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Dr.Héctor Domínguez Hernández
Residente Imagenología
Platica básica acerca de las estructuras que conforman la silueta cardíaca, mediciones básicas en la placa simple, incluye también mediastina e hilios pulmonares.

Dr.Héctor Domínguez Hernández
Residente Imagenología
Platica básica acerca de las estructuras que conforman la silueta cardíaca, mediciones básicas en la placa simple, incluye también mediastina e hilios pulmonares.

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TORAX 2 PARTE (SILUETA CARDIACA E HILIOS)

  1. 1. Dr.Héctor Domínguez Hernández Residente Imagenología, Diagnóstica y Terapéutica TÓRAX
  2. 2. phy, etc.), its aperture is increased (Fig. 1.12). 1 Course of the thoracic aorta. The retrocardiac descending aorta can be as a paravertebral band shadow (arrows). This should be distinguished from avertebral secondary shadow (arrowheads). a b c Fig. 1.12a–c Shape of the aortic arch. Depending on the rotation of the film or the degree of elongation (as in hypertension), the projection of the aortic arch is perpendicular or oblique to the imaging plane. ANATOMÍA CARDÍACA • Proyección PA. • La concavidad prominente del mediastino entre la hora 1 y 2 corresponde al arco aórtico. • La aorta sigue un curso retrocardiáco descendente , puede ser identificada caudalmente como una banda paravertebral ancha.
  3. 3. a b c Fig. 1.12a–c Shape of the aortic arch. Depending on the rotation of the film or the degree of elongation (as in hypertension), the projection of the aortic arch is perpendicular or oblique to the imaging plane. La forma del arco aórtico depende significativamente de la posición de la proyección. Cuando existe rotación izquierda, la apertura del arco pórtico disminuye; en la rotación derecha, la apertura se incrementa. ARCO AÓRTICO
  4. 4. Fig. 1.13 Plain posteroanterior chest radiograph in a 22-year-old woman (examination following contact with tuberculosis patients). Typical cardiopulmonary findings for this age group. The upper margin of the left cardiomediastinal silhouette is formed by the aortic arch (black arrows), the left pulmonary artery (white arrows), and the atrial appendage (black arrowheads). La ventana aortopulmonar, es típicamente cóncava, cualquier convexidad que protruya en esta localización debe ser interpretada como sugestivo de masa.
  5. 5. BORDE CARDIÁCO IZQUIERDO
  6. 6. General BORDE CARDIÁCO IZQUIERDO
  7. 7. Fig. 1.15 Ill-defined cardiac border with a pleuropericardial callus on the left side. Moderately enlarged left heart without signs of decompensation with slight shadowing in chronic emphysematous bronchitis. The cardiac silhouette is obliter- ated at the typical locations. Fig. 1.16 CT image (detail enlargement) of a pleuroper Narrow projection of pericardial fatty tissue with normal ad Note that the terminal segment of the left cardiac border above the diaphragm is often ill-defined (Fig. 1.14). This is due to the calluses or epicardial fat or connective tissue found here (Fig. 1.15). Large fat pads can simulate enlargement of the heart or an apical cardiac aneurysm. CT demonstrates the fat content clearly (Fig. 1.16). " In a healthy person, the left contour of the diaphragm is visible through the medial heart shadow as far as the paravertebral shadow. This is due to the difference in absorption at the inter- face between the air-filled lower lobe and the diaphragm, which has soft-tissue density (see silhouette sign, Chapter 3). a b c d Fig. 1.14a–d Ill-defined border of the left cardiac apex. The part of the left cardiac border adjacent to the diaphragm is often difficult to evaluate due to the projections of the pericardial fatty tissue (b) or calluses (c,d) located here. arc of the left cardiac border, extending as m (Fig. 1.17), is produced by the left ventri- train the right ventricle may occasionally ontour as well. To differentiate between ateral view must be obtained in the same ricle which is of normal size on the lateral te to the left cardiac border on the frontal al segment of the left cardiac border above en ill-defined (Fig. 1.14). This is due to the ial fat or connective tissue found here pads can simulate enlargement of the heart aneurysm. CT demonstrates the fat content the left contour of the diaphragm is visible heart shadow as far as the paravertebral o the difference in absorption at the inter- ir-filled lower lobe and the diaphragm, e density (see silhouette sign, Chapter 3). a El borde inferior de la silueta cardiaca es mal delimitado, debido a la presencia de grasa pericárdica.
  8. 8. BORDE CARDIÁCO IZQUIERDO
  9. 9. El ventrículo derecho generalmente no forma parte de la silueta cardiaca.
  10. 10. Fig. 1.21 Plain posteroanterior chest radiograph in a 22-year-old woman (examination following contact with tuberculosis patients). Typical cardiopulmonary findings for this age group. The right border of the cardiomediastinal shadow is formed by the right atrium (black arrows), ascending aorta (black arrowheads), and superior vena cava (white arrows). Farther cranially the cardiomediastinal shadow widens into a funnel shape, where its right border is formed by the brachiocephalic trunk General c border in adults is produced by the right atri- ng aorta (Fig. 1.18, Fig. 1.21). The various ana- that produce the right border of the cardiome- w are often difficult to distinguish from one heless, especially in elderly hypertensive pa- onounced aortic segment, these structures can differentiated by the notches they produce. onvexity of the right atrial segment decreases s rotated to the left (RAO, pectus excavatum, d shift of the heart axis is also seen in right resulting enlargement of the right heart can ked by leftward rotation. The distance between c border and the midsagittal line should be a e-third of the right hemithorax (Fig. 1.19). of the right cardiac border merges with the su- cranially at the 10-o’clock position. , the cardiomediastinal shadow widens into a e BORDE CARDIÁCO DERECHO
  11. 11. BORDE CARDIÁCO DERECHO
  12. 12. ÍNDICE CARDIOTORÁCICO Normal: <0.5 Grado I: 0.5-0.55 Grado II: 0.56-0.60 Grado III: >0.6 a b
  13. 13. VASOS PULMONARES 1. En condiciones normales los vasos pulmonares que irrigan a los segmentos superiores son más pequeños que los de las bases pulmonares. 2. Normalmente en los lóbulos superiores los vasos son de m e n o r t a m a ñ o q u e l o s bronquios con un radio de 0.85. 3. En el hilio son del mismo tamaño. 4. En las bases son mayores con un radio de 1.35. 5. El tamaño normal de los vasos superiores es de 1-2mm.
  14. 14. PEDÍCULO VASCULAR Debe medir menos de 60mm en la proyección PA.
  15. 15. RESUMEN EN MOGULS
  16. 16. PROYECCIÓN LATERAL General El borde cardiaco anterior esta formado por el ventrículo derecho. Y ocupa 1/3 de la distancia entre el manubrio del esternón y el diafragma.
  17. 17. PROYECCIÓN LATERAL
  18. 18. General PROYECCIÓN LATERAL El borde cardiaco posterior esta formado por el ventrículo y la aurícula izquierda. Espacio de Holzknecht.
  19. 19. PROYECCIÓN LATERAL
  20. 20. LOCALIZACIÓN DE LAS VÁLVULAS
  21. 21. Fig. 1.28 Visualization of th the left ventricular outflow tra as a whole and the left atrium Fig. 1.27 Visualization of the cardiac chambers on CT. The image clearly dem- onstrates the physiologic mismatch between the thick wall of the left ventricle and the fine wall of the right ventricle, which is normally practically invisible. CAMÁRAS CARDIÁCAS
  22. 22. Fig. 1.28 Visualization of the aortic root on CT. Paracoronal reconstruction ofe image clearly dem- ARCO AÓRTICO
  23. 23. HILIO PULMONAR El hilio pulmonar representa la unión del pulmón con el mediastino y se compone en un 99% de vasos pulmonares (arterias y venas). (más conocida como tronco anterior): • Vena del lóbulo superior: tiene un trayect anterior. Forma la mayor parte del perfil de la margen lateral de la porción superior del hilio • El tronco anterior se sitúa medial respecto a contribuye a la sombra hiliar. L e p b d s é E o 1 m c h E hacia la derecha que constituyen la región supe forma un ángulo llamado “angulo venoarterial superior es venosa y la inferior arterial (arteria int En el lado izquierdo la arteria pulmonar cruza po formado por el bronquio principal y el bronquio dividirse posteriormente en las arterias lobares su La porción inferior del hilio izquierdo está f izquierda que se sitúa inmediatamante por detrá izquierdo
  24. 24. HILIO PULMONAR
  25. 25. EL HILIO IZQUIERDO NUNCA DEBE SER MÁS BAJO QUE EL HILIO DERECHO.
  26. 26. MEDIASTINO 2. mediastino medio (vascular) 3. mediastino posterior (postvascular) Esta división del mediastino corresponde a regiones fácilmente reconocibles en la proyección lateral del tórax. En la proyección PA de torax podemos identificar los contornos del mediastino que A M P
  27. 27. o - n s r - e e a l e e - , o - a - l s l ; V e r t e b r a l M e d i o Retroesternal Cardiaco Superior Figura 2 Esquema. MEDIASTINO Espacio Superior Límites • Superior: Abertura torácica superior. • I n f e r i o r : B o r d e superior del arco aórtico. • Anterior: Manubrio Esternal. • Posterior: Columna Vertebral.
  28. 28. Radiografía lateral de tórax. Anatomía radiográfica TVBI TVBI TS T R AA E Ao A B a ÁREA VÁSCULAR TRIÁNGULO DE RAIDER ESPACIO SUPERIOR
  29. 29. TVBI C TB TB AA AA SI VS T R TVBI B C dad de convexidad posterior p Con la elongación de los tronco sidad y anchura de la sombra v Se ha descrito un «nódulo» en el 3% de los pacientes estu elongación de los troncos supra por su mayor tama˜no, el tronco sea la causa la mayoría de las aunque también es posible que la arteria subclavia izquierda (fi izquierda, última rama supraaó visible por detrás de la tráquea oblicua paralela a la pared traq b) El área retrotraqueal, tambié Raider20 , está limitada por dela posterior, por detrás por la car vertebrales, y por debajo por e aórtico (fig. 5A y C). Debe ser r lo forman la parte alta de amb frecuencia las escápulas lo cru dad vertical21 (fig. 5A). Su tam hábito de los pacientes. El enfi convierte en un espacio trapez Una variante de la densidad se produce cuando los troncos s TVBI C TB TB AA AA SI VS T R TVBI B C ESPACIO SUPERIOR
  30. 30. Banda Traqueal Posterior: Grosor máximo de 2.5mm Banda Taqueal Anterior: Grosor máximo de 2.5mm Banda Traqueoesofágica: Grosor máximo 5.5mm a pared posterior de la tráquea y la pared 1 y 2,5 mm6 . A B T E ea. A) Radiografía lateral (RL) de tórax con imagen de reconstrucción sagital de tomografía co anda traqueal posterior (flechas), visible hasta el arco de la vena ácigos (flecha fina). B) RL de ra la banda traqueoesofágica (flechas), visible cuando la pared posterior de la tráquea (T) cont asiones se puede ver una línea radiotrans- a pared posterior de la tráquea y la pared un lóbulo de la ácigos). Su grosor se consid 1 y 2,5 mm6 . A B T E uea. A) Radiografía lateral (RL) de tórax con imagen de reconstrucción sagital de tomografía co banda traqueal posterior (flechas), visible hasta el arco de la vena ácigos (flecha fina). B) RL de tra la banda traqueoesofágica (flechas), visible cuando la pared posterior de la tráquea (T) cont BANDA PARATRAQUEAL POSTERIOR BANDA TRAQUEOESOFÁGICA
  31. 31. o - n s r - e e a l e e - , o - a - l s l ; V e r t e b r a l M e d i o Retroesternal Cardiaco Superior Figura 2 Esquema. MEDIASTINO Espacio Anterior Límites • Superior: Margen Superior del Arco Aórtico. • Inferior: Superficie diafragmática. • Anterior: Cuerpo del Esternón. • Posterior: Traquea y B o r d e c a r d i a c o posterior.
  32. 32. V e r t e b r a l M e d i o Retroesternal Cardiaco Superior ESPACIO RETROESTERNAL En el espacio retroesternal se encuentra la Aorta Ascendente
  33. 33. ÁREA CARDIACA ital del mismo paciente, que confirman los hallazgos de la RL. A B C ital del mismo paciente, que confirman los hallazgos de la RL. A B INCISURA CARDÍACA
  34. 34. INCISURA CARDIACA
  35. 35. o - n s r - e e a l e e - , o - a - l s l ; V e r t e b r a l M e d i o Retroesternal Cardiaco Superior Figura 2 Esquema. MEDIASTINO Espacio Medio Límites • Superior: Margen Superior del Arco Aórtico. • Inferior: Diafragma • Anterior: Traquea y Borde posterior del Corazón. • P o s t e r i o r : B o rd e anterior de la columna vertebral.
  36. 36. Radiografía lateral de tórax. Anatomía radiográfica BLSD BPI+BLSI BI BI BPD BPD BPI AO API AI AI A B C D Figura 10 Bronquios. A) Radiografía lateral (RL) de tórax a la altura hiliar. Círculo radiotr principal izquierdo y el del lóbulo superior izquierdo (BPI + BLSI). Por encima, algo más den BRONQUIOS
  37. 37. MIP en planos coronal y sagital al nivel del BI. Pared posterior del BI. : aorta descendente; AI: aurícula izquierda; Ao: arco aórtico; API: arteria pulmonar Áz: vena ácigos. A B C APD VPD BPI API AO AA APP AD API VPSD APD gura 11 Estructuras vasculares. A) Radiografía lateral de tórax centrada en los h PD), inmediatamente por encima de las venas pulmonares derechas (VPD). Arteria pu uada por encima del bronquio principal izquierdo (BPI). B) Tomografía computariz HILIOSB C AI AI Ao AA APP AD API API API VPSD VPSD VPSD AI APD APD APD de tórax centrada en los hilios pulmonares. Arteria pulmonar derec s derechas (VPD). Arteria pulmonar izquierda (API) con forma de «com . B) Tomografía computarizada (TC) de tórax con reconstrucciones B C AI AI Ao AA APP AD API API API VPSD VPSD VPSD AI APD APD APD de tórax centrada en los hilios pulmonares. Arteria pulmonar dere derechas (VPD). Arteria pulmonar izquierda (API) con forma de «com B) Tomografía computarizada (TC) de tórax con reconstrucciones
  38. 38. C. García Villafa˜ne, C.S. Pedr A C B API VAP Ao Ao VAP API C. García Villafa˜ne, C.S. Pe A C B API VAP Ao Ao VAP API VENTANA AORTO-PULMONAR
  39. 39. Radiografía lateral de tórax. Anatomía radiográfica A B C D BLM BLID VI VCI RC BLII BLII BLM s BPI I BLSI Figura 13 Área retrocardiaca. A) Radiografía lateral (RL) de tórax donde se muestra la venta delante de las paredes anteriores del bronquio del lóbulo inferior derecho (BLID) y del bronquio de ÁREA RETROCARDIÁCA
  40. 40. C. García Villafa˜ne, C.S 2 4 A B C 5 7 b b a a c d c d d 1 6 3 14 Espacio posterior o vertebral. A) Radiografía lateral (RL) de tórax normal. (1) Agujero intervertebral. (2) vertebral. (3) Altura del espacio intervertebral. (4) Muro anterior del cuerpo vertebral. (5) Pedículo. (6) Muro ESPACIO POSTERIOR C. García Villafa˜ne, C. 2 4 A B C 5 7 b b a a c d c d d 1 6 3 14 Espacio posterior o vertebral. A) Radiografía lateral (RL) de tórax normal. (1) Agujero intervertebral. (2) C. García Villafa˜ne, C 2 4 A B C 5 7 b b a a c d c d d 1 6 3 4 Espacio posterior o vertebral. A) Radiografía lateral (RL) de tórax normal. (1) Agujero intervertebral. (2
  41. 41. LÍNEAS MEDIASTÍNICAS
  42. 42. the posteromedial portion of the right lower lobe. The azygoesophageal recess represents a space lying lateral or posterior to the esophagus and anterior to the spine, extending from the level of the anterior turn of the azygos vein to the level of the aortic hiatus inferiorly (1). The right infraazy- gos pleuroesophageal stripe may also outline the recess and is formed when an air-filled esophagus and intervening pleura come in contact with the right lower lobe (12). Superiorly, the recess is continuous with the subcarinal space and may demonstrate mild left- ward convexity in that location (1,13). The middle third of the recess may be the most vari- able in appearance but typically is straight edged or shows mild leftward convexity. The lower third typically appears as a straight edge (Figs 25, 26). Right superior convexity may be seen in children and younger adults but is abnormal in the elderly. Abnormal contour and convexity may be due to lymphadenopathy, hiatal hernias (Fig 27), bron- chopulmonary-foregut malformations, esophageal neoplasms, pleural abnormalities, and cardiomeg- aly with left atrial enlargement (1,13). Posterior Wall of the Bronchus Intermedius The posterior wall of the bronchus intermedius also appears as a stripe on lateral chest radio- graphs and is important in evaluating mediastinal Figure 25. Illustration (a) and frontal chest radiograph (b) demonstrate a normal azygoesophageal recess (black line in a, arrows in b) with mild leftward convexity superiorly and a straight edge inferiorly. Figure 26. CT scan shows that the azygoesophageal recess (arrow) is an interface formed by the right lower lobe outlining the mediastinum adjacent to the esopha- gus and azygos vein. 46 January-February 2007 RG f Volume 27 ● Number 1 RECESO ACIGO-ESOFÁGICO . Illustration (a) and frontal chest radiograph (b) demonstrate a normal azygoesophageal recess (black rrows in b) with mild leftward convexity superiorly and a straight edge inferiorly. ary-February 2007 RG f Volume 27 ● Number 1 (b) demonstrate a normal azygoesophageal recess (black orly and a straight edge inferiorly. Figure 26. CT scan shows that the azygoesophageal recess (arrow) is an interface formed by the right lower lobe outlining the mediastinum adjacent to the esopha- gus and azygos vein.
  43. 43. . Illustration (a) and frontal chest radiograph (b) show a normal anterior junction line (black lines in a, b) coursing obliquely from the upper right to the lower left over the superior two-thirds of the sternum. uary-February 2007 RG f Volume 27 ● Number 1 Introduction Interpretation of chest radiographs requires radi- ologists to recognize important mediastinal lines and stripes. Lines typically measure less than 1 mm in width and are formed by air, typically within the lung, outlining thin intervening tissue on both sides (1). Lines present on chest radio- graphs include the anterior and posterior junction lines. Stripes are thicker lines formed by air out- lining thicker intervening soft tissue (1). Many stripes are seen on chest radiographs, including the left and right paratracheal stripes and the pos- terior tracheal stripe. The edge, or interface, rep- resents another component of the “lines and stripes” concept at chest radiography. Interfaces are formed when structures of different densities come in contact with one another. Many inter- faces are seen on chest radiographs, including the right and left paraspinal lines and the azygoesoph- ageal recess, which, despite their names, are ex- amples of interfaces that are important in the evaluation of mediastinal disease. In this article, we discuss and illustrate the nor- mal and abnormal appearances of the important mediastinal lines, stripes, and interfaces seen at Figure 1. Illustration (a) and frontal chest radiograph (b) show a normal anterior junction line (black lines in a, arrows in b) coursing obliquely from the upper right to the lower left over the superior two-thirds of the sternum. Figure 2. CT scan demonstrates a normal anterior junction line (arrow) formed by the apposition of the visceral and parietal pleura of the lungs with interven- ing mediastinal fat. ng t LÍNEA DE UNIÓN ANTERIOR show a normal anterior junction line (black lines in a, ower left over the superior two-thirds of the sternum. Figure 2. CT scan demonstrates a normal anterior junction line (arrow) formed by the apposition of the visceral and parietal pleura of the lungs with interven- ing mediastinal fat.
  44. 44. LÍNEA DE UNIÓN POSTERIOR the esophagus and anterior to the third through the fifth thoracic vertebrae. It appears as a straight or mildly leftward convex line, typically projecting through the trachea (Figs 4, 5) (1,3,5). The pos- terior junction line demonstrates more cranial extension than the anterior junction line and, un- like its counterpart, is seen above the clavicles. However, it may also appear as a stripe with vary- ing amounts of intervening posterior mediastinal fat. The posterior junction line represents the middle component of the posterior junction re- flection. The V-shaped superior recess lies above the line and is formed by contact between the posterior apices of the lungs and mediastinum anterior to the first and second thoracic vertebrae. The inverted V-shaped inferior recess lies below the line and is formed by contact between the lungs and the mediastinum surrounding the supe- rior intercostal veins and the posterior azygos and aortic arches (1,5). The posterior junction line has reportedly been seen on 32% of posteroante- rior chest radiographs (3). Abnormal bulging or convexity of the posterior junction line suggests a posterior mediastinal ab- normality such as esophageal masses, lymphad- Figure 4. Illustration (a) and frontal chest radiograph (b) demonstrate a normal posterior junction line (black lines in a, arrows in b) as a straight line projecting through the trachea and extending above the clavicles. Figure 5. CT scan demonstrates a normal posterior junction line (arrow), which lies posterior to the esoph- agus and is formed by the apposition of the visceral and parietal pleura of the lungs anterior to the thoracic ver- tebrae. 36 January-February 2007 RG f Volume 27 ● Number 1 . Illustration (a) and frontal chest radiograph (b) demonstrate a normal posterior junction line es in a, arrows in b) as a straight line projecting through the trachea and extending above the clavicles. February 2007 RG f Volume 27 ● Number 1 graph (b) demonstrate a normal posterior junction line ecting through the trachea and extending above the clavicles. Figure 5. CT scan demonstrates a normal posterior junction line (arrow), which lies posterior to the esoph- agus and is formed by the apposition of the visceral and parietal pleura of the lungs anterior to the thoracic ver- tebrae.
  45. 45. enopathy, aortic disease, or neurogenic tumors. As with the anterior junction line, volume loss or hyperinflation of the surrounding lung can also displace the line (1,4,5). Right Paratracheal Stripe When the visceral and parietal pleura of the right upper lobe come in contact with the right lateral border of the trachea and the intervening medias- tinal fat, air within the right lung and trachea out- lines these entities to form the right paratracheal stripe (Figs 6, 7) (1,3), which has a maximum normal thickness of 4 mm. It begins superiorly at the level of the clavicles and extends inferiorly to the right tracheobronchial angle at the level of the azygos arch. The right paratracheal stripe is per- haps the most commonly seen mediastinal line or stripe. In their classic series, Woodring and Daniel (3) reported its presence on 97% of pos- teroanterior chest radiographs. A wide variety of disease entities can cause widening or abnormal contour of the right para- tracheal stripe, such as paratracheal lymphad- enopathy, thyroid or parathyroid neoplasms (Fig 8), and tracheal carcinoma or stenosis. Pleural disease such as effusion or thickening is among the most common causes for widening of the right paratracheal stripe (1,3,4). Figure 6. Illustration (a) and frontal chest radiograph (b) demonstrate a normal right paratracheal stripe (black line in a, arrows in b). Figure 7. CT scan shows that the right paratracheal stripe (arrow) is formed by air within the right upper lobe and trachea outlining the right lateral tracheal wall, right upper lobe pleura, and intervening soft tissues. RG f Volume 27 ● Number 1 Gibbs et al 37 ration (a) and frontal chest radiograph (b) demonstrate a normal right paratracheal stripe (black 27 ● Number 1 Gibbs et al 37 Right Paratracheal Stripe When the visceral and parietal pleura of the right upper lobe come in contact with the right lateral border of the trachea and the intervening medias- tinal fat, air within the right lung and trachea out- lines these entities to form the right paratracheal stripe (Figs 6, 7) (1,3), which has a maximum normal thickness of 4 mm. It begins superiorly at the level of the clavicles and extends inferiorly to the right tracheobronchial angle at the level of the azygos arch. The right paratracheal stripe is per- haps the most commonly seen mediastinal line or stripe. In their classic series, Woodring and Daniel (3) reported its presence on 97% of pos- teroanterior chest radiographs. A wide variety of disease entities can cause widening or abnormal contour of the right para- tracheal stripe, such as paratracheal lymphad- enopathy, thyroid or parathyroid neoplasms (Fig 8), and tracheal carcinoma or stenosis. Pleural Figure 6. Illustration (a) and frontal chest radiograph (b) demonstrate a normal right paratracheal stripe (black line in a, arrows in b). Figure 7. CT scan shows that the right paratracheal stripe (arrow) is formed by air within the right upper lobe and trachea outlining the right lateral tracheal wall, right upper lobe pleura, and intervening soft tissues. Línea Paratraqueal Derecha: Grosor máximo de 4mm. LÍNEA PARATRAQUEAL DERECHA
  46. 46. Left Paratracheal Stripe The left paratracheal stripe is formed by contact between the left upper lobe and either the medi- astinal fat adjacent to the left tracheal wall or the left tracheal wall itself. Air within the trachea out- lines the intervening soft tissues, thereby forming the left paratracheal stripe. The stripe extends superiorly from the aortic arch to join with the reflection from the left subclavian artery and thus may be referred to as the left paratracheal reflec- tion (Fig 9) (6). Visible on 21%–31% of posteroanterior chest radiographs, the left paratracheal stripe is seen less frequently than the right paratracheal stripe, since it may be obscured by contact between the left lung and either the proximal left common carotid artery anteriorly or the left subclavian ar- Figure 8. Abnormal right paratracheal stripe caused by a large ectopic parathyroid adenoma in a 52-year-old man. (a) Frontal chest radiograph demonstrates widening of the right paratracheal stripe (arrow). (b) CT scan helps con- firm a large right paratracheal mass (arrow) with diffuse osteopenia from primary hyperparathyroidism. Figure 9. Illustration (a) and frontal chest radiograph (b) demonstrate a normal left paratracheal stripe (black line in a, arrows in b) extending from the aortic arch to join with the reflection from the left subclavian artery superiorly. tery posteriorly (3,6). Teaching Point eal mass (arrow) with diffuse osteopenia from primary hyperparathyroidism. LÍNEA PARATRAQUEAL IZQUIERDA
  47. 47. As with the right paratra- cheal stripe, abnormal contour or widening is commonly seen in large left-sided pleural effu- sions. Left paratracheal lymphadenopathy, neo- plasm (Fig 10), or mediastinal hematoma may also alter the normal appearance of the left para- tracheal stripe (3). Aortic-Pulmonary Stripe First described by Keats (7), the aortic-pulmo- nary stripe actually represents a mediastinal re- flection or interface formed by the pleura of the anterior left lung coming in contact with and tan- gentially reflecting over the mediastinal fat an- terolateral to the left pulmonary artery and aortic arch. The stripe is straight or mildly convex, crossing laterally over the aortic arch and the main pulmonary artery (Figs 11, 12) (1,7,8). Figure 10. Abnormal-appearing left paratracheal stripe in a 47-year-old patient with metastatic thyroid carcinoma. (a) Frontal chest radiograph demonstrates widening of the left paratracheal stripe (arrows) with mass effect on the trachea. (b) CT scan reveals a large thyroid mass (arrow) and associated supraclavicular lymphadenopathy. Figure 11. Illustration (a) and frontal chest radiograph (b) demonstrate a normal aortic-pulmonary stripe (black line in a, arrows in b) as a straight interface crossing the aortic arch and the main pulmonary artery. BANDA AORTO-PULMONAR CT scan reveals a large thyroid mass (arrow) and associated supraclavicular lymphadenopathy. Illustration (a) and frontal chest radiograph (b) demonstrate a normal aortic-pulmonary stripe (black RG f Volume 27 ● Number 1
  48. 48. LÍNEA PARAESPINAL DERECHA or nerve sheath tumors (1). Paralysis of the left vocal cord or diaphragm should also prompt a search for disease in the AP window (1,3,8). Dis- ease in structures that form the borders of the AP window (eg, aortic aneurysms) can also cause the window to have an abnormal appearance. Right Paraspinal Line The right paraspinal line is formed by the right lung and pleura coming in tangential contact with the posterior mediastinal soft tissues. Despite its name, the right paraspinal line is not a true medi- astinal line. Rather, it represents an interface be- tween the right lung and the posterior mediastinal fat and soft tissues. A thin white line enhancing the edge of the right paraspinal line does not truly exist but is perceived visually and represents a positive Mach band phenomenon. It is caused by lateral inhibition of the retina from differences in contour and optical density of structures at a well- defined interface (9). The right paraspinal line appears straight and typically extends from the 8th through the 12th thoracic vertebral levels (Figs 17, 18) (1,3). Wood- ring and Daniel (3) reported its presence on 23% of posteroanterior radiographs. The right paraspi- nal line may be displaced laterally by osteophytes or prominent mediastinal fat. However, abnormal contour or displacement may also suggest a pos- terior mediastinal abnormality such as a mediasti- nal hematoma (Fig 19), a mass, or extramedullary hematopoiesis (1,3,4). Figure 17. Illustration (a) and frontal chest radiograph (b) demonstrate a normal right paraspinal line (black line in a, arrows in b) as a thin straight line extending lateral to the thoracic spine. Figure 18. CT scan shows normal right and left paraspinal lines (arrows) formed by the lungs and pleura contacting the posterior mediastinal soft tissues. 42 January-February 2007 RG f Volume 27 ● Number 1 llustration (a) and frontal chest radiograph (b) demonstrate a normal right paraspinal line (black line February 2007 RG f Volume 27 ● Number 1 b) demonstrate a normal right paraspinal line (black line the thoracic spine. Figure 18. CT scan shows normal right and left paraspinal lines (arrows) formed by the lungs and pleura contacting the posterior mediastinal soft tissues.
  49. 49. Left Paraspinal Line The left paraspinal line is formed by tangential contact of the left lung and pleura with the poste- rior mediastinal fat, left paraspinal muscles, and adjacent soft tissues. The left paraspinal line ex- tends vertically from the aortic arch to the dia- phragm and typically lies medial to the lateral wall of the descending thoracic aorta (Figs 18, 20) (1). In some instances, however, it may lie lateral to Figure 19. Abnormal-appearing right paraspinal line in a 27-year-old patient who had sus- tained traumatic injury. (a) Frontal chest radiograph demonstrates an abnormal bulge in the right paraspinal line inferiorly (arrows). (b) CT scan reveals a large mediastinal hematoma (arrow) from multiple right-sided transverse process fractures of the thoracic spine and an associated right hemothorax. Figure 20. Illustration (a) and frontal chest radiograph (b) demonstrate a normal left paraspinal line (black line in a, arrows in b) as a thin straight line extending from the aortic arch to the diaphragm. The normal left paraspinal line typically lies medial to the lateral wall of the descending thoracic aorta. LÍNEA PARAESPINAL IZQUIERDA ht hemothorax. llustration (a) and frontal chest radiograph (b) demonstrate a normal left paraspinal line (black ws in b) as a thin straight line extending from the aortic arch to the diaphragm. The normal left

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