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Normal variations of bony components on plain chest
radiographs: Approaching with multiplanar reconstructed
computed tomography
Poster No.:
C-0970
Congress:
ECR 2010
Type:
Educational Exhibit
Topic:
Chest
Authors:
A. Yamamoto , S. Suzuki , K. Toyoda , M. Yamasaki , E. Lien , T.
1
3
1
1 1
1
2
2
3
3
O'uchi , S. Furui ; Tokyo/JP, Shiga/JP, Chiba/JP
Keywords:
normal variation, anomalous articulation, CT
DOI:
10.1594/ecr2010/C-0970
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Learning objectives
To illustrate the normal variants of bone and articulation on plain chest radiographs in
correlation with MDCT images.
To analyze, and improve understanding of bony components mimicking tumors or other
pathologic conditions on chest radiographs in contrast to reconstructed MDCT images.
Background
The ribs, scapula, clavicle, sternum, vertebra, humerus and their joints are projected on
chest radiographs. A wide variety of normal shapes, congenital or acquired deformities
and unique articulation can be detected, occasionally mimicking tumors or other
pathologic conditions.
Knowledge and recognition of the spectrum of these manifestations can be helpful in
obtaining an accurate diagnosis and avoiding unnecessary examination. We reviewed
chest images of patients who received both chest radiography and MDCT within a short
period of time in the past four years. The radiographs were compared with the MDCT
multiplanar reconstructed or volume-rendering images.
Imaging findings OR Procedure details
A wide spectrum of radiographic and MDCT findings of common and uncommon
conditions are demonstrated under six categories:
1. Ribs: accessory rib, short rib, grooves in the lower and upper margin, normal congenital
anomalies including duplication, articulation, fusion, forked rib or hypotrophic rib.
2. Scapula: hypertrophy of the coracoid process, hook-like configuration and normal
lucency including foramina-like defect .
3. Clavicle: normal asymmetry, rhomboid fossa, and grooves in the lower margin.
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4. Sternum: prominent manubrium, episternal notch of the manubrium and bifid xiphoid
process.
5. Vertebra: variations of congenital malformations, prominent transverse process,
osteophytes and other degenerative changes.
6. Others: variations of the anomalous articulation and calcification of the cartilages of
the larynx.
Ribs
Anatomic rib variants, including an accessory rib, short rib, duplication and fusion of ribs,
grooves and calcifications of the costal cartilages, may mimic lung, rib and other thoracic
wall diseases. It is important for radiologist to be familiar with the normal anatomy, the
variants, and the usual radiological appearance of the ribs.
1. Accessory ribs
Accessory ribs are supernumerary ribs arising from the seventh cervical vertebra (cervical
rib) or lumbar vertebra (lumbar rib). The cervical rib occurs in approximately 0.5%
of the population with male predominance (Figure 1)(1). Although a cervical rib is
usually asymptomatic, it is clinically important when the patient presents thoracic outlet
syndrome from compression of the brachial plexus or subclavian vessels. The lumbar rib
is occasionally seen in the chest radiograph at L1 or rarely at L2 ipsilaterally or bilaterally
th
(Figure 2). It may be confused with a 12 rib fracture in trauma patients or hypotrophy
th
of 12 rib (Figure 3).
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Fig.: 1. Cervical rib. Frontal chest radiograph (a) and VR image (b) show the bilateral
cervical rib (white arrows).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Page 4 of 65
Fig.: 2-3. Figure 2. Lumbar rib. Frontal chest radiograph (a) shows osseous protrusion
horizontally from L1, which simulates a hypertrophic transverse process of the lumbar
vertebra (arrows). VR image (b) presents the lumbar rib from L1 bilaterally (white
arrows). Figure 3. Hypotrophy of the 12th rib. Frontal chest radiograph (a) shows a
short bony protrusion from Th12, which simulates transverse process of the lumbar
vertebra or the lumbar rib (arrow). VR image (b) demonstrates the bony protrusion as
the unfused hypotrophic right 12th rib. The contralateral 12th rib is also hypotrophic.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
2. Short ribs
Frontal chest radiography sometimes shows a shortened mid-thoracic rib arch in patients
who have no history of trauma or thoracic surgery (Figure 4). Short rib is diagnosed when
the lateral margin of the affected rib is more than 4mm medial to a tangent drawn between
the lateral margins of adjacent ribs (2). Short rib occurs in approximately 16% of the
population, with right side predominance (8% on the right side, 1% on the left side, 7%
bilaterally) (2). It is reported to involve only the sixth, seventh and eighth ribs.
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Fig.: 4. Short rib. Frontal chest radiograph (a) and VR image (b) show the shortening
of the right 8th rib compared to the adjacent ribs.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
2. Costal grooves
Normal grooves in the lower margin of the ribs, which carry the intercostal arteries veins,
and nerves, can simulate tumors of the rib or pneumothorax (Figure 5)(3). The groove is
st
th
st
observed in the lower margin of the rib in all but the 1 and 12 ribs. The 1 ribs have
grooves in the upper margin formed by the subclavian vessels and the brachial plexus
(Figure 6).
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Fig.: 5-6. Figure 5. Groove in the lower margin of the rib. Frontal chest radiograph
(a) demonstrates irregular borders of the lower margins of right 9th and 10th rib. An
opacity seems to be bulging inferiorly from the inferior aspect of the 9th rib (arrow). VR
image shows (b) the grooves in the lower margins of the ribs (white arrows). Figure 6.
Groove at the superior surface of the 1st rib. Frontal chest radiograph (a) shows the
step-like groove on the superior surface of the right 1st rib (arrow). VR image (b) shows
the subclavian artery and vein along the groove (white arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
3. Other congenital anomalies and deformities of the ribs
There are various types of other congenital anomalies and deformities of the ribs including
developmental fusion, articulation (Figure 7) or bridge formation (Figure 8), and forked
rib (bifid rib) (Figure 9). These morphologic anomalies and anatomic variants are more
frequent on the right side and occur predominantly in women in 0.15-0.31% of the
population (1). Fused rib is considered to be related to a segmentation defect because it
sometimes accompanies vertebral segmentation abnormalities (4). Rib bridging involves
a more focal joining of adjacent ribs by bone outgrowths between a pair of ribs or several
adjacent ribs.
Page 7 of 65
Fig.: 7-9. Figure 7. Rib articulation. Frontal chest radiograph (a) shows the notch
arising from the superior surface of the left 5th rib (arrow). VR image (b) shows the rib
articulation between the 4th and 5th ribs (white arrow). Figure 8. Rib bridging. Frontal
chest radiograph (a) shows the rib bridging between the right 5th and 6th rib (arrow).
Note that the distance between the two ribs is narrowed. VR image (b) shows the rib
bridging (white arrow). Figure 9. Forked rib. Frontal chest radiograph (a) shows the
poorly defined opacity, which is continuous to the 5th rib in the left middle lung (arrow).
VR image (b) demonstrates the forked configuration of the left 5th rib.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
st
Rib rudiments or hypoplasia of the 1 ribs are found in 0.2% in the population (Figure 8)
(4). These should not be confused with cervical ribs.
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Fig.: 10. Hypotrophy of the 1st rib. Frontal chest radiograph (a) shows the shortened
right 1st rib. It runs straight and medially. VR image (b) demonstrates the hypotrophic
right 1st rib and failure to fuse to the costal cartilage.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
5. Calcifications of the costal cartilages.
The pattern and degree of costal cartilage calcification are unique and have been used in
forensics to determine sex and age (5, 6). Foraminal defects are occasionally observed
in the patients with the male-type calcification of the costal cartilage (Figure 11). The
asymmetrical costal calcification is easily noticed on the chest radiograph especially at
st
the 1 ribs (Figure 12).
Page 9 of 65
Fig.: 11-12.Figure 11. Foramina-like lucency of the costal cartilage. Frontal chest
radiograph (a) shows ovoid-shaped lucent areas (arrows). VR image (b) demonstrates
male-type calcification of the rib cartilages with a foramina-shaped defect. Figure 12.
Asymmetrical calcification of the right 1st costal cartilage. Frontal chest radiograph (a)
shows asymmetrical opacity of the right sternocostal joint (white arrow). VR image (b)
shows sternocostal joint calcification to be more prominent on the right compared to the
left (white double arrow). Note the foraminal defect of the sternum (box arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
6. Bone island
Bone island in the rib is a common opacity which simulates a intrapulmonary nodule on
the chest radiograph (Figure 13).
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Fig.: 13. Bone island in the rib. Frontal chest radiograph (a) shows a well-defined
nodular opacity in the right upper lung (arrow). VR image (b) shows the bone island in
the right 2nd rib (white arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Scapula
The scapulae form the posterior part of the shoulder girdle. Each scapula is a flat,
triangular bone with two surfaces, three borders and three angles (Figure 14)(7).
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Fig.: 14. Normal anatomy of the scapula. Costal/ventral, dorsal and lateral views of the
scapula.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
The costal or ventral surface presents a broad concavity, which is called subscapular
fossa. The three borders of the scapula includes the superior, axillary and vertebral
border. The borders may show normal lucency on the frontal chest radiograph (Figure
15).
The superior border is concaved, extending from the medial angle to the base of the
coracoid process. The warpage of the superior border may simulate a clasp-like cranial
margin on the frontal chest radiograph (Figure 16).
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Fig.: 15-16.Figure 15. Normal radiolucency of the wing of the scapula. Frontal chest
radiograph (a) shows the broad lucent area in the scapula (arrows). In the VR image
(b) the thickness of the axillary border, warpage of the superior border and the thinness
of the subscapular fossa are easily recognized from the same oblique view. Figure
16. Clasp-like cranial margin of the scapula. Frontal chest radiograph (a) shows the
clasp-like cranial margin of the scapula, which produces a pseudo-foramen (arrows).
VR image lateral view (b) shows the superior thin curved border, which forms the fossa
supraspinata, appears to be absent (white arrows).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
The inferior angle formed by the union of the vertebral and axillary border occasionally
forms a hook-like configuration, which may simulate intrapulmonary mass (Figure 17).
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Fig.: 17. Hook-like configuration of the inferior angle of the scapula. Frontal
chest radiograph (a) shows the hook-like configuration of the inferior angle of the
scapula (arrow), which may mimic intraparenchymal disease. VR image (b) clearly
demonstrates the configuration in the inferior angle (white arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
The coracoid process is a thick curved process arising from a broad base on the upper
part of the neck of the scapula. The ascending portion may simulate a cystic mass in
the scapula when the X-ray beam is tangential to the cortical bone (Figure 18). The
horizontal portion is flattened from above down; its upper surface is convex and irregular,
and gives attachment to the Pectoralis minor and coracoacromial ligaments. The apex is
embraced by the conjoined tendons of the origin of the Coracobrachialis and the insertion
of the short head of Biceps brachii. Hypertrophic changes of the coracoid process
or articulations between the conoid tubercle and the coracoid process are commonly
observed in elderly patients (Figure 19).
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Fig.: 18-19. Figure 18. Foramina-like defect of the scapular neck. Frontal chest
radiograph (a) shows a focal lucent area with a sclerotic rim on the superior margin
of the scapular neck (arrow). VR image (b) shows the cortical bone of the coracoid
process correlates to the lucent area on the radiograph (horizontal portion of the
coracoid process cut away) (arrowheads). Figure 19. Hypertrophy of the coracoid
process. Frontal chest radiograph (a) shows the hypertrophic change of the coracoid
process (arrow). The distal inferior aspect of the clavicle demonstrates a notch-like
deformity along the coracoclavicular ligament (arrowhead). On the VR image (b)
the formation of the coracoclavicular joint and its degenerative change are clearly
observed.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Clavicle
The clavicle is a long bone with a medullary cavity of intramembranous origin. Medially
it articulates with the manubrium to form the sternoclavicular joint. Laterally it articulates
with the acromion process of the scapula at the acromioclavicular joint (7). The body of
the clavicle is formed by two primary ossification centers, one medial and one lateral,
which appear during the 5
th
and 6
th
week of fetal life. The third ossification center is
Page 15 of 65
secondary and represents the only epiphysis at the medial end of the bone. The normal
asymmetry of the clavicle of the medial secondary ossification center is commonly seen
in the healthy individuals (Figure 20)(8).
An irregular concavity (rhomboid fossa) may sometimes be present on the inferior surface
near the medial end of the bone at the attachment of the costoclavicular ligament (Figure
21)(8).
Fig.: 20-21. Figure 20. Normal asymmetry of the clavicle. Frontal chest radiograph
shows the normal asymmetry of the medial ends of the clavicle. Figure 21. Rhomboid
fossa. Frontal chest radiograph (a) and VR image (b) demonstrate the rhomboid fossa,
the site of attachment of the rhomboid ligament between the first rib and the clavicle. It
may simulate bone destruction or a cavitary lesion in the lung.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
The lateral inferior surface of the clavicle sometimes appears irregular at the insertion
of the trapezoid muscle (Figure 22). An irregularity may also be observed on the medial
superior surface of the clavicle caused by the subclavian artery and vein (Figure 23).
Page 16 of 65
Fig.: 22-23. Figure 22. Groove of the lower margin of the lateral inferior aspect of
the clavicle. Frontal chest radiograph (a) and VR image (b) show the groove for the
insertion of the coracoclavicular ligament (arrows). Figure 23. Groove of the lower
margin of the medial inferior aspect of the clavicle. Frontal chest radiograph (a) shows
fine irregularity of the inferior margins of the clavicle. VR image (b) demonstrates that
the irregularity matches the point at which the subclavian artery and vein run through
(arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Sternum
The sternum is a flat bone, slightly convex anteriorly and concave posteriorly. It consists
of three parts: the manubrium, body, and xiphoid process (Figure 24)(7).
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Fig.: 24. Normal anatomy of the sternum. VR of the frontal view shows the normal
anatomy of the sternum.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
The manubrium is the broadest portion of the sternum. It has a superior central notch and
two lateral fossae that articulate with the clavicles. The manubrium also articulates with
the first and second ribs and the body of the sternum (9,10). The body of the sternum
is flat, with an irregular anterior surface. Superiorly, it articulates with the manubrium at
the manubriosternal joint and with the xiphoid process inferiorly. The xiphoid process is a
thin elongated bone that is subject to many variations (Figure 25). It is cartilaginous early
in life and may be ossified and fused to the sternal body in old age (11,12).
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Fig.: 25. Bifid xiphoid process. Oblique lateral chest radiograph (a) shows two notches
of the xiphoid process (arrow). VR images of the same oblique view as the radiograph
(b) and frontal view (c) demonstrate the bifid xiphoid process (arrowheads).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Two small notches of the jugular notch are occasionally observed on the frontal chest
radiograph. They may be vestiges of the episternal bones (Figure 26).
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Fig.: 26. Episternal notch of the sternum. Frontal chest radiograph (a) and VR image
(b) show the nodular opacity close to the superolateral aspect of the manubrium
(arrows).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Episternal ossicles are retro- or supramanubrial accessory bones that result from
supernumerary ossification centers. They are found in 1.5% of the population. They may
be unilateral or bilateral, pyramidal in shape, and have a diameter of 2-15 mm (Figure 27).
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Fig.: 27. Episternal ossicles of the sternum. Frontal chest radiograph(a), axial (b)
and VR images of CT scan (c) show two small bones in back of dorsal aspect of the
manubrium (arrows).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Sternal foramen, which originates from the incomplete fusion of a pair of sternebrae, has
been incidentally detected on CT in nearly 5% of the population (Figure 12)(13).
Degenerative change is the most common abnormality affecting the sternoclavicular,
costosterna and manubriosternal joints (Figure 28,29)(14). Radiography is capable of
depicting osteophytes, synovial joint fusion and calcification in these patients.
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Fig.: 28-29. Figure 28. Degenerative change of the right costoclavicular joint. Frontal
chest radiograph (a) shows a well-marginated opacity which continues to the right
1st rib (arrow). VR image (b) shows ossification of the right costoclavicular joint and
osteophytes protruding caudally from the inferior aspect (white arrow). Figure 29.
Degenerative change of the manubriosternal joint. A lateral chest radiograph (a) shows
a notch-like opacity protruding into the thoracic cavity (arrow). Sagittal reconstructed
CT scan (b) shows an osteophyte of the manubriosternal joint (white arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Vertebra
A normal vertebra has a body and posterior elements. Many intrinsic and extrinsic
diseases, including congenital or acquired processes, may alter the normal vertebral body
configuration. Such diseases often demonstrate specific shapes of vertebrae.
1. Variations of congenital malformations
The abnormal configurations of the body of a vertebra including agenesis, hemivertebra,
coronal cleft, butterfly vertebra, block vertebra, limbus vertebra or hypoplasia are lead by
Page 22 of 65
failures in fusion of two ossification centers (15). The dysraphism is defined as incomplete
or absent fusion of midline neural, mesenchymal, and cutaneous structures. The occult
spinal dysraphism is sometimes diagnosed with radiographs (Figure 30).
Fig.: 30. Congenital dysraphism of the vertebra. Frontal chest radiograph (a) and VR
image (b) demonstrate congenital dysraphism of C1-Th6 vertebrae.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Pediculate anomalies include hypoplastic pedicle, retroisthmic defect and pediculate
cleft. The retroisthmic defect is observed independently or in co-existence with other
pediculate anomalies (Figure 31)(16).
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Fig.: 31. Retroisthmic defect of the vertebra. Frontal radiograph, (a) axial CT (b) and
VR images (c) (dorsal view) demonstrate the retroisthmic defect of the vertebra From
Th12 to L1 with no other complications of the vertebral body or posterior element.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
2. Normal structures that may mimic disease
Normal structures sometimes mimic vertebral body fracture on chest radiographs. They
include the venous sinus, in adults and synchondroses or cancellous bone in children
(Figure 32). In lean patients, transverse processes sometimes simulate nodules in the
lung or right hilar region (Figure 33).
Page 24 of 65
Fig.: 32-33. Figure 32. Venous sinuses of the vertebrae. Lateral chest radiograph (a)
shows thin, linear horizontal lucencies in the mid-portion of the vertebrae (arrows). On
sagittal reconstructed CT scan (b), the venous sinus groove is shown as roughness of
the traveculae (white arrows). Figure 33. Transverse process of the thoracic vertebra.
Frontal chest radiograph (a) and VR image (b) demonstrate the right transverse
process of the thoracic vertebra (arrows). The transverse process may be confused
with hilar or intraparenchymal nodules owing to the varying angle and extension.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
3. Degenerative change of the vertebrae (Spondylosis deformans)
Degenerative changes of the vertebrae commonly simulate nodules in the lung or bone
tumors in elderly patients as a result of the shearing of the outer annular (Sharpey's)
fibers. They rupture with disc herniation, which separates the anterior and longitudinal
spinal ligaments from the vertebral bodies. Reactive bone formation at these sites of
disruption results in the formation of horizontal and vertical ostephytes (Bumpy vertebra)
(Figure 34,35)(15). Bumpy vertebrae show prominent osteophytes typically prominent
on the right side of vertebrae. The left aspect of the vertebrae might retain their normal
shape because of the pulsation of the descending aorta.
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Fig.: 34-35. Figure 34. Bumpy vertebra. Frontal chest radiograph (a) and VR image
(b) demonstrate hypertrophy of the costovertebral articulations at multiple levels
with right-side predominance (arrow). Figure 35. Vertebral ostephytes. Lateral chest
radiograph (a) shows nodule-like opacity simulating retrocardial intraparenchymal mass
(arrow). Sagittal reconstructed CT scan (b) demonstrates the osteophytes bridging the
endoplates (white arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
The costovertebral joint may also represent hypertrophy at one or several levels. It can
be confused with paravertebral or paratracheal mass (Figure 36).
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Fig.: 36. Degeneration of the costovertebral articulation. Frontal chest radiograph (a),
axial (b) and coronal (c) reconstructed CT scans show the degenerative changes of the
costovertebral articulation, which is an indication of pulmonary pseudolesion (arrows).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
A Schmorl's node is a contour defect in the endplate of a vertebra resulting from central
herniation of a portion of the disc into the adjacent vertebra body (15). A defect or
weakness in the endplate leads to such disc herniation. A Schmorl's node is seen as a
radiolucent defect with a sclerotic margin subjacent to the endplate (Figure 37).
Page 27 of 65
Fig.: 37. Schmorl's node. Lateral chest radiograph (a), Sagittal reconstructed CT (b)
and axial CT (c) scans show the schmorl's node as a lucent defect with a sclerotic rim
subjacent to the vertebral endplate (arrows). A small Schmorl's node co-exists at the
left margin of the vertebra (white arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Other degenerative changes include calcification of perivertebral ligaments(Figure 38),
enthesopathy, and vacuum phenomenon in the disc (Figure 39). Those commonly seen
in the frontal and lateral chest radiograph of elderly patients may simulate vertebral or
perivertebral diseases.
Page 28 of 65
Fig.: 38-39. Figure 38. Calcification of the interspinous ligament. Lateral chest
radiograph (a) and VR image (b) show the calcification of the interspinous ligament,
which may simulate a fracture of the processus spinosus (arrows). Figure 39. Vacuum
phenomenon. Lateral chest radiograph (a) and sagittal reconstructed CT scan (b) show
intervertebral gas (arrows). Note the osteophytes at multiple levels.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Others
1. Variations of anomalous articulations
On chest radiographs, various anomalous articulations are observed between rib and rib,
rib and scapula or rib and vertebra (Figure40-44). It is important that the radiologist be
familiar with the variations in anomalous articulations.
Page 29 of 65
Fig.: 40-41. Figure 40. Anomalous articulation between the 1st and 2nd ribs. Frontal
chest radiograph (a) and lateral view VR image (b) demonstrate the articulation
between the left 1st and 2nd ribs (arrows). Figure 41. Aneurysm formation caused by
anomalous articulation between the 1st and 2nd ribs. Frontal chest radiograph (a) and
lateral view VR image (b) demonstrate the articulation between the left 1st and 2nd
ribs (arrows). VR image (c) with intravenous contrast medium shows the aneurysmal
formation at the thoracic inlet caused by the anomalous articulation (white box arrow).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Page 30 of 65
Fig.: 42-43. Figure 42. Anomalous articulation in the 1st rib. Frontal chest radiograph
(a) and coronal reconstructed CT scan (b) show the anomalous articulation in the right
1st rib simulating a fracture (arrows). Figure 43. Anomalous articulation between the
ribs. Frontal chest radiograph (a) and coronal reconstructed CT scan (b) show the
anomalous articulation between the 4th and 5th ribs (arrows).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Page 31 of 65
Fig.: 44. Anomalous articulation between the rib and scapula. Frontal chest radiograph
(a), axial CT (b) and VR image (c) demonstrate the articulation between the scapula
and adjacent rib.
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
2. Calcification of the cartilages of the larynx
The calcification of the cartilages of the larynx occurs in the healthy patients
asymmetrically or heterogeneously on the frontal radiograph (Figure 45).
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Fig.: 45. Calcification of the cartilages of the larynx. Frontal chest radiograph (a)
shows the crown-shaped opacity laying over the cervical spine (arrows). VR image (b)
shows dense calcification of the thyroid and arytenoids cartilages (white box arrows).
References: A. Yamamoto; Radiology, Teikyo University, Tokyo, JAPAN
Page 33 of 65
Images for this section:
Fig. 1: 1. Cervical rib. Frontal chest radiograph (a) and VR image (b) show the bilateral
cervical rib (white arrows).
Page 34 of 65
Fig. 2: 2-3. Figure 2. Lumbar rib. Frontal chest radiograph (a) shows osseous protrusion
horizontally from L1, which simulates a hypertrophic transverse process of the lumbar
vertebra (arrows). VR image (b) presents the lumbar rib from L1 bilaterally (white arrows).
Figure 3. Hypotrophy of the 12th rib. Frontal chest radiograph (a) shows a short bony
protrusion from Th12, which simulates transverse process of the lumbar vertebra or
the lumbar rib (arrow). VR image (b) demonstrates the bony protrusion as the unfused
hypotrophic right 12th rib. The contralateral 12th rib is also hypotrophic.
Page 35 of 65
Fig. 3: 4. Short rib. Frontal chest radiograph (a) and VR image (b) show the shortening
of the right 8th rib compared to the adjacent ribs.
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Fig. 4: 5-6. Figure 5. Groove in the lower margin of the rib. Frontal chest radiograph (a)
demonstrates irregular borders of the lower margins of right 9th and 10th rib. An opacity
seems to be bulging inferiorly from the inferior aspect of the 9th rib (arrow). VR image
shows (b) the grooves in the lower margins of the ribs (white arrows). Figure 6. Groove at
the superior surface of the 1st rib. Frontal chest radiograph (a) shows the step-like groove
on the superior surface of the right 1st rib (arrow). VR image (b) shows the subclavian
artery and vein along the groove (white arrow).
Page 37 of 65
Fig. 5: 7-9. Figure 7. Rib articulation. Frontal chest radiograph (a) shows the notch
arising from the superior surface of the left 5th rib (arrow). VR image (b) shows the rib
articulation between the 4th and 5th ribs (white arrow). Figure 8. Rib bridging. Frontal
chest radiograph (a) shows the rib bridging between the right 5th and 6th rib (arrow). Note
that the distance between the two ribs is narrowed. VR image (b) shows the rib bridging
(white arrow). Figure 9. Forked rib. Frontal chest radiograph (a) shows the poorly defined
opacity, which is continuous to the 5th rib in the left middle lung (arrow). VR image (b)
demonstrates the forked configuration of the left 5th rib.
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Fig. 6: 10. Hypotrophy of the 1st rib. Frontal chest radiograph (a) shows the shortened
right 1st rib. It runs straight and medially. VR image (b) demonstrates the hypotrophic
right 1st rib and failure to fuse to the costal cartilage.
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Fig. 7: 11-12.Figure 11. Foramina-like lucency of the costal cartilage. Frontal chest
radiograph (a) shows ovoid-shaped lucent areas (arrows). VR image (b) demonstrates
male-type calcification of the rib cartilages with a foramina-shaped defect. Figure 12.
Asymmetrical calcification of the right 1st costal cartilage. Frontal chest radiograph (a)
shows asymmetrical opacity of the right sternocostal joint (white arrow). VR image (b)
shows sternocostal joint calcification to be more prominent on the right compared to the
left (white double arrow). Note the foraminal defect of the sternum (box arrow).
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Fig. 8: 13. Bone island in the rib. Frontal chest radiograph (a) shows a well-defined
nodular opacity in the right upper lung (arrow). VR image (b) shows the bone island in
the right 2nd rib (white arrow).
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Fig. 9: 14. Normal anatomy of the scapula. Costal/ventral, dorsal and lateral views of
the scapula.
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Fig. 10: 15-16.Figure 15. Normal radiolucency of the wing of the scapula. Frontal chest
radiograph (a) shows the broad lucent area in the scapula (arrows). In the VR image
(b) the thickness of the axillary border, warpage of the superior border and the thinness
of the subscapular fossa are easily recognized from the same oblique view. Figure
16. Clasp-like cranial margin of the scapula. Frontal chest radiograph (a) shows the
clasp-like cranial margin of the scapula, which produces a pseudo-foramen (arrows).
VR image lateral view (b) shows the superior thin curved border, which forms the fossa
supraspinata, appears to be absent (white arrows).
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Fig. 11: 17. Hook-like configuration of the inferior angle of the scapula. Frontal chest
radiograph (a) shows the hook-like configuration of the inferior angle of the scapula
(arrow), which may mimic intraparenchymal disease. VR image (b) clearly demonstrates
the configuration in the inferior angle (white arrow).
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Fig. 12: 18-19. Figure 18. Foramina-like defect of the scapular neck. Frontal chest
radiograph (a) shows a focal lucent area with a sclerotic rim on the superior margin
of the scapular neck (arrow). VR image (b) shows the cortical bone of the coracoid
process correlates to the lucent area on the radiograph (horizontal portion of the coracoid
process cut away) (arrowheads). Figure 19. Hypertrophy of the coracoid process. Frontal
chest radiograph (a) shows the hypertrophic change of the coracoid process (arrow).
The distal inferior aspect of the clavicle demonstrates a notch-like deformity along
the coracoclavicular ligament (arrowhead). On the VR image (b) the formation of the
coracoclavicular joint and its degenerative change are clearly observed.
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Fig. 13: 20-21. Figure 20. Normal asymmetry of the clavicle. Frontal chest radiograph
shows the normal asymmetry of the medial ends of the clavicle. Figure 21. Rhomboid
fossa. Frontal chest radiograph (a) and VR image (b) demonstrate the rhomboid fossa,
the site of attachment of the rhomboid ligament between the first rib and the clavicle. It
may simulate bone destruction or a cavitary lesion in the lung.
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Fig. 14: 22-23. Figure 22. Groove of the lower margin of the lateral inferior aspect of the
clavicle. Frontal chest radiograph (a) and VR image (b) show the groove for the insertion
of the coracoclavicular ligament (arrows). Figure 23. Groove of the lower margin of the
medial inferior aspect of the clavicle. Frontal chest radiograph (a) shows fine irregularity
of the inferior margins of the clavicle. VR image (b) demonstrates that the irregularity
matches the point at which the subclavian artery and vein run through (arrow).
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Fig. 15: 24. Normal anatomy of the sternum. VR of the frontal view shows the normal
anatomy of the sternum.
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Fig. 16: 25. Bifid xiphoid process. Oblique lateral chest radiograph (a) shows two notches
of the xiphoid process (arrow). VR images of the same oblique view as the radiograph
(b) and frontal view (c) demonstrate the bifid xiphoid process (arrowheads).
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Fig. 17: 26. Episternal notch of the sternum. Frontal chest radiograph (a) and VR image
(b) show the nodular opacity close to the superolateral aspect of the manubrium (arrows).
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Fig. 18: 27. Episternal ossicles of the sternum. Frontal chest radiograph(a), axial (b)
and VR images of CT scan (c) show two small bones in back of dorsal aspect of the
manubrium (arrows).
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Fig. 19: 28-29. Figure 28. Degenerative change of the right costoclavicular joint. Frontal
chest radiograph (a) shows a well-marginated opacity which continues to the right 1st rib
(arrow). VR image (b) shows ossification of the right costoclavicular joint and osteophytes
protruding caudally from the inferior aspect (white arrow). Figure 29. Degenerative
change of the manubriosternal joint. A lateral chest radiograph (a) shows a notch-like
opacity protruding into the thoracic cavity (arrow). Sagittal reconstructed CT scan (b)
shows an osteophyte of the manubriosternal joint (white arrow).
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Fig. 20: 30. Congenital dysraphism of the vertebra. Frontal chest radiograph (a) and VR
image (b) demonstrate congenital dysraphism of C1-Th6 vertebrae.
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Fig. 21: 31. Retroisthmic defect of the vertebra. Frontal radiograph, (a) axial CT (b) and
VR images (c) (dorsal view) demonstrate the retroisthmic defect of the vertebra From
Th12 to L1 with no other complications of the vertebral body or posterior element.
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Fig. 22: 32-33. Figure 32. Venous sinuses of the vertebrae. Lateral chest radiograph (a)
shows thin, linear horizontal lucencies in the mid-portion of the vertebrae (arrows). On
sagittal reconstructed CT scan (b), the venous sinus groove is shown as roughness of
the traveculae (white arrows). Figure 33. Transverse process of the thoracic vertebra.
Frontal chest radiograph (a) and VR image (b) demonstrate the right transverse process
of the thoracic vertebra (arrows). The transverse process may be confused with hilar or
intraparenchymal nodules owing to the varying angle and extension.
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Fig. 23: 34-35. Figure 34. Bumpy vertebra. Frontal chest radiograph (a) and VR image (b)
demonstrate hypertrophy of the costovertebral articulations at multiple levels with rightside predominance (arrow). Figure 35. Vertebral ostephytes. Lateral chest radiograph (a)
shows nodule-like opacity simulating retrocardial intraparenchymal mass (arrow). Sagittal
reconstructed CT scan (b) demonstrates the osteophytes bridging the endoplates (white
arrow).
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Fig. 24: 36. Degeneration of the costovertebral articulation. Frontal chest radiograph (a),
axial (b) and coronal (c) reconstructed CT scans show the degenerative changes of the
costovertebral articulation, which is an indication of pulmonary pseudolesion (arrows).
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Fig. 25: 37. Schmorl's node. Lateral chest radiograph (a), Sagittal reconstructed CT (b)
and axial CT (c) scans show the schmorl's node as a lucent defect with a sclerotic rim
subjacent to the vertebral endplate (arrows). A small Schmorl's node co-exists at the left
margin of the vertebra (white arrow).
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Fig. 26: 38-39. Figure 38. Calcification of the interspinous ligament. Lateral chest
radiograph (a) and VR image (b) show the calcification of the interspinous ligament,
which may simulate a fracture of the processus spinosus (arrows). Figure 39. Vacuum
phenomenon. Lateral chest radiograph (a) and sagittal reconstructed CT scan (b) show
intervertebral gas (arrows). Note the osteophytes at multiple levels.
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Fig. 27: 40-41. Figure 40. Anomalous articulation between the 1st and 2nd ribs. Frontal
chest radiograph (a) and lateral view VR image (b) demonstrate the articulation between
the left 1st and 2nd ribs (arrows). Figure 41. Aneurysm formation caused by anomalous
articulation between the 1st and 2nd ribs. Frontal chest radiograph (a) and lateral view
VR image (b) demonstrate the articulation between the left 1st and 2nd ribs (arrows).
VR image (c) with intravenous contrast medium shows the aneurysmal formation at the
thoracic inlet caused by the anomalous articulation (white box arrow).
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Fig. 28: 42-43. Figure 42. Anomalous articulation in the 1st rib. Frontal chest radiograph
(a) and coronal reconstructed CT scan (b) show the anomalous articulation in the right
1st rib simulating a fracture (arrows). Figure 43. Anomalous articulation between the ribs.
Frontal chest radiograph (a) and coronal reconstructed CT scan (b) show the anomalous
articulation between the 4th and 5th ribs (arrows).
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Fig. 29: 44. Anomalous articulation between the rib and scapula. Frontal chest radiograph
(a), axial CT (b) and VR image (c) demonstrate the articulation between the scapula and
adjacent rib.
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Fig. 30: 45. Calcification of the cartilages of the larynx. Frontal chest radiograph (a) shows
the crown-shaped opacity laying over the cervical spine (arrows). VR image (b) shows
dense calcification of the thyroid and arytenoids cartilages (white box arrows).
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Conclusion
Correlation of plain chest radiographs and MDCT multiplanar reconstructed or volumerendering images dramatically improve understanding of radiographic anatomy of
complicated and overlapping thoracic bony components. It is important for radiologists
to be familiar with the normal anatomy, the variants, and the radiological appearance of
the bony components.
Personal Information
A. Yamamoto, S. Suzuki, K. Toyoda, M. Yamasaki, E. Lien, T. O'uchi, S. Furui.
Department of Radiology, Teikyo University, 2-11-1 Kaga Itabashiku, Tokyo, Japan.
mail to: [email protected]
M. Yamasaki; Department of Radiology, Kohka Public Hospital, Shiga, Japan.
E. Lien, T. O'uchi; Department of Radiology, Kameda Medical Center, Chiba, Japan.
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