Download Non-invasive imaging of aberrant right subclavian artery pathologies

The British Journal of Radiology, 82 (2009), 73–78
PICTORIAL REVIEW
Non-invasive imaging of aberrant right subclavian artery
pathologies and aberrant right vertebral artery
1
M KARCAALTINCABA,
M ARIYUREK, MD
MD,
1
M HALILOGLU,
MD,
1
E OZKAN,
MD,
2
M KOCAK,
MD,
1
D AKINCI,
MD
and
1
1
Department of Radiology, Hacettepe University School of Medicine, Ankara, Turkey and 2Department of Radiology,
Medical College of Wisconsin, Milwaukee, WI, USA
ABSTRACT. Here, we review the CT and MR angiography findings of aberrant right
subclavian and right vertebral arteries, with emphasis on the differences between these
structures. In addition, non-invasive imaging findings of aberrant right subclavian
artery pathologies, including arteritis, aneurysm and dissection, are discussed.
Received: 13 April 2006
Revised: 8 October 2006
Accepted: 15 November
2006
DOI: 10.1259/bjr/44929969
’ 2009 The British Institute of
Radiology
Recent developments in non-invasive CT and MR
angiographic imaging allow the diagnosis of aortic arch
anomalies and the visualization of pathological findings of
anomalous arteries. Imaging features of these anomalies
and the spectrum of their pathologies should be known so
that a confident diagnosis can be given. The combination of
three-dimensional and axial images may provide better
understanding of the vascular anatomy compared with
conventional angiography. Aberrant right subclavian artery
(ARSA) is the most common aortic arch anomaly, with an
incidence of 1–2% [1, 2]. Although aneurysm and dissection
of the ARSA has been described in the literature, arteritis of
this anomaly is first described here [1–5]. Aberrant right
vertebral artery is an extremely rare anomaly and may
mimic an ARSA by its retro-oesophageal course [6].
Non-invasive angiography using multidetector CT and
MRI has now become a routine application [7, 8]. The
advantages of multidetector CT angiography are ease of
application, wider use of the technique and simultaneous
visualization of adjacent anatomic structures. MR angiography provides high-quality multiphasic imaging without the risk of increased radiation dose, which is a
significant problem with CT angiography. The aim of this
pictorial review is to demonstrate non-invasive MR and
CT angiographic findings from patients with normal and
pathological aberrant right subclavian arteries (aneurysm
and arteritis) and an aberrant right vertebral artery.
Embryology and anatomy
ARSA develops as a result of interruption between the
right common carotid artery and the ARSA in the
Address correspondence to: Musturay Karcaaltincaba, Department
of Radiology, Hacettepe University School of Medicine, Ankara,
Turkey. E-mail: [email protected]
The British Journal of Radiology, January 2009
developing double aortic arch [9]. In the ARSA, the right
fourth aortic arch and the proximal right dorsal aorta
involute and the right seventh intersegmental artery
develops from a persistent dorsal aorta (Figure 1). An
aortic (Kommerell̀s) diverticulum may be present at the
origin of this vessel, representing the remnant of the
distal right aortic arch [1]. The ARSA is located posterior
to the oesophagus on axial CT images, and can be seen as
the last branch from the posterior margin of the aortic
arch on three-dimensional images (Figure 2). The ARSA
can indent the oesophagus and the trachea posteriorly,
resulting in dysphagia lusoria and airway narrowing,
respectively.
Maethods and materials
We reviewed retrospectively our archive for ARSA and
its associated pathologies diagnosed between 2001 and
2003, and identified aneurysm and arteritis of ARSA and
dissection of the right vertebral artery originating from
ARSA. Three-dimensional non-invasive angiographic
images were obtained by MR angiography and multidetector (4- and 8-channel) CT angiography. Volumerendered, maximum intensity projection (MIP) and multiplanar reformatted (MPR) images were obtained after the
reconstruction of the axial slices. The aberrant right
vertebral artery was incidentally diagnosed.
Aneurysm
Aneurysmal dilatation of the proximal segment of an
ARSA is not infrequent, occurring in 8% of cases. Such an
aneurysm can be associated with the Kommerell̀s
diverticulum and is thought to develop secondary to
atherosclerosis. Almost half of the cases with an ARSA
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M Karcaaltincaba, M Haliloglu, E Ozkan et al
Figure 1. A diagram showing the
normal embryological development
of the aortic arch and the development of an aberrant right subclavian
artery (ARSA). (a) Normal embryological anatomy of aortic arches are
displayed. (b) During normal development, most of the aortic arches
involute and the 4th arch forms the
aortic arch. Also, the right dorsal
aorta involutes. (c) ARSA develops as
a result of persistent right dorsal
aorta (known as Kommerell’s diveritculum) and involution of the right
4th embryologic arch. Emrbyological aortic arches are represented
in purple and involuted ones in
grey. Arches in red represent persistent embryological structures in
adult life (b,c).
aneurysm ruptured with conservative management,
prompting some authors to recommend surgery even
in asymptomatic cases [1, 3]. In our case, we diagnosed
an ARSA aneurysm in a patient with a truncus arteriosus
anomaly (Figure 3). Interestingly, the left pulmonary
artery was rising from the aortic arch and was
compressed between the ARSA aneurysm and the aortic
arch in this patient. Although an ARSA aneurysm can
compress the trachea, left pulmonary artery compression
by such an aneurysm has not been described before.
Arteritis
Atherosclerosis can involve the ARSA, resulting in
stenosis; however, stenosis owing to arteritis of an ARSA
has not been described previously. Arteritis of the ARSA
developed secondary to Takayasu arteritis in our patient
(Figure 4). CT angiography allowed the diagnosis in this
case. Diagnosis of ARSA arteritis is important because
failure to recognize this anomaly may result in a change
in the surgical treatment approach or the failure of
Figure 2. A 35-year-old man with an incidentally diagnosed aberrant right subclavian artery (ARSA). (a) On CT angiography (left
anterior oblique projection), the ARSA is seen as the last branch from the aortic arch (arrow). (b) CT angiography (posterior
projection) shows the ARSA as the only posterior branch (arrow). (c) An axial image shows the ARSA posterolateral to the
oesophagus (arrow).
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The British Journal of Radiology, January 2009
Pictorial review: Non-invasive imaging of aberrant right subclavian and right vertebral artery pathologies
Figure 3. A 2-year-old girl with an aberrant right subclavian artery (ARSA) aneurysm and truncus arteriosus anomaly. (a,b) CT
angiography (left posterior and superior projections) images show a dilated ARSA and fusiform aneurysm (long arrow). Note the
left pulmonary artery (short arrow) arising from the aortic arch (double arrow). (c) Coronal multiplanar reformatted image
shows narrowing of the left pulmonary artery (arrow) between the ARSA aneurysm (asterisk) and the aortic arch (AA). (d) An
axial CT image showing the ARSA (asterisk) traversing posterior to the aortic arch and indenting the posterior wall of the
trachea (T).
treatment by stenosis using vascular interventional
techniques [10].
Dissection
Dissection of an ARSA is very rare, and only 16 cases
have been reported in the literature [3]. Non-invasive
imaging plays a major role in the diagnosis of dissection.
Established criteria for the classification of dissection are not
valid in cases with ARSA, because it arises distal to the left
subclavian artery. Failure to recognize this anomaly and
The British Journal of Radiology, January 2009
cross-clamping of the aorta proximal to the origin of the left
subclavian artery during surgery can result in brainstem
infarct secondary to occlusion of the blood supply to both
vertebral arteries [5]. We observed the dissection of the right
vertebral artery originating from an ARSA (Figure 5). We
thought that dissection in this patient might have developed
because of hypermobility of the ARSA and a susceptibility
to rotational forces resulting from the increased length of
the artery. Mulligan et al [5] suggested that an ARSA may
show increased susceptibility to atherosclerosis and its
associated complications, including aneurysms, dissections
and stenosis in accordance with our observation.
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M Karcaaltincaba, M Haliloglu, E Ozkan et al
Figure 4. A 40-year-old woman with Takayasu arteritis and aberrant right subclavian artery (ARSA) involvement, resulting in
right-sided subclavian steal. (a,b) CT angiography (superior left anterior oblique and left posterior oblique projections) shows
severe stenosis of the ARSA (arrow). Note that vasculitis involves the retro-oesophageal segment, sparing the distal ARSA and
Kommerell̀s diverticulum. (c) Axial CT image shows the normal calibre of the Kommerell̀s diverticulum (arrow). (d) Coronal thin
maximum intensity projection image demonstrates wall thickening and narrowing of the ARSA, consistent with vasculitis. These
findings were not visible on conventional angiography.
Aberrant right vertebral artery
An aberrant right vertebral artery arises from the dorsal
margin of the aortic arch as the last branch, similar to an
ARSA [6]. The proximal segment of the aberrant right
vertebral artery is located posterior to the oesophagus and,
cranially, the artery ascends to the vertebral foramen, in
contradistinction to an ARSA that travels towards the right
shoulder (Figure 6). Diagnosis of aberrant right vertebral
artery is important especially in patients with dissection
who will undergo surgical treatment, because failure to do
so may result in bilateral brain stem infarction after crossclamping of the aorta proximal to the left subclavian
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artery. The aberrant right vertebral artery may mimic an
ARSA, especially when it is stenotic, by its retrooesophageal course. However, a normal right subclavian
artery exists in the presence of an aberrant right vertebral
artery, and has a small calibre compared with the ARSA.
Conclusions
Familiarity with the non-invasive imaging findings of
ARSA pathologies and aberrant right vertebral artery is
crucial for correct diagnosis. It should be kept in mind that
other pathological conditions may coexist with ARSA.
The British Journal of Radiology, January 2009
Pictorial review: Non-invasive imaging of aberrant right subclavian and right vertebral artery pathologies
Figure 5. A 42-year-old man with right vertebral artery (RVA) dissection (arrow) and aberrant right subclavian artery (ARSA).
(a,b) MR angiography, coronal thin maximum intensity projection and coronal volume-rendered projections show a dissected
vertebral artery arising from the ARSA. (c,d). Diffusion-weighted MR image and head CT image show infarct in the right
cerebellum as a result of dissection.
The British Journal of Radiology, January 2009
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M Karcaaltincaba, M Haliloglu, E Ozkan et al
Figure 6. A 59-year-old woman with an incidentally diagnosed aberrant right vertebral artery (RVA). (a) Axial CT image shows
the retro-oesophageal course of the aberrant RVA. (b) Curved planar reformatted image shows the aberrant RVA traversing
towards the right vertebral canal. (c,d) CT angiography (left posterior oblique projections) shows the aberrant RVA as the last
branch from the posterior aspect of the aortic arch. Kommerell̀s diverticulum (arrow) is also seen at the origin of the aberrant
RVA. LCCA, left common carotid artery; RCCA, right common carotid artery; LVA, left vertebral artery; LSA, left subclavian artery;
RSA, right subclavian artery. Reprinted with permission from [6].
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