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1101
Azygoesophageal CT Appearance
Steven James
W. Fitzgerald1
S. Donaldson2
Recess:
Normal
in Children
The azygoesophageal recess is the interface tinum and the right lower lobe. The configuration
of the subcarinal portion of the mediasof the recess on CT can be used as a
sensitive indicator of abnormality in the mediastinum. In normal adults the recess is concave. A convex contour is a normal variant, particularly in young adults. The normal appearance of the azygoesophageal recess in children has not been studied. Accordingly, we reviewed chest CT examinations performed in 253 children ranging from 1 month to 20 years old. Forty patients were excluded from further analysis either because the recess could not be evaluated properly or because underlying disease caused the mediastinum
to
configurations
have
an
abnormal
was observed
configuration.
An
in the remaining
age-related
213 patients.
spectrum
A convex
of
or straight
normal
contour
was found in 96% of children less than 3 years old. Scans of children 3-12 years old revealed a spectrum of configurations. The typical adult concave configuration was seen in 78% of adolescents more than 12 years old. Overall, in only 90 (42%) of 213 children in this study was a concave recess observed on CT. Our experience shows a convex azygoesophageal recess on CT should be considered the normal configuration in infants and young children. Recognition of this age-related variation is useful in the CT evaluation of the mediastinum in children. 158:1101-1104,
AJR
May
1992
The azygoesophageal recess (AER) is the interface of the subcarinal mediastinum and the right lower lobe. The AER extends from the azygous arch to the diaphragm. A variety of mediastinal, esophageal, and vascular abnormalities can affect the AER and its configuration. The configuration of the recess can be used as an indicator of disease in the mediastinum [1 2]. The CT appearance of the AER in adults has been reported to be normally concave to the right side. A convex recess is considered a normal variant, occurring in 7-21 % [3-5], especially in young adults [6]. The normal contour of the AER in children has not been described. Accordingly, this study was initiated to evaluate the configuration of the AER on CT in children. ,
Materials Received March sion December
15, 1991 ; accepted 1 0, 1991.
after
revi-
Presented at the annual meeting of the Society for Pediatric Radiology, Cincinnati, April 1990. 1 Department of Radiology, Northwestem Memorial Hospital, 710 N. Fairbanks Ct., Chicago, IL 6061 1 . Address reprint requests to S. W. Fitzgerald. 2 Department of Radiology, Children’s Memorial Hospital,
2300 Children’s
0361 -803X/92/1585-1 C American Roentgen
Plaza, Chicago, 101 Ray Society
IL 60614.
and Methods
We retrospectively reviewed 253 CT examinations of the chest performed at Children’s Memorial Hospital. All examinations were done on a GE 9800 CT scanner. Infants and young children
were
inspiration. sec
scanning
respectively. material hand
imaged
All patients
(total injected
times
in quiet were and
respiration. scanned
with
either
Cooperative while 5-
they or
were
1 0-mm
children supine. collimation
patients), azygous
scanned
at
in suspended
were 5-
or
obtained 1 0-mm
Approximately 40% of the patients included in this study received dose of 3 ml nonionic contrast material per kilogram body weight), as a bolus.
The
patients
in this
study
ranged
The sample consisted of 142 boys and 1 1 1 girls. Eight patients because we could not evaluate the AER adequately because or
were Images
atelectasis continuation
in the right
lower
of interruption
lobe
(two
patients),
of the
inferior
from
to 20
were excluded of large pleural
right-sided vena
1 month
cava
aortic (two
arch
with
2-
intervals, IV contrast
which
was
years
old.
from the study effusions (two (two
patients).
patients), A second
I 1102
FITZGERALD
TABLE
1: Indications
Downloaded from www.ajronline.org by Health Sciences Library on 10/07/13 from IP address 129.78.72.28. Copyright ARRS. For personal use only; all rights reserved
Clinical
for Chest
14
May 1992
Nonconcave Concave
AER
(7)
46 (22)
neoplasm
Musculoskeletal neoplasm Lymphoproliferative disordera Pulmonary infection/AIDSa Airway disorders
30 (14)
Hematologic
disorders
13
(6)
Congenital Trauma
anomaliesa
8
(4)
39 (18) 24 (11) 1 7 (8) 13
0 0
0
(6)
w
9 (4)
Miscellaneousa Patients
AJR:158,
.
No. of Patients
CNS neoplasm
a
DONALDSON
CT in 213 Patients
Indication
Abdominal/pelvic
AND
with
any mediastinal
abnormalities
on chest
CT were
excluded
from this study. Patient
group of 32 patients was excluded on the basis of an abnormal mediastinal configuration owing to obvious underlying disease. This resulted in a final group of 21 3 patients to serve as our normal subjects.
Most
the chest
(Table
tinal
disease
of these
patients
did
have
1). We did not include
in any
compartment
was
known
disease
any patient noted
in whom
outside
on CT.
Analysis of our review resulted in an age-related distribution of AER configurations (Fig. 2). When broken down by age groups, 85 (85%) of 1 00 children less than 6 years old had a convex AER. More significantly, 62 (95%) of 65 infants and children less than 3 years old were found to have a convex AER. The second group of children, ranging from 6 to 12
of convex,
graph shows distribution of azygoesophageal recess (AER) by age. Nonconcave AERs include both convex and straight
AER contours. Convex AERs predominate
in children less than 10 years
old.
of
Results
distribution
(years)
medias-
The configuration of the AER was assessed from hard-copy images of the mediastinum filmed at standard console settings (window = 350 H/level = 50 H). The AER was evaluated from the level of the azygous arch to the right hemidiaphragm. The contour of the AER was scored at the level of the right main bronchus as either convex, straight, or concave (Fig. 1). The appearance of the AER at all levels, as well as the location of the azygous vein, azygous node chain, and esophagus, were noted.
years old, had an intermediate
Fig. 2.-Bar configuration
Age
straight,
and concave AER contours. Convex AERS were found in 25 (47%) of 53 children in this range. Finally, in adolescents 1220 years old, the more typical adult-type concave AER was noted in 47 (78%) of 60. Overall, 1 23 (58%) of 21 3 children
evaluated had a convex AER. No differences between boys and girls were observed. Most of the convex AERs were found on the most cephalad
scans, just beneath
the azygous
arch. The convex
or straight
configuration at this level was uniformly due to the azygous vein. The convexity extended caudad for several scans and then was noted to become concave (Fig. 3). However, some normal patients were noted to have a convex AER on the more caudal images (Fig. 4) because of the esophagus (7%); this was primarily due to esophageal reflux. No patient was found to have a convex AER extending continuously from the azygous arch to the diaphragm. AER
Discussion Heitzman [7] defined the azygoesophageal recess as the intrusion of the medial aspect of the right lower lobe, the crista pulmonis, into the posterior mediastinum. The AER is well developed in most persons, and its medial boundary is readily recognized as a smooth arc, with concavity directed to the right, extending caudad from the azygous arch to the diaphragm. The concave configuration of the AER in adults
Fig. 1.-Axial CT scans of mediastinum at level of carina in three children. A, Convex azygoesophageal recess (AER) resulting from azygous vein (arrow). B, Straight AER configuration, again as a result of azygous vein (arrowhead). C, Concave AER (arrow).
Downloaded from www.ajronline.org by Health Sciences Library on 10/07/13 from IP address 129.78.72.28. Copyright ARRS. For personal use only; all rights reserved
AJR:158,
CT
May 1992
on CT examinations is well alteration of AER contour mality in the mediastinum. scribed as a normal variant 6], the latter being seen in
OF
AZYGOESOPHAGEAL
RECESS
established [1 2]. Attention to an allows detection of subtle abnorConvex AERS have been de-
1103
CHILDREN
Our review shows that the configuration of the AER in children differs significantly from that seen in adults. The distribution of AER contours in our study showed a definite age-related distribution. In young children, especially infants, the AER was found to be convex in the overwhelming majority. In fact, scans in only three of 65 children less than 3 years old showed the AER to be concave. The distribution of AER contour varied with increasing age. Children 6-1 2 years old had an intermediate spectrum of AERs, divided nearly equally
,
in adults in 7-21 % of cases [3, 4, young
IN
adults.
among convex, straight, and concave. In adolescents, the frequency of convex AERs dropped to 22%, a number compatible with previously reported adult studies. The convexity of the AER in our normal patients was Fig. 3.-Transverse CT scan near aortic hiatus shows concave appearance of azygoesophageal recess (arrowhead) on more caudal
confined
primarily
scans
occasionally The azygous
to those
scans
just inferior
to the azygous
arch. The convexity of the AER was clearly related to the azygous vein at levels near the arch, while the esophagus did
found in most patients mdcpendently of age and configuration
at level of carina.
scanned
produce a convex AER on more caudal scans. vein was confidently identified in most patients
with or without
IV contrast
material.
However,
several cases with minimal mediastinal fat, contrast tration was necessary to confirm that the azygous
in
adminisvein was
responsible for a convex AER. Scanning at more caudal levels showed a transition to a consistently concave recess. This is related to the course of the azygous vein, which enters the chest via the aortic hiatus posteriorly and then ascends obliquely to join the superior vena cava. This helps to explain the difference in the appearance of the AER as the chest is
Fig.
4.-Transverse
CT
scanned more caudally. Consideration was given to what factors might help explain the age variation of AER contours. The obvious choice would
scan
shows convexity of azygoesophageal recess caused by barium reflux in esophagus (arrow).
a variation
be
nately,
.
in the size of the azygous
our retrospective
review
vein itself. Unfortu-
did not allow
determination
8.0
bedy area
7.0
senlacs a. a.
6.0
..-
,
.eit
/--
5.0 I
/
Fig. 5.-Data obtained from chest radiographs show age-related changes in azygous vein size vs other anatomic variables. A transition at age 3 in relative size of azygous vein might explain
=
4.0 subcetaeeess
tissee
some of age-related variation in azygoesophageal recess we have observed.
(Reprinted
from Wishart
[8].)
with
permission
3.0 ,
1
2
3
4
5
6 Act
7 IN
8 TillS
9
10
11
12
13
14
1104
FITZGERALD
AND
Downloaded from www.ajronline.org by Health Sciences Library on 10/07/13 from IP address 129.78.72.28. Copyright ARRS. For personal use only; all rights reserved
of cardiac or fluid status, respiratory phase, or cardiac cycle. Any or all of these factors might be expected to affect the CT appearance of the azygous vein. Previously reported work on
azygous vein size, as determined from chest radiographs [8], showed that the azygous vein increased in size in children from
birth to 3 years of age, paralleling growth curves of soft tissue and other body structures. Beyond age 3, while other structures continued relatively constant growth rates, the size ofthe azygous vein was found to plateau (Fig. 5). This resulted in a relative decrease in the size of the azygous vein compared
with other structures the age-related patients. In summary,
within the chest. This might help explain
transition our findings
of AER suggest
scans is commonly observed a spectrum of AER configuration CT
configurations that
seen
a convex
in our
AER
on
in children. We have noted with an age-related distri-
bution in children. The azygous vein is primarily responsible for this lack of AER concavity. Recognition of the variation of the AER contour on chest CT scans is important in the
accurate
evaluation
of the mediastinum
in children.
DONALDSON
AJR:158, May 1992
ACKNOWLEDGMENT We
thank
Susan
Sloan
for assistance
in manuscript
preparation.
REFERENCES 1 . Golden RL, Heitzman ER, Proto AV. Computed tomography of the mediastinum: normal anatomy and indications for the use of CT. Radiology 1977:124:235-241 2. Lund G, Lien HH. Computed tomography of the azygo-esophageal recess: normal appearances. Acta Radiol 1982:23:225-230 3. Landay MJ. Azygous vein abutting the posterior wall of the right main and upper lobe bronchi: a normal CT variant. AJR 1983:140:461-462 4. Lund G, Lien HH. Abnormalities of the azygo-esophageal recess at computed tomography. Acta Radiol 1983;24:3-10 5. Glazer HS, Aronberg DJ, Sagel SS. Pitfalls in CT recognition of mediastinal lymphadenopathy. AJR 1985;144:267-274 6. Onitsuka H, Kuhns LR. Dextroconvexity of the mediastinum in the azygoesophageal recess: a normal CT variant in young adults. Radiology 1980;135: 126 7. Heitzman ER. The mediastinum, 2nd ed. Berlin: Springer-Verlag, 1988 8. Wishart DL. Normal azygous vein width in children. Radiology 1972:104:115-118
1101
Azygoesophageal CT Appearance
Steven James
W. Fitzgerald1
S. Donaldson2
Recess:
Normal
in Children
The azygoesophageal recess is the interface tinum and the right lower lobe. The configuration
of the subcarinal portion of the mediasof the recess on CT can be used as a
sensitive indicator of abnormality in the mediastinum. In normal adults the recess is concave. A convex contour is a normal variant, particularly in young adults. The normal appearance of the azygoesophageal recess in children has not been studied. Accordingly, we reviewed chest CT examinations performed in 253 children ranging from 1 month to 20 years old. Forty patients were excluded from further analysis either because the recess could not be evaluated properly or because underlying disease caused the mediastinum
to
configurations
have
an
abnormal
was observed
configuration.
An
in the remaining
age-related
213 patients.
spectrum
A convex
of
or straight
normal
contour
was found in 96% of children less than 3 years old. Scans of children 3-12 years old revealed a spectrum of configurations. The typical adult concave configuration was seen in 78% of adolescents more than 12 years old. Overall, in only 90 (42%) of 213 children in this study was a concave recess observed on CT. Our experience shows a convex azygoesophageal recess on CT should be considered the normal configuration in infants and young children. Recognition of this age-related variation is useful in the CT evaluation of the mediastinum in children. 158:1101-1104,
AJR
May
1992
The azygoesophageal recess (AER) is the interface of the subcarinal mediastinum and the right lower lobe. The AER extends from the azygous arch to the diaphragm. A variety of mediastinal, esophageal, and vascular abnormalities can affect the AER and its configuration. The configuration of the recess can be used as an indicator of disease in the mediastinum [1 2]. The CT appearance of the AER in adults has been reported to be normally concave to the right side. A convex recess is considered a normal variant, occurring in 7-21 % [3-5], especially in young adults [6]. The normal contour of the AER in children has not been described. Accordingly, this study was initiated to evaluate the configuration of the AER on CT in children. ,
Materials Received March sion December
15, 1991 ; accepted 1 0, 1991.
after
revi-
Presented at the annual meeting of the Society for Pediatric Radiology, Cincinnati, April 1990. 1 Department of Radiology, Northwestem Memorial Hospital, 710 N. Fairbanks Ct., Chicago, IL 6061 1 . Address reprint requests to S. W. Fitzgerald. 2 Department of Radiology, Children’s Memorial Hospital,
2300 Children’s
0361 -803X/92/1585-1 C American Roentgen
Plaza, Chicago, 101 Ray Society
IL 60614.
and Methods
We retrospectively reviewed 253 CT examinations of the chest performed at Children’s Memorial Hospital. All examinations were done on a GE 9800 CT scanner. Infants and young children
were
inspiration. sec
scanning
respectively. material hand
imaged
All patients
(total injected
times
in quiet were and
respiration. scanned
with
either
Cooperative while 5-
they or
were
1 0-mm
children supine. collimation
patients), azygous
scanned
at
in suspended
were 5-
or
obtained 1 0-mm
Approximately 40% of the patients included in this study received dose of 3 ml nonionic contrast material per kilogram body weight), as a bolus.
The
patients
in this
study
ranged
The sample consisted of 142 boys and 1 1 1 girls. Eight patients because we could not evaluate the AER adequately because or
were Images
atelectasis continuation
in the right
lower
of interruption
lobe
(two
patients),
of the
inferior
from
to 20
were excluded of large pleural
right-sided vena
1 month
cava
aortic (two
arch
with
2-
intervals, IV contrast
which
was
years
old.
from the study effusions (two (two
patients).
patients), A second
I 1102
FITZGERALD
TABLE
1: Indications
Downloaded from www.ajronline.org by Health Sciences Library on 10/07/13 from IP address 129.78.72.28. Copyright ARRS. For personal use only; all rights reserved
Clinical
for Chest
14
May 1992
Nonconcave Concave
AER
(7)
46 (22)
neoplasm
Musculoskeletal neoplasm Lymphoproliferative disordera Pulmonary infection/AIDSa Airway disorders
30 (14)
Hematologic
disorders
13
(6)
Congenital Trauma
anomaliesa
8
(4)
39 (18) 24 (11) 1 7 (8) 13
0 0
0
(6)
w
9 (4)
Miscellaneousa Patients
AJR:158,
.
No. of Patients
CNS neoplasm
a
DONALDSON
CT in 213 Patients
Indication
Abdominal/pelvic
AND
with
any mediastinal
abnormalities
on chest
CT were
excluded
from this study. Patient
group of 32 patients was excluded on the basis of an abnormal mediastinal configuration owing to obvious underlying disease. This resulted in a final group of 21 3 patients to serve as our normal subjects.
Most
the chest
(Table
tinal
disease
of these
patients
did
have
1). We did not include
in any
compartment
was
known
disease
any patient noted
in whom
outside
on CT.
Analysis of our review resulted in an age-related distribution of AER configurations (Fig. 2). When broken down by age groups, 85 (85%) of 1 00 children less than 6 years old had a convex AER. More significantly, 62 (95%) of 65 infants and children less than 3 years old were found to have a convex AER. The second group of children, ranging from 6 to 12
of convex,
graph shows distribution of azygoesophageal recess (AER) by age. Nonconcave AERs include both convex and straight
AER contours. Convex AERs predominate
in children less than 10 years
old.
of
Results
distribution
(years)
medias-
The configuration of the AER was assessed from hard-copy images of the mediastinum filmed at standard console settings (window = 350 H/level = 50 H). The AER was evaluated from the level of the azygous arch to the right hemidiaphragm. The contour of the AER was scored at the level of the right main bronchus as either convex, straight, or concave (Fig. 1). The appearance of the AER at all levels, as well as the location of the azygous vein, azygous node chain, and esophagus, were noted.
years old, had an intermediate
Fig. 2.-Bar configuration
Age
straight,
and concave AER contours. Convex AERS were found in 25 (47%) of 53 children in this range. Finally, in adolescents 1220 years old, the more typical adult-type concave AER was noted in 47 (78%) of 60. Overall, 1 23 (58%) of 21 3 children
evaluated had a convex AER. No differences between boys and girls were observed. Most of the convex AERs were found on the most cephalad
scans, just beneath
the azygous
arch. The convex
or straight
configuration at this level was uniformly due to the azygous vein. The convexity extended caudad for several scans and then was noted to become concave (Fig. 3). However, some normal patients were noted to have a convex AER on the more caudal images (Fig. 4) because of the esophagus (7%); this was primarily due to esophageal reflux. No patient was found to have a convex AER extending continuously from the azygous arch to the diaphragm. AER
Discussion Heitzman [7] defined the azygoesophageal recess as the intrusion of the medial aspect of the right lower lobe, the crista pulmonis, into the posterior mediastinum. The AER is well developed in most persons, and its medial boundary is readily recognized as a smooth arc, with concavity directed to the right, extending caudad from the azygous arch to the diaphragm. The concave configuration of the AER in adults
Fig. 1.-Axial CT scans of mediastinum at level of carina in three children. A, Convex azygoesophageal recess (AER) resulting from azygous vein (arrow). B, Straight AER configuration, again as a result of azygous vein (arrowhead). C, Concave AER (arrow).
Downloaded from www.ajronline.org by Health Sciences Library on 10/07/13 from IP address 129.78.72.28. Copyright ARRS. For personal use only; all rights reserved
AJR:158,
CT
May 1992
on CT examinations is well alteration of AER contour mality in the mediastinum. scribed as a normal variant 6], the latter being seen in
OF
AZYGOESOPHAGEAL
RECESS
established [1 2]. Attention to an allows detection of subtle abnorConvex AERS have been de-
1103
CHILDREN
Our review shows that the configuration of the AER in children differs significantly from that seen in adults. The distribution of AER contours in our study showed a definite age-related distribution. In young children, especially infants, the AER was found to be convex in the overwhelming majority. In fact, scans in only three of 65 children less than 3 years old showed the AER to be concave. The distribution of AER contour varied with increasing age. Children 6-1 2 years old had an intermediate spectrum of AERs, divided nearly equally
,
in adults in 7-21 % of cases [3, 4, young
IN
adults.
among convex, straight, and concave. In adolescents, the frequency of convex AERs dropped to 22%, a number compatible with previously reported adult studies. The convexity of the AER in our normal patients was Fig. 3.-Transverse CT scan near aortic hiatus shows concave appearance of azygoesophageal recess (arrowhead) on more caudal
confined
primarily
scans
occasionally The azygous
to those
scans
just inferior
to the azygous
arch. The convexity of the AER was clearly related to the azygous vein at levels near the arch, while the esophagus did
found in most patients mdcpendently of age and configuration
at level of carina.
scanned
produce a convex AER on more caudal scans. vein was confidently identified in most patients
with or without
IV contrast
material.
However,
several cases with minimal mediastinal fat, contrast tration was necessary to confirm that the azygous
in
adminisvein was
responsible for a convex AER. Scanning at more caudal levels showed a transition to a consistently concave recess. This is related to the course of the azygous vein, which enters the chest via the aortic hiatus posteriorly and then ascends obliquely to join the superior vena cava. This helps to explain the difference in the appearance of the AER as the chest is
Fig.
4.-Transverse
CT
scanned more caudally. Consideration was given to what factors might help explain the age variation of AER contours. The obvious choice would
scan
shows convexity of azygoesophageal recess caused by barium reflux in esophagus (arrow).
a variation
be
nately,
.
in the size of the azygous
our retrospective
review
vein itself. Unfortu-
did not allow
determination
8.0
bedy area
7.0
senlacs a. a.
6.0
..-
,
.eit
/--
5.0 I
/
Fig. 5.-Data obtained from chest radiographs show age-related changes in azygous vein size vs other anatomic variables. A transition at age 3 in relative size of azygous vein might explain
=
4.0 subcetaeeess
tissee
some of age-related variation in azygoesophageal recess we have observed.
(Reprinted
from Wishart
[8].)
with
permission
3.0 ,
1
2
3
4
5
6 Act
7 IN
8 TillS
9
10
11
12
13
14
1104
FITZGERALD
AND
Downloaded from www.ajronline.org by Health Sciences Library on 10/07/13 from IP address 129.78.72.28. Copyright ARRS. For personal use only; all rights reserved
of cardiac or fluid status, respiratory phase, or cardiac cycle. Any or all of these factors might be expected to affect the CT appearance of the azygous vein. Previously reported work on
azygous vein size, as determined from chest radiographs [8], showed that the azygous vein increased in size in children from
birth to 3 years of age, paralleling growth curves of soft tissue and other body structures. Beyond age 3, while other structures continued relatively constant growth rates, the size ofthe azygous vein was found to plateau (Fig. 5). This resulted in a relative decrease in the size of the azygous vein compared
with other structures the age-related patients. In summary,
within the chest. This might help explain
transition our findings
of AER suggest
scans is commonly observed a spectrum of AER configuration CT
configurations that
seen
a convex
in our
AER
on
in children. We have noted with an age-related distri-
bution in children. The azygous vein is primarily responsible for this lack of AER concavity. Recognition of the variation of the AER contour on chest CT scans is important in the
accurate
evaluation
of the mediastinum
in children.
DONALDSON
AJR:158, May 1992
ACKNOWLEDGMENT We
thank
Susan
Sloan
for assistance
in manuscript
preparation.
REFERENCES 1 . Golden RL, Heitzman ER, Proto AV. Computed tomography of the mediastinum: normal anatomy and indications for the use of CT. Radiology 1977:124:235-241 2. Lund G, Lien HH. Computed tomography of the azygo-esophageal recess: normal appearances. Acta Radiol 1982:23:225-230 3. Landay MJ. Azygous vein abutting the posterior wall of the right main and upper lobe bronchi: a normal CT variant. AJR 1983:140:461-462 4. Lund G, Lien HH. Abnormalities of the azygo-esophageal recess at computed tomography. Acta Radiol 1983;24:3-10 5. Glazer HS, Aronberg DJ, Sagel SS. Pitfalls in CT recognition of mediastinal lymphadenopathy. AJR 1985;144:267-274 6. Onitsuka H, Kuhns LR. Dextroconvexity of the mediastinum in the azygoesophageal recess: a normal CT variant in young adults. Radiology 1980;135: 126 7. Heitzman ER. The mediastinum, 2nd ed. Berlin: Springer-Verlag, 1988 8. Wishart DL. Normal azygous vein width in children. Radiology 1972:104:115-118
