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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3752_Библиотеки_им_академика_М_И_Перельмана
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common femoral artery. The external iliac artery gives off
other small branches, such as small muscular branches and
the cremasteric artery, which runs in the spermatic cord.
The common femoral artery, which begins below the
inguinal ligament, is a short vessel which usually has a length
of 4 cm and gives off the superfi cial femoral artery and deep
femoral artery at approximately the level of the lesser trochanter of the femur. Most commonly, there is also a slightly
more lateral branch given off at the same level, which is the
circumfl ex femoral artery. The term “superfi cial femoral
artery” is still used commonly by physicians, whereas anatomists favor the name “femoral artery”. In regard to femoral
venous anatomy, there has been some shift in nomenclature
among physicians in order to avoid confusion when thrombi
of the vein are reported. Drop of the descriptor “superfi cial”
from the femoral vein can avoid confusion as the vein is part
of the deep venous system.
The femoral artery courses anteromedially in the thigh. In
the middle third of the thigh, the femoral artery enters the
adductor canal or eponymously, Hunter’s canal. This is a
frequent site of atherosclerotic disease. At the junction of the
middle and lower third of the thigh, the femoral artery exits
the adductor canal and changes name to the popliteal artery.
The popliteal artery is a common site of several unique
diseases including cystic adventitial disease and popliteal
artery entrapment syndrome. Knee dislocation injuries may
damage the popliteal artery. At approximately the level of
the knee, the popliteal artery gives off medial and lateral
geniculate branches. These branches may serve as important
collaterals for reconstitution of the popliteal artery from the
ab
Fig. 17.8 CT angiography is useful in demonstrating the internal
mammary arteries in patients in whom aortocoronary bypass is planned.
The course of the left internal mammary artery ( white arrows ) is
demonstrated on the curved plane reformatted view ( a ) and also on the
volume rendered view ( b ). In evaluating the subclavian artery and its
branches, injection of contrast should be made via the contralateral
extremity in order to ensure that streaking from dense venous contrast
does not occur
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profunda using geniculate collateral pathways in the setting
of femoral artery occlusion.
The popliteal artery continues behind the knee and gives
off the anterior tibial artery. In most patients, the anterior
tibial artery gives off the dorsalis pedis artery, which courses
along the dorsal aspect of the foot. The other main branch of
the popliteal artery is the tibioperoneal trunk. This divides
into the posterior tibial artery and peroneal artery. Variations
in this conventional anatomy occur approximately 10 % of
the time, with the most common variant being a high takeoff
of the anterior tibial at or above the level of the knee joint. A
true trifurcation followed by a hypoplastic or absent posterior
tibial artery are the next most common variants, while high
origin of the posterior tibial artery is rare. The peroneal
artery runs in the deep compartment of the lower portion of
the lower extremity and usually terminates above the ankle
in collateral branches to the posterior tibial and dorsalis
pedis arteries. The posterior tibial artery runs posterior to the
medial maleolus of the ankle and frequently can be palpated
at this point. The plantar arch is an arcade of vessels which
may be primarily served by either the dorsalis pedis artery or
the posterior tibial artery. The main vessel supplying the
plantar arch should be noted and included in CT angiography
reports.
CT has an advantage in comparison to conventional
angiography in demonstrating 3-D vascular anatomy and
variants in the context of muscular and osseous anatomy.
Variants which contribute to clinically signifi cant arterial
disease are rare and some variants may not cause signifi cant
vascular pathology. Rarely, for example, the external iliac
artery may be absent, and the common femoral artery arises
from the internal iliac artery (Fig. 17.9 ). This common
variant would not be expected to cause clinically signifi cant
manifestations of arterial disease [ 26 ].
Rarely, the main lower extremity artery may arise from
the internal iliac artery, and courses posteriorly to the ischial
tuberosity. This variant is known as a persistent sciatic artery.
The anomalous course of the artery along the ischial tuberosity can result in premature atherosclerotic disease (Fig. 17.10 )
and also in formation of aneurysms (Fig. 17.11 ). Typically,
occlusion or aneurysm formation occurs where the artery
courses behind the ischial tuberosity. Vascular pathology is
thought to occur due to repetitive underlying trauma due to
impact of the ischial tuberosity onto the artery [ 27 ].
For variants where abnormal muscular anatomy may contribute to pathology, the arterial tree may be better imaged
with MRI. In general imaging of the muscular structures of the
extremities, MRI has advantages relative to CT angiography,
ab
Fig. 17.9 ( a , b ) An unusual variant is shown in which there is
congenital absence of the external iliac artery. The internal iliac artery
( white arrow ) in this case takes a course posteriorly to give off the
anterior and posterior divisions, before continuing anteriorly to give off
the common femoral artery
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including better resolution of soft tissue structures such as
musculature and joints. Non-contrast MR angiography techniques also permit imaging with the extremity in different
positions, without the use of ionizing radiation.
Abnormalities and Diseases of the Peripheral
Arteries
Atherosclerotic Disease
Atherosclerosis is by far the most common disease of the
peripheral arterial tree [ 28 ]. At times, patients may present
with concomitant cerebrovascular disease and coronary
atherosclerotic disease, although some patients with atherosclerotic disease may present with peripheral ischemia
as their initial manifestation. The presence of peripheral
arterial disease signifi cantly contributes to worsened
morbidity and mortality, likely because it is a marker of
systemic atherosclerotic disease burden. Patients with
peripheral arterial disease have a four to fi vefold increase
in risk of myocardial infarction or stroke [ 29 , 30 ].
Peripheral arterial disease is a common condition, occurring in 10–25 % of patients over the age of 55. The incidence
increases with age at a rate of 0.3 % per year in men aged
40–55 and at a rate of 1 % per year in men over the age of 75.
Up to 70–80 % of affected individuals are symptomatic,
although only a minority of patients will eventually require
revascularization. Twenty fi ve percent of patients with
peripheral arterial disease will require some medical or surgical treatment. Because of their increased morbidity and
mortality, all patients with peripheral arterial disease should
ab
Fig. 17.10 ( a , b ) Images of the right lower extremity are shown in a
patient with bilateral persistent sciatic arteries. Note that the persistent
sciatic artery ( white arrows ) is occluded at the level of the ischial
tuberosity ( white arrowhead ). There is also a second long segment of
probable occlusion of the persistent sciatic artery in the thigh. There is,
however, reconstitution of the vessel via large profunda collaterals after
both occlusions
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have aggressive control of their atherosclerotic risk factors;
however, only about 25 % of patients are actually treated
[ 31 , 32 ].
Peripheral CT angiography can demonstrate atherosclerosis at a very early stage in the disease process. Low attenuation plaques, likely related to an early phase of plaque
evolution, may be seen [ 33 ]. Plaques may be calcifi ed or
non-calcifi ed, and may not cause stenosis until very late in
the disease course (Fig. 17.12 ). Densely calcifi ed atheroscle-
rotic plaques in the peripheral arterial tree may somewhat
degrade CT angiography image quality, although this is less
of a concern when imaging the extremities compared to the
coronary arteries due to the larger caliber of vessels and the
lower potential for motion and other artifacts.
Atherosclerotic plaques may be present throughout the
vascular tree. Typically aortic atherosclerotic disease begins
in the infrarenal aorta and becomes more severe closer to the
aortic bifurcation. A rarer variant in some patients with atherosclerotic disease is the development of arborifi ed, endoaortic calcifi ed plaques, which predominantly protrude into
the lumen, and are usually most pronounced in the juxtamesenteric and juxtarenal aorta. This variant has been termed a
“coral reef” aorta (Fig. 17.13 ) [ 34 ]. Recognition of this vari-
ant of atherosclerotic disease is important since patients with
endoaortic calcifi c proliferation are at higher risk for postcatheterization embolic phenomenon. It has been suggested
that patients with a ‘coral reef aorta’ should not undergo
endovascular interventions which necessitate crossing of the
juxtamesenteric aorta should be avoided in patients with a
“coral reef aorta” [ 35 , 36 ].
In the peripheral tree, atherosclerotic disease may be multifocal and usually consists of mixed attenuation plaques. CT
angiography is useful in demonstrating stenoses of 50 % or
greater, which may contribute to patient symptoms. Specifi c
features of each plaque that should be described include the
location of the lesion, degree of stenosis, and length of the
plaque. When CT angiography is used for plaque characterization, descriptors for plaque attenuation may be added, with
reporting of plaques as calcifi ed, non- calcifi ed, or mixed
plaque. Further evaluation of lesions with stenoses is commonly pursued with catheterization for measurement of pressure gradients. Specifi c criteria for intervention have also been
delineated, based on the degree of patient symptoms [ 37 ].
Atherosclerotic disease may cause a number of symptoms
depending on the site of involvement. Several syndromes
have been characterized based on the distribution of atherosclerotic disease. For example, subclavian steal syndrome
results from proximal stenosis in the subclavian artery
(Fig. 17.14 ). As a result of stenosis, the distal subclavian
artery may receive collateral fl ow from the vertebral arteries.
Reversal of fl ow through the ipsilateral vertebral artery commonly ensues. Because of the relatively rich brain collateral
a b c
Fig. 17.11 (Same patient as in Fig. 16.9 ). ( a – c ) Images of the left
lower extremity are shown in a patient with bilateral persistent sciatic
arteries ( white arrows ). Note the presence of a large aneurysm extending
just above the ischial tuberosity ( white arrowhead ). Note also that the
vessel is less well opacifi ed distal to the aneurysm due to stagnant fl o w
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system, only a small percentage of patients with this reversal
of fl ow will present with symptoms related to vertebrobasilar
insuffi ciency. These symptoms are commonly worsened during exercise of the upper extremity, which results in increased
fl ow to the extremity and worsened steal from the cerebrovascular circulation. Leriche syndrome is a constellation of
symptoms which results from aortic and bilateral iliac artery
disease, including gluteal and lower extremity claudication,
penile impotence, and lower extremity atrophy.
Similar to assessment of aortic aneurysms, duplex ultrasound is the most cost effective strategy for surveillance of
popliteal or femoral aneurysms. CT angiography, however, is
also favored over other imaging modalities for accurate sizing of the proximal and distal arterial landing zones prior to
endovascular peripheral aneurysm repair. Evaluation of
thrombus and patency of runoff vessels is also easily accomplished by preoperative CT angiography.
Grafts and Stents in the Arterial Tree
In addition to being a non-invasive modality with excellent
spatial resolution, CT angiography has several other
advantages in the evaluation of the treated vascular system. In comparison to MRI and MR angiography, CT angiography is advantageous for visualization of stents. On
MRI, stents may be visualized only as artifacts and the
internal lumen may be non-visualized due to susceptibility
effects. Even when the internal lumen is visualized, the
stented segment generally is incompletely evaluated by
MR angiography. Other metallic structures including surgical clips may also induce artifacts on MRI, including
signal void and failure of fat saturation, whereas artifacts
from surgical devices are generally less signifi cant on
CT. Dual source or dual energy CT further potentiates
visualization of high attenuation, metallic structures with
ab
Fig. 17.12 ( a , b ) Multifocal atherosclerosis is demonstrated on these volume rendered views of the lower extremities. The femur, tibia, and fi bula
have been subtracted from the fi eld of view in order to better demonstrate the arterial anatomy
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less signifi cant obscuration of adjacent anatomy due to
minimizing of streaking.
Stents in peripheral arterial structures are typically
well- seen using thick MIP images (Fig. 17.15 ). This
allows visualization of stent struts and exclusion of strut
fractures. Stents are easily depicted as high attenuation
structures. Stents are frequently well-evaluated on postcontrast and non-contrast images. In the short axis view,
stent struts are frequently seen as regularly spaced, hyperattenuating foci at the rim of the artery, commonly in a
hexagonal array (Fig. 17.16 ). Because of the relatively
high attenuation of metallic stents, and because of the
phenomenon of “blooming” on CT, a very bright stent
may appear to be outside the confines of the wall of a vessel. The limitations of stent depiction on coronary CT are
less significant in evaluation of the peripheral arterial tree
due to the larger internal diameter of stents commonly
employed in the peripheral vessels and also due to the
absence of motion and other artifacts that can limit the
evaluation of stented coronary arteries. In-stent restenosis
in the peripheral vasculature is usually easily evaluated
using CT angiography.
a
c
b
Fig. 17.13 Views from a CT angiogram of the abdomen are shown
with transverse ( a , b ) and sagittal ( c ) images shown. A “coral reef”
aorta is present with dense endoaortic calcifi c proliferation. Densely
calcifi ed, endoluminal, arborifi ed plaques are present ( white arrows ) in
the juxtamesenteric aorta
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ab
Fig. 17.14 Images from a CT
angiogram are shown in a patient
with known coronary artery
disease and concomitant
symptoms of subclavian steal.
The oblique sagittal ( a ) and
volume rendered (b) views show
a focal, shelf-like area of
narrowing near the origin of the
left subclavian artery ( arrow , ( a )
and ( b )). In this case,
identifi cation of this stenosis was
useful as an explanation of the
patient’s symptoms. Preoperative
identifi cation of subclavian
stenosis is also important in
patients in whom aortocoronary
bypass is planned, as this
condition may impede optimal
fl ow through the internal
mammary artery
ab
Fig. 17.15 Stents are well-depicted on CT angiography. In this case, the stent is seen on the volume rendered view ( yellow arrow , a ) and also on
the orthogonal, curved plane reformatted views ( white arrows , b )
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Graft material is also well evaluated on CT. Bypass grafts
are commonly recognized as long, smooth, branchless tubes
connected to the native vasculature on 3-D colored, lit projections (Fig. 17.17 ). On axial views, the excluded, unopaci-
fi ed, native vessels are frequently visible. The connections
between graft material and native vessel lumen may be
enlarged and irregular, as a result of the patch angioplasty
frequently performed at anastomosis sites. Grafts commonly
are comprised of either interposed veins, Dacron, or
expanded polytetrafl uoroethylene (PTFE). In some cases,
where increased torsional effects are anticipated and may
compromise grafts, reinforced graft material is commonly
abc
Fig. 17.16 A stent is the left common iliac artery is shown. The stent is present on the volume rendered view ( a ) and also on the curved plane
reformatted views ( b ). Note that, in the short axis of the vessel ( c ), the stent is seen as a hexagonal array of hyperattenuating struts
abd
c
Fig. 17.17 Bilateral, aortofemoral bypass grafts are present ( white
arrows ) and are seen as unusually smooth appearing structures connect-
ing portions of the vascular tree. The occluded, native vessels are visualized on the transverse view ( b , white arrowheads ), but are not
visualized on the volume rendered view ( a ) since the native arteries are
not opacifi ed. Enlargement and irregularity may be present at anastomotic sites as shown in this transverse CT image taken at the level of the
patient’s anastomoses ( white , open arrowheads , c ). Note that the patient
also has aortic and celiac stents ( black arrows , d )
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employed. The rings of such grafts are typically visible as
corrugated on CT angiography (Fig. 17.18 ).
Trauma
CT angiography as a modality has multiple features that
make it ideal for imaging of the arterial tree in the setting of
trauma. First, intimal fl aps and abnormalities of the wall of
the artery are better depicted by CT angiography compared
to MR angiography, and may be better seen on CT than on
ultrasound, especially within the bony pelvis where bowel
gas and patient body habitus may limit duplex evaluation.
CT angiography is also useful in demonstrating the entire
arterial tree in a less time-intensive fashion than ultrasound
or MR angiography. Concomitant post-traumatic deformities
to the muscles and bones may also be simultaneously demonstrated on CT (Fig. 17.19 ).
CT signs of arterial injury include contrast extravasation,
vessel non-opacifi cation, abrupt vessel occlusion, focal vessel narrowing/spasm, pseudoaneurysm, intimal fl ap, or arteriovenous fi stula. Traumatic injury to vessels may ensue
after blunt or penetrating trauma and may be seen in association with fractures which displace vessels [ 16 ].
Fibromuscular Dysplasia
Although fi bromuscular dysplasia is a common cause of stenosis in the renal or carotid arteries, it is less commonly
encountered elsewhere in the peripheral arterial tree. When
involving the peripheral arteries, fi bromuscular dysplasia
most commonly occurs in the external iliac artery, which is
the third most common site of fi bromuscular dysplasia in the
body. As in other parts of the body, the classifi cation system
for fi bromuscular dysplasia is based on the layer of the artery
involved, with medial fi broplasia being the most common
form. The most typical appearance of fi bromuscular dysplasia is apparent beading of the vessel and is due to several,
closely approximated weblike areas of narrowing with intervening outpouchings of the vessel from post- stenotic dilatation (Fig. 17.20 ) [ 38 ]. Other forms of fi bromuscular dysplasia
may have a variety of appearances [ 39 ]. Conventional angi-
ography may have an advantage in demonstrating this entity
compared with CT, due to the inherently higher spatial resolution of conventional angiographic images.
Other Diseases of the Systemic Arteries
Cystic adventitial disease is a rare entity, which may affect
any artery adjacent to a joint and presents as a smooth narrowing without atherosclerotic disease. The narrowing is
accompanied by cystic structures along the course of the
artery. The most common artery affected is the popliteal.
MRI is the preferred modality for depicting the cysts which
occur along the vessel, although low attenuation cysts are
commonly observed on CT [ 40 , 41 ].
Popliteal artery entrapment syndrome can occur due to a
number of abnormalities in the relationship between the
popliteal artery and the muscles of the popliteal space. The
most common abnormal muscle in this case is the medial
ab
Fig. 17.18 A bifemoral bypass graft ( white arrows ) is evident with a typical, corrugated appearance, which is well seen on the volume rendered
view ( a ) and the curved planar reformatted view ( b )
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a
b
Fig. 17.19 CT angiography is useful in the setting of trauma. A
surface-rendered view ( a ) shows the deformity in the outer contour of
the extremity. CT angiography simultaneously demonstrates osseous
structures, demonstrating a dislocation at the knee ( b , c ). The osseous
structures may be subtracted, however, in order to better demonstrate
the underlying arterial anatomy ( d ). In this case, resultant occlusion of
the popliteal artery is also present ( white arrow , d )
ab
Fig. 17.20 Fibromuscular dysplasia is shown in the external iliac
artery, which is the third most common site for this entity, following the
internal carotid and renal arteries. The classic, beaded appearance of the
external iliac artery ( arrow ) is demonstrated on a reformatted view from
the patient’s abdominal CT ( a ), but is more clearly demonstrated on the
conventional angiography ( b ), due to the higher spatial resolution
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