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.
3. 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.
4. 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
5. 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.
8. 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.
11. 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
14. 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.
17. 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.
22. 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
23. Fig. 1.28 Visualization of the aortic root on CT. Paracoronal reconstruction ofe image clearly dem-
ARCO AÓRTICO
24. 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
27. 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
29. Radiografía lateral de tórax. Anatomía radiográfica
TVBI
TVBI
TS
T
R
AA
E
Ao
A
B
a
ÁREA
VÁSCULAR
TRIÁNGULO DE
RAIDER
ESPACIO SUPERIOR
30. 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
31. 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
34. 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
37. 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
38. 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
39. 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
40. 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
41. 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
43. 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.
44. . 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.
45. 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.
46. 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
47. 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
48. 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
49. 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.
50. 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