AJR 2003; 181:1409-1414
© American Roentgen Ray Society
MR Angiography of Anomalous Branches of the Internal Carotid Artery
Akira Uchino1,
Akihiro Sawada,
Yukinori Takase and
Sho Kudo
1 All authors: Department of Radiology, Saga Medical School, 5-1-1 Nabeshima,
Saga 849-8501, Japan.
Received December 2, 2002;
accepted after revision March 27, 2003.
Address correspondence to A. Uchino
(uchino{at}post.saga-med.ac.jp).
Introduction
Cerebral arterial variations are of many types
[1,
2,2].
Because of the improvements in the image quality of MR angiography offered by
the three-dimensional (3D) time-of-flight (TOF) technique, these variations
now appear incidentally and frequently during routine MR angiography. This
pictorial essay shows several types of anomalous branches of the internal
carotid artery (ICA) detected on MR angiography with a 1.5-T imager. Although
anomalous branches of the ICA usually have no clinical significance, knowledge
of the variations is useful and important for the interpretation of cranial MR
angiography because the variations can influence surgical and interventional
procedure.
MR Angiography Technique
During the past 6 years, approximately 900 patients underwent cranial MR
angiography with the 3D TOF technique at our institution. All patients were
scanned with a 1.5-T imager (Signa Horizon, General Electric Medical Systems,
Milwaukee, WI). Repetition time was 33.3–57 msec, echo time was
2.9–4.6 msec, and field of view was 16 x 16 cm. The imaging matrix
was 256 x 160 or 256 x 192, and the number of excitations was 1.
Thus, the scanning time was approximately 10 min. Maximum-intensity-projection
images in the horizontal rotation view were routinely displayed
stereoscopically over 180°.
Anomalous Branches of the ICA Detected on MR Angiography
The ICA may have numerous anomalous branches. The variations we present in
this pictorial essay are illustrated in
Figure 1, which also indicates
where each anomaly is illustrated in the figures that follow. We discuss these
variations in numeric order. We know the importance of the embryologic source
of these variations, but we will omit the embryology of the persistent fetal
carotid–vertebrobasilar anastomoses because the main purpose of this
article is to show MR angiographic images of the variations and because
well-written articles on the embryology of this anatomic region have already
been published in this journal
[1,
2,2].
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Fig. 1. —Drawing in lateral projection shows anomalous branches of
internal carotid artery: a = internal carotid artery, b = vertebral artery, c
= basilar artery, d = ophthalmic artery, e = anterior cerebral artery, f =
middle cerebral artery, g = posterior cerebral artery. Numbers indicate which
following figures illustrate anomalies: 2, persistent hypoglossal artery;
3–5, persistent trigeminal artery; 5, fetal origin of the posterior
cerebral artery; 6, persistent trigeminal artery variant; 7, persistent dorsal
ophthalmic artery; 8, carotid–anterior cerebral artery anastomosis; 9,
hyperplastic anterior choroidal artery; 10, duplicated middle cerebral artery;
11, persistent primitive olfactory artery.
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Persistent Carotid–Vertebrobasilar Anastomoses
Persistent hypoglossal artery.—The persistent hypoglossal
artery (Fig. 2A,
2B) is the second most common
carotid–vertebrobasilar artery anastomosis. In approximately 900
patients, we found one persistent hypoglossal artery. Its incidence is
reported to be 0.02–0.1% [3]. The persistent hypoglossal artery leaves
the ICA as a large extracranial branch. It passes through the hypoglossal
canal, and the basilar trunk originates from the persistent hypoglossal
artery. Definitive diagnosis of the persistent hypoglossal artery can be made
by recognition of an anomalous artery in the enlarged hypoglossal canal
[2,2].
However, the persistent hypoglossal artery may not be found during routine
cranial MR angiography because in most patients the hypoglossal canals are not
included in routine imaging slabs.
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Fig. 2A. —59-year-old woman with right persistent hypoglossal artery.
Anteroposterior MR angiogram shows large anomalous artery (arrows)
arising from cervical right internal carotid artery and supplying basilar
artery.
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Persistent trigeminal artery.—The persistent trigeminal
artery is the most cephalically located and frequently occurring persistent
carotid–vertebrobasilar anastomosis. Its incidence is reported to be
0.1–0.6% in large angiographic series [3]. The persistent trigeminal
artery has two types, the lateral type and the medial type
[2,2].
Both are equally common. The persistent trigeminal artery is also classified
according to the configuration of the ipsilateral posterior cerebral artery
(Fig. 3A,
3B,
3C,
3D). In the Saltzman type 1
[4] persistent trigeminal
artery, the posterior communicating artery is absent. In the Saltzman type 2
persistent trigeminal artery, the ipsilateral posterior cerebral artery arises
directly from the ICA and the P1 segment is absent, which indicates a fetal
origin of the posterior cerebral artery [3]. The basilar artery is usually
hypoplastic caudad to the anastomosis in both Saltzman types.
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Fig. 3A. —Drawings shows four types of persistent trigeminal artery in
inferosuperior projection. Drawing shows lateral type, Saltzman type 1. a =
internal carotid artery, b = basilar artery, c = posterior communicating
artery, d = posterior cerebral artery.
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We found three lateral-type persistent trigeminal arteries (Fig.
4A,
4B). The lateral type
originates from the precavernous segment of the ICA and courses
posterolaterally along the trigeminal nerve; it anastomoses with the mid
portion of the basilar artery.
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Fig. 4A. —68-year-old woman with right lateral type and Saltzman type 1
[3] persistent trigeminal artery. Inferosuperior (A) and lateral
(B) projections of partial maximum-intensity-projection image of MR
angiogram of right hemisphere show extremely large anomalous artery (thick
arrows) arising from precavernous right internal carotid artery. Proximal
basilar artery (short thin arrow, A) is hypoplastic. Note lack
of ipsilateral posterior communicating artery (long thin arrow,
B).
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Fig. 4B. —68-year-old woman with right lateral type and Saltzman type 1
[3] persistent trigeminal artery. Inferosuperior (A) and lateral
(B) projections of partial maximum-intensity-projection image of MR
angiogram of right hemisphere show extremely large anomalous artery (thick
arrows) arising from precavernous right internal carotid artery. Proximal
basilar artery (short thin arrow, A) is hypoplastic. Note lack
of ipsilateral posterior communicating artery (long thin arrow,
B).
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The medial-type persistent trigeminal artery is also called the
"intrasellar persistent trigeminal artery" or the
"transhypophyseal persistent trigeminal artery." We found two
medial-type persistent trigeminal arteries (Fig.
5A,
5B,
5C). The medial type arises
from the precavernous ICA and courses posteromedially. It compresses the
pituitary gland and penetrates the dorsum sellae, and it anastomoses with the
midbasilar artery. This persistent trigeminal artery type is clinically
important because transsphenoidal surgery for pituitary adenoma is dangerous
in patients who have this variant
[5].
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Fig. 5A. —44-year-old man with left medial type and Saltzman type 2 [3]
persistent trigeminal artery. Inferosuperior projection shows anomalous artery
(thick arrow) arising from left internal carotid artery and coursing
posteromedially. Note ipsilateral fetal origin of posterior cerebral artery
(thin arrow).
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Fig. 5B. —44-year-old man with left medial type and Saltzman type 2 [3]
persistent trigeminal artery. Slightly left anterior oblique projection shows
anomalous artery (thick arrow) arising from precavernous internal
carotid artery and anastomosing with basilar artery. Proximal basilar artery
(thin straight arrow) is hypoplastic. Note azygos anterior cerebral
artery (curved arrow).
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Fig. 5C. —44-year-old man with left medial type and Saltzman type 2 [3]
persistent trigeminal artery. T2-weighted coronal fast spin-echo image (TR/TE,
3,500/88) shows anomalous flow void (arrow) in sella.
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Persistent trigeminal artery variant.—Cerebellar arteries
arising from the precavernous ICA without connection with the basilar artery
are regarded as persistent trigeminal artery variants
[6]. We found five persistent
trigeminal artery variants: four anteroinferior cerebellar arteries and one
superior cerebellar artery (Fig.
6A,
6B). The anteroinferior
cerebellar artery is the most common type, but both the posteroinferior
cerebellar artery and the superior cerebellar artery can arise from the ICA.
Visualization and recognition of these anomalous arteries may be difficult
because persistent trigeminal artery variants are usually small in caliber.
Careful interpretation of the stereoscopically displayed MR angiographic
images is essential.
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Fig. 6A. —56-year-old man with left persistent trigeminal artery
variant. Stereoscopic left anterior oblique projections show small anomalous
artery (arrows, A) arising from precavernous left internal
carotid artery. Anomalous artery has typical configuration of superior
cerebellar artery.
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Fig. 6B. —56-year-old man with left persistent trigeminal artery
variant. Stereoscopic left anterior oblique projections show small anomalous
artery (arrows, A) arising from precavernous left internal
carotid artery. Anomalous artery has typical configuration of superior
cerebellar artery.
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Persistent Dorsal Ophthalmic Artery
The ophthalmic artery arising from the cavernous ICA is rare and only
marginally recognizable. We found two ophthalmic arteries of this type (Fig.
7A,
7B). According to Ogawa et al.
[7], two primitive ophthalmic
arteries exist during the early embryonal stage. Normally, the ventral
ophthalmic artery persists and the dorsal ophthalmic artery regresses, but in
some instances, the dorsal ophthalmic artery persists and the ventral
ophthalmic artery regresses. This anomalous ophthalmic artery enters the orbit
via the superior orbital fissure instead of the optic canal.
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Fig. 7A —65-year-old man with left persistent dorsal ophthalmic
artery. Inferosuperior (A) and slightly right anterior oblique
(B) projections show left ophthalmic artery (arrows) arising
from cavernous internal carotid artery.
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Fig. 7B —65-year-old man with left persistent dorsal ophthalmic
artery. Inferosuperior (A) and slightly right anterior oblique
(B) projections show left ophthalmic artery (arrows) arising
from cavernous internal carotid artery.
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Carotid–Anterior Cerebral Artery Anastomosis
In rare instances, the anterior cerebral artery arises from the ICA at the
level of the origin of the ophthalmic artery
[8]. This anomalous artery is
also referred to as an "infraoptic course of the anterior cerebral
artery." We found two anterior cerebral arteries of this kind (Fig.
8A,
8B). The embryogenesis of this
anomaly is unclear. For some reason, this variation generally occurs on the
right side. Anterior communicating artery anomalies such as aneurysms are
frequently associated with this anomalous anterior cerebral artery.
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Fig. 8A. —9-month-old male infant with right carotid–anterior
cerebral artery anastomosis. Anteroposterior (A) and lateral (B)
projections of partial maximum-intensity-projection image of right hemisphere
show that right anterior cerebral artery (arrows) arises from
internal carotid artery at level of origin of ophthalmic artery.
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Fig. 8B. —9-month-old male infant with right carotid–anterior
cerebral artery anastomosis. Anteroposterior (A) and lateral (B)
projections of partial maximum-intensity-projection image of right hemisphere
show that right anterior cerebral artery (arrows) arises from
internal carotid artery at level of origin of ophthalmic artery.
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Fetal Origin of the Posterior Cerebral Artery
The posterior cerebral artery frequently arises directly from the
supraclinoid ICA without communication to the basilar artery (Fig.
5A,
5B,
5C). This variation is called
the "fetal origin of the posterior cerebral artery," and its
reported incidence is 10% on the right, 10% on the left, and 8% bilaterally
[1].
Hyperplastic Anterior Choroidal Artery
The temporooccipital branches of the posterior cerebral artery may arise
from the anterior choroidal artery. In such cases, the anterior choroidal
artery is hyperplastic. We found only one anterior choroidal artery of this
type (Fig. 9A,
9B). However, the anterior
choroidal artery is usually so small that visualization and recognition of its
anomalies may be difficult on MR angiograms. The prevalence of the
hyperplastic anterior choroidal artery is reported to be 1.1–2.3% in
angiographic series [9].
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Fig. 9A. —58-year-old man with left hyperplastic anterior choroidal
artery. Curved arrows indicate posterior communicating artery and branch of
posterior cerebral artery. Inferosuperior projection shows anomalous artery
(arrows) that arises from left supraclinoid internal carotid artery
and supplies calcarine artery.
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Fig. 9B. —58-year-old man with left hyperplastic anterior choroidal
artery. Curved arrows indicate posterior communicating artery and branch of
posterior cerebral artery. Lateral projection of left carotid and basilar
arteries shows hyperplastic anterior choroidal artery (arrows).
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Duplicated Middle Cerebral Artery
The middle cerebral artery is sometimes duplicated. We found 14 duplicated
middle cerebral arteries (Fig.
10A,
10B). Their MR angiographic
incidence is reported to be 2.1%
[10]. The duplicated middle
cerebral artery is the temporal branch of the middle cerebral artery, which
arises directly from the terminal portion of the ICA. In contrast, the frontal
branch of the middle cerebral artery, arising from the anterior cerebral
artery, is regarded as an accessory middle cerebral artery.
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Fig. 10A. —54-year-old woman with duplicated left middle cerebral
artery. inferosuperior (A) and slightly right anterior oblique
(B) projections show left temporal branch of left middle cerebral
artery (large arrow) arising directly from terminal portion of left
internal carotid artery. Note fenestration of proximal basilar artery
(small arrow, A).
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Fig. 10B. —54-year-old woman with duplicated left middle cerebral
artery. inferosuperior (A) and slightly right anterior oblique
(B) projections show left temporal branch of left middle cerebral
artery (large arrow) arising directly from terminal portion of left
internal carotid artery. Note fenestration of proximal basilar artery
(small arrow, A).
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Persistent Primitive Olfactory Artery
The proximal anterior cerebral artery in rare instances takes an extremely
long anteroinferomedial course along the ipsilateral olfactory tract and makes
a hairpin turn posterosuperiorly. We found one such case (Fig.
11A,
11B). This anomalous anterior
cerebral artery is regarded as a persistent primitive olfactory artery.
Normally, the primitive olfactory artery regresses and remains as the
recurrent artery of Heubner. When the anterior cerebral artery arises
abnormally from the distal portion of the primitive olfactory artery, the
proximal portion of the artery continues along the olfactory tract.
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Fig. 11A. —18-year-old man with persistent primitive olfactory artery.
slightly right anterior oblique (A) and lateral (B) projections
of partial maximum-intensity-projection image of right hemisphere show
proximal right anterior cerebral artery (arrows) with extremely long
anteroinferomedial course and posterosuperior hairpin turn.
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Fig. 11B. —18-year-old man with persistent primitive olfactory artery.
slightly right anterior oblique (A) and lateral (B) projections
of partial maximum-intensity-projection image of right hemisphere show
proximal right anterior cerebral artery (arrows) with extremely long
anteroinferomedial course and posterosuperior hairpin turn.
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References
- Caldemeyer KS, Carrico JB, Mathews VP. The radiology and embryology
of anomalous arteries of the head and neck. AJR1998; 170:197
–203[Free Full Text]
- Luh GY, Dean BL, Tomsick TA, Wallace RC. The persistent fetal
carotid–vertebrobasilar anastomoses. AJR1999; 172:1427
–1432[Free Full Text]
- Hahnel S, Hartmann M, Jansen O, Sartor K. Persistent hypoglossal
artery: MRI, MRA and digital subtraction angiometry.
Neuroradiology 2001;43
: 767–769[Medline]
- Saltzman G. Patent primitive trigeminal artery studied by cerebral
angiography. Acta Radiol1959; 51:329
–336[Medline]
- Meaney JF, Sallomi DF, Miles JB. Transhypophyseal primitive
trigeminal artery: demonstration with MRA. J Comput Assist
Tomogr 1994;18:991
–994[Medline]
- Uchino A, Kato A, Takase Y, Kudo S. Persistent trigeminal artery
variants detected by MR angiography. Eur Radiol2000; 10:1801
–1804[Medline]
- Ogawa T, Miyauchi T, Kato T, Tamakawa Y. Internal carotid origin of
double ophthalmic arteries. Neuroradiology1990; 32:508
–510[Medline]
- Given CA II, Morris PP. Recognition and importance of an infraoptic
anterior cerebral artery: case report. AJNR2002; 23:452
–454[Abstract/Free Full Text]
- Takahashi S, Suga T, Kawata Y, Sakamoto K. Anterior choroidal
artery: angiographic analysis of variations and anomalies.
AJNR 1990;11:719
–729[Abstract]
- Uchino A, Kato A, Takase Y, Kudo S. Middle cerebral artery
variations detected by magnetic resonance angiography. Eur
Radiol 2000;10:560
–563[Medline]
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Introduction
MR Angiography Technique
