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Radiography CPD activity for 2015

Article: A8 (15)

TOPIC:

LEARNING FROM THE PULMONARY VEINS

Approved for three (3) Clinical Continuing Educational Units

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999CHEST IMAGING

Diego Varona Porres, MD • Óscar Persiva Morenza, MPH • Esther Pallisa, MD • Alberto Roque, MD • Jorge Andreu, MD • Manel Martínez, MD

The purpose of this article is to review the basic embryology and anato-my of the pulmonary veins and the various imaging techniques used to evaluate the pulmonary veins, as well as the radiologic findings in dis-eases affecting these structures. Specific cases highlight the clinical im-portance of the imaging features, particularly the findings obtained with multidetector computed tomography (CT). Pulmonary vein disease can be broadly classified into congenital or acquired conditions. Congenital disease, which often goes unnoticed until patients are adults, mainly in-cludes (a) anomalies in the number or diameter of the vessels and (b) ab-normal drainage or connection with the pulmonary arterial tree. Acquired disease can be grouped into (a) stenosis and obstruction, (b) hypertension, (c) thrombosis, (d) calcifications, and (e) collateral circulation. Pulmonary vein stenosis or obstruction, which often has important clinical repercus-sions, is frequently a result of radiofrequency ablation complications, neo-plastic infiltration, or fibrosing mediastinitis. The most common cause of pulmonary venous hypertension is chronic left ventricular failure. This condition is difficult to differentiate from veno-occlusive pulmonary dis-ease, which requires a completely different treatment. Pulmonary vein thrombosis is a rare, potentially severe condition that can have a local or distant cause. Calcifications have been described in rheumatic mitral valve disease and chronic renal failure. Finally, the pulmonary veins can act as conduits for collateral circulation in cases of obstruction of the su-perior vena cava. Multidetector CT is an excellent modality for imaging evaluation of the pulmonary veins, even when the examination is not spe-cifically tailored for their assessment.©RSNA, 2013 • radiographics.rsna.org

Learning from the Pulmonary Veins1

ONLINE-ONLY SA-CME

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LEARNING OBJECTIVES

After completing this journal-based SA-

CME activity, partic-ipants will be able to:

■ Describe the ra-diologic anatomy of the pulmonary veins and the imaging techniques used to study these struc-tures, particularly multidetector CT.

■ List the various diseases affecting the pulmonary veins and the differential diagnosis of these conditions.

■ Discuss the clini-cal importance and the radiologic diag-nosis of pulmonary vein disease.

Abbreviation: PAPVR = partial anomalous pulmonary venous return

RadioGraphics 2013; 33:999–1022 • Published online 10.1148/rg.334125043 • Content Codes: 1From the Department of Radiology, Hospital Vall d’Hebrón, Passeig Vall d’Hebrón 119, 08035 Barcelona, Spain. Recipient of a Certificate of Merit award for an education exhibit at the 2011 RSNA Annual Meeting. Received March 27, 2012; revision requested April 24 and received January 15, 2013; accepted January 25. For this journal-based SA-CME activity, the authors, editor, and reviewers have no financial relationships to disclose. Address correspondence to D.V.P. (e-mail: [email protected]).

©RSNA, 2013

1000 July-August 2013 radiographics.rsna.org

IntroductionThe pulmonary veins should be evaluated care-fully during imaging examinations of the chest so that pathologic conditions are not overlooked. An embryologic and anatomic understanding of the pulmonary veins is of great value, particularly in the investigation of congenital disease or in the evaluation of patients before radiofrequency abla-tion for the treatment of atrial fibrillation.

Several imaging modalities are used to assess the pulmonary veins, including chest radiogra-phy, echocardiography, magnetic resonance (MR) imaging, and computed tomography (CT). Mul-tidetector CT is an excellent technique for this purpose and is currently available in many radiol-ogy departments worldwide.

The purpose of this article is to review the basic embryology and anatomy of the pulmonary veins and the various imaging techniques used to evaluate the pulmonary veins, as well as the ra-diologic findings in diseases affecting these struc-tures, with particular emphasis on their multide-tector CT appearance. Two major disease groups are covered: (a) congenital disease, which mainly includes abnormalities in the number or diameter of the pulmonary veins, drainage anomalies, and anomalous connections with the pulmonary arte-rial tree; and (b) acquired disease, which includes stenosis or obstruction, hypertension, thrombosis, calcifications, and collateral circulation. With the exclusion of congenital causes, pulmonary vein stenosis or obstruction occurs in neoplastic dis-ease and nonneoplastic disease (fibrosing medias-tinitis or tuberculosis-related pulmonary destruc-tion) and as a complication of radiofrequency ablation or lung surgery. Pulmonary venous hypertension is usually caused by left ventricular failure but may result from other conditions, such as veno-occlusive disease. Pulmonary vein throm-bosis can be caused by a local process, such as lo-cal extension of a thoracic neoplasm or prior sur-gery, or by a distant process, such as idiopathic thrombosis. Calcifications of the pulmonary veins have been described as rare findings in patients with rheumatic fever or chronic renal failure. Fi-nally, collateral circulation can develop in cases of pulmonary vein compromise, as occurs in a systemic-to-pulmonary venous shunt, which is an unusual collateral vessel arising in patients with superior vena cava obstruction. Although some

categories may overlap in this grouping of the types of pulmonary vein disease, the grouping enables organization and facilitates comprehen-sion of the related information.

Embryology and AnatomyA thorough understanding of pulmonary vein anatomy is important in certain clinical situations:

1. Congenital disease: Variations may occur in the number, diameter, and normal drainage of the pulmonary veins.

2. Atrial fibrillation: The pulmonary veins contribute to originating and maintaining atrial fibrillation. With regard to radiofrequency abla-tion, which is a common treatment for chronic atrial fibrillation, radiologic evaluation of the pulmonary vein anatomy and anatomic variants is highly useful before the procedure.

3. Pulmonary neoplasm: In non–small cell lung cancer, extension into the intrapericardial portion of the pulmonary veins is a criterion for T4 staging on the basis of the current classification (1).

Knowledge of the embryologic development of the pulmonary veins is useful for understand-ing the congenital variants and anomalies that are often observed. During the first 2 months of fetal development, the lungs drain to the systemic veins (2), and the common primitive pulmonary vein forms from a pouch in the dor-sal wall of the primitive left atrium (2,3). When the primitive lungs are fused to the common pulmonary vein, the connections that allow pul-monary venous return to the systemic veins are obliterated (2,3). Thus, the common pulmonary vein is incorporated into the left atrium, and four well-differentiated pulmonary veins arise, two of which drain each lung (2,3). Abnormal resorption of the embryonic structures can lead to (a) alterations in the diameter or the number of pulmonary veins or (b) abnormal drainage to the systemic veins or right atrium.

In normal conditions, the four pulmonary veins carry oxygenated blood from both lungs and drain into the left atrium, as follows: (a) the right superior pulmonary vein drains the right upper and middle lobes; (b) the left superior pulmonary vein drains the left upper lobe and lingula; and (c) the two inferior pulmonary veins drain the lower lobes.

At the pulmonary hilum, the superior pul-monary veins are located anterior and caudal to the pulmonary arteries. Unlike the intrapul-

RG • Volume 33 Number 4 Varona Porres et al 1001

Figure 1. Diagram of the common normal patterns and variations of pulmonary vein anatomy. Solid black lines are variant accessory veins. A, Typical normal pat-tern. B, Left common trunk. C, Accessory right middle pulmonary vein. D, Two accessory right middle pulmonary veins. E, One accessory right middle pulmonary vein and one accessory right upper pulmonary vein. F, Right top pulmonary vein (dashed black line).

monary portion of the pulmonary arteries, the pulmonary veins are not located near the bron-chi; instead, these veins follow the course of the intersegmental septa. Thus, the pulmonary veins can be differentiated from the segmental arter-ies, which run adjacent to the corresponding bronchus (4).

The ostia of the inferior pulmonary veins are more dorsal and medial than those of the supe-rior pulmonary veins (2), and the ostia of the left pulmonary veins are located higher than those of the right pulmonary veins (5). Knowledge of the size and morphology of the pulmonary veins and their ostia is important because consider-able differences may be seen among patients. The pulmonary veins tend to be smaller in women, although this difference reaches significance only for the left superior pulmonary vein (6). The pulmonary veins are not perfectly round; the an-teroposterior diameter is smaller than the supero-inferior diameter, especially in the left veins (5,6). Furthermore, the diameter of the pulmonary veins generally increases as they approach the left atrium, with the exception of the left inferior pulmonary vein, the diameter of which usually decreases as it enters the atrium, a finding that must be taken into consideration when evaluating possible stenosis at this location (6). In addition, the diameters of the superior pulmonary veins are larger than those of the inferior pulmonary veins, although significant differences are not seen in patients with chronic atrial fibrillation, in whom

the diameters of the inferior pulmonary veins increase in size to equal those of the superior pulmonary veins (5). In addition, variations may occur in the diameter and position of the pul-monary vein ostia according to the phase of the cardiac cycle (7).

Various normal patterns and variations have been described in the study of pulmonary vein anatomy (5,7) (Fig 1). The typical pattern is four pulmonary veins and four well-differenti-ated ostia. This configuration is seen in 60%–70% of the population (7). Atypical anatomic patterns are found in approximately 38% of the population (5); hence, it is important to be fa-miliar with them. Anatomic variants on the left side are relatively simple, basically consisting of convergence of the left pulmonary veins in a common trunk that drains into the left atrium. Two subtypes of this variant occur: a short or a long left common trunk. The short left common trunk is the second most common normal ana-tomic pattern, occurring in 15% of the popula-tion. Anatomic variants on the right side are less common and tend to be more complex, with one or more accessory veins that have their own connections to the left atrium independently of the superior and inferior pulmonary veins. These variants mainly include (a) one accessory right middle pulmonary vein, (b) two accessory right middle pulmonary veins, and (c) one accessory


Figure 2. Right top pulmonary vein draining the posterior segment of the right upper lobe in a 48-year-old man in whom contrast-enhanced multidetector CT was performed for follow-up of follicular lymphoma. (a) Oblique coronal maximum intensity projection image shows the accessory right pulmonary vein (arrow). (b) Oblique posterior three-dimensional reconstruction image depicts the accessory vein (arrow).

right middle pulmonary vein and one accessory right upper pulmonary vein. Other infrequent variations are also seen: a superior segment right lower lobe vein, basilar segments of the right lower lobe, and a right top pulmonary vein. A right top pulmonary vein enters the left atrium at a point superomedial to the right superior pulmonary vein and drains the superior right lower lobe segment, the posterior right upper lobe segment, or both segments (7) (Fig 2).

The pulmonary veins have an intrapericardial portion in their distal segment. The left superior pulmonary vein has the longest intrapericardial segment, which ranges from 11 mm to 13.7 mm; and the right inferior pulmonary vein has the shortest intrapericardial segment, which ranges from 4.5 mm to 11 mm (8). These data may be of interest in certain clinical situations; for example, the left superior pulmonary vein is the most com-mon focus of atrial fibrillation, and the right in-ferior pulmonary vein is the least common (8). Furthermore, one group of investigators has re-ported that when obliteration of the superior pul-monary veins is demonstrated, there is a likelihood of intrapericardial extension of a lung tumor (9). Nonetheless, these data must be taken with cau-tion because the CT study was performed without a multisection technique (9).

Fluid may accumulate in the pericardial recess of the right inferior pulmonary vein, a finding that simulates lymphadenopathy or a pericardial cyst (Fig 3). On CT images of these patients, fluid in the pericardial recess may lend the ap-pearance of a mass surrounding the right inferior pulmonary vein close to its entrance into the left atrium, with an absence of mass effect on the vessel, and with fluid attenuation. However, at-tenuation values may be higher than expected for fluid in some cases, a fact that complicates the diagnosis (10).

The pulmonary veins are covered with a myo-cardial layer extending from the left atrium for an average length of 9.3 mm (11). The portion of myocardium extending onto the pulmonary veins is a frequent source of atrial fibrillation, and the left superior pulmonary vein, which has the longest segment of myocardium, is the focal cause of atrial fibrillation in as many as half of the cases (12).

Imaging TechniquesEvaluation of the pulmonary veins can be un-dertaken with several imaging modalities, each of which has specific indications, advantages, and disadvantages. Chest radiography can be used as the initial imaging modality for pulmo-nary vein assessment and is particularly useful in cases of pulmonary venous hypertension caused


Figure 3. Disseminated carcinoid tumor of the ileum in a 67-year-old woman in whom multidetec-tor CT was performed for disease follow-up. Axial contrast-enhanced multidetector CT image shows fluid accumulation (arrows) in the pericardial recess of the right inferior pulmonary vein.

by left ventricular failure. In the normal postero-anterior radiograph, the right superior pulmo-nary vein is consistently lateral to the artery, the right inferior pulmonary vein is more horizontal than the artery, and the left inferior pulmonary vein is more vertical, with a course similar to that of the artery. The diameter of the vessels depends on the flow; hence, in a posteroanterior radiograph obtained with the subject standing, the vessel diameters are seen to gradually de-crease from the lower lobes to the upper lobes (diameters of 3 mm at the first intercostal space and as much as 6 mm or more in vessels im-mediately above the diaphragm) (13). Although chest radiography is a widely available modality that involves relatively little radiation exposure, the resolution of these anatomic structures is low, and interpretation of the images requires training and experience.

Echocardiography is the first-line choice for the evaluation of congenital cardiopathies, in-cluding pulmonary venous anomalies (3). Trans-esophageal echocardiography is especially useful for investigating the left atrium for the presence of thrombi, a finding that is an absolute contra-indication to the use of radiofrequency ablation to treat atrial fibrillation (12,14), but the inferior pulmonary veins cannot be evaluated properly with transesophageal echocardiography (6). However, in one prospective study, Huang et al

(15) have shown that transthoracic echocardiog-raphy enables reliable examination of all of the pulmonary veins. Training and experience are also needed for precise interpretation of echocar-diographic examinations.

MR imaging can be used (a) to evaluate con-genital cardiopathies that cause pulmonary vein compromise or (b) as an alternative to multidetec-tor CT to study the anatomy of the pulmonary veins and left atrium before radiofrequency abla-tion. However, MR imaging is contraindicated in patients with pacemakers or defibrillators (12,14). Additional drawbacks are the lengthy duration of the MR imaging examination and the fact that it may be impossible to perform MR imaging in patients with claustrophobia and those unable to cooperate because of their clinical condition. The main advantage of MR imaging is that it does not expose the patient to ionizing radiation.

Multidetector CT enables assessment of (a) the extension of neoplastic and nonneoplastic infiltra-tive diseases into the pulmonary veins and (b) the presence of calcifications. This modality is also highly suitable for anatomic evaluation before interventional procedures. The choice of electro-cardiographically gated or nongated CT depends on the practice in the individual center because adequate images of the pulmonary veins can be obtained without cardiac gating (14,16). Never-theless, electrocardiographically gated cardiac CT provides higher-quality images for postprocessing with three-dimensional reconstruction techniques, thereby enabling better evaluation of the pulmo-nary vein ostia and of complications after radiofre-quency ablation, such as pulmonary vein stenosis, as well as the detection of unsuspected coronary artery disease (4,14). The main advantages of multidetector CT are the short examination time, multiplanar capability, and high anatomic resolu-tion, whereas the disadvantages include elevated radiation exposure and the possible detrimental effect on renal function caused by administration of intravenous contrast material.

Congenital ConditionsCongenital anomalies affecting the pulmonary veins may go unnoticed until adulthood, when they are commonly diagnosed incidentally. In general, congenital conditions comprise (a) anom-alies in the number or diameter of the vessels and (b) abnormal drainage or connection with the pulmonary arterial tree (Table).


Congenital Anomalies Affecting the Pulmonary Veins

Group and Type of Anomaly Concept Clinical Manifestations Radiologic Diagnosis

Anomalies in number

Anomalous unilateral single pulmonary vein

Single pulmonary vein join-ing left atrium after unit-ing all of the pulmonary veins from one lung

No vascular shunt, may be associated with hypoge-netic lung syndrome

May be mistaken for scimi-tar syndrome or pulmo-nary arteriovenous malfor-mation, multidetector CT enables the diagnosis

Anomalies in diameter

Congenital unilateral pulmonary vein stenosis or atresia

Failed incorporation of the common pulmonary vein into the left atrium

Recurrent infections and hemoptysis, associated with congenital cardi-opathy in 50% of cases

Multidetector CT findings: small hemithorax with ipsilateral mediastinal deviation, small ipsilateral pulmonary artery, smooth left atrial wall at the pul-monary vein insertion site, and soft-tissue and lung parenchymal abnormalities

Pulmonary vein varix

Enlarged diameter of a pul-monary vein without an arterial connection

No symptoms; hemopty-sis or thromboembolic disease

Chest radiographic findings: mimics pulmonary nodule or mediastinal mass, mul-tidetector CT enables the diagnosis

Drainage anomalies

Right-sided PAPVR

Right pulmonary vein that most commonly drains into the superior vena cava

Right upper lobe pulmo-nary vein is most often affected, association with atrial septal defect

Multidetector CT findings: predominant upper lobe pulmonary vein drains directly into the superior vena cava

Left-sided PAPVR

Left upper pulmonary vein with a vertical course joining the left brachioce-phalic vein

Incidental finding, adults with normal heart

Multidetector CT can depict the anomalous pulmonary vein

Scimitar syndrome

Pulmonary vein draining into an infradiaphragmatic vein, associated with right pulmonary hypoplasia

May be associated with other congenital abnor-malities

Chest radiographic findings: small right lung, heart displacement to the right, and scimitar sign

Levoatrio- cardinal vein

Anomalous pulmonary vein connecting the left atrium with the systemic venous system

Associated with the hypo-genetic lung syndrome

Chest radiographic findings: mimics unilateral single pulmonary vein, multide-tector CT can depict the anomalous pulmonary vein

Connection with pulmonary arterial tree

Pulmonary arteriovenous malformation

Abnormal communication between a pulmonary ar-tery and a pulmonary vein

Association with Rendu-Osler-Weber syndrome, increased risk of cerebral abscess, stroke, and pul-monary hemorrhage

Chest radiographic findings: mimics a pulmonary nod-ule or mass, multidetector CT enables detection, characterization, and follow-up


Figure 4. Right anomalous unilateral single pulmonary vein in a 58-year-old woman who underwent contrast-enhanced multidetector CT. (a) Posteroanterior radiograph shows increased size of the right pulmonary hilum (arrows). (b) Posterior oblique three-dimensional reconstruction image depicts the anomalous right pulmonary vein (arrows).

Anomalous Unilateral Single Pulmonary VeinAn anomalous unilateral single pulmonary vein is extremely unusual, with few cases described in the literature. This anomaly consists of an abnor-mal solitary pulmonary vein that joins one side of the left atrium after uniting the pulmonary veins from one lung (17). The term meandering pulmonary vein has also been used to refer to this condition (18).

This anomaly is more common on the right side, although it may be found bilaterally (17,19). An anomalous unilateral single pulmonary vein may have a juxtahilar location (20), and the anomaly is depicted on chest radiographs as a serpentine tubular opacity adjacent to the pulmo-nary hilum. The diagnosis is straightforward with multidetector CT, which enables clear depiction of the anomalous vein, particularly with three-dimen-sional reconstruction (21) (Fig 4).

An anomalous unilateral single pulmonary vein may be associated with other pulmonary anomalies such as pulmonary hypoplasia or partial anomalous pulmonary venous return (PAPVR) (17,21). The differential diagnosis of anomalous unilateral single pulmonary vein should include (a) scimitar syndrome, in which the pulmonary vein connects at a point other than the left atrium; (b) arteriovenous malfor-

mations, with connection to a pulmonary arte-rial branch; and (c) pulmonary nodules (21).

Because there is no vascular shunt, no treat-ment is required for an anomalous unilateral single pulmonary vein. For this reason, it is im-portant to differentiate this condition from others that may require treatment (17).

Congenital Unilateral Pulmonary Vein Stenosis or AtresiaCongenital unilateral pulmonary vein stenosis or atresia consists of complete or partial oblitera-tion of the pulmonary veins on one side (22–24), which results from failed incorporation of the common pulmonary vein into the left atrium during embryologic development. Histologically, congenital unilateral pulmonary vein stenosis or atresia is characterized by uncontrolled growth of connective tissue cells, with medial hypertrophy and fibrosis of the intima of the pulmonary vein, which results in obstruction (22,23).

Congenital unilateral pulmonary vein stenosis or atresia does not show a predilection for ei-ther side and usually manifests with pulmonary symptoms during the first 3 years of life (23), although cases have been described in adults


Figure 5. Congenital unilateral atresia of the pulmonary veins in an asymptomatic 48-year-old man. (a) Axial contrast-enhanced multidetector CT image (mediastinal window) depicts the wall of the left atrium, which has a smooth contour on the right side (arrow). (b) Axial contrast-enhanced multidetector CT image (lung window) shows a small right lung with septal thickening (arrows).

(24). Congenital unilateral pulmonary vein atre-sia is associated with congenital heart disease or anomalous pulmonary venous return in ap-proximately 50% of cases. In children, congeni-tal unilateral pulmonary vein stenosis or atresia may occur as an isolated, rapidly progressing anomaly (22,24). The presenting symptoms for congenital unilateral pulmonary vein stenosis or atresia can include recurrent pulmonary infec-tion, dyspnea on exertion, and, occasionally, hemoptysis (23).

Chest radiographs of patients with congenital unilateral pulmonary vein stenosis or atresia may show a small lung and reticular opacities with Kerley B lines (23,25). The characteristic CT findings are a small lung with ipsilateral medi-astinal deviation, unilateral stenosis or absence of pulmonary venous drainage, and a small ip-silateral pulmonary artery. The left atrial wall is completely smooth at the expected insertion site of the pulmonary vein (Fig 5). Abnormal conflu-ent soft tissue can also be observed, which is due to the pulmonary-to-systemic venous collateral circulation (24). The pulmonary parenchyma ipsilateral to pulmonary vein atresia shows radio-logic features of pulmonary venous hypertension: interlobular septal thickening, peribronchovascu-lar thickening, and ground-glass opacities (24).

The differential diagnosis in relation to the mediastinal and hilar soft-tissue findings in adult patients with congenital unilateral pulmonary vein stenosis or atresia should include pulmonary neoplasm and fibrosing mediastinitis (24). Treat-ment of congenital unilateral pulmonary vein stenosis or atresia may be surgical or may involve

balloon dilation or stent placement. Lung trans-plantation is considered in cases of severe pulmo-nary vein stenosis (22).

Pulmonary Vein VarixPulmonary vein varix consists of a focal dilatation of a pulmonary vein segment that does not have an arterial connection, with the dilatation usually occurring close to the entrance of the vein into the left atrium (22,26). The varix can be congeni-tal or acquired and, in the latter case, sometimes develops in association with chronic pulmonary hypertension or mitral valve disease. Patients are usually asymptomatic, but hemoptysis caused by rupture or thromboembolic disease has been de-scribed (22,26).

Chest radiographs of pulmonary vein varix show a well-defined nodular opacity without calcifications. Depending on where the varix is located, the opacity may simulate a pulmonary nodule or mediastinal or hilar lymphadenopa-thy (26,27) (Fig 6). The differential diagnosis of pulmonary vein varix should include mediasti-nal or hilar lymphadenopathy, an arteriovenous malformation, and a pulmonary nodule (22). Multidetector CT, especially when performed with three-dimensional reconstruction or maxi-mum intensity projection, facilitates the diagnosis (22,26). No treatment is needed for asymptom-atic patients, but for symptomatic patients, surgi-cal resection may be required (22).

Partial Anomalous Pulmonary Venous ReturnIn PAPVR, rather than an anomalous pulmonary vein draining into the left atrium, one anomalous pulmonary vein drains into a systemic vein, pro-


Figure 7. Atrial septal defect and pulmonary hypertension in a 44-year-old man who underwent con-trast-enhanced multidetector CT. (a) Axial maximum intensity projection image shows an anomalous pulmonary vein (arrow) from the right upper lobe draining into the superior vena cava. (b) Axial contrast-enhanced multidetector CT image depicts the atrial septal defect (*).

Figure 6. Surgically treated complex congenital cardiomyopathy in a 27-year-old woman. (a) Posteroan-terior chest radiograph shows a nodular opacity (arrows) projected over the right cardiac border. (b) Axial contrast-enhanced multidetector CT image shows a right inferior pulmonary vein varix (arrow).

ducing a left-to-right shunt. The prevalence of this condition ranges from 0.4% to 0.7% (3). Patients with PAPVR are often asymptomatic or show few symptoms; and in most cases, PAPVR is detected incidentally. If the anomaly compromises 50% or more of the pulmonary venous flow, it may be-come clinically significant (3). Left-sided PAPVR seems to be found more often in adults than in children, whereas right-sided PAPVR is reported more commonly in children (28).

Right-sided PAPVR consists of an anomalous pulmonary vein that drains into the superior

vena cava, azygos vein, coronary sinus, or infe-rior vena cava (2). In right-sided PAPVR, right upper lobe flow most commonly drains into the superior vena cava, and the condition is often associated with a high sinus venosus atrial sep-tal defect near the orifice of the superior vena cava (Fig 7). Because this type of atrial septal defect is clinically silent, the associated PAPVR may be the clue leading to the diagnosis of atrial septal defect (2).


Figure 9. Scimitar syndrome in an asymptomatic 26-year-old man who underwent multidetector CT. (a) Posteroanterior chest radiograph shows a small right lung caused by pulmonary hypoplasia and a curved opacity (arrows) in the lower portion of the lung, a finding consistent with scimitar syndrome. (b) Oblique coronal three-dimensional reconstruction image shows the anomalous pulmonary vein (purple) that drains into the inferior vena cava, a finding con-sistent with scimitar syndrome. An anomalous artery (green) arising from the abdominal aorta and irrigat-ing the right lower lobe is also depicted.

Figure 8. Pulmonary nodule in a 53-year-old man with a diagnosis of a primary lung neoplasm, who was awaiting surgery. Axial contrast-enhanced multidetector CT image shows a cavitated and spiculated nodule (white arrow) in the left upper lobe and a PAPVR (black arrow) from the left upper lobe to the left brachiocephalic vein. The patient underwent left upper lobectomy, with no complications.

Left-sided PAPVR commonly affects venous drainage of the left upper lobe and tends to be an incidental finding in adults with a normal heart (2). The affected vessel is typically a vertical vein that joins the left brachiocephalic vein or the coro-nary sinus (3). In the case of brachiocephalic vein thrombosis caused by a central venous catheter, there can be a right-to-left shunt (29). The dif-ferential diagnosis of left-sided PAPVR includes a persistent left superior vena cava, although mul-tidetector CT findings allow easy differentiation between the two conditions.

Detection of PAPVR may be important in pa-tients who are candidates for lobectomy to treat a primary pulmonary neoplasm. When the PAPVR is located in the same lobe as the neoplasm, lo-bectomy can be performed without anticipated problems (Fig 8). However, when PAPVR is found in a pulmonary lobe other than that af-fected by the neoplasm, some investigators have suggested that the PAPVR should be corrected during lobectomy to prevent possible right-sided heart failure caused by increased blood flow through this anomalous vein (30–32).

PAPVR with an anomalous pulmonary vein that drains into the inferior vena cava, the por-tal vein, hepatic veins, or other veins below the diaphragm is associated with right pulmonary hypoplasia and is typically referred to as the scimitar syndrome or, alternatively, as the hypo-genetic lung syndrome or pulmonary venolobar syndrome (2,3) (Fig 9). In this syndrome, the pulmonary artery is hypoplastic or aplastic, and


Figure 10. Levoatriocardinal vein in an asymptomatic 37-year-old man who underwent contrast-en-hanced multidetector CT. (a) Coronal maximum intensity projection image depicts an anomalous vein (arrow) connecting the left atrium to the inferior vena cava. (b) Coronal minimum intensity projection image shows an absence of the middle lobe bronchus caused by right pulmonary hypoplasia.

the right lung may have the appearance of a left lung with only two lobes (33). Congenital heart conditions are observed in approximately one-fourth of these patients, with atrial septal defect being the most common (2,33). Other associated anomalies include anomalous pulmonary sys-temic circulation, extralobar pulmonary seques-tration, horseshoe lung, pulmonary arteriovenous malformation, bronchogenic cyst, and accessory diaphragm (2,33).

The typical radiographic finding in the scimi-tar syndrome is a curved opacity lateral to the right cardiac border and extending toward the inferior vena cava, with the opacity increasing in diameter caudally as it approaches the inferior vena cava. This appearance, known as the scimi-tar sign, corresponds to an anomalous pulmonary vein and is usually associated with a small right lung and cardiac dextroposition.

CT angiography performed with multiplanar reconstruction, maximum intensity projection, and three-dimensional reconstruction enables evaluation of the trajectory and the drainage of the anomalous pulmonary vein that are charac-teristic of this syndrome (22). This technique is also useful for assessing possible pulmonary ir-rigation by an anomalous systemic artery, which may be a cause of hemoptysis, pulmonary hyper-tension, and pulmonary parenchymal or bron-chial tree anomalies (22). Lastly, in patients who have undergone reimplantation of an anomalous pulmonary vein into the left atrium, CT angi-ography enables the evaluation of postoperative

complications such as thrombosis or stenosis of the reimplanted pulmonary vein (22).

Levoatriocardinal VeinLevoatriocardinal vein is an uncommon entity and is defined as an anomalous connection between the left atrium and a vein from the systemic venous system that is embryologically derived from the cardinal veins (34,35). The pre-dominant pattern is a direct connection between the left atrium and a systemic vein (34), a pattern that is associated with a hypogenetic lung. There may also be a connection between one of the pul-monary veins and the systemic veins (36).

On radiographs, the appearance of a levo-atriocardinal vein is similar to that of an anoma-lous unilateral single pulmonary vein. CT shows findings of hypogenetic lung syndrome and an anomalous vein that connects the left atrium to a systemic vein (Fig 10).

Pulmonary Arteriovenous MalformationIn pulmonary arteriovenous malformation, which is also known as arteriovenous fistula, an abnormal direct communication occurs between a pulmonary artery and a pulmonary vein without a capillary network, a finding resulting from an embryonic developmental defect of the pulmonary capil-laries (22,37). The congenital form is the most common, but acquired pulmonary arteriovenous


Figure 11. Persistent right-to-left shunt observed at echocardiography in a 47-year-old woman with a history of surgically treated foramen ovale who underwent contrast-enhanced multidetector CT. (a) Axial contrast-enhanced multidetector CT image (pulmonary window) depicts a pulmonary arteriovenous mal-formation (arrow) in the middle lobe. (b) Oblique sagittal three-dimensional reconstruction image clearly shows the pulmonary arteriovenous malformation (arrow).

malformation may develop in patients after sur-gery for cyanotic congenital cardiopathies (Glenn and Fontan procedures), in patients with chronic liver disease, and in patients with a history of tuberculosis or actinomycosis (22). Pulmonary arteriovenous malformation can be single or mul-tiple. The anomaly is associated with Rendu-Osler-Weber syndrome (hereditary hemorrhagic telangi-ectasia) in as many as 60% of cases (37).

The symptoms of this anomaly depend on the size of the lesion. Patients with pulmonary arteriovenous malformations smaller than 2 cm may be asymptomatic (22). If the malformation is larger or if there are multiple pulmonary arte-riovenous malformations, the patient may present with hypoxemia, brain infarction or abscess, and paradoxical embolism (22,37). More than 70% of all pulmonary arteriovenous malformations involve a single artery and a single vein, and as many as 50% of patients have more than one malformation (37).

On radiographs, a pulmonary arteriovenous malformation may resemble a pulmonary nod-ule. The lesions are located in the lower lobes in 50%–70% of cases (22). Contrast material–enhanced echocardiography is a sensitive tech-nique for detecting right-to-left shunts; hence, negative findings from this examination rule out

pulmonary arteriovenous malformation, whereas positive findings should be followed with CT (38). Multidetector CT enables detection and evaluation of the angioarchitecture and size of the lesion and is useful in posttreatment follow-up (22,37).

Pulmonary arteriovenous malformation re-quires treatment when the lesion is larger than 2–3 cm. Percutaneous transcatheter embolization is the treatment of choice (22,37) (Fig 11).

Acquired Conditions

Pulmonary Vein Stenosis or ObstructionPulmonary vein stenosis or obstruction may be difficult to manage, and the mortality rate is considerable (39). In adults, the most common causes of pulmonary vein stenosis or obstruc-tion are radiofrequency ablation complications, neoplastic infiltration, and fibrosing mediastinitis. Other causes include surgical complications (eg, heart surgery, correction of anomalous pulmo-nary venous return, or lung transplantation) and infiltration or extrinsic compression by a benign inflammatory process (eg, sarcoidosis or tubercu-losis) (39,40).

Any thoracic neoplasm can potentially ex-tend to the pulmonary veins (41). Primary lung neoplasms can give rise to stenosis or invasion of the intrapericardial portion of the pulmonary


Figure 12. Diagram of the patterns of neoplasm-related findings observed in the pulmonary veins (neoplasm is black). A, Extrinsic compression. B, Complete obstruction. C, Extracardiac neoplasm with tumor thrombus. D, Cardiac neoplasm with tumor thrombus. E, Neoplastic infiltration of the pulmonary vein wall with-out complete obstruction.

Figure 13. Stage IV primary non–small cell lung carcinoma in a 54-year-old man. Axial contrast-enhanced multidetector CT image (mediastinal window) shows a mediastinal mass causing extrin-sic compression of the right inferior pulmonary vein (white arrow) and complete obstruction of the left inferior pulmonary vein (black arrow) by the same mass.

veins and the left atrium (9). A left atrial tumor, whether it is primary or secondary (eg, second-ary to a primary lung neoplasm) can extend to the pulmonary veins. Primary sarcomas can also affect the pulmonary veins (42,43). Extension of a lung neoplasm to the left atrium through a pulmonary vein can result in death caused by cardiac arrest or massive systemic tumor emboli-zation of multiple organs (44).

Extension of a primary lung neoplasm to the great vessels confers a staging of T4 in the new TNM (tumor-node-metastasis) classification and has a clear influence on the prognosis of affected patients (5-year survival, ≤22%) (45). Invasion of the intrapericardial portion of the pulmonary veins is considered a stage T4 tumor, whereas extrapericardial pulmonary vein involvement is not deemed stage T4 (1). Invasion of the great vessels is generally a contraindication for surgery, but resection is possible if there is only minimal invasion of the left atrium adjacent to the inser-tion site of the pulmonary vein (45).

Diagnostic imaging has demonstrated two basic patterns of pulmonary vein involvement with neoplastic disease: extrinsic compression or invasion (Fig 12). Extrinsic compression by a mediastinal mass or lung neoplasm causes ste-nosis. Neoplastic invasion of a pulmonary vein can lead to (a) obstruction of the vessel close to its point of entrance into the left atrium (Fig 13); (b) thrombosis by an extracardiac or atrial neoplasm; or (c) wall irregularities, with loss of the normal venous contour (Fig 14).

CT remains the most widely used modality for staging pulmonary neoplasms. Multidetec-tor CT is extremely useful for evaluating vas-cular invasion, but MR angiography is also of value for this purpose (46). Several CT signs of pulmonary vein and left atrial invasion have been described: (a) absence of depiction of the pulmonary vein and its entrance into the left atrium, (b) a left atrial filling defect with contrast material uptake, and (c) continuity


between the pulmonary tumor and the left atrial filling defect (47). In a study of 325 patients un-dergoing CT before surgery for a primary lung neoplasm, Choe et al (9) found that oblitera-tion of a pulmonary vein at its entrance to the left atrium was depicted in 19 patients. Surgical findings demonstrated pericardial invasion in 14 patients. Choe et al (9) concluded that the prob-ability of intrapericardial extension of a tumor is high in patients with superior pulmonary vein obliteration, whereas inferior pulmonary vein obliteration is a less reliable sign. Thus, in pri-mary lung neoplasms, the most reliable sign of intrapericardial invasion of a pulmonary vein is obliteration of the pulmonary vein close to its entrance into the left atrium, especially in the case of a superior pulmonary vein.

Fibrosing mediastinitis can cause pulmonary vein stenosis in adults (39,40). The condition involves proliferation of acellular collagen and fibrous tissue in the mediastinum (48), a finding that is possibly caused by an abnormal immune response in cases of histoplasmosis or tubercu-losis or occurs as a result of an unknown cause. Fibrosing mediastinitis tends to occur in young patients, but it has been described in a wide age range (48). The signs and symptoms depend on the extent of obstruction of the superior vena cava, the pulmonary veins or arteries, the cen-tral airway, and the esophagus. Superior vena cava syndrome is the most common presenting form of fibrosing mediastinitis (49). Pulmonary vein obstruction can manifest with progressive dyspnea and hemoptysis (called “pseudo–mitral

stenosis syndrome”). With lengthy duration, pul-monary vein stenosis can result in pulmonary arterial hypertension and cor pulmonale (48,49). Pulmonary vein occlusion can lead to pulmonary infarction (48).

Chest radiographs of patients with fibrosing mediastinitis usually show nonspecific find-ings, such as (a) widening of the mediastinum; (b) mediastinal or hilar calcifications, which are found in as many as 86% of patients; (c) pul-monary opacities caused by atelectasis or recur-rent pneumonia; (d) decreased diameter of the pulmonary artery and vascularity of the affected lung; and (e) radiologic findings of localized pul-monary venous hypertension caused by pulmo-nary vein obstruction, findings such as peribron-chovascular and septal thickening and localized edema (48).

At CT, two forms of fibrosing mediastinitis are seen: focal (82% of cases) and diffuse (18% of cases). In the focal form, a soft-tissue mass, often with calcifications, is depicted in the right para-tracheal, subcarinal, or hilar region (Fig 15). The diffuse form, which is likely idiopathic, affects multiple mediastinal compartments and may not show calcifications (48). In addition to allowing evaluation of vascular stenosis or obstruction, CT also enables assessment of pulmonary parenchy-mal abnormalities.

The prognosis is better for patients with the focal form of fibrosing mediastinitis and in cases with hilar involvement, for which surgery may be possible. Local treatment of the vessels or the obstructed airway with laser therapy, balloon di-lation, stent insertion, or venous grafts can also be attempted (48).

Figure 14. Primary squamous cell lung car-cinoma in a 57-year-old man who underwent contrast-enhanced multidetector CT. Coronal multiplanar reconstruction image shows a right parahilar mass (*) invading the inferior wall of the right inferior pulmonary vein (arrow) at its entrance into the left atrium. The neoplasm was treated with chemotherapy and radiation therapy because poor pulmonary function pre-cluded surgery.


Figure 16. Unilateral left lung destruction in an 83-year-old man with a history of tuberculosis in childhood. (a) Axial contrast-enhanced multidetector CT image shows nearly total destruction of the left pulmonary parenchyma (*) and stenosis of the left superior pulmonary vein (arrow). (b) Axial con-trast-enhanced multidetector CT image shows stenosis of the left inferior pulmonary vein (arrow).

Sarcoidosis is another reported cause of pul-monary vein stenosis or obstruction, which results from vascular invasion by granulomas or perivas-cular fibrosis (39,50). In our experience, posttu-berculotic pulmonary destruction is another cause of pulmonary vein stenosis or obstruction, a find-ing that has not been described in the literature. Unilateral pulmonary destruction, typically mani-

festing on the left side, can be a late complication of pulmonary tuberculosis (51,52). In a series of 22 patients at our institution, a decrease in the diameter of the pulmonary artery and pulmonary veins ipsilateral to the destroyed lung was observed in 19 patients (86.4%) (Fig 16).

Figure 15. Superior vena cava syndrome caused by focal fibrosing mediastinitis in a 74-year-old woman who underwent contrast-enhanced multidetector CT. (a) Coronal oblique maximum intensity projection image shows that a right paratracheal mass (*) with calcifications obstructs the superior vena cava, which results in stenosis of the right superior pulmonary vein (arrow). (b) Coronal oblique maxi-mum intensity projection image shows stenosis of the right inferior pulmonary vein (arrow).


Figure 17. Paroxysmal atrial fibrillation treated with radiofrequency ablation of the left pulmonary veins in a 48-year-old man who underwent multidetector CT. (a) Axial electrocardiographically gated multidetector CT image (mediastinal window) shows substantial stenosis of the left superior pulmonary vein, with increased attenuation of the adjacent mediastinal fat (arrow). (b) Posterior oblique three-dimensional reconstruction image depicts stenoses (arrows) of the two left pulmonary veins, which re-quired treatment with angioplasty.

After radiofrequency ablation, pulmonary vein stenosis is found, to a lesser or greater degree, in 1%–10% of the patients who undergo this treat-ment for atrial fibrillation; however, the incidence of moderate to severe stenosis is 1.4% or less (7). This complication should be suspected in any pa-tient who has received this treatment and presents with respiratory symptoms such as dyspnea or hemoptysis, even weeks or months after the pro-cedure (39).

This type of postprocedural stenosis may or may not be significant from a hemodynamic perspective. When stenosis is significant, it can lead to pulmonary infarction and may be associ-ated with fibrosing mediastinitis, veno-occlusive pulmonary disease, and even pulmonary arterial hypertension with time (12). In general, severe stenosis may develop in patients who have under-gone procedures with more than 30 W of ablation energy (53). Dissection and perforation are other ablation-related complications affecting the pul-monary veins (12).

The chest radiographs of patients with pul-monary vein stenosis after radiofrequency ab-lation can be normal or can show pulmonary opacities that represent edema or venous in-farctions, with or without pleural effusion (7). Contrast-enhanced CT can enable the diagnosis by directly depicting the stenosis and other asso-ciated features, such as pulmonary parenchymal

septal thickening caused by localized pulmonary venous hypertension, peripheral opacities caused by infarctions, and increased attenuation of me-diastinal fat adjacent to the stenosis, a finding resulting from inflammation and mediastinal fibrosis (53) (Fig 17).

Treatment of acquired postprocedural stenosis relies almost exclusively on catheter-related tech-niques. Balloon angioplasty provides good initial results, but restenosis occurs in more than 50% of patients (7,39). Stent placement is associated with a better medium-term prognosis (39).

Surgical treatment of anomalous pulmonary venous drainage in the pediatric population gives rise to acquired pulmonary vein stenosis in approximately 10% of cases (39). Anastomotic vascular stenosis is observed in less than 4% of patients who have undergone lung transplanta-tion, with stenotic complications being more frequent at the arterial anastomoses than at the venous anastomoses (54) (Fig 18). The risk of pulmonary infarction is higher during the im-mediate postoperative period. The prognosis of postoperative acquired pulmonary vein stenosis is poor, and the condition may lead to pulmo-nary graft failure; however, good results have been reported with angioplasty and stent place-ment (54,55).

Pulmonary Venous HypertensionPulmonary venous hypertension, a finding es-tablished at pressures of 15 mm Hg or greater, is


Figure 19. Mitral and aortic valve disease in a 74-year-old man presenting with dyspnea on exertion who underwent multidetector CT. (a) Coronal maximum intensity projection image shows increased diameters of the superior pulmonary vessels (arrows), a finding that was due to vascular redistribution caused by heart failure with pulmonary venous hypertension. (b) Axial multidetector CT image (lung window) shows septal thickening (arrows) and a bilateral pleural effusion (*) that is more prominent on the right side.

due to an increase in the resistance to blood flow to more than the level of resistance of the pulmo-nary capillaries (56). The most frequent cause is chronic left ventricular failure (57,58), although there can be other cardiac causes, such as mitral valve stenosis, left atrial thrombus, left atrial neo-plasms (myxoma, sarcoma, or metastasis), and congenital heart disease (58).

On chest radiographs of patients with early left ventricular failure, the diameters of the su-perior and inferior pulmonary veins may be sim-ilar. As pulmonary vascular pressure increases, the diameter of the superior pulmonary veins increases with respect to the diameter of the

inferior pulmonary veins as a result of flow re-distribution. Interstitial pulmonary edema with septal thickening then develops and, ultimately, alveolar edema, with poorly defined confluent pulmonary opacities that appear and disappear rapidly and change in distribution during a short period of time (56,58).

The CT findings in pulmonary venous hyper-tension include interlobular septal thickening, pleural effusion, and pulmonary edema (Fig 19). Pulmonary arterial hypertension may mani-fest with the retrograde transmission of elevated

Figure 18. Bilateral lung transplantation in a 50-year-old man. Axial contrast-enhanced multidetector CT image (mediastinal window) shows considerable stenosis (arrow) of the right superior pulmonary vein. The patient underwent repeat surgery, and a thrombus compressing the right superior pulmonary vein was discovered.


Figure 20. Veno-occlusive disease and pulmonary arterial hypertension in a 35-year-old woman who was awaiting lung transplantation. (a) Axial multidetector CT image (lung window) shows subtle cen-trilobular nodules in both upper lobes, a finding that was more prominent on the right side. (b) Axial multidetector CT image (lung window) centered in the left lower lobe also shows centrilobular nodules with isolated septal thickening (arrows).

venous pressures through pulmonary capillaries (57). In pulmonary venous hypertension caused by left-sided heart disease, the left atrium is of-ten dilated, whereas this finding is rarely seen in veno-occlusive pulmonary disease.

Veno-occlusive pulmonary disease, another possible cause of pulmonary venous hyperten-sion, is characterized histologically by organized and recanalized thrombi and eccentric intimal fibrosis in the pulmonary veins and venules (57). This condition predominantly affects children and young adults, and its etiology is unknown. The clinical manifestations are (a) slowly pro-gressive dyspnea, which is the most common symptom, and (b) episodes of acute pulmonary edema (57,59).

CT findings indicative of pulmonary arterial hypertension, along with interstitial and alveolar edema, are characteristic of veno-occlusive pul-monary disease (57). The main CT features are a small central pulmonary vein, interlobular septal thickening, patches of centrilobular ground-glass opacities, right ventricular dilatation, pleural effu-sion, and mediastinal lymphadenopathy (57) (Fig 20). Patients with veno-occlusive pulmonary dis-ease treated with vasodilator drugs are at a risk of developing fatal pulmonary edema (60); hence, diagnosis of the disease is important in these pa-

tients. Lung transplantation is the treatment of choice in severe cases because it offers the only real possibility for cure (59).

Pulmonary Vein ThrombosisPulmonary vein thrombosis is a rare but poten-tially serious condition. Acquired pulmonary vein thrombosis can have various causes, including pulmonary neoplasm, surgical complications of lung transplantation or lobectomy, radiofre-quency ablation complications, fibrosing medi-astinitis, or mitral stenosis with a left atrial clot (61). The signs and symptoms are nonspecific, and the clinical manifestations may be acute (pul-monary infarction) or more insidious (progressive or recurrent pulmonary edema) (61,62).

The most frequent malignant cause of pulmo-nary vein thrombosis is a primary lung neoplasm (Fig 21). However, pulmonary vein thrombosis can also occur in relation to metastatic sarcoma (62,63). Factors that may contribute to thrombo-sis secondary to neoplasm are a hypercoagulable state or mechanical compression of a pulmonary vein (63). Systemic embolization can occur when a tumor invades a pulmonary vein (63). Chest ra-diographs may yield variable nonspecific findings, such as pulmonary opacities, pleural effusion, and interstitial opacities. Both CT and MR imag-ing are effective for depicting the thrombus (63).

Postoperative pulmonary vein thrombosis may be seen in patients undergoing lobectomy


Figure 22. Non–small cell primary lung carcinoma in a 76-year-old man who was surgically treated with left pneumonectomy. Axial contrast-enhanced multi-detector CT image depicts a thrombus (arrow) in the postoperative stump of a left pulmonary vein. Multi-detector CT performed at 4 months after surgery (im-age not shown) disclosed that the thrombus had pro-gressed, although the patient remained asymptomatic.

Figure 21. Non–small cell lung neoplasm in an 80-year-old man who underwent contrast-enhanced multidetector CT. (a) Coronal multiplanar reconstruction im-age shows a mass (*) in the left upper lobe that extends toward the left superior pulmonary vein (arrow). (b) Coronal dual-modality image obtained with com-bined positron emission tomography and CT depicts the pulmonary mass, with intense uptake of fluorine 18 fluorodeoxyglucose, extending toward the left supe-rior pulmonary vein. These findings are consistent with a tumor thrombus (arrow).

or lung transplantation (64,65). In patients un-dergoing lobectomy, pulmonary vein thrombosis often occurs in the early postoperative period (66); and in patients who have undergone lung

transplantation, 15% of cases of pulmonary vein thrombosis manifest during the first 48 hours (67). Pulmonary vein thrombosis can lead to gangrene of the lung and can require a repeat intervention, although development of collateral circulation through the intercostal veins may prevent this complication (64). Clinical follow-up of surgical patients is important to detect complications. Thrombosis of the pulmonary vein stump sometimes occurs after pneumo-nectomy (Fig 22). This occurrence is similar to postoperative thrombosis of a pulmonary artery stump. Neither circumstance has clinical importance.

Idiopathic pulmonary vein thrombosis has been described in cases of hemoglobinopathy (68). The symptoms are nonspecific, as in other causes of pulmonary vein thrombosis, and the potential complications include pulmonary gan-grene, peripheral embolus, and massive hemop-tysis (68–70). The diagnosis can be established with (a) transesophageal echocardiography, (b) MR imaging, which can distinguish between tumor and thrombus, and (c) CT after injection of intravenous contrast material in the late phase to reduce flow artifacts (68) (Fig 23).


Figure 24. Rheumatic mitral valve stenosis treated with a mitral valve prosthesis in a 68-year-old woman who had atrial fibrillation. Axial nonenhanced multidetector CT image shows extensive wall calcifications (arrows) in the right superior pulmonary vein and left atrium.

Figure 23. Polycythemia vera in a 62-year-old woman with multiple previous thrombotic episodes who presented to the emergency room with chest pain and dyspnea. (a) Axial contrast-enhanced mul-tidetector CT image obtained in the early (arterial) phase shows filling defects (arrows) in the subseg-mental branches of the left inferior pulmonary artery, findings related to a pulmonary thromboembolus. (b) Axial contrast-enhanced multidetector CT image obtained during the late (venous) phase depicts a thrombus (arrow) in one branch of the right superior pulmonary vein. The patient was treated with anti-coagulant drugs, and both the arterial and the venous thrombi ultimately resolved.

Pulmonary Vein CalcificationsPulmonary vein calcifications are rare and have been described in two clinical situations: mitral valve diseases of rheumatic origin and chronic renal failure (71,72). Pulmonary vein calcifica-tion in long-term rheumatic mitral valve disease is associated with atrial fibrillation, considerable left atrial dilatation, a high prevalence of dyspnea, and a female predominance (71). Calcifications related to chronic renal failure are associated with cardiac arrhythmias and are due to deposits of extraskeletal metastatic calcium (72).

Pulmonary vein calcifications may be more prevalent in patients with atrial fibrillation, and these calcifications play a role in the pathogenesis of the atrial fibrillation. In a study of patients with atrial fibrillation who were examined with

electron-beam CT, pulmonary vein calcifications were observed in 16.6% of patients with nonval-vular atrial fibrillation refractory to pharmaco-logic treatment (73).

The CT diagnosis of pulmonary vein calcifica-tions is based on the presence of left atrial dilata-tion and extensive calcifications in the left atrial


wall. The calcifications sometimes occur in the form of “moldlike” calcifications that extend into the interatrial septum and the distal portion of the pulmonary vein (71) (Fig 24).

Collateral CirculationIn superior vena cava obstruction or pulmo-nary vein stenosis, the pulmonary veins may be involved in collateral circulation (74–77). Sys-temic-to-pulmonary venous shunts sometimes develop in cases of superior vena cava obstruc-tion, usually as a result of malignant causes, although such shunts may also be secondary to benign conditions (74,75). Systemic-to-pulmo-nary venous shunts have been observed in 9% of cases of superior vena cava syndrome with col-lateral circulation (76).

Systemic-to-pulmonary venous shunts can be anatomic, congenital, or acquired (74,75). In the anatomic type, the bronchial veins and pulmonary veins are connected through a preexisting bron-chial venous plexus located in the bronchial walls and peribronchovascular connective tissue. In the congenital type, there are three mechanisms of development: (a) anomalous pulmonary venous return with inverse blood flow, (b) an embryologic levoatriocardinal vein remnant that connects the posterior cardinal venous system to the pulmonary vein, or (c) a persistent left superior vena cava. The acquired type of systemic-to-pulmonary venous shunt consists of inflammation-induced newly formed vessels that connect subpleural portions of the pulmonary veins to intercostal veins through pleural adhesions (Fig 25).

At CT, particularly multidetector CT with three-dimensional reconstruction, the cause of the superior vena cava obstruction, its exact level, and other collateral pathways can be detected (75). Because a systemic-to-pulmonary venous shunt produces a right-to-left shunt, a systemic-to-pulmonary venous shunt should be considered in all patients with unexplained hypoxia; cardio-pulmonary symptoms may manifest in as many as 89% of cases (76).

ConclusionsThe pulmonary veins can be evaluated with several imaging techniques, among which multi-detector CT stands out because of its currently wide accessibility and excellent depiction of these vascular structures, even in nontargeted examina-tions. An understanding of the embryology and anatomy of the pulmonary veins is essential in certain clinical situations, such as evaluation of patients with atrial fibrillation who are candidates for radiofrequency ablation and assessment of congenital pulmonary vein anomalies.

Much can be learned from the pulmonary veins. Careful radiologic examination of these structures can be used to (a) distinguish condi-tions causing highly similar clinical manifesta-tions (eg, pulmonary vein stenosis caused by either malignant disease or fibrosing mediasti-nitis can lead to superior vena cava syndrome with similar symptoms), (b) differentiate be-tween diseases that do require treatment and

Figure 25. Right paratracheal mass correspond-ing to a primary lung neoplasm in a 71-year-old man who underwent contrast-enhanced multide-tector CT. Coronal maximum intensity projection image shows that the primary lung neoplasm caused obstruction of the superior vena cava (*) and that a collateral vein (arrows) connects the subpleural and intercostal circulations with the right superior pulmonary vein.


those that do not (eg, congenital conditions are rarely treated), (c) indicate the presence of silent pathologic conditions (eg, PAPVR detec-tion may be the clue to diagnosing atrial septal defect), and (d) provide useful information for deciding to treat with interventional therapy (eg, size of pulmonary arteriovenous malformation to indicate embolization) or medical therapy (eg, ruling out veno-occlusive pulmonary disease in candidates for vasodilator therapy). A great va-riety of diseases can affect the pulmonary veins, and some of these diseases are not completely understood. Classification of pulmonary venous pathologic findings into large groups may facili-tate the differential diagnosis.

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3. Dillman JR, Yarram SG, Hernandez RJ. Imaging of pulmonary venous developmental anomalies. AJR Am J Roentgenol 2009;192(5):1272–1285.

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5. Kato R, Lickfett L, Meininger G, et al. Pulmonary vein anatomy in patients undergoing catheter abla-tion of atrial fibrillation: lessons learned by use of magnetic resonance imaging. Circulation 2003;107 (15):2004–2010.

6. Kim YH, Marom EM, Herndon JE II, McAdams HP. Pulmonary vein diameter, cross-sectional area, and shape: CT analysis. Radiology 2005;235(1): 43–49; discussion 49–50.

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1

Stim In which

QUESTIONNAIRE A8 (15)

EMBRYOLOGY AND ANATOMY Question 1: A thorough understanding of pulmonary vein anatomy is important in which of the following clinical situations?

A: Pulmonary neoplasm B: Congenital disease C: Atrial fibrillation D: All of the above

Question 2: In normal conditions, the four pulmonary veins carry oxygenated blood from both lungs and drain into the left atrium as follows: [Tick the correct statements]

A: The right superior pulmonary vein drains the right upper and lower lobes

B: The left superior pulmonary vein drains the right upper lobe and lingula

C: The two inferior pulmonary veins drain the lower lobes

D: None of the above E: All of the above

Question 3: Which of the following statements are TRUE?

A: The pulmonary veins tend to be smaller in women B: The diameter of pulmonary veins generally

increases as they approach the left atrium C: The diameter of the left inferior pulmonary vein

generally decreases as it enters the atrium D: All of the above

Question 4: Various normal patterns and variations have been described in the study of pulmonary vein anatomy. Which of the following statements are TRUE?

A: The typical pattern is four pulmonary veins and four well-differentiated ostia

B: This configuration is seen in up to 50% of the population

C: Atypical anatomic patterns are found in approximately 38% of the population

D: The long left common trunk is the second most common normal anatomic pattern

E: Anatomic variants on the right side are common and tend to be more complex

IMAGING TECHNIQUES Question 5: Chest radiography can be used as the initial imaging modality for pulmonary vein assessment and is particularly useful in cases of pulmonary venous hypertension caused by left ventricular failure. Is this statement TRUE or FALSE?

A: TRUE B: FALSE

Question 6: Choose the correct statement(s).

A: Training and experience are needed in the interpretation of radiographic images and echocardiographic examinations

B: Adequate images of the pulmonary veins cannot be obtained without cardiac gating

C: Patients with newer generation pacemakers or defibrillators can undergo MR imaging

D: All of the above

CONGENITAL CONDITIONS

Question 7: A finding at chest radiography of a small right lung, heart displacement to the right and the scimitar sign, is indicative of which of the following?

A: Right-sided PAPVR B: Left-sided PAPVR C: Pulmonary vein varix D: None of the above

Question 8: The finding on chest radiography of a pulmonary nodule mimic or mediastinal mass, is indicative of which of the following?

A: Scimitar syndrome B: Levoatriocardinal vein C: Pulmonary vein varix D: Pulmonary arteriovenous malformation

LEARNING FROM THE PULMONARY VEINS

INSTRUCTIONS Read through the article and answer the multiple choice questions provided here. Questions are based on the reading material only

and therefore no additional research needs to be done

Please note that some questions may have more than one answer; in the case of the latter please “tick” every correct answer.

When done, fax through only your answer sheet to the fax number given on the answer sheet and wait for your 24hour receipt of confirmation SMS.

2

AQUIRED CONDITIONS Question 15: Is the following statement TRUE or FALSE? “Pulmonary vein stenosis or obstruction may be difficult to manage, and the mortality rate is considerable”

A: TRUE B: FALSE

Question 16: Is it TRUE that extension of a lung neoplasm to the left atrium through a pulmonary vein can result in death caused by cardiac arrest or massive systemic tumor embolization of multiple organs?

A: TRUE B: FALSE

Question 17: Which of the following are CT signs of pulmonary vein and left atrial invasion?

A: Absence of depiction of the pulmonary vein and its entrance into the left atrium

B: A left atrial filling defect with contrast material uptake

C: Continuity between the pulmonary tumor and the left atrial filling defect

D: All of the above Question 18: Is it TRUE that in primary neoplasms the most reliable sign of intrapericardial invasion of a pulmonary vein is obliteration of the pulmonary vein close to its entrance into the left atrium, especially in the case of a superior pulmonary vein?

A: YES B: NO

Question 19: Chest radiographs of patients with fibrosing mediastinitis usually show which of the following nonspecific findings?

A: Mediastinal or hilar calcifications B: Increased diameter of the pulmonary artery C: Narrowing of the mediastinum D: Pulmonary opacities

Question 20: Is it TRUE or FALSE that at CT, two forms of mediastinitis are seen: focal (18%) and diffuse (82%)?

A: TRUE B: FALSE

Question 9: Because there is no vascular shunt, no treatment is required for an anomalous unilateral single pulmonary vein. For this reason, it is important to differentiate this condition from others that may require treatment. Is this statement TRUE or FALSE?

A: TRUE B: FALSE

Question 10: Which of the following are TRUE with reference to congenital unilateral pulmonary vein stenosis or atresia?

A: It shows a predilection for the left side B: Chest radiographs may show a small lung and

reticular opacities with Kerley B lines C: The presenting symptoms in children can include

recurrent pulmonary infection, dyspnea on exertion and, occasionally, hemoptysis

D: All of the above Question 11: Is it TRUE that chest radiographs of pulmonary vein varix show a well-defined nodular opacity without calcifications?

A: YES B: NO

Question 12: Which of the following are TRUE with reference to PAPVR?

A: Patients are generally symptomatic B: Left-sided PAPVR seems to be found more often

in children, whereas right-sided PAPVR is reported more commonly in adults

C: Detection of PAPVR may be important in patients who are candidates for lobectomy to treat a primary pulmonary neoplasm

D: All of the above Question 13: The radiographic finding of a curved opacity lateral to the right cardiac border and extending toward the inferior vena cava, with the opacity increasing in diameter caudally as it approaches the inferior vena cava, is known as which of the following?

A: Blade sign B: Scimitar sign C: Sword sign

Question 14: Which of the following are TRUE with reference to

pulmonary arteriovenous malformation?

A: A malformation larger than 2cm may present with hypoxia, brain infarction or abscess and paradoxical embolism

B: More than 70% of malformations involve a single artery and a single vein

C: On radiographs, a malformation may resemble a pulmonary nodule

3

Question 21: Which of the following are TRUE with reference to radiofrequency ablation?

A: Pulmonary vein stenosis is found in 10% – 25% of

patients who undergo this treatment

B: The complication of stenosis should be suspected

in any patient who has received this treatment

and presents with respiratory symptoms such as

dyspnea or hemoptysis

C: These symptoms present one to two weeks after

the procedure

D: All of the above

Question 22: Contrast enhanced CT can enable the diagnosis by directly depicting the stenosis and which of the following associated features?

A: Pulmonary parenchymal septal thickening

B: Peripheral opacities

C: Increased attenuation of mediastinal fat adjacent

to the stenosis

D: All of the above

Question 23: Portal venous hypertension is established at which pressure?

A: 5 mm Hg or more

B: 10 mm Hg or more

C: 15 mm Hg or more

Question 24: On chest radiographs of patients with early left ventricular failure, which of the following are found?

A: The diameters of the superior and inferior

pulmonary veins differ markedly

B: As pulmonary vascular pressure increases, the

diameter of the superior pulmonary veins

increases with respect to the diameter of the

inferior pulmonary veins

C: Interstitial pulmonary edema with septal

thickening then develops

Question 25: What are the main CT features of veno-occlusive pulmonary disease?

A: Pleural effusion

B: Mediastinal lymphadenopathy

C: A small pulmonary vein

D: Right ventricular dilatation

E: All of the above

Question 26: Is it TRUE that with reference to pulmonary vein thrombosis, chest radiographs may yield specific findings?

A: YES

B: NO

Question 27: Diagnosis of idiopathic pulmonary vein thrombosis can be established through which of the following?

A: Transesophageal echocardiography B: MR imaging which can distinguish between tumor and thrombus C: CT after injection of intravenous contrast material in the late phase to reduce flow artefacts D: US E: Radiography

Question 28: Which of the following are TRUE with reference to pulmonary vein calcifications?

A: It is a common occurrence

B: It has been described in many clinical situations

C: It may be more prevalent in patients with atrial

fibrillation

D: All of the above

Question 29: Is it TRUE that the CT diagnosis of pulmonary vein calcifications is based on the presence of left atrial dilatation and extensive calcifications in the left atrial wall?

A: YES

B: NO

4

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A8 (15) LEARNING FROM THE PULMONARY VEINS

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