume-rendered CT image obtained with airway trapezoids shows a view down the thoracic inlet. Color trapezoids were applied to the vasculature, and the SVC (large arrow) is seen anterior to the carina (small arrow). (d) Left posterior oblique volume-rendered CT image shows the inferior vena cava (large arrow) entering the right atrium (small arrow).
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Figure 6b. (a) Right anterior oblique volume-rendered CT image shows an enhanced SVC (large solid arrow) coursing behind the ascending aortic arch (small solid arrow) to enter the right atrium (open arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids. Color trapezoids were assigned to the SVC (large arrow), which can be seen curving anterior to the right pulmonary hilum (small arrow). (c) Superior volume-rendered CT image obtained with airway trapezoids shows a view down the thoracic inlet. Color trapezoids were applied to the vasculature, and the SVC (large arrow) is seen anterior to the carina (small arrow). (d) Left posterior oblique volume-rendered CT image shows the inferior vena cava (large arrow) entering the right atrium (small arrow).
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Figure 6c. (a) Right anterior oblique volume-rendered CT image shows an enhanced SVC (large solid arrow) coursing behind the ascending aortic arch (small solid arrow) to enter the right atrium (open arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids. Color trapezoids were assigned to the SVC (large arrow), which can be seen curving anterior to the right pulmonary hilum (small arrow). (c) Superior volume-rendered CT image obtained with airway trapezoids shows a view down the thoracic inlet. Color trapezoids were applied to the vasculature, and the SVC (large arrow) is seen anterior to the carina (small arrow). (d) Left posterior oblique volume-rendered CT image shows the inferior vena cava (large arrow) entering the right atrium (small arrow).
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Figure 6d. (a) Right anterior oblique volume-rendered CT image shows an enhanced SVC (large solid arrow) coursing behind the ascending aortic arch (small solid arrow) to enter the right atrium (open arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids. Color trapezoids were assigned to the SVC (large arrow), which can be seen curving anterior to the right pulmonary hilum (small arrow). (c) Superior volume-rendered CT image obtained with airway trapezoids shows a view down the thoracic inlet. Color trapezoids were applied to the vasculature, and the SVC (large arrow) is seen anterior to the carina (small arrow). (d) Left posterior oblique volume-rendered CT image shows the inferior vena cava (large arrow) entering the right atrium (small arrow).
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The inferior vena cava pierces the diaphragm at T8 through the vena caval foramen in the central tendon. The phrenic nerve and the vena cava are separated by the fibrous pericardium in the mediastinum (Fig 6d).
A persistent left SVC drains through the oblique vein of Marshall behind the left atrium into the coronary sinus of the right atrium and receives the left subclavian and left jugular veins. This phenomenon occurs in 0.3% of healthy persons and in 4.3% of patients with congenital heart disease (9). It most commonly comes to the attention of the radiologist when there is concern regarding placement of a left-sided central venous catheter.
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Coronary Sinus, Cardiac and Pericardiophrenic Veins, and Vein Grafts
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The coronary sinus drains most of the coronary veins. It runs in the posterior atrioventricular groove and terminates at the right atrium near the inferior vena cava (Fig 7a, 7b). In the anterior interventricular groove, the great cardiac vein runs alongside the left anterior descending coronary artery. It continues as the coronary sinus in the atrioventricular groove. The small cardiac veins run in the anterior interventricular groove and the middle cardiac vein runs in the posterior interventricular groove to join the coronary sinus (Fig 7c).
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Figure 7a. (a) Left lateral volume-rendered CT image of the heart shows the coronary sinus (long solid arrow) fed by a small cardiac vein (short solid arrow). The left anterior descending coronary artery (open arrow) is noted. (b) Posterior volume-rendered CT image shows the coronary sinus (long straight solid arrow) entering the right atrium (open arrow). The right coronary artery (short straight solid arrow) and a branch tributary of the small cardiac vein (curved arrow) are also seen. (c) Inferior volume-rendered CT image shows the middle cardiac vein (short solid arrow) in the posterior interventricular groove. The coronary sinus (long solid arrow) and right coronary artery (open arrow) are also seen.
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Figure 7b. (a) Left lateral volume-rendered CT image of the heart shows the coronary sinus (long solid arrow) fed by a small cardiac vein (short solid arrow). The left anterior descending coronary artery (open arrow) is noted. (b) Posterior volume-rendered CT image shows the coronary sinus (long straight solid arrow) entering the right atrium (open arrow). The right coronary artery (short straight solid arrow) and a branch tributary of the small cardiac vein (curved arrow) are also seen. (c) Inferior volume-rendered CT image shows the middle cardiac vein (short solid arrow) in the posterior interventricular groove. The coronary sinus (long solid arrow) and right coronary artery (open arrow) are also seen.
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Figure 7c. (a) Left lateral volume-rendered CT image of the heart shows the coronary sinus (long solid arrow) fed by a small cardiac vein (short solid arrow). The left anterior descending coronary artery (open arrow) is noted. (b) Posterior volume-rendered CT image shows the coronary sinus (long straight solid arrow) entering the right atrium (open arrow). The right coronary artery (short straight solid arrow) and a branch tributary of the small cardiac vein (curved arrow) are also seen. (c) Inferior volume-rendered CT image shows the middle cardiac vein (short solid arrow) in the posterior interventricular groove. The coronary sinus (long solid arrow) and right coronary artery (open arrow) are also seen.
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Drainage of the pericardium, pleura, and diaphragm is provided by the pericardiophrenic veins, which travel with the phrenic nerve between the mediastinal pleura and the pericardium. These veins may be single or multiple and drain into the left superior intercostal vein or into the brachiocephalic veins opposite the jugular vein. They anastomose with the inferior phrenic veins, which drain to the inferior vena cava or renal vein, and help complete a network that provides alternate pathways for blood return if the SVC is obstructed. The left pericardiophrenic vein may join the left internal mammary vein in its last few centimeters or the left highest intercostal vein. The left pericardiophrenic vein will enter the left superior intercostal, internal mammary, or thymic vein (10) (Fig 8).
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Figure 8a. (a) Anterior volume-rendered CT image shows the pericardiophrenic veins (long arrows) draped around the heart. The thymic vein plexus and intermammary vein collateral vessels (short arrow) are also seen. (b) Left lateral volume-rendered CT image shows the two left pericardiophrenic veins (white arrows) on the surface of the heart. The internal mammary veins (open arrow) and left superior intercostal vein (solid black arrow) are also seen. The patient had obstruction of the left brachiocephalic vein and SVC. (c) Right anterior oblique volume-rendered CT image shows the pericardiophrenic vein (long white arrow) along the right border of the heart (view equivalent to placement of the patient in the right anterior oblique position). The connection to the phrenic vein (short white arrow), the right internal mammary vein (straight black arrow), and an unnamed collateral vessel (curved arrow) are also seen. (d) Superior volume-rendered CT image shows the two left pericardiophrenic veins (white arrow) along the left border of the heart. The superior intercostal vein (curved arrow) and intermammary plexus (straight black arrow) are also seen. (e) Inferior MIP CT image shows the phrenic veins (large arrows) with a "hot spot" of contrast material in the quadrate lobe (segment 4b) (small arrow), which is related to obstruction of the SVC. The exact cause of the "hot" quadrate lobe is unclear, but it is thought to be related to collateral flow through the liver. (f) Inferior volume-rendered CT image of the right hemidiaphragm shows the numerous phrenic veins on its surface (long arrows). A pericardial effusion is noted (short arrow).
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Figure 8b. (a) Anterior volume-rendered CT image shows the pericardiophrenic veins (long arrows) draped around the heart. The thymic vein plexus and intermammary vein collateral vessels (short arrow) are also seen. (b) Left lateral volume-rendered CT image shows the two left pericardiophrenic veins (white arrows) on the surface of the heart. The internal mammary veins (open arrow) and left superior intercostal vein (solid black arrow) are also seen. The patient had obstruction of the left brachiocephalic vein and SVC. (c) Right anterior oblique volume-rendered CT image shows the pericardiophrenic vein (long white arrow) along the right border of the heart (view equivalent to placement of the patient in the right anterior oblique position). The connection to the phrenic vein (short white arrow), the right internal mammary vein (straight black arrow), and an unnamed collateral vessel (curved arrow) are also seen. (d) Superior volume-rendered CT image shows the two left pericardiophrenic veins (white arrow) along the left border of the heart. The superior intercostal vein (curved arrow) and intermammary plexus (straight black arrow) are also seen. (e) Inferior MIP CT image shows the phrenic veins (large arrows) with a "hot spot" of contrast material in the quadrate lobe (segment 4b) (small arrow), which is related to obstruction of the SVC. The exact cause of the "hot" quadrate lobe is unclear, but it is thought to be related to collateral flow through the liver. (f) Inferior volume-rendered CT image of the right hemidiaphragm shows the numerous phrenic veins on its surface (long arrows). A pericardial effusion is noted (short arrow).
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Figure 8c. (a) Anterior volume-rendered CT image shows the pericardiophrenic veins (long arrows) draped around the heart. The thymic vein plexus and intermammary vein collateral vessels (short arrow) are also seen. (b) Left lateral volume-rendered CT image shows the two left pericardiophrenic veins (white arrows) on the surface of the heart. The internal mammary veins (open arrow) and left superior intercostal vein (solid black arrow) are also seen. The patient had obstruction of the left brachiocephalic vein and SVC. (c) Right anterior oblique volume-rendered CT image shows the pericardiophrenic vein (long white arrow) along the right border of the heart (view equivalent to placement of the patient in the right anterior oblique position). The connection to the phrenic vein (short white arrow), the right internal mammary vein (straight black arrow), and an unnamed collateral vessel (curved arrow) are also seen. (d) Superior volume-rendered CT image shows the two left pericardiophrenic veins (white arrow) along the left border of the heart. The superior intercostal vein (curved arrow) and intermammary plexus (straight black arrow) are also seen. (e) Inferior MIP CT image shows the phrenic veins (large arrows) with a "hot spot" of contrast material in the quadrate lobe (segment 4b) (small arrow), which is related to obstruction of the SVC. The exact cause of the "hot" quadrate lobe is unclear, but it is thought to be related to collateral flow through the liver. (f) Inferior volume-rendered CT image of the right hemidiaphragm shows the numerous phrenic veins on its surface (long arrows). A pericardial effusion is noted (short arrow).
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Figure 8d. (a) Anterior volume-rendered CT image shows the pericardiophrenic veins (long arrows) draped around the heart. The thymic vein plexus and intermammary vein collateral vessels (short arrow) are also seen. (b) Left lateral volume-rendered CT image shows the two left pericardiophrenic veins (white arrows) on the surface of the heart. The internal mammary veins (open arrow) and left superior intercostal vein (solid black arrow) are also seen. The patient had obstruction of the left brachiocephalic vein and SVC. (c) Right anterior oblique volume-rendered CT image shows the pericardiophrenic vein (long white arrow) along the right border of the heart (view equivalent to placement of the patient in the right anterior oblique position). The connection to the phrenic vein (short white arrow), the right internal mammary vein (straight black arrow), and an unnamed collateral vessel (curved arrow) are also seen. (d) Superior volume-rendered CT image shows the two left pericardiophrenic veins (white arrow) along the left border of the heart. The superior intercostal vein (curved arrow) and intermammary plexus (straight black arrow) are also seen. (e) Inferior MIP CT image shows the phrenic veins (large arrows) with a "hot spot" of contrast material in the quadrate lobe (segment 4b) (small arrow), which is related to obstruction of the SVC. The exact cause of the "hot" quadrate lobe is unclear, but it is thought to be related to collateral flow through the liver. (f) Inferior volume-rendered CT image of the right hemidiaphragm shows the numerous phrenic veins on its surface (long arrows). A pericardial effusion is noted (short arrow).
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Figure 8e. (a) Anterior volume-rendered CT image shows the pericardiophrenic veins (long arrows) draped around the heart. The thymic vein plexus and intermammary vein collateral vessels (short arrow) are also seen. (b) Left lateral volume-rendered CT image shows the two left pericardiophrenic veins (white arrows) on the surface of the heart. The internal mammary veins (open arrow) and left superior intercostal vein (solid black arrow) are also seen. The patient had obstruction of the left brachiocephalic vein and SVC. (c) Right anterior oblique volume-rendered CT image shows the pericardiophrenic vein (long white arrow) along the right border of the heart (view equivalent to placement of the patient in the right anterior oblique position). The connection to the phrenic vein (short white arrow), the right internal mammary vein (straight black arrow), and an unnamed collateral vessel (curved arrow) are also seen. (d) Superior volume-rendered CT image shows the two left pericardiophrenic veins (white arrow) along the left border of the heart. The superior intercostal vein (curved arrow) and intermammary plexus (straight black arrow) are also seen. (e) Inferior MIP CT image shows the phrenic veins (large arrows) with a "hot spot" of contrast material in the quadrate lobe (segment 4b) (small arrow), which is related to obstruction of the SVC. The exact cause of the "hot" quadrate lobe is unclear, but it is thought to be related to collateral flow through the liver. (f) Inferior volume-rendered CT image of the right hemidiaphragm shows the numerous phrenic veins on its surface (long arrows). A pericardial effusion is noted (short arrow).
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Figure 8f. (a) Anterior volume-rendered CT image shows the pericardiophrenic veins (long arrows) draped around the heart. The thymic vein plexus and intermammary vein collateral vessels (short arrow) are also seen. (b) Left lateral volume-rendered CT image shows the two left pericardiophrenic veins (white arrows) on the surface of the heart. The internal mammary veins (open arrow) and left superior intercostal vein (solid black arrow) are also seen. The patient had obstruction of the left brachiocephalic vein and SVC. (c) Right anterior oblique volume-rendered CT image shows the pericardiophrenic vein (long white arrow) along the right border of the heart (view equivalent to placement of the patient in the right anterior oblique position). The connection to the phrenic vein (short white arrow), the right internal mammary vein (straight black arrow), and an unnamed collateral vessel (curved arrow) are also seen. (d) Superior volume-rendered CT image shows the two left pericardiophrenic veins (white arrow) along the left border of the heart. The superior intercostal vein (curved arrow) and intermammary plexus (straight black arrow) are also seen. (e) Inferior MIP CT image shows the phrenic veins (large arrows) with a "hot spot" of contrast material in the quadrate lobe (segment 4b) (small arrow), which is related to obstruction of the SVC. The exact cause of the "hot" quadrate lobe is unclear, but it is thought to be related to collateral flow through the liver. (f) Inferior volume-rendered CT image of the right hemidiaphragm shows the numerous phrenic veins on its surface (long arrows). A pericardial effusion is noted (short arrow).
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With improved imaging quality and rendering techniques, we are seeing saphenous vein grafts placed for coronary artery disease. Their location and course are determined by the sites of treated coronary artery stenoses (Fig 9).
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Figure 9. Right anterior oblique volume-rendered CT image (equivalent to placement of the patient in the right anterior oblique position) shows a saphenous vein bypass graft (arrow) of the right coronary artery. The graft extends from the ascending aorta to an anastomosis in the proximal right coronary artery.
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Azygos, Hemiazygos, and Accessory Hemiazygos Veins
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The azygos, hemiazygos, and accessory hemiazygos veins are formed from what remains of the posterior cardinal veins. As the continuation of the ascending right lumbar vein, the azygos vein arises where the right subcostal vein joins the ascending lumbar vein and goes through the aortic opening of the diaphragm along with the aorta, through the right crus of the diaphragm, and continues cephalad on the vertebral bodies posterior to the esophagus, to the right of the thoracic duct and anterior to the right intercostal arteries. Superiorly, it forms a cranial arch at the right side of the carina over the root (hilum) of the right lung at T4, the right upper lobe bronchus, and the truncus of the right pulmonary artery behind the sternal angle opposite the second right costal cartilage. It enters the posterior aspect of the SVC just above its entry into the fibrous pericardium (Fig 10a–10c).
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Figure 10a. (a) Right lateral volume-rendered CT image shows the azygos vein (large arrow) arching anteriorly to the SVC (small arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids shows the azygos vein (solid arrow) arching anteriorly toward the SVC and lateral to the trachea (open arrow). (c) Right lateral volume-rendered CT image obtained with airway trapezoids shows the relationship of the azygos vein (long arrow) to the right hilum (short arrow). (d) Anterior volume-rendered CT image shows the accessory hemiazygos vein (large arrow) behind the aorta (small arrow). (e) Left anterior oblique volume-rendered CT image (equivalent to placement of the patient in the left anterior oblique position) shows the accessory hemiazygos vein (large white arrow) fed by multiple intercostal veins (small white arrows). Black arrow = third rib.
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Figure 10b. (a) Right lateral volume-rendered CT image shows the azygos vein (large arrow) arching anteriorly to the SVC (small arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids shows the azygos vein (solid arrow) arching anteriorly toward the SVC and lateral to the trachea (open arrow). (c) Right lateral volume-rendered CT image obtained with airway trapezoids shows the relationship of the azygos vein (long arrow) to the right hilum (short arrow). (d) Anterior volume-rendered CT image shows the accessory hemiazygos vein (large arrow) behind the aorta (small arrow). (e) Left anterior oblique volume-rendered CT image (equivalent to placement of the patient in the left anterior oblique position) shows the accessory hemiazygos vein (large white arrow) fed by multiple intercostal veins (small white arrows). Black arrow = third rib.
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Figure 10c. (a) Right lateral volume-rendered CT image shows the azygos vein (large arrow) arching anteriorly to the SVC (small arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids shows the azygos vein (solid arrow) arching anteriorly toward the SVC and lateral to the trachea (open arrow). (c) Right lateral volume-rendered CT image obtained with airway trapezoids shows the relationship of the azygos vein (long arrow) to the right hilum (short arrow). (d) Anterior volume-rendered CT image shows the accessory hemiazygos vein (large arrow) behind the aorta (small arrow). (e) Left anterior oblique volume-rendered CT image (equivalent to placement of the patient in the left anterior oblique position) shows the accessory hemiazygos vein (large white arrow) fed by multiple intercostal veins (small white arrows). Black arrow = third rib.
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Figure 10d. (a) Right lateral volume-rendered CT image shows the azygos vein (large arrow) arching anteriorly to the SVC (small arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids shows the azygos vein (solid arrow) arching anteriorly toward the SVC and lateral to the trachea (open arrow). (c) Right lateral volume-rendered CT image obtained with airway trapezoids shows the relationship of the azygos vein (long arrow) to the right hilum (short arrow). (d) Anterior volume-rendered CT image shows the accessory hemiazygos vein (large arrow) behind the aorta (small arrow). (e) Left anterior oblique volume-rendered CT image (equivalent to placement of the patient in the left anterior oblique position) shows the accessory hemiazygos vein (large white arrow) fed by multiple intercostal veins (small white arrows). Black arrow = third rib.
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Figure 10e. (a) Right lateral volume-rendered CT image shows the azygos vein (large arrow) arching anteriorly to the SVC (small arrow). (b) Left lateral volume-rendered CT image obtained with airway trapezoids shows the azygos vein (solid arrow) arching anteriorly toward the SVC and lateral to the trachea (open arrow). (c) Right lateral volume-rendered CT image obtained with airway trapezoids shows the relationship of the azygos vein (long arrow) to the right hilum (short arrow). (d) Anterior volume-rendered CT image shows the accessory hemiazygos vein (large arrow) behind the aorta (small arrow). (e) Left anterior oblique volume-rendered CT image (equivalent to placement of the patient in the left anterior oblique position) shows the accessory hemiazygos vein (large white arrow) fed by multiple intercostal veins (small white arrows). Black arrow = third rib.
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Azygos vein tributaries are as follows: the right intercostal veins including the superior or supreme intercostal veins into the posterior arch and lower eight posterior intercostal veins; the hemiazygos and accessory hemiazygos veins; and the esophageal veins, mediastinal branches, and bronchial branches.
At T8-9, two hemiazygos veins join the azygos vein posterior to the aorta, although they may rarely travel anterior to it. The hemiazygos veins course longitudinally on the left side of the thoracic vertebral bodies and are highly variable in their anatomy. The superior vein is named the accessory hemiazygos vein, and the inferior one is the hemiazygos vein (Fig 10d, 10e).
Tributaries of the hemiazygos and accessory hemiazygos veins are as follows: the posterior intercostal veins; the left ascending lumbar, left renal, and left subcostal veins; the intercostal, bronchial, esophageal, and mediastinal veins; and the accessory hemiazygos and azygos veins.
By forming a connection between the superior and inferior venae cavae, the azygos and hemiazygos systems are a vital collateral pathway in cases where these major pathways of venous return are obstructed. Flow direction will depend on the level of obstruction. There are marked variations in the azygos and hemiazygos systems. With congenital interruption of the inferior vena cava between the kidneys and the liver, the azygos vein takes over drainage through the aortic hiatus.
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Intercostal Veins
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Intercostal veins may be divided into the supreme or highest intercostal veins, superior intercostal veins, and standard intercostal veins. In each intercostal space are one posterior and two anterior intercostal veins. The anterior veins drain into the musculophrenic and internal mammary veins. The lower eight posterior intercostal veins drain into the azygos vein on the right and the accessory hemiazygos and hemiazygos veins on the left. The first intercostal space is drained by the supreme intercostal vein, which drains into an ipsilateral vertebral or brachiocephalic vein (Fig 11a–11c). The second, third, and possibly fourth veins drain into a common vessel, the superior intercostal (highest intercostal) vein, which drains into the brachiocephalic veins. The left superior intercostal vein usually receives the accessory hemiazygos vein. This is sometimes termed the aortic nipple (11) due to a focal lateral contour opacity seen on anterior radiographs of the aortic arch (Fig 11d, 11e).
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Figure 11a. (a) Right anterior oblique volume-rendered CT image shows the intercostal vein tributaries (short arrows) of the azygos vein (long arrow). (b) Anterior oblique volume-rendered CT image shows the intercostal veins (short solid arrows) connecting the lateral thoracic vein (long solid arrow) and the azygos vein (open arrow). (c) Posterior volume-rendered CT image of the anterior chest wall shows the intercostal veins (short arrow) coursing medially to the internal thoracic vein (long arrow). (d) Axial superior two-dimensional CT image shows the left superior intercostal vein (straight white arrow) extending around the aortic arch (curved arrow). The left brachiocephalic vein (large black arrow) and accessory hemiazygos vein (small black arrow) are also seen. (e) Left lateral volume-rendered CT image shows the superior intercostal vein (large straight solid arrow) extending around the aortic arch as the aortic nipple. The internal mammary (curved arrow), pericardiophrenic (medium-sized straight solid arrow), phrenic (small straight solid arrow), and accessory hemiazygos (open arrow) veins are also seen. The patient had an obstructive thrombus in the left brachiocephalic vein and SVC.
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Figure 11b. (a) Right anterior oblique volume-rendered CT image shows the intercostal vein tributaries (short arrows) of the azygos vein (long arrow). (b) Anterior oblique volume-rendered CT image shows the intercostal veins (short solid arrows) connecting the lateral thoracic vein (long solid arrow) and the azygos vein (open arrow). (c) Posterior volume-rendered CT image of the anterior chest wall shows the intercostal veins (short arrow) coursing medially to the internal thoracic vein (long arrow). (d) Axial superior two-dimensional CT image shows the left superior intercostal vein (straight white arrow) extending around the aortic arch (curved arrow). The left brachiocephalic vein (large black arrow) and accessory hemiazygos vein (small black arrow) are also seen. (e) Left lateral volume-rendered CT image shows the superior intercostal vein (large straight solid arrow) extending around the aortic arch as the aortic nipple. The internal mammary (curved arrow), pericardiophrenic (medium-sized straight solid arrow), phrenic (small straight solid arrow), and accessory hemiazygos (open arrow) veins are also seen. The patient had an obstructive thrombus in the left brachiocephalic vein and SVC.
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Figure 11c. (a) Right anterior oblique volume-rendered CT image shows the intercostal vein tributaries (short arrows) of the azygos vein (long arrow). (b) Anterior oblique volume-rendered CT image shows the intercostal veins (short solid arrows) connecting the lateral thoracic vein (long solid arrow) and the azygos vein (open arrow). (c) Posterior volume-rendered CT image of the anterior chest wall shows the intercostal veins (short arrow) coursing medially to the internal thoracic vein (long arrow). (d) Axial superior two-dimensional CT image shows the left superior intercostal vein (straight white arrow) extending around the aortic arch (curved arrow). The left brachiocephalic vein (large black arrow) and accessory hemiazygos vein (small black arrow) are also seen. (e) Left lateral volume-rendered CT image shows the superior intercostal vein (large straight solid arrow) extending around the aortic arch as the aortic nipple. The internal mammary (curved arrow), pericardiophrenic (medium-sized straight solid arrow), phrenic (small straight solid arrow), and accessory hemiazygos (open arrow) veins are also seen. The patient had an obstructive thrombus in the left brachiocephalic vein and SVC.
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Figure 11d. (a) Right anterior oblique volume-rendered CT image shows the intercostal vein tributaries (short arrows) of the azygos vein (long arrow). (b) Anterior oblique volume-rendered CT image shows the intercostal veins (short solid arrows) connecting the lateral thoracic vein (long solid arrow) and the azygos vein (open arrow). (c) Posterior volume-rendered CT image of the anterior chest wall shows the intercostal veins (short arrow) coursing medially to the internal thoracic vein (long arrow). (d) Axial superior two-dimensional CT image shows the left superior intercostal vein (straight white arrow) extending around the aortic arch (curved arrow). The left brachiocephalic vein (large black arrow) and accessory hemiazygos vein (small black arrow) are also seen. (e) Left lateral volume-rendered CT image shows the superior intercostal vein (large straight solid arrow) extending around the aortic arch as the aortic nipple. The internal mammary (curved arrow), pericardiophrenic (medium-sized straight solid arrow), phrenic (small straight solid arrow), and accessory hemiazygos (open arrow) veins are also seen. The patient had an obstructive thrombus in the left brachiocephalic vein and SVC.
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Figure 11e. (a) Right anterior oblique volume-rendered CT image shows the intercostal vein tributaries (short arrows) of the azygos vein (long arrow). (b) Anterior oblique volume-rendered CT image shows the intercostal veins (short solid arrows) connecting the lateral thoracic vein (long solid arrow) and the azygos vein (open arrow). (c) Posterior volume-rendered CT image of the anterior chest wall shows the intercostal veins (short arrow) coursing medially to the internal thoracic vein (long arrow). (d) Axial superior two-dimensional CT image shows the left superior intercostal vein (straight white arrow) extending around the aortic arch (curved arrow). The left brachiocephalic vein (large black arrow) and accessory hemiazygos vein (small black arrow) are also seen. (e) Left lateral volume-rendered CT image shows the superior intercostal vein (large straight solid arrow) extending around the aortic arch as the aortic nipple. The internal mammary (curved arrow), pericardiophrenic (medium-sized straight solid arrow), phrenic (small straight solid arrow), and accessory hemiazygos (open arrow) veins are also seen. The patient had an obstructive thrombus in the left brachiocephalic vein and SVC.
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Pulmonary Veins
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During embryonic development, two pulmonary veins from each lung unite as a single common pulmonary vein to enter the left auricle. As this common pulmonary vein and the right and left pulmonary veins are assumed into the developing left ventricle, one is left with four individual pulmonary veins, but variations in the absorptive process can lead to variations in the number, site, and branching pattern of pulmonary vein assignments. The pulmonary veins do not closely follow the bronchi, and they run in intersegmental septa. They drain the lungs and enter the left atrium from superior and inferior to the oblique fissure on each side. The portion of the left atrium defined by the boundaries of the pulmonary veins is the anterior wall of the oblique pericardial sinus, which is separated from the esophagus by the fibrous pericardium (Figs 12, 13).
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Figure 13a. (a) Left anterior oblique volume-rendered CT image shows the superior and inferior pulmonary veins (short straight arrows) draining medially under the main pulmonary artery (long straight arrow) and aortic arch (curved arrow). (b) Right lateral volume-rendered CT image shows the right superior and inferior pulmonary veins (short arrows) behind the SVC (long arrow). (c) Posterior volume-rendered CT image shows the pulmonary veins (thick straight arrows) entering the left atrium (curved arrow). Note the relationship to the pulmonary arteries (thin straight arrows). (d) Volume-rendered CT image obtained from the patient’s right side with airway and color trapezoids shows the superior and inferior pulmonary veins (white arrows) anterior and inferior to the left main-stem bronchus (black arrow). (e) Volume-rendered CT image obtained from the patient’s left side with airway and color trapezoids shows the superior and inferior pulmonary veins (short solid arrows) and their relationship to the SVC (open arrow), right upper lobe bronchus (long solid arrow), and right lower lobe bronchus (arrowhead).
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Figure 13b. (a) Left anterior oblique volume-rendered CT image shows the superior and inferior pulmonary veins (short straight arrows) draining medially under the main pulmonary artery (long straight arrow) and aortic arch (curved arrow). (b) Right lateral volume-rendered CT image shows the right superior and inferior pulmonary veins (short arrows) behind the SVC (long arrow). (c) Posterior volume-rendered CT image shows the pulmonary veins (thick straight arrows) entering the left atrium (curved arrow). Note the relationship to the pulmonary arteries (thin straight arrows). (d) Volume-rendered CT image obtained from the patient’s right side with airway and color trapezoids shows the superior and inferior pulmonary veins (white arrows) anterior and inferior to the left main-stem bronchus (black arrow). (e) Volume-rendered CT image obtained from the patient’s left side with airway and color trapezoids shows the superior and inferior pulmonary veins (short solid arrows) and their relationship to the SVC (open arrow), right upper lobe bronchus (long solid arrow), and right lower lobe bronchus (arrowhead).
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Figure 13c. (a) Left anterior oblique volume-rendered CT image shows the superior and inferior pulmonary veins (short straight arrows) draining medially under the main pulmonary artery (long straight arrow) and aortic arch (curved arrow). (b) Right lateral volume-rendered CT image shows the right superior and inferior pulmonary veins (short arrows) behind the SVC (long arrow). (c) Posterior volume-rendered CT image shows the pulmonary veins (thick straight arrows) entering the left atrium (curved arrow). Note the relationship to the pulmonary arteries (thin straight arrows). (d) Volume-rendered CT image obtained from the patient’s right side with airway and color trapezoids shows the superior and inferior pulmonary veins (white arrows) anterior and inferior to the left main-stem bronchus (black arrow). (e) Volume-rendered CT image obtained from the patient’s left side with airway and color trapezoids shows the superior and inferior pulmonary veins (short solid arrows) and their relationship to the SVC (open arrow), right upper lobe bronchus (long solid arrow), and right lower lobe bronchus (arrowhead).
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Figure 13d. (a) Left anterior oblique volume-rendered CT image shows the superior and inferior pulmonary veins (short straight arrows) draining medially under the main pulmonary artery (long straight arrow) and aortic arch (curved arrow). (b) Right lateral volume-rendered CT image shows the right superior and inferior pulmonary veins (short arrows) behind the SVC (long arrow). (c) Posterior volume-rendered CT image shows the pulmonary veins (thick straight arrows) entering the left atrium (curved arrow). Note the relationship to the pulmonary arteries (thin straight arrows). (d) Volume-rendered CT image obtained from the patient’s right side with airway and color trapezoids shows the superior and inferior pulmonary veins (white arrows) anterior and inferior to the left main-stem bronchus (black arrow). (e) Volume-rendered CT image obtained from the patient’s left side with airway and color trapezoids shows the superior and inferior pulmonary veins (short solid arrows) and their relationship to the SVC (open arrow), right upper lobe bronchus (long solid arrow), and right lower lobe bronchus (arrowhead).
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Figure 13e. (a) Left anterior oblique volume-rendered CT image shows the superior and inferior pulmonary veins (short straight arrows) draining medially under the main pulmonary artery (long straight arrow) and aortic arch (curved arrow). (b) Right lateral volume-rendered CT image shows the right superior and inferior pulmonary veins (short arrows) behind the SVC (long arrow). (c) Posterior volume-rendered CT image shows the pulmonary veins (thick straight arrows) entering the left atrium (curved arrow). Note the relationship to the pulmonary arteries (thin straight arrows). (d) Volume-rendered CT image obtained from the patient’s right side with airway and color trapezoids shows the superior and inferior pulmonary veins (white arrows) anterior and inferior to the left main-stem bronchus (black arrow). (e) Volume-rendered CT image obtained from the patient’s left side with airway and color trapezoids shows the superior and inferior pulmonary veins (short solid arrows) and their relationship to the SVC (open arrow), right upper lobe bronchus (long solid arrow), and right lower lobe bronchus (arrowhead).
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The superior pulmonary veins are found in front of the pulmonary arteries (Fig 13a). In the left lung root, the superior pulmonary vein is in front of the left bronchus and the inferior pulmonary vein is below it. In the right lung root, the pulmonary veins are similarly distributed above and below the right bronchus. The right lung root lies within the curve of the azygos vein. All are enclosed in the pulmonary ligament, a reflection of pleura that enlarged with pulmonary vein enlargement (Fig 13d, 13e).
Anatomy of the pulmonary veins is becoming increasingly important with ablative therapies for cardiac arrhythmia and their follow-up (12,13).
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Other Thoracic Veins
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Thymic and inferior thyroid veins drain to the brachiocephalic veins (Fig 14). The vertebral Batson plexus is a complex venous system along the length of the spinal canal both internally and externally. These veins communicate freely with each other and with the veins of the spinal cord and vertebral, intercostal, lumbar, and lateral sa-cral veins. The chest wall venous return does not follow the arteries. A radiating network of veins forms above the umbilicus and drains to the lateral thoracic vein and axillary vein (Fig 15). The lateral thoracic vein may be united with the superficial epigastric vein by a thoracoepigastric vein.
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Figure 14a. (a) Anterior volume-rendered CT image shows the complex plexus of thymic, inferior thyroid, and intermammary veins (arrow), which is seen between the internal thoracic veins. (b) Left lateral volume-rendered CT image shows the complex of thymic, inferior thyroid, and intermammary veins (arrow), which is seen posterior to the internal thoracic veins in the anterior mediastinum.
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Figure 14b. (a) Anterior volume-rendered CT image shows the complex plexus of thymic, inferior thyroid, and intermammary veins (arrow), which is seen between the internal thoracic veins. (b) Left lateral volume-rendered CT image shows the complex of thymic, inferior thyroid, and intermammary veins (arrow), which is seen posterior to the internal thoracic veins in the anterior mediastinum.
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Figure 15a. (a) Anterior volume-rendered CT image shows the veins of the right anterior chest wall (arrows) in a patient with obstruction of the left brachiocephalic vein. Collateralization to the deep systemic veins is through transthoracic, external jugular, intercostal, and thyroid veins. (b) Right anterior volume-rendered CT image shows the veins of the right anterior chest wall (arrows).
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Figure 15b. (a) Anterior volume-rendered CT image shows the veins of the right anterior chest wall (arrows) in a patient with obstruction of the left brachiocephalic vein. Collateralization to the deep systemic veins is through transthoracic, external jugular, intercostal, and thyroid veins. (b) Right anterior volume-rendered CT image shows the veins of the right anterior chest wall (arrows).
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Conclusions
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Systemic and pulmonary veins of the thorax form a complex network of venous drainage (14,15). Multi–detector row CT and volume rendering can harness data in two-dimensional images to aid appreciation of this anatomy. It is important to recognize these normal veins and their relationships in image interpretation. Congenital anomalies, surgical shunts, and collateral vessels are seen routinely in clinical practice and may present a complex two-dimensional pattern that can be simplified by application of three-dimensional techniques that merge the tortuous branches.
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Footnotes
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Abbreviations: MIP = maximum intensity projection,
SVC = superior vena cava
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References
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Abstract
LEARNING OBJECTIVES
