纵隔淋巴结CT

PICTORIAL REVIEW CT of thoracic lymph nodes. Part I: anatomy and drainage 1T SUWATANAPONGCHED, MD and 2D S GIERADA, MD 1Department of Radiology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, 270, Rama VI Road, Rajthevi, Bangkok 10400, Thailand and 2Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 South Kingshighway Blvd, Campus Box 8131, Saint Louis, Missouri 63110, USA ABSTRACT. CT is the primary non-invasive technique for the diagnostic evaluation of thoracic lymph nodes. The CT patterns and anatomic location of thoracic lymph node involvement can provide important clues in the diagnosis of many diseases. Part I of the pictorial review illustrates the anatomic location and drainage of thoracic lymph nodes in the chest wall, mediastinum and lungs through examples of pathologic involvement. Part II of the pictorial review focuses on CT patterns of lymph node involvement in various pulmonary and extrapulmonary diseases, differential diagnoses based on CT findings and pitfalls. Received 11 April 2005 Revised 23 June 2005 Accepted 11 July 2005 DOI: 10.1259/bjr/26411607 ’ 2006 The British Institute of Radiology CT is the primary non-invasive technique for the diagnostic evaluation of thoracic lymph nodes. Lymph node abnormalities are depicted by CT as an increase in nodal size and/or number or change in attenuation. Although these findings are non-specific, patterns of thoracic lymph node involvement can provide important clues in the diagnosis of many pulmonary and extra- pulmonary diseases. Part I of this pictorial review illustrates the anatomic location and drainage of thoracic lymph nodes in the chest wall, mediastinum and lungs through examples of pathologic involvement. Part II focuses on CT patterns of lymph node involvement in various pulmonary and extrapulmonary diseases. Classification of thoracic lymph nodes As in other parts of the body, thoracic lymph nodes are named using descriptive terminology according to the blood vessels or visceral structures to which they are most closely related, or by their general anatomic location. Although there are slight differences in the classification of the thoracic nodes [1–5], they can be divided into those of the chest wall and those of the intrathoracic contents. To facilitate accurate pathologic staging and analysis of treatment outcomes in lung cancer, a classification scheme for mediastinal and pulmonary lymph nodes (Figure 1) has been devised by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer (UICC) [5], based on surgically recognizable anatomic landmarks. Chest wall nodes The axillary nodes (Figures 2 and 3) receive superficial lymphatic drainage from the upper limbs, breasts and pectoral muscles excluding their medial portions, pari- etal pleura, and skin and muscles of the trunk above the umbilicus and iliac crest [1, 2]. The lymph flow is directed toward the terminal nodal group in the axillary apices. The efferent vessels from this group unite as the subclavian trunk, which finally drains directly or indi- rectly into the jugulo-subclavian venous confluence [1, 2, 6]. A few efferents usually reach the supraclavicular nodes, a well-recognized route for the spread of breast cancer [1, 2, 6]. The internal mammary (internal thoracic or paraster- nal) nodes (Figure 4) lie at the anterior ends of the intercostal spaces, along the internal mammary (internal thoracic) vessels. They receive lymphatic drainage from the anterior diaphragmatic nodes, anterosuperior por- tion of the liver, medial part of the breasts, and deeper structures of the anterior chest and upper anterior abdominal wall [2]. Their efferent channels may empty into the right lymphatic duct, the thoracic duct, or the inferior deep cervical nodes [3, 6]. The posterior intercostal nodes (Figures 5 and 6), located near the heads and necks of the posterior ribs, receive lymphatic drainage from the posterolateral intercostal spaces, posterolateral breasts, parietal pleura, vertebrae and spinal muscles [2–4]. The efferent vessels from the upper intercostal spaces end in the thoracic duct on the left, and in one of the lymphatic trunks on the right [2–4]. Those from the lower four to seven intercostal spaces unite to form a common trunk, which empties into the thoracic duct or cisterna chyli [2–4]. The juxtavertebral (pre-vertebral or paravertebral) nodes lie along the anterior and lateral aspects of the vertebral bodies, most numerous from T8 to T12 (Figures 5 and 6) [3, 4]. They communicate with posterior mediastinal lymph nodes [3] and the posterior intercostal nodes, and similarly drain to the right lymphatic duct or thoracic duct [3, 4].Address correspondence to: D S Gierada. The British Journal of Radiology, 79 (2006), 922–928 922 The British Journal of Radiology, November 2006 The diaphragmatic nodes are located on or just above the thoracic surface of the diaphragm and are divided into three groups [2–4, 7]. The anterior (pre-pericardial or cardiophrenic) group (Figure 6) is located anterior to the pericardium, posterior to the xiphoid process, and in the right and left cardiophrenic fat. This node group receives afferent drainage from the anterior part of the diaphragm and its pleura, and the anterosuperior portion of the liver. They drain to the internal mammary nodes alongside the xiphoid and can provide a route for retrograde spread of breast cancer to the liver, via lymphatics of the rectus abdominis muscle when the upper internal thoracic trunks are blocked [4]. The middle (juxtaphrenic or lateral) (Figure 7) group receives lymph from the central diaphragm and from the convex surface of the liver on the right [2]. The posterior (retrocrural) group (Figure 8), lying behind the dia- phragmatic crura and anterior to the spine, receives lymph from the posterior part of the diaphragm and communicates with the posterior mediastinal nodes and para-aortic nodes in the upper abdomen [2, 4]. When diaphragmatic nodes are enlarged, widespread disease in other locations is usually present, so biopsy of these sites is uncommon [7]. Mediastinal lymph nodes Anterior mediastinal group This group includes the highest mediastinal (station 1, Figures 1 and 3a), pre-vascular (station 3A, Figures 1 and 3b), and para-aortic (station 6, Figures 1 and 9) (b)(a) Figure 1. Revised American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer (UICC) regional nodal stations for lung cancer staging. (From Mountain CF, Dresler CM. Regional lymph node classification for lung cancer staging. Chest 1997;111:1718–23 [5]. Reprinted with permission). (a) Drawing illustrates mediastinum lymph node stations in the frontal projection. Ao 5 aortic arch, PA 5 main pulmonary artery, 1 (red) 5 highest mediastinal nodes, 2R and 2L (dark blue) 5 right and left upper paratracheal nodes, 4R and 4L (orange) 5 right and left lower paratracheal nodes, 7 (blue) 5 subcarinal nodes, 8 (grey) 5 para-oesophageal nodes, 9 (brown) 5 pulmonary ligament nodes, 10R and 10L (yellow) 5 right and left hilar nodes, 11R and 11L (green)5 right and left interlobar nodes, 12R and 12L (pink)5 right and left lobar nodes, 13R and 13L (pink) 5 right and left segmental nodes, 14R and 14L (pink)5 right and left subsegmental nodes. (b) Illustration of mediastinum lymph node stations in the left anterior oblique projection. Ao 5 aortic arch, PA 5 main pulmonary artery, 3 (pink) 5 pre-vascular and retrotracheal nodes, 5 (black) 5 subaortic nodes, 6 (red) 5 para-aortic nodes. Figure 2. Enhanced CT scan in a 66-year-old woman with lymphoma showing multiple enlarged bilateral axillary lymph nodes (arrows). Pictorial review: CT of thoracic lymph nodes The British Journal of Radiology, November 2006 923 (b)(a) Figure 3. A 65-year-old man with chronic lymphocytic leukaemia. (a) Enhanced CT scan demonstrates enlarged right axillary nodes (arrowheads) and right interpectoral (Rotter) node (black arrow) lying between pectoralis major (M) and minor (m) muscles. Nodes in the subpectoral and interpectoral regions are included in the axillary nodal group. Also seen are enlarged highest mediastinal nodes (station 1; white arrows) defined by their location cranial to the superior margin of the left brachiocephalic vein, behind and to the right and left sides of the trachea. (b) Enhanced CT scan at the lower level shows bilaterally enlarged axillary nodes (arrowheads), including left subpectoral nodes (open arrow) underneath the left pectoralis minor muscle (m). There are enlarged pre-vascular nodes (station 3A; white arrows), which lie between the superior margin of the left brachiocephalic vein (V) and the superior margin of the aortic arch, and anterior to its large arterial branches; enlarged retrotracheal node (station 3P; black arrow), which lies behind the trachea and above the inferior aspect of azygos vein arch; and enlarged right upper paratracheal nodes (station 2R; wavy arrow), which are located above the superior margin of the aortic arch. Figure 4. Enhanced CT scan at the level of the main pulmonary artery in a 55-year-old woman with left breast cancer demonstrating enlarged left internal mammary node (arrow). Note normal right internal mammary vessels (wavy arrow) and a portion of primary cancer in the left breast (asterisk). Figure 5. Enhanced CT scan of a 31-year-old man with lymphoma showing enlarged, necrotic right and left inter- costal nodes (white arrows) as well as enlarged left paravertebral (arrowheads) and retrocrural (black arrows) nodes. Note a left pleural effusion (E) with pleural nodules (small white arrows), splenectomy clips and coeliac adeno- pathy (N). A 5 aorta. T Suwatanapongched and D S Gierada 924 The British Journal of Radiology, November 2006 nodes [2, 3, 5, 8]. They receive afferent vessels from the thymus, thyroid, heart and pericardium, diaphragmatic and mediastinal pleura, and middle diaphragmatic nodes [2, 3]. Their efferent channels join those from the paratracheal, tracheobronchial and internal mammary nodes, to form the right and left bronchomediastinal trunks, which may empty to the right lymphatic duct, the thoracic duct, or open independently into the jugulo- subclavian venous confluence [2, 3]. Paratracheal and tracheobronchial groups These groups receive drainage from most parts of the lungs and bronchi, thoracic trachea, heart and some efferents from the upper para-oesophageal nodes of the posterior mediastinal group [2, 4]. The nodes comprising these groups include the upper (station 2R, 2L, Figures 1 and 3b) and lower (station 4R, 4L, Figures 1, 9 and 10) paratracheal, subaortic (aortopulmonary window, sta- tion 5, Figures 1, 11, and 12), retrotracheal (station 3P, Figures 1 and 3b), and subcarinal (station 7, Figures 1 and 12) nodes [2, 3, 5]. The azygos node, located medial to the azygos arch, is included in station 4R [5]. The upper paratracheal nodes link the lower paratracheal and inferior deep cervical nodes [10]. The subcarinal nodes are contiguous with the hilar nodes and drain to the paratracheal nodes, preferentially to the right [11]. Figure 6. Enhanced CT scan in a 69-year-old woman with lymphoma showing enlarged bilateral paravertebral nodes (white arrows), left intercostal node (open arrow) and anterior diaphragmatic nodes (black arrows). Note bilateral pleural effusions (E). Figure 7. Non-enhanced CT scan in a 28-year-old woman with metastatic papillary serous adenocarcinoma of the ovary revealing enlarged, densely calcified right middle diaphragmatic nodes (arrow), located lateral to the intrathoracic end of the inferior vena cava (V) and near the insertion of the right phrenic nerve. Figure 8. CT scan through the upper abdomen in a 45-year- old man with distal oesophageal carcinoma (not shown) revealing enlarged retrocrural lymph nodes (large arrows) and liver metastases (small arrows). Figure 9. Non-enhanced CT scan in the same patient as in Figure 7 revealing enlarged, calcified para-aortic nodes (station 6; arrows), lying anterior and lateral to the aortic arch (A) below its superior margin. Also seen is right lower paratracheal lymphadenopathy (station 4R; open arrow). V 5 superior vena cava. (From Glazer HS, Molina PL, Siegel MJ, Sagel SS. High-attenuation mediastinal masses on unen- hanced CT. AJR Am J Roentgenol 1991;156:45–50 [8]. Reprinted with permission). Pictorial review: CT of thoracic lymph nodes The British Journal of Radiology, November 2006 925 Figure 10. Enhanced CT scan in a 73-year-old man with left lower lobe lung cancer (not shown) showing enlarged right lower paratracheal nodes (large arrow) lying medial to the azygos vein (V) and enlarged left lower paratracheal nodes (station 4L; open arrow) lying medial to ligamentum arteriosum (small arrows). Lower paratracheal nodes lie caudal to the top of the aortic arch. (From Sagel SS, Slone RM. Lung. In: Lee JKT, Sagel SS, Stanley RJ, Heiken JP, editors. Computed body tomography with MRI correlation, 3rd edn. Philadelphia, PA: Lippincott-Raven Publishers, 1998:351–454 [9]. Reprinted with permission). Figure 11. Enhanced CT scan in a 58-year-old woman with carcinoid tumour showing enhancing subaortic lymphade- nopathy (station 5; arrows) within the aortopulmonary window region. This group is located lateral to the ligamentum arteriosum (not seen). Note primary tumour in the left upper lobe (open arrow). Figure 12. Enhanced CT scan in a 65-year-old man with diffuse pulmonary lymphangitic carcinomatosis secondary to non-small cell lung cancer (not shown) demonstrating enlarged subcarinal (station 7; curved arrow), para-oesopha- geal (black arrow), right hilar (station 10R; large white arrows) and left hilar (station 10L; open arrow) nodes. Hilar nodes are outside the mediastinal pleura, below the top of the upper lobe bronchi. Note enlarged subaortic (arrow- head) and para-aortic (small white arrow) nodes. Oe 5 oesophagus. Figure 13. Enhanced CT scan in a 65-year-old man with non- small cell lung cancer demonstrating metastasis to left pulmonary ligament node (station 9; curved arrow) from left lower lobe lung cancer (straight arrow). Oe 5 oesopha- gus, A 5 aorta. (From Sagel SS, Slone RM. Lung. In: Lee JKT, Sagel SS, Stanley RJ, Heiken JP, editors. Computed body tomography with MRI correlation, 3rd edn. Philadelphia, USA: Lippincott-Raven Publishers, 1998:351–454 [9]. Reprinted with permission). T Suwatanapongched and D S Gierada 926 The British Journal of Radiology, November 2006 Thus, the left lower lobe is the most common primary site for contralateral mediastinal lymph node metastasis in lung cancer. Posterior mediastinal group The posterior mediastinal nodes are comprised of the para-oesophageal (station 8, Figures 1 and 12) and pulmonary ligament (station 9, Figures 1 and 13) nodes [4, 5]. The para-oesophageal nodes receive afferent vessels from the thoracic oesophagus, posterior pericar- dium, diaphragm, posterior diaphragmatic nodes and the left hepatic lobe, and are more numerous on the left [2]. The pulmonary ligament nodes receive drainage from the basilar segments of the lower lobes and lower half of the oesophagus [4]. The efferents from the posterior mediastinal nodes communicate with the tracheobronchial group, particularly subcarinal nodes, and drain chiefly into the thoracic duct, but also drain to the subdiaphragmatic para-aortic or coeliac nodes [3, 4]. Lymph nodes of the lungs Lymph nodes are located along the bronchi and can be divided into hilar (station 10R, 10L, Figures 1 and 12) and intrapulmonary nodes [5, 10]. The latter consist of interlobar (station 11R, 11L, Figures 1 and 14), lobar (station 12R, 12L, Figures 1 and 14), segmental (station 13R, 13L, Figures 1, 14 and 15), subsegmental (station 14R, 14L, Figures 1 and 16) and intraparenchymal intrapulmonary (Figure 17) nodes [5, 9, 12]. Most of the lymphatic flow of the lungs is directed toward the interlobar and hilar nodes, which drain into the subcarinal nodes or directly into the lower paratracheal nodes [3, 4, 10, 11]. The normal hilar and interlobar nodes are frequently visible, particularlywith thinner (1–3 mm) collimation and intravenous contrast administration [13]. Recognition of these nodes is important to avoid misdiagnosis of pulmonary embolism. Intraparenchymal intrapulmonary nodes may present as indeterminate subpleural pulmon- ary nodules in the lower parts of the lungs [12]. Figure 14. Enhanced CT scan in a 29-year-old woman with sarcoidosis demonstrating enlarged right lobar node (station 12R; arrowhead) at the bifurcation of the bronchus inter- medius, right segmental node (open arrow) adjacent to the right middle lobe lateral segmental bronchus, and left interlobar nodes (station 11R and 11L; white arrows) between the lingular and left lower lobe superior segmental bronchus. Note enlarged subcarinal nodes (black arrows) and bilateral pulmonary involvement. Figure 15. Enhanced CT scan in the same patient as in Figure 12 showing enlarged right and left segmental nodes (station 13R and 13L; large white arrows) lying adjacent to the segmental bronchi (small white arrows) and enlarged para-oesophageal nodes (black arrows). Figure 16. Axial CT scan with lung-window setting in a 59- year-old man with myocardial infarction showing a 1 cm, indeterminate, solitary pulmonary nodule containing an eccentric calcific focus in the right middle lobe (arrow). Wedge resection revealed a subsegmental lymph node (station 14R) with calcified granuloma. Pictorial review: CT of thoracic lymph nodes The British Journal of Radiology, November 2006 927 References 1. Johnson D, Ellis H. Pectoral girdle and upper limb. In: Standring S, editor. Gray’s anatomy, 39th edn. Edinburgh, Scotland: Churchill Livingstone, 2005:817–49. 2. Johnson D, Shah P. Thorax. In: Standring S, editor. Gray’s anatomy, 39th edn. Edinburgh, Scotland: Churchill Livingstone, 2005:951–1079. 3. Fraser RS, Mu¨ller NL, Colman N, Pare´ PD. The lymphatic system of the lungs, pleura, and mediastinum. In: Fraser RS, Mu¨ller NL, Colman N, Pare´ PD, editors. Fraser and Pare´’s diagnosis of diseases of the chest, 4th edn. Philadelphia, PA: W.B. Saunders Company, 1999:172–95. 4. Weinberg JA. The intrathoracic lymphatics. In: Haagensen CD, editor. The lymphatics in cancer. Philadelphia, PA: W.B. Saunders Company, 1972:231–99. 5. Mountain CF, Dresler CM. Regional lymph node classifica- tion for lung cancer staging. Chest 1997;111:1718–23. 6. Haagensen CD. Lymphatics of the breasts. In: Haagensen CD, editor. The lymphatics in cancer. Philadelphia, PA: W.B Saunders Company, 1972:300–98. 7. Aronberg DJ, Peterson RR, Glazer HS, Sagel SS. Superior diaphragmatic lymph nodes: CT assessment. J Comput Assist Tomogr 1986;10:937–41. 8. Glazer HS, Molina PL, Siegel MJ, Sagel SS. High-attenuation mediastinal masses on unenhanced CT. AJR Am J Roentgenol 1991;156:45–50. 9. Sagel SS, Slone RM. Lung. In: Lee JKT, Sagel SS, Stanley RJ, Heiken JP, editors. Computed body tomography with MRI correlation, 3rd edn. Philadelphia, PA: Lippincott-Raven Publishers, 1998:351–454. 10. Nohl-Oser HC. Surgery of the lung, general management and operative technique. In: Nohl-Oser HC, editor. Surgery of the lung. New York, NY: Thieme-Stratton Inc., 1981:38– 184. 11. Shields TW. Mediastinal lymph nodes. In: Shields TW, editor. Mediastinal surgery. Philadelphia, PA: Lea & Febiger, 1991:14–8. 12. Bankoff MS, McEniff NJ, Bhadelia RA, Garcia-Moliner M, Daly BDT. Prevalence of pathologically proven intrapul- monary lymph nodes and their appearance on CT. AJR Am J Roentgenol 1996;167:629–30. 13. Shimoyama K, Murata K, Takahashi M, Morita R. Pulmonary hilar lymph node metastases from lung cancer: evaluation based on morphology at thin- section, incremental, dynamic CT. Radiology 1997;203: 187–95. (b)(a) Figure 17. A 58-year-old man with bronchioloalveo